There looks to be a good chance of a TD becoming a TC as it passes over Fiji's two main islands from the NW this weekend. Very active convection and looking more organised this morning. Models then have it doing a U-turn and backtracking a few days later…
Tropical Disturbance Summary For area Equator to 25S, 160E to 120W
ISSUED FROM RSMC NADI Apr 150916 UTC.
TROPICAL DISTURBANCE 17F CENTRE [1005HPA] WAS LOCATED NEAR 14.05S
176.0E AT 150600UTC. TD17F SLOW MOVING. POSITION POOR. ORGANISATION
REMAINS POOR. CONVECTION CONTINUE TO FLUCTUATE OVER SUPPOSE LLCC.
SYSTEM LIES UNDER AN UPPER ANTICYCLONIC CIRCULATION IN A LOW SHEARED
ENVIRONMENT. SST IS AROUND 29 DEGREES CELSIUS. GLOBAL MODELS HAVE
PICKED UP THE SYSTEM AND MOVE IT WESTWARD THAN SOUTHWARDS WITH
GRADUAL INTENSIFICATION.
POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE IN THE
NEXT 24 TO 48 HOURS IS MODERATE.
ABPW10 PGTW 151330
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND
/SOUTH PACIFIC OCEANS REISSUED/151330Z-160600ZAPR2016//
RMKS
...
2. SOUTH PACIFIC AREA (WEST COAST OF SOUTH AMERICA TO 135 EAST):
A. TROPICAL CYCLONE SUMMARY: NONE.
B. TROPICAL DISTURBANCE SUMMARY:
(1) AN AREA OF CONVECTION HAS PERSISTED NEAR 14.5S 175.0E,
APPROXIMATELY 240 NM NORTHWEST OF NADI, FIJI. ANIMATED ENHANCED
INFRARED SATELLITE IMAGERY DEPICTS A BROAD LOW-LEVEL CIRCULATION
CENTER WITH FRAGMENTED BANDING. A 151011Z METOP-B 89GHZ IMAGE SHOWS
FRAGMENTED, CURVED BANDING WRAPPING BROADLY INTO AN ILL-DEFINED
CENTER. UPPER-LEVEL ANALYSIS INDICATES A MARGINALLY-FAVORABLE
ENVIRONMENT WITH MODERATE VERTICAL WIND SHEAR OFFSET BY ENHANCED
POLEWARD OUTFLOW. DYNAMIC MODEL GUIDANCE INDICATES A GENERALLY
SOUTHEASTWARD TRACK TOWARD FIJI WITH GRADUAL INTENSIFICATION.
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004 MB. THE
POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS MEDIUM.
…
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Update: JTWC issued a TC Formation Alert for the TD currently just west of Fiji after passing through the main islands over the weekend. RSMC Nadi have only had its chances as low since last night…
WTPS21 PGTW 180400
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
150 NM EITHER SIDE OF A LINE FROM 16.7S 176.9W TO 11.6S 175.5W
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 27 TO 32 KNOTS. METSAT
IMAGERY AT 180000Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 16.1S 176.9W. THE SYSTEM IS MOVING EAST-NORTHEASTWARD AT 07
KNOTS.
2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 17.4S
179.5E, IS NOW LOCATED NEAR 16.1S 176.9W, APPROXIMATELY 375 NM WEST-
SOUTHWEST OF PAGO PAGO, AMERICAN SAMOA. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY DEPICTS A CONSOLIDATING LOW LEVEL CIRCULATION
CENTER (LLCC) WITH LIMITED CENTRAL CONVECTION. A 162125Z AMSU-B
MICROWAVE IMAGE SHOWED A WELL DEFINED LLCC WITH THE ASSOCIATED
CONVECTION SHEARED JUST SOUTHEAST. A 162037Z ASCAT PASS FURTHER
ILLUSTRATED THE LLCC WITH 30 KNOT WINDS WRAPPING AROUND THE
SYMMETRIC LLCC AND ISOLATED 35 KNOT WINDS LOCATED WITHIN THE
CONVECTION TO THE SOUTHEAST. ENVIRONMENTAL ANALYSIS INDICATES A
MARGINAL BUT IMPROVING ENVIRONMENT WITH 15 TO 20 KNOT VERTICAL WIND
SHEAR AND STRONG POLEWARD DIVERGENCE. DYNAMIC MODEL GUIDANCE SHOWS
THE DISTURBANCE TRACKING NORTHEASTWARD INTO A LOW VWS ENVIRONMENT
WITH WEAK DEVELOPMENT. SEA SURFACE TEMPERATURES NEAR 30 CELSIUS ARE
CONDUCIVE FOR FURTHER DEVELOPMENT. MAXIMUM SUSTAINED SURFACE WINDS
ARE ESTIMATED AT 27 TO 32 KNOTS. MINIMUM SEA LEVEL PRESSURE IS
ESTIMATED TO BE NEAR 1000 MB. BASED ON THE CURRENT STRUCTURE AND
IMPROVING ENVIRONMENT, THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
190400Z.//
Tropical Disturbance Summary For area Equator to 25S, 160E to 120W
ISSUED FROM RSMC NADI Apr 180842 UTC.
TROPICAL DEPRESSION 17F CENTRE [1000HPA] WAS LOCATED NEAR 15.6S
176.0W AT 180600UTC. TD17F SLOW MOVING. POSITION POOR. SST AROUND 28
DEGREES CELSIUS.
ORGANISATION POOR. CONVECTION REMAINS PERSISTANT. CYCLONIC
CIRCULATION EXTENDS UPTO 700HPA. SYSTEM LIES UNDER AN UPPER DIFFLUENT
REGION IN A LOW TO MODERATE SHEARED ENVIRONMENT.
SOME GLOBAL MODELS HAVE PICKED UP THE SYSTEM AND MOVE IT
NORTHEASTWARDS THAN TOWARDS THE WEST-NORTHWEST WITH SLIGHT
INTENSIFICATION.
POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE IN THE
NEXT 24 TO 48 HOURS IS LOW.
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The TD, currently between Fiji and Samoa, began its turn back towards northern Fiji around midnight last night, allowing it to become a little more organised. RSMC have only increased its 24-48 hr chances to 'low-to-moderate'. However, main convection previously offset to the SE of its more symmetric LLCC looks more central this morning…
Tropical Disturbance Summary For area Equator to 25S, 160E to 120W
ISSUED FROM RSMC NADI Apr 182321 UTC.
TROPICAL DEPRESSION 17F CENTRE [1000HPA] WAS LOCATED NEAR 15.2S
175.3W AT 181800UTC. TD17F SLOW MOVING. POSITION POOR. SST AROUND 28
DEGREES CELSIUS.
ORGANISATION POOR. CONVECTION REMAINS PERSISTANT. CYCLONIC
CIRCULATION EXTENDS UPTO 700HPA. SYSTEM LIES UNDER AN UPPER DIFFLUENT
REGION IN A LOW TO MODERATE SHEARED ENVIRONMENT.
SOME GLOBAL MODELS HAVE PICKED UP THE SYSTEM AND MOVE IT
NORTHEASTWARDS THAN TOWARDS THE WEST-NORTHWEST WITH SLIGHT
INTENSIFICATION.
POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE IN THE
NEXT 24 TO 48 HOURS IS LOW TO MODERATE.
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JTWC maintained their TC Formation Alert this afternoon, with a high chance of formation now either tonight or tomorrow (RSMC Nadi not quite so optimistic)…
WTPS21 PGTW 190400
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
140 NM EITHER SIDE OF A LINE FROM 14.6S 175.8W TO 11.4S 177.7W
WITHIN THE NEXT 06 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 25 TO 30 KNOTS. METSAT
IMAGERY AT 190000Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 14.3S 175.9W. THE SYSTEM IS MOVING NORTH-NORTHWESTWARD AT 06
KNOTS.
2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 16.1S
176.9E, IS NOW LOCATED NEAR 14.3S 175.9W, APPROXIMATELY 305 NM WEST
OF PAGO PAGO, AMERICAN SAMOA. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS A CONSOLIDATING LOW LEVEL CIRCULATION CENTER (LLCC)
WITH LIMITED CENTRAL CONVECTION. A 190251Z SSMI MICROWAVE IMAGE
SHOWS A WELL DEFINED LLCC WITH ASSOCIATED, LIMITED CONVECTION
WRAPPING ALONG THE SOUTHERN AND WESTERN PERIPHERIES. A 181800Z
PARTIAL WINDSAT PASS FURTHER SHOWS 20 TO 25 KNOT WINDS ALONG THE
WESTERN PERIPHERY OF THE LLCC. ENVIRONMENTAL ANALYSIS INDICATES A
MARGINAL, BUT IMPROVING, ENVIRONMENT WITH 10 TO 15 KNOT VERTICAL
WIND SHEAR (VWS) AND AN EASTWARD OUTFLOW CHANNEL ON THE POLEWARD
SIDE. DYNAMIC MODEL GUIDANCE SHOWS THE DISTURBANCE TRACKING
NORTHWESTWARD INTO A MARGINALLY BETTER VWS ENVIRONMENT WITH
CORRESPONDING SLOW CONSOLIDATION. SEA SURFACE TEMPERATURES NEAR 30
CELSIUS ARE CONDUCIVE FOR FURTHER DEVELOPMENT. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1002 MB. BASED ON THE CURRENT
STRUCTURE AND IMPROVING ENVIRONMENT, THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 6-24
HOURS REMAINS HIGH. THIS SUPERSEDES REF A.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
200400Z.//
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Good flaring overnight. RSMC Nadi issued its first Advisory earlier this morning and increased this low's TC chances to 'moderate' for the next 24-48 hrs…
TROPICAL DISTURBANCE ADVISORY NUMBER A1 ISSUED FROM RSMC NADI
Apr 191349 UTC.
TROPICAL DEPRESSION TD17F CENTRE 1002HPA WAS LOCATED NEAR 13.5S
176.7W AT 191200UTC. POSITION FAIR BASED ON GOES HR IMAGERY AND
PERIPHERAL SURFACE REPORTS. TD17F MOVING NORTH-NORTHWEST AT ABOUT 05
KNOTS. MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT
ABOUT 25 KNOTS.
DEEP CONVECTION HAS INCREASED IN THE PAST 6 HOURS. ORGANISATION
REMAINS POOR. CYCLONIC CIRCULATION EXTENDS UPTO 500HPA. SYSTEM LIES
SOUTH OF AN UPPER RIDGE IN A LOW TO MODERATE SHEARED ENVIRONMENT. SST
AROUND 30 DEGREE CELCIUS. DVORAK ANALYSIS BASED ON 0.25 WRAP YEILDS
DT=1.5, MET AND PT AGREE. FT BASED ON DT. THUS, YIELDING
T1.5/1.5/S0.0/24HRS.
GLOBAL MODELS HAVE PICKED UP THE SYSTEM AND MOVE IT NORTHWEST THEN
EAST WITH GRADUAL INTENSIFICATION.
POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE IN THE
NEXT 24 TO 48 HOURS IS MODERATE.
FORECASTS :
AT 12 HRS VALID AT 200000 UTC 13.0S 177.6W MOV WNW AT 05KT WITH 30 KT
CLOSE TO CENTRE
AT 24 HRS VALID AT 201200 UTC 12.7S 177.9W MOV NW AT 04KT WITH 30 KT
CLOSE TO CENTRE.
OUTLOOK:
AT 36 HRS VALID AT 210000 UTC 12.6S 178.0W MOV NNW AT 03KT WITH 35 KT
CLOSE TO CENTRE
AT 48 HRS VALID AT 211200 UTC 12.3S 177.5W MOV NE AT 03KT WITH 40 KT
CLOSE TO CENTRE.
THE NEXT TOPICAL DISTURBANCE ADVISORY ON TD17F WILL BE ISSUED AROUND
192000UTC.
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JTWC referring to this low as a TC this afternoon, even though they currently only 30 kt 1-minute winds. Earlier this morning RSMC Nadi upgraded its TC chances in the next 24-48 hrs to 'moderate-to-high'…
WTPS31 PGTW 200300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE WARNING//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI//180351ZAPR2016//
AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT.//
RMKS/
1. TROPICAL CYCLONE 20P (TWENTY) WARNING NR 001
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
200000Z --- NEAR 13.1S 178.2W
MOVEMENT PAST SIX HOURS - 285 DEGREES AT 10 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
…
REMARKS:
200300Z POSITION NEAR 13.0S 178.4W. TROPICAL CYCLONE 20P (TWENTY),
LOCATED APPROXIMATELY 316 NM WEST OF AVATA SAMOA, HAS TRACKED WEST-
NORTHWESTWARD AT 10 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY DEPICTS DEEP CONVECTION
CONSOLIDATING AROUND A LOW-LEVEL CIRCULATION CENTER (LLCC) WHICH IS
CURRENTLY COVERED BY A CENTRAL DENSE OVERCAST (CDO). A 192043Z AMSU-
B 89GHZ IMAGE SHOWS THAT THE DEEP CONVECTION IS RESTRICTED TO THE
NORTHEASTERN QUADRANT OF THE SYSTEM WITH SOME MODERATE CONVECTIVE
BANDS BEGINNING TO FORM TO THE SOUTHEAST OF THE LLCC. THE
CORRESPONDING 192043Z ASCAT-B PASS INDICATES BROAD AREAS OF 20-25
KNOT WINDS BOTH NORTH AND SOUTH OF THE LLCC, WHILE AN EARLIER
191747Z WINDSAT PASS SHOWED A FEW 30-35 KNOT UNFLAGGED PLOTS. THE
INITIAL INTENSITY IS ASSESSED AT 30 KNOTS BASED ON DVORAK ESTIMATES
BETWEEN 30 AND 35 KNOTS FROM KNES AND PGTW RESPECTIVELY. UPPER-LEVEL
ANALYSIS INDICATES TC 20P IS CURRENTLY IN A MARGINALLY FAVORABLE
ENVIRONMENT WITH LOW-MODERATE (10 TO 20 KNOTS) VERTICAL WIND SHEAR
(VWS), MODERATE POLEWARD OUTFLOW AND SEA SURFACE TEMPERATURES (SSTS)
OF 30 DEG CELSIUS. TC 18P IS CURRENTLY TRACKING WEST-NORTHWESTWARD
UNDER THE INFLUENCE A TRANSIENT RIDGE TO THE SOUTH. BY TAU 24, THIS
RIDGE WILL WEAKEN AND SHIFT EASTWARD, ALLOWING THE NEAR EQUATORIAL
RIDGE (NER) TO BECOME THE DOMINATE STEERING MECHANISM, RESULTING IN
A TURN OF TC 20P BACK TO AN EASTWARD TRACK BY TAU 36. THROUGH THE
REMAINDER OF THE FORECAST PERIOD THE SYSTEM IS FORECAST TO TRACK
EAST THEN SOUTHEASTWARD UNDER THE INFLUENCE OF THE NER. TC 20P IS
FORECAST TO SLOWLY INTENSIFY OVER THE NEXT 24 HOURS, AS THE UPPER-
LEVEL ENVIRONMENT REMAINS MARGINAL DUE TO MODERATE VWS AND THE
ENTRAINMENT OF RELATIVELY DRY AIR FROM THE WEST. AFTER TAU 24, THE
MOISTURE ENVELOPE WILL IMPROVE, VWS WILL DECREASE AND OUTFLOW WILL
IMPROVE AS THE SYSTEM TAPS INTO THE UPPER-LEVEL WESTERLIES, ALLOWING
FURTHER INTENSIFICATION, BEFORE PEAKING AT 60 KNOTS BY TAU 72.
THROUGH THE REMAINDER OF THE FORECAST PERIOD, TC 20P WILL SLOWLY
WEAKEN AS IT ENCOUNTERS HIGHER VWS. DYNAMIC MODEL GUIDANCE IS IN
FAIRLY TIGHT AGREEMENT IN THE OVERALL TRACK BUT THERE IS HIGH
UNCERTAINTY IN THE TIMING AND LOCATION OF THE TURN BACK TOWARDS THE
EAST, THEREFORE, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST TRACK.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 200000Z IS 8 FEET. NEXT WARNINGS
AT 200900Z, 201500Z, 202100Z AND 210300Z. THIS CANCELS AND
SUPERSEDES REF A (WTPS22 PGTW 190400).//
TROPICAL DISTURBANCE ADVISORY NUMBER A3 ISSUED FROM RSMC NADI
Apr 200145 UTC.
TROPICAL DEPRESSION TD17F CENTRE 998HPA WAS LOCATED NEAR 12.5S 178.4W
AT 20000UTC. POSITION FAIR BASED ON GOES HR IMAGERY AND PERIPHERAL
SURFACE REPORTS. TD17F MOVING NORTHWEST AT ABOUT 09 KNOTS. MAXIMUM
10-MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT ABOUT 30 KNOTS.
DEEP CONVECTION HAS INCREASED IN THE PAST 12 HOURS WITH BANDS TRYING
TO WRAPPING LLCC. ORGANISATION HAS IMPROVED IN LAST 12 HOURS.
CYCLONIC CIRCULATION EXTENDS UPTO 500HPA. SYSTEM LIES SOUTH OF AN
UPPER RIDGE IN A LOW TO MODERATE SHEARED ENVIRONMENT. SST AROUND 30
DEGREE CELCIUS. DVORAK ANALYSIS BASED ON 0.45 WRAP YIELDS DT=2.5, MET
AND PT AGREE. FT BASED ON DT. THUS, YIELDING T2.5/2.5/D1.0/24HRS.
GLOBAL MODELS MAINTAIN AN INITIAL NORTHWEST MOVEMENT THEN TURN
EASTWARD WITH FURTHER INTENSIFICATION.
POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE IN THE
NEXT 24 TO 48 HOURS IS MODERATE TO HIGH.
...
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RSMC Nadi expect to name this TD by morning, and with conditions improving in the next day or so, should get to at least Cat 2 as it heads back towards Samoa…
TROPICAL DISTURBANCE ADVISORY NUMBER A4 ISSUED FROM RSMC NADI
Apr 200755 UTC.
TROPICAL DEPRESSION TD17F CENTRE 998HPA WAS LOCATED NEAR 12.6S 179.4W
AT 200600UTC. POSITION FAIR BASED ON GOES HR IMAGERY AND PERIPHERAL
SURFACE REPORTS. TD17F MOVING WEST-NORTHWEST AT ABOUT 09 KNOTS.
MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT ABOUT 30
KNOTS.
DEEP CONVECTION REMAINS PERSISTENT WITH BAND TRYING TO WRAP AROUND
LLCC. ORGANISATION HAS IMPROVED IN LAST 24 HOURS. CYCLONIC
CIRCULATION EXTENDS UP TO 500HPA. SYSTEM LIES IN A MODERATE UPPER
DIVERGENCE REIGION AND IN A LOW TO MODERATE SHEARED ENVIRONMENT. SST
AROUND 30 DEGREE CELCIUS. DVORAK ANALYSIS BASED ON 0.5 WRAP YIELDS
DT=2.5, MET AND PT AGREE. FT BASED ON DT. THUS, YIELDING
T2.5/2.5/D1.0/24HRS.
GLOBAL MODELS MAINTAIN AN INITIAL WEST-NORTHWEST MOVEMENT THEN TURN
EASTWARD WITH FURTHER INTENSIFICATION.
POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE IN THE
NEXT 09 TO 12 HOURS IS HIGH.
…
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TC Amos was named by RSMC Nadi at around 1am our time this morning and should continue to gradually strengthen over the next 48 hrs…
TROPICAL DISTURBANCE ADVISORY NUMBER A5 ISSUED FROM RSMC NADI
Apr 201349 UTC.
TROPICAL CYCLONE AMOS CENTRE 995HPA WAS LOCATED NEAR 12.8S 179.8W AT
201200UTC. POSITION FAIR BASED ON HIMAWARI-8 IMAGERY AND PERIPHERAL
SURFACE REPORTS. AMOS MOVING WEST-SOUTHWEST AT ABOUT 04 KNOTS.
MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT ABOUT 35
KNOTS.EXPECT SUSTAINED WINDS OF 35 KNOTS CLOSE TO THE CENTRE.
DEEP CONVECTION REMAINS PERSISTENT WITH BAND TRYING TO WRAP AROUND
LLCC. ORGANISATION HAS IMPROVED IN LAST 24 HOURS. CYCLONIC
CIRCULATION EXTENDS UP TO 500HPA. SYSTEM LIES IN A MODERATE UPPER
DIVERGENCE REIGION AND IN A LOW SHEARED ENVIRONMENT. SST AROUND 30
DEGREE CELCIUS.OUTFLOW GOOD TO THE SOUTH. DVORAK ANALYSIS BASED ON
0.55-0.6 WRAP YIELDS DT=3.0, MET AND PT AGREE. FT BASED ON DT. THUS,
YIELDING T3.0/3.0/D1.5/24HRS.
FORECASTS :
AT 12 HRS VALID AT 210000 UTC 12.8S 179.9E MOV W AT 02KT WITH 40 KT
CLOSE TO CENTRE
AT 24 HRS VALID AT 211200 UTC 12.6S 179.7W MOV ENE AT 02KT WITH 50 KT
CLOSE TO CENTRE.
OUTLOOK:
AT 36 HRS VALID AT 220000 UTC 12.3S 178.8W MOV ENE AT 05KT WITH 55 KT
CLOSE TO CENTRE
AT 48 HRS VALID AT 221200 UTC 12.3S 177.4W MOV E AT 06KT WITH 60 KT
CLOSE TO CENTRE.
WTPS31 PGTW 201500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 20P (AMOS) WARNING NR 003//
RMKS/
1. TROPICAL CYCLONE 20P (AMOS) WARNING NR 003
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
201200Z --- NEAR 12.8S 178.8W
MOVEMENT PAST SIX HOURS - 290 DEGREES AT 03 KTS
POSITION ACCURATE TO WITHIN 045 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
…
REMARKS:
201500Z POSITION NEAR 12.8S 178.9W.
TROPICAL CYCLONE 20P (AMOS), LOCATED APPROXIMATELY 353 NM WEST OF
AVATA SAMOA, HAS TRACKED WEST-NORTHWESTWARD AT 03 KNOTS OVER THE
PAST SIX HOURS. THE CURRENT POSITION IS BASED ON RECENT FIXES FROM
MULTIPLE REPORTING AGENCIES AND A 200917Z ASCAT PASS. ADDITIONALLY,
THE PREVIOUS STORM POSITION HAS BEEN ADJUSTED SLIGHTLY TO THE EAST
BASED ON A REASSESSMENT OF AVAILABLE MICROWAVE SATELLITE IMAGERY.
THE CURRENT INTENSITY ESTIMATE OF 35 KNOTS IS CONSISTENT WITH RECENT
SUBJECTIVE DVORAK VALUES. TC 20P HAS SLOWED AS THE PRIMARY STEERING
MECHANISM BEGINS TO SWITCH FROM A WEAKENING SUBTROPICAL RIDGE TO
SOUTH TO A BUILDING NEAR-EQUATORIAL RIDGE TO THE NORTH. THE CYCLONE
IS EXPECTED TO REMAIN IN A WEAK STEERING ENVIRONMENT FOR THE NEXT 24
HOURS OR SO BEFORE THE NEAR-EQUATORIAL RIDGE BUILDS SUFFICIENTLY TO
CARRY THE SYSTEM EASTWARD AND GRADUALLY SOUTHEASTWARD THROUGH THE
EXTENDED RANGE AHEAD OF A DEVELOPING MID-LATITUDE TROUGH. SLOW
INTENSIFICATION SHOULD OCCUR THROUGH TAU 72 AS THE LOW LEVEL
CIRCULATION CONTINUES TO CONSOLIDATE AND POLEWARD OUTFLOW IMPROVES.
WEAKENING IS ANTICIPATED AFTER TAU 72 AS VERTICAL WIND SHEAR
INCREASES AHEAD OF THE APPROACHING MID-LATITUDE TROUGH. NUMERICAL
MODELS ARE IN GOOD AGREEMENT REGARDING THE GENERAL TRACK SCENARIO,
BUT THERE IS SIGNIFICANT UNCERTAINTY IN THE TRACK DIRECTION OVER THE
NEXT SEVERAL DAYS. THE CURRENT TRACK FORECAST LIES NEAR TO THE MULTI-
MODEL CONSENSUS AND MAJORITY OF THE TRACK FORECAST GUIDANCE. GIVEN
NOTED UNCERTAINTY, THERE IS LOW CONFIDENCE IN THE TRACK FORECAST.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 201200Z IS 12 FEET. NEXT WARNINGS
AT 202100Z, 210300Z, 210900Z AND 211500Z.//
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Good convective banding wrapping around a tightening LLCC this morning (albeit temporally exposed)…
TROPICAL DISTURBANCE ADVISORY NUMBER A6 ISSUED FROM RSMC NADI
Apr 201944 UTC.
TROPICAL CYCLONE AMOS CENTRE 995HPA WAS LOCATED NEAR 12.6S 179.9W AT
201800UTC. POSITION FAIR BASED ON HIMAWARI-8 IMAGERY AND PERIPHERAL
SURFACE REPORTS. AMOS MOVING WEST-NORTHWEST AT ABOUT 06 KNOTS.
MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT ABOUT 35
KNOTS.
DEEP CONVECTION REMAINS PERSISTENT WITH BAND TRYING TO WRAP AROUND
LLCC FROM NORTH. ORGANISATION HAS SLIGHTLY DECREASED WITH CLOUD TOPS
WARMING FROM THE SOUTH. CYCLONIC CIRCULATION EXTENDS UP TO 400HPA.
SYSTEM LIES IN A MODERATE UPPER DIVERGENCE REGION AND IN A LOW
SHEARED ENVIRONMENT. SST AROUND 30 DEGREE CELCIUS. OUTFLOW GOOD TO THE
SOUTH. DVORAK ANALYSIS BASED ON 0.6 WRAP YIELDS DT=3.0, MET AND PT
AGREE. FT BASED ON DT. THUS, YIELDING T3.0/3.0/D1.0/24HRS.
...
WTPS31 PGTW 202100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 20P (AMOS) WARNING NR 004//
RMKS/
1. TROPICAL CYCLONE 20P (AMOS) WARNING NR 004
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
201800Z --- NEAR 12.6S 179.6W
MOVEMENT PAST SIX HOURS - 285 DEGREES AT 08 KTS
POSITION ACCURATE TO WITHIN 040 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
…
REMARKS:
202100Z POSITION NEAR 12.6S 179.5W.
TROPICAL CYCLONE 20P (AMOS), LOCATED APPROXIMATELY 529 NM WEST OF
PAGO PAGO, HAS TRACKED WEST-NORTHWESTWARD AT 08 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A
BROAD AREA OF DENSE OVERCAST JUST TO THE NORTHWEST OF THE LOW LEVEL
CIRCULATION CENTER (LLCC). SATELLITE IMAGERY ALSO SHOWS IMPROVED
CONSOLIDATION AND TIGHTER BANDING OVER THE LAST SIX HOURS. A
201813Z SSMIS MICROWAVE IMAGE CONFIRMS A TIGHTENING LLCC AND GIVES
HIGH CONFIDENCE TO THE INITIAL POSITION. THE CURRENT INTENSITY IS
ASSESSED AT 40 KNOTS AND IS CONSISTENT WITH RECENT SUBJECTIVE DVORAK
ESTIMATES FROM ALL AGENCIES. SEA SURFACE TEMPERATURES ARE FAVORABLY
WARM, AND THERE IS A STRONG POLEWARD OUTFLOW CHANNEL SUPPORTING
DEVELOPMENT. HOWEVER, AN UPPER-LEVEL POINT SOURCE IS POSITIONED TO
THE NORTHEAST AND CONTRIBUTING TO SOME CONVERGENCE ALOFT WHICH IS
CURRENTLY LIMITING THE RATE OF INTENSIFICATION. TC AMOS IS CURRENTLY
SLOWING DUE TO A TRANSITION IN THE STEERING ENVIRONMENT AS A NEAR-
EQUATORIAL RIDGE IS BUILDING TO THE NORTHEAST. OVER THE NEXT 12 TO
24 HOURS THIS RIDGE WILL BUILD SUFFICIENTLY TO SHIFT THE TRACK
SOUTHEASTWARD, AND TC AMOS IS EXPECTED TO INTENSIFY. BEYOND TAU 48
VERTICAL WIND SHEAR IS EXPECTED TO INCREASE AS A MID-LATITUDE TROUGH
MOVES IN FROM THE SOUTH WEST. DYNAMIC MODEL GUIDANCE IS IN GOOD
AGREEMENT WITH THE FORECAST TRACK SCENARIO, BUT THERE EXISTS
SIGNIFICANT UNCERTAINTY BETWEEN MODELS IN THE TRACK DIRECTION IN THE
EXTENDED FORECAST. THE CURRENT FORECAST TRACK LIES NEAR THE MULTI-
MODEL CONSENSUS AND MAJORITY OF THE TRACK FORECAST GUIDANCE. GIVEN
THE UNCERTAINTY, THERE IS LITTLE CONFIDENCE IN THE FORECAST TRACK.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 201800Z IS 14 FEET. NEXT
WARNINGS AT 210300Z, 210900Z, 211500Z AND 212100Z.
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Amos appears to have become quasi-stationary today, and although it has weakened slightly, JTWC now expect it to reach at least Cat 3 by tomorrow night…
TROPICAL DISTURBANCE ADVISORY NUMBER A7 ISSUED FROM RSMC NADI
Apr 210135 UTC.
TROPICAL CYCLONE AMOS CENTRE 995HPA WAS LOCATED NEAR 12.6S 179.5W AT
210000UTC. POSITION FAIR BASED ON HIMAWARI-8 IMAGERY AND PERIPHERAL
SURFACE REPORTS. AMOS MOVING NORTHEAST AT ABOUT 02 KNOTS. MAXIMUM
10-MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT ABOUT 35 KNOTS.
DEEP CONVECTION REMAINS PERSISTENT WITH BAND TRYING TO WRAP AROUND
LLCC FROM NORTH AND NEW CONVECTION DEVELOPING NEAR LLCC. ORGANISATION
HAS SLIGHTLY DECREASED WITH CLOUD TOPS WARMING TO THE SOUTH IN PAST 6
HOURS. CYCLONIC CIRCULATION EXTENDS UP TO 400HPA. SYSTEM LIES IN A
MODERATE UPPER DIVERGENCE REGION AND IN A LOW SHEARED ENVIRONMENT.
SST AROUND 30 DEGREE CELCIUS. OUTFLOW GOOD TO THE SOUTH. DVORAK
ANALYSIS BASED ON 0.5 WRAP YIELDS DT=2.5, MET AND PT AGREE. FT BASED
ON DT. THUS, YIELDING T2.5/3.0/D0.5/24HRS.
THOUGH THE SYSTEM HAS WEAKENED SLIGHTLY, GLOBAL MODELS MAINTAIN A
REINTENSIFICATION OVER THE NEXT 6 TO 12 HOURS WITH AN EASTWARD TRACK.
...
WTPS31 PGTW 210300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 20P (AMOS) WARNING NR 005//
RMKS/
1. TROPICAL CYCLONE 20P (AMOS) WARNING NR 005
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
210000Z --- NEAR 12.5S 179.5W
MOVEMENT PAST SIX HOURS - 045 DEGREES AT 01 KTS
POSITION ACCURATE TO WITHIN 025 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
…
REMARKS:
210300Z POSITION NEAR 12.5S 179.4W.
TROPICAL CYCLONE (TC) 20P (AMOS), LOCATED APPROXIMATELY 525 NM WEST
OF PAGO PAGO, AMERICAN SAMOA, HAS TRACKED NORTHEASTWARD AT 01 KNOT
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
(MSI) SHOWS A CONSOLIDATING SYSTEM WITH A BROAD CENTRAL DENSE
OVERCAST OBSCURING THE LOW LEVEL CIRCULATION CENTER THAT APPEARS TO
BE STATIONARY. THE INITIAL POSITION IS BASED ON THE MSI LOOP WITH LOW
CONFIDENCE. THE INITIAL INTENSITY IS BASED ON AN OVERALL ASSESSMENT
OF DVORAK ESTIMATES FROM ALL REPORTING AGENCIES. UPPER LEVEL ANALYSIS
INDICATES TC 20P IS IN AN AREA OF LIGHT VERTICAL WIND SHEAR (VWS) AND
STRONG POLEWARD OUTFLOW. HOWEVER, AN INDUCED TROUGH TO THE NORTHEAST
IS CAUSING SUBSIDENCE ALONG THE NORTHEAST QUADRANT AND INHIBITING
SIGNIFICANT DEVELOPMENT. TC AMOS HAS BECOME QUASI-STATIONARY (QS) AS
IT TRANSITIONS INTO A NEW STEERING MECHANISM - A NEAR EQUATORIAL
RIDGE (NER) BUILDING IN FROM THE NORTHEAST. THE NER WILL SLOWLY
NUDGE THE TC EASTWARD OVER THE NEXT 12-36 HOURS THEN SOUTHEASTWARD AT
A FASTER RATE. THE CYCLONE IS EXPECTED TO SLOWLY INTENSIFY, PEAKING
AT 85 KNOTS NEAR TAU 48 BEFORE GRADUALLY WEAKENING DUE TO INCREASING
VWS AS IT MOVES MORE POLEWARD. DYNAMIC MODEL GUIDANCE IS IN GOOD
AGREEMENT WITH THE FORECAST TRACK SCENARIO, HOWEVER, DUE TO THE
UNCERTAINTY CAUSED BY THE QS MOTION IN THE INITIAL PHASE, THERE IS
OVERALL LOW CONFIDENCE IN THE JTWC FORECAST TRACK. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 210000Z IS 15 FEET. NEXT WARNINGS AT
211500Z AND 220300Z.//
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Unlike GFS, ECMWF currently have Amos over Niue in about 10 days time, after a few loop-de-loops…
Amos is looking much better organised this evening and was sporting a visible ragged eye earlier. JTWC expect Amos to begin a rapid intensification phase, peaking at Cat 4 by late Saturday…
TROPICAL DISTURBANCE ADVISORY NUMBER A8 ISSUED FROM RSMC NADI
Apr 210738 UTC.
TROPICAL CYCLONE AMOS CENTRE 993HPA CATEGORY WAS LOCATED NEAR 13.0S
179.3W AT 210600UTC. POSITION FAIR BASED ON HIMAWARI-8 IMAGERY AND
PERIPHERAL SURFACE REPORTS. AMOS MOVING SOUTH-SOUTHEAST AT ABOUT 04
KNOTS. MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT
ABOUT 40 KNOTS. EXPECT WINDS OVER 33 KNOTS WITHIN 90 NAUTICAL MILES
OF CENTRE.
DEEP CONVECTION REMAINS PERSISTENT WITH CONVECTIVE BAND WRAPPING
AROUND LLCC. ORGANISATION HAS IMPROVED IN PAST 6 HOURS WITH CLOUD
TOPS COOLOING PAST 3 HOURS. CYCLONIC CIRCULATION EXTENDS UP TO
300HPA. SYSTEM LIES IN A MODERATE UPPER DIVERGENCE REGION AND IN A
LOW SHEARED ENVIRONMENT. SST AROUND 30 DEGREE CELCIUS. OUTFLOW GOOD
TO THE SOUTH. DVORAK ANALYSIS BASED ON 0.7 WRAP YIELDS DT=3.0, MET
AND PT AGREE. FT BASED ON DT. THUS, YIELDING T3.0/3.0/D0.5/24HRS.
GLOBAL MODELS MAINTAIN AN EASTERLY TRACK WITH FURTHER
INTENSIFICATION.
…
WTPS31 PGTW 210900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 20P (AMOS) WARNING NR 006//
RMKS/
1. TROPICAL CYCLONE 20P (AMOS) WARNING NR 006
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
210600Z --- NEAR 13.0S 179.3W
MOVEMENT PAST SIX HOURS - 125 DEGREES AT 04 KTS
POSITION ACCURATE TO WITHIN 040 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
…
REMARKS:
210900Z POSITION NEAR 13.0S 179.0W.
TROPICAL CYCLONE (TC) 20P (AMOS), LOCATED APPROXIMATELY 507 NM WEST
OF PAGO PAGO, AMERICAN SAMOA, HAS TRACKED SOUTHEASTWARD AT 04 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
DEPICTS A SLOWLY CONSOLIDATING LOW-LEVEL CIRCULATION CENTER WITH
CYCLING DEEP CONVECTION OBSCURING A RAGGED BUT DEFINED CENTER.
DESPITE THE UNIMPRESSIVE DEEP CONVECTIVE STRUCTURE, A 210603Z
WINDSAT COMPOSITE 37GHZ COLOR IMAGE DEPICTS A WELL-DEFINED MICROWAVE
EYE FEATURE SURROUNDED BY A CYAN RING WITH MULTIPLE CONVECTIVE
BANDING WRAPPING INTO THE CENTER. THIS EXCELLENT LOW-LEVEL
STRUCTURE, IN COMBINATION WITH THE RADIAL OUTFLOW, SUGGESTS AN
IMMINENT RAPID INTENSIFICATION PHASE. THE CURRENT INTENSITY IS
ASSESSED AT 45 KNOTS BASED ON DVORAK INTENSITY ESTIMATES OF T3.0 (45
KNOTS)--HOWEVER, THE MICROWAVE HINTS AT A SLIGHTLY HIGHER INTENSITY
OF 50 TO PERHAPS 55 KNOTS. TC 20P HAS TURNED SOUTHEASTWARD AND IS
FORECAST TO ACCELERATE EASTWARD TO SOUTHEASTWARD AS IT TRACKS ALONG
THE PERIPHERY OF THE NEAR-EQUATORIAL STEERING RIDGE. OVERALL,
DYNAMIC GUIDANCE IS IN GOOD AGREEMENT AND SUPPORTS THE JTWC FORECAST
TRACK WITH HIGH CONFIDENCE. AS PREVIOUSLY MENTIONED, ENVIRONMENTAL
CONDITIONS ARE FAVORABLE THEREFORE TC 20P IS EXPECTED TO RAPIDLY
INTENSIFY TO A PEAK INTENSITY OF 95 KNOTS BY TAU 48. AFTER TAU 72,
THE SYSTEM SHOULD WEAKEN AS IT BEGINS TO ENCOUNTER INCREASING
WESTERLY FLOW. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 210600Z IS 15
FEET. NEXT WARNINGS AT 211500Z, 212100Z, 220300Z AND 220900Z.//
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TC Amos was upgraded to Cat 2 by RSMC Nadi earlier this morning and now expect him to reach Cat 3 by tomorrow morning, possibly even Cat 4 tomorrow night according to JTWC, which doesn't bode well for Samoa on Sunday…
TROPICAL DISTURBANCE ADVISORY NUMBER A9 ISSUED FROM RSMC NADI
Apr 211351 UTC.
TROPICAL CYCLONE AMOS CENTRE 989HPA CATEGORY 2 WAS LOCATED NEAR 12.8S
178.9W AT 211200UTC. POSITION FAIR BASED ON HIMAWARI-8/GOES IR
IMAGERY AND PERIPHERAL SURFACE REPORTS. AMOS MOVING EAST-NORTHEAST AT
ABOUT 04 KNOTS. MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE
ESTIMATED AT ABOUT 50 KNOTS. EXPECT WINDS OVER 47 KNOTS WITHIN 30
NAUTICAL MILES OF CENTRE AND OVER 33 KNOTS WITHIN 80 NAUTICAL MILES
OF CENTRE.
DEEP CONVECTION REMAINS PERSISTENT WITH CONVECTIVE BANDS WRAPPING
AROUND LLCC. ORGANISATION HAS IMPROVED IN PAST 12 HOURS. SYSTEM LIES
IN A MODERATE TO STRONG UPPER DIVERGENCE REGION AND IN A LOW SHEARED
ENVIRONMENT. SST AROUND 30 DEGREE CELCIUS. OUTFLOW GOOD TO THE SOUTH.
DVORAK ANALYSIS BASED ON 0.75 WRAP WITH WHITE BAND YIELDS DT=3.5, MET
AND PT AGREE. FT BASED ON DT. THUS, YIELDING T3.5/3.5/D0.5/24HRS.
GLOBAL MODELS MAINTAIN AN EASTERLY TRACK WITH FURTHER
INTENSIFICATION.
...
WTPS31 PGTW 211500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 20P (AMOS) WARNING NR 007//
RMKS/
1. TROPICAL CYCLONE 20P (AMOS) WARNING NR 007
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
211200Z --- NEAR 12.7S 178.9W
MOVEMENT PAST SIX HOURS - 090 DEGREES AT 03 KTS
POSITION ACCURATE TO WITHIN 045 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
…
REMARKS:
211500Z POSITION NEAR 12.7S 178.6W.
TROPICAL CYCLONE (TC) 20P (AMOS), LOCATED APPROXIMATELY 488 NM WEST
OF PAGO PAGO, AMERICAN SAMOA, HAS TRACKED EASTWARD AT 03 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
DEPICTS A COMPACT, CONSOLIDATING LOW-LEVEL CIRCULATION CENTER WITH
IMPROVED CONVECTIVE STRUCTURE EVIDENT IN A 210702Z SSMIS 91GHZ IMAGE
AND A 210603Z WINDSAT COMPOSITE 37GHZ COLOR IMAGE. THE WINDSAT 37GHZ
COLOR IMAGE DEPICTS A WELL-DEFINED MICROWAVE EYE FEATURE SURROUNDED
BY A CYAN RING WITH MULTIPLE CONVECTIVE BANDING WRAPPING INTO THE
CENTER. THIS EXCELLENT LOW-LEVEL STRUCTURE, IN COMBINATION WITH THE
RADIAL OUTFLOW, SUGGESTS AN IMMINENT RAPID INTENSIFICATION PHASE.
THE CURRENT INTENSITY IS ASSESSED AT 55 KNOTS BASED ON DVORAK
INTENSITY ESTIMATES OF T3.5 (55 KNOTS). TC 20P HAS TRACKED SLOWLY
EASTWARD AND IS FORECAST TO ACCELERATE EASTWARD TO SOUTHEASTWARD AS
IT TRACKS ALONG THE PERIPHERY OF THE NEAR-EQUATORIAL STEERING RIDGE.
OVERALL, DYNAMIC GUIDANCE IS IN TIGHT AGREEMENT AND SUPPORTS THE
JTWC FORECAST TRACK WITH HIGH CONFIDENCE. AS PREVIOUSLY MENTIONED,
ENVIRONMENTAL CONDITIONS ARE FAVORABLE THEREFORE TC 20P IS EXPECTED
TO RAPIDLY INTENSIFY TO A PEAK INTENSITY OF 95 KNOTS BY TAU 48.
AFTER TAU 72, THE SYSTEM SHOULD WEAKEN AS IT BEGINS TO ENCOUNTER
INCREASING WESTERLY FLOW. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 211200Z
IS 18 FEET. NEXT WARNINGS AT 212100Z, 220300Z, 220900Z AND 221500Z.//
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Wow! JTWC now have TC Amos approaching Samoa as the equivalent of a mid-Cat 4 on Sunday morning. It's also starting to look more likely that Western Samoa will take a direct hit.
TROPICAL DISTURBANCE ADVISORY NUMBER A11 ISSUED FROM RSMC NADI
Apr 220130 UTC.
TROPICAL CYCLONE AMOS CENTRE 980HPA CATEGORY 2 WAS LOCATED NEAR 12.5S
177.3W AT 220000UTC. POSITION FAIR BASED ON HIMAWARI-8/GOES VIS
IMAGERY AND PERIPHERAL SURFACE REPORTS. AMOS MOVING EAST AT ABOUT 05
KNOTS. MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT
ABOUT 60 KNOTS.
EXPECT WINDS OVER 47 KNOTS WITHIN 30 NAUTICAL MILES OF CENTRE
AND OVER 33 KNOTS WITHIN 80 NAUTICAL MILES OF CENTRE.
DEEP CONVECTION REMAINS PERSISTENT WITH CONVECTIVE BANDS TIGHTLY
WRAPPING AROUND LLCC. ORGANISATION GOOD. SYSTEM LIES IN A MODERATE TO
STRONG UPPER DIVERGENCE REGION AND IN A LOW SHEARED ENVIRONMENT. SST
AROUND 30 DEGREE CELCIUS. OUTFLOW GOOD TO THE SOUTH. DVORAK ANALYSIS
BASED ON 1.3 WRAP YIELDS DT=4.0. MET AND PT AGREE. FT BASED ON DT.
THUS, YIELDING T4.0/4.0/D1.5/24HRS.
GLOBAL MODELS MAINTAIN AN INITIAL EASTERLY TRACK AND THEN
SOUTHEASTWARD WITH FURTHER INTENSIFICATION.
FORECASTS :
AT 12 HRS VALID AT 221200 UTC 12.6S 175.9W MOV E AT 07KT WITH 70 KT
CLOSE TO CENTRE
AT 24 HRS VALID AT 230000 UTC 13.0S 174.4W MOV ESE AT 08KT WITH 75 KT
CLOSE TO CENTRE.
OUTLOOK:
AT 36 HRS VALID AT 231200 UTC 13.5S 173.0W MOV ESE AT 08KT WITH 75 KT
CLOSE TO CENTRE
AT 48 HRS VALID AT 240000 UTC 14.3S 171.8W MOV ESE AT 07KT WITH 75 KT
CLOSE TO CENTRE.
THE NEXT TROPICAL DISTURBANCE ADVISORY ON TC AMOS WILL BE ISSUED
AROUND 220800UTC.
WTPS31 PGTW 220300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 20P (AMOS) WARNING NR 009//
RMKS/
1. TROPICAL CYCLONE 20P (AMOS) WARNING NR 009
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
220000Z --- NEAR 12.4S 177.4W
MOVEMENT PAST SIX HOURS - 070 DEGREES AT 09 KTS
POSITION ACCURATE TO WITHIN 020 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
…
REMARKS:
220300Z POSITION NEAR 12.4S 177.1W.
TROPICAL CYCLONE (TC) 20P (AMOS), LOCATED APPROXIMATELY 407 NM
WEST-NORTHWEST OF PAGO PAGO, AMERICAN SAMOA, HAS TRACKED EAST-
NORTHEASTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A SYSTEM THAT CONTINUES
TO CONSOLIDATE AS IT MAINTAINS A DEEP CENTRAL DENSE OVERCAST FEATURE
THAT IS COVERING THE LOW LEVEL CIRCULATION CENTER. THE INITIAL
POSITION IS BASED ON THE MSI LOOP AND EXTRAPOLATED FROM A 212143Z
BULLSEYE ASCAT PASS WITH FAIR CONFIDENCE. THE INITIAL INTENSITY IS
BASED ON CONGRUENT DVORAK ESTIMATES FROM PGTW, KNES, AND NFFN. UPPER
LEVEL ANALYSIS INDICATES TC 20P IS IN AN AREA OF LIGHT VERTICAL WIND
SHEAR (VWS) AND STRONG NEAR-RADIAL OUTFLOW WITH SOME SUBSIDENCE ALONG
THE NORTHEAST QUADRANT. TC AMOS IS EXPECTED TO INTENSIFY OVER THE
NEXT 36 HOURS PEAKING AT 105 KNOTS AS IT TRACKS EAST THEN
SOUTHEASTWARD ALONG THE SOUTHERN PERIPHERY OF A NEAR-EQUATORIAL RIDGE
(NER). AFTERWARDS, INCREASING VWS ASSOCIATED WITH THE PREVAILING
WESTERLIES WILL BEGIN TO ERODE THE SYSTEM. DYNAMIC MODEL GUIDANCE IS
IN GOOD AGREEMENT FOR THE FIRST 48 HOURS. BEYOND THAT, A GROUP OF
TRACKERS INCLUDING GFDN, NVGM, AND COTC INDICATE A MORE POLEWARD
TRACK, PRESUMABLY IN RESPONSE TO AN EXTENSION OF THE NER. DUE TO THE
UNCERTAINTY IN THE EXTENDED FORECAST THERE IS OVERALL LOW CONFIDENCE
IN THE JTWC FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT
220000Z IS 20 FEET. NEXT WARNINGS AT 221500Z AND 230300Z.//
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Amos was upgraded to a Severe Cat 3 TC by RSMC Nadi this afternoon …
HURRICANE WARNING 034 ISSUED FROM RSMC NADI Apr 220408 UTC.
TROPICAL CYCLONE AMOS CENTRE 975HPA CATEGORY 3 WAS LOCATED NEAR 12.5 SOUTH 177.1
WEST AT 220300 UTC.
POSITION FAIR.
REPEAT POSITION 12.5S 177.1W AT 220300 UTC.
CYCLONE MOVING EAST AT 06 KNOTS.
EXPECT SUSTAINED WINDS OF 65 KNOTS CLOSE TO THE CENTRE, INCREASING TO 75 KNOTS
IN THE NEXT 12 TO 24 HOURS.
…
TROPICAL DISTURBANCE ADVISORY NUMBER A12 ISSUED FROM RSMC NADI
Apr 220502 UTC.
***** CORRECTION TO TC AMOS CATEGORY *****
TROPICAL CYCLONE AMOS CENTRE 975HPA CATEGORY 3 WAS LOCATED NEAR 12.5S
177.1W AT 220300UTC. POSITION FAIR BASED ON HIMAWARI-8/GOES VIS
IMAGERY AND PERIPHERAL SURFACE REPORTS. AMOS MOVING EAST AT ABOUT 03
KNOTS. MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT
ABOUT 65 KNOTS.
EXPECT WINDS OVER 63 KNOTS WITHIN 25 NAUTICAL MILES OF CENTRE,
OVER 47 KNOTS WITHIN 30 NAUTICAL MILES OF CENTRE,
AND OVER 33 KNOTS WITHIN 80 NAUTICAL MILES OF CENTRE.
DEEP CONVECTION REMAINS PERSISTENT WITH EYE DISCERNIBLE ON VIS
IMAGERY. ORGANISATION GOOD. SYSTEM LIES IN A MODERATE TO STRONG UPPER
DIVERGENCE REGION AND IN A LOW SHEARED ENVIRONMENT. SST AROUND 30
DEGREE CELCIUS. OUTFLOW GOOD TO THE SOUTH. DVORAK ANALYSIS BASED ON
1.4 WRAP YIELDS DT=4.5. MET AND PT AGREE. FT BASED ON DT. THUS,
YIELDING T4.5/4.5/D1.5/24HRS.
GLOBAL MODELS MAINTAIN AN INITIAL EASTERLY TRACK AND THEN TURN IT
SOUTHEASTWARD WITH FURTHER INTENSIFICATION.
…
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RSMC Nadi now coming more inline with JTWC. They currently have Amos at 973 hPa with 130 km/h max mean-winds, increasing to about 160 km/h tomorrow (or bordering on Cat 4)…
TROPICAL DISTURBANCE ADVISORY NUMBER A13 ISSUED FROM RSMC NADI
Apr 220749 UTC.
TROPICAL CYCLONE AMOS CENTRE 973HPA CATEGORY 3 WAS LOCATED NEAR 12.5S
176.8W AT 220600UTC. POSITION FAIR BASED ON HIMAWARI-8/GOES IR
IMAGERY AND PERIPHERAL SURFACE REPORTS. AMOS MOVING EAST AT ABOUT 06
KNOTS. MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT
ABOUT 70 KNOTS.
EXPECT WINDS OVER 63 KNOTS WITHIN 15 NAUTICAL MILES OF CENTRE,
OVER 47 KNOTS WITHIN 30 NAUTICAL MILES OF CENTRE,
AND OVER 33 KNOTS WITHIN 55 NAUTICAL MILES OF CENTRE.
DEEP CONVECTION REMAINS PERSISTENT. ORGANISATION GOOD. SYSTEM LIES IN
A STRONG UPPER DIVERGENCE REGION AND IN A LOW SHEARED ENVIRONMENT.
SST AROUND 30 DEGREE CELCIUS. OUTFLOW GOOD TO THE SOUTH. SYSTEM IS
BEING STEERED TO THE EAST BY THE WESTERLY DEEP LAYER MEAN WIND FLOW.
DVORAK ANALYSIS BASED ON EMBEDDED CENTRE PATTERN WITH LLCC EMBEDDED
IN W YIELDS DT=5.0. MET=4.5 AND PT=4.5. FT BASED ON MET. THUS,
YIELDING T4.5/4.5/D1.5/24HRS.
GLOBAL MODELS MAINTAIN AN INITIAL EASTERLY TRACK AND THEN TURN IT
SOUTHEASTWARD WITH FURTHER INTENSIFICATION.
FORECASTS :
AT 12 HRS VALID AT 221800 UTC 12.8S 175.6W MOV ESE AT 06KT WITH 80 KT
CLOSE TO CENTRE
AT 24 HRS VALID AT 230600 UTC 13.3S 174.3W MOV ESE AT 06KT WITH 85 KT
CLOSE TO CENTRE.
OUTLOOK:
AT 36 HRS VALID AT 231800 UTC 13.8S 173.1W MOV ESE AT 07KT WITH 85 KT
CLOSE TO CENTRE
AT 48 HRS VALID AT 240600 UTC 14.4S 172.1W MOV ESE AT 06KT WITH 85 KT
CLOSE TO CENTRE.
THE NEXT TROPICAL DISTURBANCE ADVISORY ON TC AMOS WILL BE ISSUED
AROUND 221400UTC.
WTPS31 PGTW 220900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TROPICAL CYCLONE 20P (AMOS) WARNING NR 010
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
220600Z --- NEAR 12.5S 177.0W
MOVEMENT PAST SIX HOURS - 090 DEGREES AT 06 KTS
POSITION ACCURATE TO WITHIN 040 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT
…
REMARKS:
220900Z POSITION NEAR 12.5S 176.7W.
TROPICAL CYCLONE (TC) 20P (AMOS), LOCATED APPROXIMATELY 383 NM WEST-
NORTHWEST OF PAGO PAGO, AMERICAN SAMOA, HAS TRACKED EASTWARD AT 06
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY DEPICTS A COMPACT, CONSOLIDATING LOW-LEVEL CIRCULATION
CENTER WITH A FORMATIVE EYE. A 220650Z SSMIS 91GHZ IMAGE SHOWS
TIGHTLY-CURVED BANDING WRAPPING INTO A MICROWAVE EYE FEATURE. TC 20P
HAS RAPIDLY INTENSIFIED OVER THE PAST 24 HOURS, INCREASING ABOUT 30
KNOTS FROM 45 KNOTS TO 75 KNOTS. THE CURRENT INTENSITY IS ASSESSED
AT 75 KNOTS BASED ON DVORAK INTENSITY ESTIMATES OF T4.5 (77 KNOTS)
FROM KNES AND PGTW. UPPER-LEVEL ANALYSIS INDICATES NEAR-RADIAL
OUTFLOW, WHICH SHOULD SUPPORT CONTINUED INTENSIFICATION OVER THE
NEXT 48 HOURS. TC 20P IS FORECAST TO TRACK EAST-SOUTHEASTWARD TO
SOUTHEASTWARD AS IT TRACKS ALONG THE PERIPHERY OF THE NEAR-
EQUATORIAL STEERING RIDGE. THIS TRACK WILL DRIVE THE SYSTEM ABOUT 80-
90 NM SOUTH OF PAGO PAGO WITH THE GALE-FORCE WINDS JUST SKIRTING
AMERICAN SAMOA. AFTER TAU 48, THE SYSTEM SHOULD TURN SOUTH-
SOUTHEASTWARD AS A WEAK EXTENSION OF THE STEERING RIDGE BUILDS TO
THE NORTHEAST. AFTER TAU 72, TC 20P WILL RESUME A MORE EASTWARD
TRAJECTORY AS IT BEGINS TO ENCOUNTER SUBTROPICAL WESTERLIES, WHICH
WILL PRODUCE A WEAKENING TREND. OVERALL, DYNAMIC GUIDANCE IS IN GOOD
AGREEMENT AND SUPPORTS THE JTWC FORECAST TRACK WITH HIGH CONFIDENCE.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 220600Z IS 24 FEET. NEXT WARNINGS
AT 221500Z, 222100Z, 230300Z AND 230900Z.//
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Central pressure at around midnight was 965 hPa (a drop of 24 hPa in 24 hrs), with max mean-winds of about 150 km/h. RSMC Nadi now also expect Amos to become a low-end Cat 4 by tonight, while JTWC is going for the equivalent of about a high-end Cat 4 TC...
TROPICAL DISTURBANCE ADVISORY NUMBER A14 ISSUED FROM RSMC NADI
Apr 221338 UTC.
SEVERE TROPICAL CYCLONE AMOS CENTRE 965HPA CATEGORY 3 WAS LOCATED
NEAR 12.4S 176.4W AT 221200UTC. POSITION FAIR BASED ON
HIMAWARI-8/GOES IR IMAGERY AND PERIPHERAL SURFACE REPORTS. AMOS
MOVING EAST AT ABOUT 06 KNOTS. MAXIMUM 10-MINUTE AVERAGE WINDS NEAR
THE CENTRE ESTIMATED AT ABOUT 80 KNOTS.
EXPECT WINDS OVER 63 KNOTS WITHIN 15 NAUTICAL MILES OF CENTRE,
OVER 47 KNOTS WITHIN 30 NAUTICAL MILES OF CENTRE,
AND OVER 33 KNOTS WITHIN 50 NAUTICAL MILES OF CENTRE.
DEEP CONVECTION REMAINS PERSISTENT. ORGANISATION GOOD. SYSTEM LIES IN
A STRONG UPPER DIVERGENCE REGION AND IN A LOW SHEARED ENVIRONMENT.
SST AROUND 30 DEGREE CELCIUS. OUTFLOW GOOD TO THE EAST AND SOUTH.
SYSTEM IS BEING STEERED TO THE EAST BY THE WESTERLY DEEP LAYER MEAN
WIND FLOW. DVORAK ANALYSIS BASED ON EMBEDDED CENTRE PATTERN WITH LLCC
EMBEDDED IN CMG YIELDS DT=5.0. MET AND PT AGREE. FT BASED ON MET.
THUS, YIELDING T5.0/5.0/D1.5/24HRS.
GLOBAL MODELS MAINTAIN AN INITIAL EASTERLY TRACK AND THEN TURN IT
SOUTHEASTWARD WITH FURTHER INTENSIFICATION.
FORECASTS :
AT 12 HRS VALID AT 230000 UTC 12.8S 175.2W MOV ESE AT 06KT WITH 85 KT
CLOSE TO CENTRE
AT 24 HRS VALID AT 231200 UTC 13.2S 174.0W MOV ESE AT 06KT WITH 90 KT
CLOSE TO CENTRE.
OUTLOOK:
AT 36 HRS VALID AT 240000 UTC 13.8S 173.0W MOV ESE AT 06KT WITH 90 KT
CLOSE TO CENTRE
AT 48 HRS VALID AT 241200 UTC 14.4S 172.1W MOV ESE AT 06KT WITH 85 KT
CLOSE TO CENTRE.
THE NEXT TROPICAL DISTURBANCE ADVISORY ON TC AMOS WILL BE ISSUED
AROUND 222000UTC.
WTPS31 PGTW 221500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TROPICAL CYCLONE 20P (AMOS) WARNING NR 011
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
221200Z --- NEAR 12.4S 176.3W
MOVEMENT PAST SIX HOURS - 090 DEGREES AT 08 KTS
POSITION ACCURATE TO WITHIN 030 NM
POSITION BASED ON EYE FIXED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT
…
REMARKS:
221500Z POSITION NEAR 12.5S 176.0W.
TROPICAL CYCLONE (TC) 20P (AMOS), LOCATED APPROXIMATELY 346 NM WEST-
NORTHWEST OF PAGO PAGO, AMERICAN SAMOA, HAS TRACKED EASTWARD AT 08
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY CONTINUES TO DEPICT A COMPACT, CONSOLIDATING SYSTEM WITH AN
INCIPIENT EYE. A 220926Z METOP-B 89GHZ IMAGE SHOWS TIGHTLY-CURVED
BANDING WRAPPING INTO A COMPACT CORE WITH A MICROWAVE EYE FEATURE.
TC 20P HAS RAPIDLY INTENSIFIED OVER THE PAST 24 HOURS, INCREASING
ABOUT 35 KNOTS FROM 55 KNOTS TO 90 KNOTS. THE CURRENT INTENSITY IS
ASSESSED AT 90 KNOTS BASED ON DVORAK INTENSITY ESTIMATES OF T5.0 (90
KNOTS) TO T5.5 (102 KNOTS). UPPER-LEVEL ANALYSIS INDICATES NEAR-
RADIAL OUTFLOW, WHICH SHOULD SUPPORT CONTINUED INTENSIFICATION OVER
THE NEXT 48 HOURS. TC 20P IS FORECAST TO TRACK EAST-SOUTHEASTWARD TO
SOUTHEASTWARD AS IT TRACKS ALONG THE PERIPHERY OF THE NEAR-
EQUATORIAL STEERING RIDGE. THIS TRACK WILL DRIVE THE SYSTEM ABOUT 70-
80 NM SOUTH OF PAGO PAGO WITH THE GALE-FORCE SUSTAINED WINDS JUST
SKIRTING AMERICAN SAMOA. AFTER TAU 48, THE SYSTEM SHOULD TURN SOUTH-
SOUTHEASTWARD AS A WEAK EXTENSION OF THE STEERING RIDGE BUILDS TO
THE NORTHEAST. AFTER TAU 72, TC 20P WILL RESUME A MORE EASTWARD
TRAJECTORY AS IT BEGINS TO ENCOUNTER SUBTROPICAL WESTERLIES, WHICH
WILL PRODUCE A WEAKENING TREND. OVERALL, DYNAMIC GUIDANCE IS IN GOOD
AGREEMENT AND SUPPORTS THE JTWC FORECAST TRACK WITH HIGH CONFIDENCE.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 221200Z IS 28 FEET. NEXT WARNINGS
AT 222100Z, 230300Z, 230900Z AND 231500Z.//
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JTWC now have Amos looking like making landfall on Samoa's largest island of Savai'i at around midday tomorrow, with roughly the equivalent of 180 km/h 10-mniute mean-winds and gusts to about 250 km/h…
WTPS31 PGTW 222100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 20P (AMOS) WARNING NR 012//
RMKS/
1. TROPICAL CYCLONE 20P (AMOS) WARNING NR 012
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
221800Z --- NEAR 12.4S 175.7W
MOVEMENT PAST SIX HOURS - 100 DEGREES AT 09 KTS
POSITION ACCURATE TO WITHIN 040 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT
…
REMARKS:
222100Z POSITION NEAR 12.5S 175.4W.
TROPICAL CYCLONE 20P (AMOS), LOCATED APPROXIMATELY 313 NM WEST-
NORTHWEST OF PAGO PAGO, AMERICAN SAMOA HAS TRACKED EASTWARD AT 09
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED IMAGERY
DEPICTS STRONG FLARING CENTRAL CONVECTION WITH AN ASSOCIATED DENSE
OVERCAST LAYER OBSCURING THE LOW LEVEL CIRCULATION CENTER, GIVING
FAIR CONFIDENCE TO THE INITIAL POSITION. THE INITIAL INTENSITY IS
ASSESSED AT 90 KNOTS AND IS IN ALIGNMENT WITH SUBJECTIVE DVORAK
ESTIMATES FROM PGTW, NFFN AND KNES. CURRENTLY THE ENVIRONMENT IS
FAVORABLE FOR FURTHER DEVELOPMENT AS A STRONG POLEWARD OUTFLOW
EXISTS AND SEA SURFACE TEMPERATURES ARE WARM. UPPER-LEVEL
NORTHEASTERLY WINDS ARE PRESENT CREATING SOME SUBSIDENCE, BUT APPEAR
TO HAVE RELAXED SOME IN THE LAST SIX HOURS. TC AMOS IS EXPECTED TO
INTENSIFY IN THE NEXT 24 TO 36 HOURS REACHING A PEAK INTENSITY OF
110 KNOTS AS OUTFLOW AND VERTICAL WIND SHEAR CONDITIONS CONTINUE TO
IMPROVE. CURRENTLY TC AMOS IS TRAVELING EASTWARD ALONG THE SOUTHERN
BOUNDARY OF A NEAR-EQUATORIAL RIDGE. BY TAU 48 AN EXTENSION OF THE
STEERING RIDGE WILL DEVELOP, BRIEFLY SLOWING THE STORM AND SHIFTING
THE TRACK SLIGHTLY TO THE SOUTH. BEYOND TAU 48, VERTICAL WIND SHEAR
IS ALSO EXPECTED TO INCREASE AS TC AMOS APPROACHES SUBTROPICAL
WESTERLIES TO THE SOUTH. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT
FOR THE FIRST 36 HOURS. BEYOND TAU 36 THERE IS A DEGREE OF
UNCERTAINTY TO THE POSITION AND DEPTH OF THE SOUTHWARD TURN AND IN
THE EXTENDED TRACK AS TC AMOS INTERACTS WITH THE SUBROPICAL
WESTERLIES. DUE TO THE MENTIONED UNCERTAINTY, THERE IS LOW
CONFIDENCE IN THE FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT
221800Z IS 28 FEET. NEXT WARNINGS AT 230300Z, 230900Z, 231500Z AND
232100Z.
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Both RSMC Nadi and JWTC now have Amos making landfall on Samoa's two main islands around midday tomorrow as a low-end Cat 4. This is likely to be Samoa's worst TC since since Evan devastated its main islands in Dec 2012...
TROPICAL DISTURBANCE ADVISORY NUMBER A15 ISSUED FROM RSMC NADI
Apr 230156 UTC.
SEVERE TROPICAL CYCLONE AMOS CENTRE 965HPA CATEGORY 3 WAS LOCATED
NEAR 12.4S 174.5W AT 230000UTC. POSITION FAIR BASED ON
HIMAWARI-8/GOES IR IMAGERY AND PERIPHERAL SURFACE REPORTS. AMOS
MOVING EAST AT ABOUT 07 KNOTS. MAXIMUM 10-MINUTE AVERAGE WINDS NEAR
THE CENTRE ESTIMATED AT ABOUT 80 KNOTS.
EXPECT WINDS OVER 63 KNOTS WITHIN 15 NAUTICAL MILES OF CENTRE,
OVER 47 KNOTS WITHIN 30 NAUTICAL MILES OF CENTRE,
AND OVER 33 KNOTS WITHIN 50 NAUTICAL MILES OF CENTRE.
DEEP CONVECTION REMAINS PERSISTENT. ORGANISATION GOOD. SYSTEM LIES IN
A STRONG UPPER DIVERGENCE REGION AND IN A LOW SHEARED ENVIRONMENT.
SST AROUND 30 DEGREE CELCIUS. OUTFLOW GOOD TO THE EAST AND SOUTH.
SYSTEM IS BEING STEERED TO THE EAST BY THE WESTERLY DEEP LAYER MEAN
WIND FLOW. DVORAK ANALYSIS BASED ON EMBEDDED CENTRE PATTERN WITH LLCC
EMBEDDED IN CMG YIELDS DT=5.0. MET AND PT AGREE. FT BASED ON MET.
THUS, YIELDING T5.0/5.0/D1.5/24HRS.
GLOBAL MODELS MAINTAIN AN INITIAL EASTERLY TRACK AND THEN TURN IT
SOUTHEASTWARD WITH FURTHER INTENSIFICATION.
FORECASTS :
AT 12 HRS VALID AT 231200 UTC 12.9S 173.2W MOV ESE AT 07KT WITH 85 KT
CLOSE TO CENTRE
AT 24 HRS VALID AT 240000 UTC 13.6S 172.3W MOV SE AT 06KT WITH 90 KT
CLOSE TO CENTRE.
OUTLOOK:
AT 36 HRS VALID AT 241200 UTC 14.1S 171.7W MOV SE AT 04KT WITH 90 KT
CLOSE TO CENTRE
AT 48 HRS VALID AT 250000 UTC 14.7S 171.5W MOV SSE AT 03KT WITH 85 KT
CLOSE TO CENTRE.
THE NEXT TROPICAL DISTURBANCE ADVISORY ON TC AMOS WILL BE ISSUED
AROUND 230800UTC.
WTPS31 PGTW 230300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 20P (AMOS) WARNING NR 013//
RMKS/
1. TROPICAL CYCLONE 20P (AMOS) WARNING NR 013
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
230000Z --- NEAR 12.4S 174.9W
MOVEMENT PAST SIX HOURS - 095 DEGREES AT 08 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT
…
REMARKS:
230300Z POSITION NEAR 12.5S 174.6W. TROPICAL CYCLONE 20P (AMOS),
LOCATED APPROXIMATELY 270 NM WEST-NORTHWEST OF PAGO PAGO, HAS
TRACKED EASTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS CENTRAL DEEP
CONVECTION MAINTAINING A CENTRAL DENSE OVERCAST FEATURE THAT IS
MASKING THE LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL
POSITION IS BASED ON THE MSI LOOP AND EXTRAPOLATED FROM A 222121Z
AMSU-B 89 GHZ MICROWAVE IMAGE SHOWING TIGHT CONVECTIVE BANDING INTO
A VERY COMPACT MICROWAVE CIRCULATION CENTER, GIVING FAIR CONFIDENCE
TO THE INITIAL POSITION. THE INITIAL INTENSITY IS ASSESSED AT 90
KNOTS BASED ON CONSISTENT SUBJECTIVE DVORAK ESTIMATES FROM PGTW,
KNES AND NFFN. UPPER LEVEL ANALYSIS INDICATES TC 20P IS CURRENTLY IN
AN AREA OF LIGHT (5-10 KNOTS) VERTICAL WIND SHEAR (VWS) WITH A
STRONG POLEWARD OUTFLOW CHANNEL, WITH SOME CONVERGENCE AND
SUBSIDENCE EVIDENT ON THE EASTERN SIDE OF THE SYSTEM SOMEWHAT
LIMITING THE OUTFLOW IN THAT QUADRANT. TC AMOS IS TRACKING OVER AN
AREA OF VERY WARM SEA SURFACE TEMPERATURES (SSTS) NEAR 30 DEG
CELSIUS, PROVIDING ADDITIONAL SUPPORT TO THE SYSTEM. TC AMOS IS
EXPECTED TO INTENSIFY OVER THE NEXT 24 HOURS REACHING A PEAK
INTENSITY OF 100 KNOTS AS OUTFLOW AND VERTICAL WIND SHEAR CONDITIONS
CONTINUE TO BE FAVORABLE AS IT TRACKS EAST-SOUTHEASTWARD ALONG THE
SOUTHERN PERIPHERY OF A NEAR-EQUATORIAL RIDGE (NER). AFTER TAU 36 AN
EXTENSION OF THE STEERING NER BUILDS IN ON THE SOUTHEASTERN
PERIPHERY OF THE STORM, SLOWING THE FORWARD MOTION AND TURNING THE
SYSTEM ONTO A MORE SOUTHERLY TRACK OVER UPOLU ISLAND, SAMOA. DUE TO
LAND INTERACTION WITH UPOLU, TC AMOS WILL WEAKEN SLIGHTLY BEFORE
EMERGING BACK OVER WATER ON THE SLOW SOUTHERLY TRACK. BY TAU 72, TC
AMOS WILL BEGIN TO INTERACT WITH THE UPPER-LEVEL WESTERLY FLOW AND
TRANSITION TO A SOUTHEASTWARD TRACK WHILE QUICKLY WEAKENING AS
INCREASING VWS AND DECREASING SSTS WILL ERODE THE SYSTEM. DYNAMIC
MODEL GUIDANCE IS IN FAIRLY GOOD AGREEMENT THROUGH TAU 48 WITH THE
MAJORITY OF AVAILABLE MODEL TRACKERS TIGHTLY CLUSTERED ABOUT THE
FORECAST TRACK, WITH INCREASING UNCERTAINTY REGARDING THE SPEED AND
TRACK IN THE LATER TAUS, RESULTING IN LOW CONFIDENCE IN THE JTWC
FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 230000Z IS 28
FEET. NEXT WARNINGS AT 230900Z, 231500Z, 232100Z AND 240300Z.//
NNNN
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Yes, Samoa's capital looks to be right in the firing-line.
RSMC Nadi now expect Amos to remain a Cat 3 with mean winds of 150 km/h and a central pressure of 965 hPa. Amos's centre is currently only about 60-70 km off the NE coast off Samoa's largest island of Savai'i, and looks like he'll skirt along Savai'i and Upolu's northern coasts tonight and tomorrow morning.
TROPICAL DISTURBANCE ADVISORY NUMBER A16 ISSUED FROM RSMC NADI
Apr 230745 UTC.
SEVERE TROPICAL CYCLONE AMOS CENTRE 965HPA CATEGORY 3 WAS LOCATED
NEAR 12.9S 173.3W AT 230600UTC. POSITION FAIR BASED ON
HIMAWARI-8/GOES IR IMAGERY AND PERIPHERAL SURFACE REPORTS. AMOS
MOVING EAST-SOUTHEAST AT ABOUT 13 KNOTS. MAXIMUM 10-MINUTE AVERAGE
WINDS NEAR THE CENTRE ESTIMATED AT ABOUT 80 KNOTS.
EXPECT WINDS OVER 63 KNOTS WITHIN 15 NAUTICAL MILES OF CENTRE,
OVER 47 KNOTS WITHIN 30 NAUTICAL MILES OF CENTRE,
AND OVER 33 KNOTS WITHIN 50 NAUTICAL MILES OF CENTRE.
DEEP CONVECTION REMAINS PERSISTENT. ORGANISATION GOOD. SYSTEM LIES IN
A MODERATE TO STRONG UPPER DIVERGENCE REGION AND IN A LOW SHEARED
ENVIRONMENT. SST AROUND 30 DEGREE CELCIUS. OUTFLOW GOOD TO THE EAST
AND SOUTH. SYSTEM IS BEING STEERED TO THE EAST-SOUTHEAST BY THE
WEST-NORTHWEST DEEP LAYER MEAN WIND FLOW. DVORAK ANALYSIS BASED ON
EMBEDDED CENTRE PATTERN WITH LLCC EMBEDDED IN CMG YIELDS DT=5.0. MET
AND PT AGREE. FT BASED ON MET. THUS, YIELDING T5.0/5.0/D0.5/24HRS.
GLOBAL MODELS MAINTAIN A SOUTHEASTWARD TRACK WITH GRADUAL WEAKENING.
FORECASTS :
AT 12 HRS VALID AT 231800 UTC 13.5S 172.3W MOV ESE AT 06KT WITH 85 KT
CLOSE TO CENTRE
AT 24 HRS VALID AT 240600 UTC 14.0S 171.5W MOV SE AT 05KT WITH 85 KT
CLOSE TO CENTRE.
OUTLOOK:
AT 36 HRS VALID AT 241800 UTC 14.6S 171.1W MOV SE AT 05KT WITH 75 KT
CLOSE TO CENTRE
AT 48 HRS VALID AT 250600 UTC 15.1S 170.8W MOV SSE AT 05KT WITH 65 KT
CLOSE TO CENTRE.
THE NEXT TROPICAL DISTURBANCE ADVISORY ON TC AMOS WILL BE ISSUED
AROUND 231400UTC.
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JTWC also have Amos currently peaking at Cat 3. However, rather than making landfall, they seem to have his LLCC passing just off the northern coasts of Samoa's two main islands tonight and tomorrow morning, then passing directly over American Samoa's main island of Tutuila later tomorrow...
WTPS31 PGTW 230900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 20P (AMOS) WARNING NR 014//
RMKS/
1. TROPICAL CYCLONE 20P (AMOS) WARNING NR 014
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
230600Z --- NEAR 12.8S 173.2W
MOVEMENT PAST SIX HOURS - 105 DEGREES AT 15 KTS
POSITION ACCURATE TO WITHIN 040 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT
…
REMARKS:
230900Z POSITION NEAR 13.0S 172.8W.
TROPICAL CYCLONE 20P (AMOS), LOCATED APPROXIMATELY 171 NM WEST-
NORTHWEST OF PAGO PAGO, HAS TRACKED EAST-SOUTHEASTWARD AT 15 KNOTS
OVER THE PAST SIX HOURS. THE CURRENT POSITION IS BASED ON RECENT
MICROWAVE SATELLITE IMAGERY INCLUDING A 230528Z CORIOLIS AND A
230623Z SSMIS PASS. THE INTENSITY OF 90 KNOTS IS CONSISTENT WITH
SUBJECTIVE DVORAK INTENSITY ESTIMATES FROM MULTIPLE REPORTING
AGENCIES. TC 20P HAS ACCELERATED EAST-SOUTHEASTWARD OVER THE PAST
SIX HOURS UNDER THE STEERING INFLUENCE OF A NEAR-EQUATORIAL RIDGE TO
THE NORTH AND EAST. THIS RECENT CHANGE IN STORM MOTION HAS RESULTED
IN A SIGNIFICANT EASTWARD SHIFT IN THE ANTICIPATED TRACK, WHICH NOW
TAKES THE SYSTEM OVER TUTUILA, AMERICAN SAMOA WITHIN THE NEXT 24
HOURS. THE NEAR-EQUATORIAL RIDGE WILL REMAIN THE PRIMARY STEERING
INFLUENCE THROUGHOUT THE FORECAST PERIOD, ALTHOUGH THE RIDGE IS
EXPECTED TO WEAKEN AND STEER THE SYSTEM MORE SLOWLY POLEWARD IN THE
MEDIUM TO EXTENDED RANGE. TC 20P WILL REMAIN QUITE INTENSE FOR THE
NEXT FEW DAYS DUE TO STRONG POLEWARD OUTFLOW AND PASSAGE OVER VERY
WARM WATER. GRADUAL WEAKENING IS ANTICIPATED LATER IN THE FORECAST
PERIOD DUE TO INCREASING VERTICAL WIND SHEAR AND DECREASING
DIVERGENCE ALOFT. NUMERICAL MODELS ARE GENERALLY IN GOOD AGREEMENT
REGARDING THE OVERALL FORECAST SCENARIO, PARTICULARLY IN THE NEAR-
TERM, ALTHOUGH SPREAD INCREASES SIGNIFICANTLY IN THE LATER TAUS AS A
FEW MODELS DEPICT THE SYSTEM STALLING AS IT DISSIPATES WHILE OTHERS
DEPICT ACCELERATION INTO THE MID-LATITUDE WESTERLY FLOW PATTERN. THE
CURRENT FORECAST LIES CLOSE TO THE MULTI-MODEL CONSENSUS WITH HIGH
CONFIDENCE IN THE NEAR-TERM AND LOW CONFIDENCE IN THE EXTENDED
PERIOD. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 230600Z IS 28 FEET. NEXT
WARNINGS AT 232100Z AND 240900Z.//
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Satellite fixes appear to put Amos's LLCC passing about 17 km north of Fagamalo, Savai'i (main island), and about 34 km north of Apia, Upolu overnight. They appear to have escaped the worst of the winds, but there have been reports of heavy rain and flooding.
TROPICAL DISTURBANCE ADVISORY NUMBER A17 ISSUED FROM RSMC NADI
Apr 231341 UTC.
SEVERE TROPICAL CYCLONE AMOS CENTRE 970HPA CATEGORY 3 WAS LOCATED
NEAR 13.4S 171.8W AT 231200UTC. POSITION FAIR BASED ON
HIMAWARI-8/GOES IR IMAGERY AND PERIPHERAL SURFACE REPORTS. AMOS
MOVING EAST-SOUTHEAST AT ABOUT 15 KNOTS. MAXIMUM 10-MINUTE AVERAGE
WINDS NEAR THE CENTRE ESTIMATED AT ABOUT 80 KNOTS.
EXPECT WINDS OVER 63 KNOTS WITHIN 10 NAUTICAL MILES OF CENTRE.
EXPECT WINDS OVER 47 KNOTS WITHIN 30 NAUTICAL MILES IN NORTH
SEMICIRCLE
AND WITHIN 15 NAUTICAL MILES IN SOUTH
SEMICIRCLE.
EXPECT WINDS OVER 33 KNOTS WITHIN 50 NAUTICAL MILES IN NORTH
SEMICIRCLE
AND WITHIN 20 NAUTICAL MILES IN SOUTHWEST
QUADRANT
AND WITHIN 25 NAUTICAL MILES IN SOUTHEAST
QUADRANT.
DEEP CONVECTION REMAINS PERSISTENT. ORGANISATION GOOD. SYSTEM LIES IN
A MODERATE TO STRONG UPPER DIVERGENCE REGION AND IN A LOW TO MODERATE
SHEARED ENVIRONMENT. SST AROUND 30 DEGREE CELCIUS. OUTFLOW GOOD TO
THE EAST AND SOUTH. SYSTEM IS BEING STEERED TO THE EAST-SOUTHEAST BY
THE WEST-NORTHWEST DEEP LAYER MEAN WIND FLOW. DVORAK ANALYSIS BASED
ON EMBEDDED CENTRE PATTERN WITH LLCC EMBEDDED IN CMG YIELDS DT=5.0.
MET AND PT AGREE. FT BASED ON MET. THUS, YIELDING
T5.0/5.0/S0.0/24HRS.
GLOBAL MODELS MAINTAIN A SOUTHEASTWARD TRACK WITH GRADUAL WEAKENING.
WTPS31 PGTW 231500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 20P (AMOS) WARNING NR 015//
RMKS/
1. TROPICAL CYCLONE 20P (AMOS) WARNING NR 015
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
231200Z --- NEAR 13.4S 172.0W
MOVEMENT PAST SIX HOURS - 115 DEGREES AT 13 KTS
POSITION ACCURATE TO WITHIN 045 NM
POSITION BASED ON CENTER LOCATED BY A COMBINATION OF
SATELLITE AND SYNOPTIC DATA
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT
…
REMARKS:
231500Z POSITION NEAR 13.6S 171.7W.
TROPICAL CYCLONE 20P (AMOS), LOCATED APPROXIMATELY 93 NM NORTHWEST
OF PAGO PAGO, HAS TRACKED EAST-SOUTHEASTWARD AT 13 KNOTS OVER THE
PAST SIX HOURS. THE CURRENT POSITION IS BASED ON RECENT SATELLITE
FIXES FROM PGTW, KNES, AND PHFO. THE INTENSITY OF 90 KNOTS IS
CONSISTENT WITH SUBJECTIVE DVORAK CURRENT INTENSITY ESTIMATES FROM
MULTIPLE REPORTING AGENCIES. TC 20P HAS CONTINUED TO TRACK RAPIDLY
EAST-SOUTHEASTWARD UNDER THE STEERING INFLUENCE OF A NEAR-EQUATORIAL
RIDGE DURING THE PAST SIX HOURS. BASED ON RECENT STORM MOTION, NEAR-
TERM FORECAST TRACK SPEEDS HAVE INCREASED AND THE NEAR- TO MEDIUM-
TERM TRACK FORECAST HAS SHIFTED SLIGHTLY TO THE EAST FROM THE
PREVIOUS FORECAST. THE CENTER OF TC 20P IS NOW EXPECTED TO PASS NEAR
TUTUILA, AMERICAN SAMOA WITHIN THE NEXT 12 TO 18 HOURS. NEAR-
EQUATORIAL RIDGING WILL LIKELY REMAIN THE PRIMARY STEERING INFLUENCE
THROUGHOUT THE FORECAST PERIOD. HOWEVER, TRACK SPEED IS EXPECTED TO
DECREASE SIGNIFICANTLY BETWEEN 12 AND 36 HOURS DUE TO AN
ANTICIPATED, TEMPORARY WEAKENING OF THE STEERING RIDGE. STRONG
POLEWARD OUTFLOW AND PASSAGE OVER WARM WATER HAVE ENABLED TC 20P TO
MAINTAIN INTENSITY DESPITE A SLIGHTLY INCREASE IN VERTICAL WIND
SHEAR OVER THE PAST SIX HOURS. GRADUAL WEAKENING IS ANTICIPATED IN
THE MEDIUM TO EXTENDED FORECAST PERIOD DUE TO INCREASING VERTICAL
WIND SHEAR AND DECREASING DIVERGENCE ALOFT. NUMERICAL MODELS ARE
GENERALLY IN GOOD AGREEMENT REGARDING THE OVERALL FORECAST SCENARIO,
PARTICULARLY IN THE NEAR-TERM, ALTHOUGH SPREAD INCREASES
SIGNIFICANTLY IN THE LATER TAUS AS A FEW MODELS DEPICT THE SYSTEM
STALLING AND DISSIPATING WHILE OTHERS DEPICT ACCELERATION INTO THE
MID-LATITUDE WESTERLY FLOW PATTERN. THE CURRENT FORECAST LIES CLOSE
TO THE MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE IN THE NEAR-TERM
TRACK DIRECTION AND LOW CONFIDENCE IN TRACK DIRECTION AND SPEED
DURING THE EXTENDED PERIOD. MAXIMUM SIGNIFICANT WAVE HEIGHT AT
231200Z IS 28 FEET. NEXT WARNINGS AT 232100Z, 240300Z, 240900Z AND
241500Z.//
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I can,t understand how just last night you were posting the latest info that it was predicted to pass by midday today
and yet it was easy to see, at that time, it had accelerated and would pass overnight...anyone could see that...
maybe its a date line thing mix up/confusion?
Samoa is on the other side of the date line, i.e 23 hours behind us
Manukau heads obs wrote:I can,t understand how just last night you were posting the latest info that it was predicted to pass by midday today
and yet it was easy to see, at that time, it had accelerated and would pass overnight...anyone could see that...
maybe its a date line thing mix up/confusion?
Samoa is on the other side of the date line, i.e 23 hours behind us
That's what I said yesterday afternoon. However, last night I said that he'll pass just north of Samoa's main two islands "tonight and tomorrow morning" (which is now this morning) and American Samoa "later tomorrow" (which is now today).
I had noticed that both JTWC and RSMC Nadi had been underestimating Amos's forward speed post Advisories (probably hard to get regular fixes when the LLCC is cloud-covered). So what I said was way more accurate than what they had in their recent forecasts.
