Tropical Cyclones Winston & Tatiana

[Manukau heads obs]

this is a great video sequence of the cyclone sat animation
https://www.facebook.com/NWSWPC/videos/ ... 0/?fref=nf

[jamie]

amazing video that. You can really see how the cyclone was interacting with islands. The eye dances around a lot (almost like it was trying to hit the islands) as soon as it starting hitting the small islands and then the interaction with Viti Levu really pulled the eye south.

[melja]

Point taken but I still think it being called the most powerful ever in the southern hemisphere and the second most powerful in the world to make landfall is pushing it don't you think? Just a question from a fellow weather watcher so don't bag people who might think differently.

[Manukau heads obs]

it made landfall right when at its peak though (at its peak the eye was larger, it was very symetrical (good radial outflow in all qaurters), and the cloud tops were very cold and the eye wall was very uniform and complate)
and if you count the small islands in the channel it passed directly over, too
often cyclones weaken just before making landfall
so that is a key thing to take into consideration

try telling the people who's house is just a foundation and where the sea level rose 12m and the hills are stripped to bare dirt or people have lost loved ones, that you happen to think, yeah, nah, it was not as powerfull as they say

[jamie]

The heta on Niue was a cracker. Did a study at school on it. Waves crashed up over their clifs. Some up to like 30m if I remember right

[Nev]

Hey folks, let's keep things civil.

I think the point melja made about whether or not Winston is the strongest TC to make landfall in the southern hemisphere or second strongest in the world is quite a valid one. That claim appears to have originated from America based on JTWC's estimates, which (even correcting 1-minute vs. 10-minute mean-winds) have at times varied considerably from Fiji Met's estimates.

The same point was raised on Weatherzone's forum and I think esteemed BoM climatologist, Blair Trewin summed it up pretty well with the comment below…

Important to compare like with like here (you're probably sick of hearing me say that). One reason for inconsistency in reports is that JTWC (like other American agencies) measure maximum sustained winds over a 1-minute period, whereas most other agencies use a 10-minute period. All other things being equal, 10-minute maximum sustained winds are typically about 12% lower than 1-minute maximum winds, so the JTWC figure of 185 mph (298 km/h) equates to about 260 km/h for a 10-minute maximum.

Winston is the strongest South Pacific storm in the JTWC analysis (i.e. they've analysed it as having higher sustained winds than their analysis for Pam, among others). Whether Fiji ultimately analyse Winston as being stronger than Pam remains to be seen. What you can't do is compare the JTWC winds for one cyclone to the Fiji (or Australian) ones for another without correcting for the averaging period.

Ultimately, the uncertainties in satellite TC assessment (for a typical cyclone, probably +/- 0.5 to 1 category) are such that you can't conclude with confidence that any individual storm was the strongest, but you can reasonably conclude that Winston was, at least, one of the strongest TCs on record in the South Pacific (and is almost certainly the strongest to hit Fiji).

[melja]

The Heta on niue sure was a cracker, having spent 7 days there in Nov last year seeing the damage still there and hearing the stories i do have some respect! how about locking your whole family in a shipping container to ride out the storm and being washed to the center of the island and as Jamie said the whole yes whole island is surrounded by 30m cliffs and no beaches at all.
I got shown a coral boulder the size of a car that got deposited over 1km inland in the middle of a house.

[Nev]

Mod Note: I've cleaned up a couple of personal attacks in recent posts, which were probably a little uncalled for and not really the sort of thing the rest of us really want to be reading. Probably should have been done sooner, but I've been a little preoccupied lately.

[Nev]

Winston was downgraded to Cat 3 yesterday evening. Conditions improved a little earlier yesterday allowing some slight re-intensification, including a more well defined eye. However, later in the day the entrainment of a band of dry air began hindering any further development, although Winston still maintains a fairly ragged eye. Earlier this morning RSMC Nadi had a central pressure of 950 hPa, with max winds of about 160 km/h.

TROPICAL DISTURBANCE ADVISORY NUMBER A50 ISSUED FROM RSMC NADI
Feb 221319 UTC.

SEVERE TROPICAL CYCLONE WINSTON CENTRE 950HPA WAS LOCATED NEAR 18.3S
172.3E AT 221200 UTC. POSITION GOOD BASED ON HR MTSAT EIR AND
PERIPHERAL SURFACE REPORTS. CYCLONE MOVING SOUTHWEST AT ABOUT 03
KNOTS. MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT
ABOUT 85 KNOTS.
…
EYE PARTIALLY CLOUD FILLED BUT STILL DISCERNIBLE. DEEP CONVECTION
REMAINS PERSISTENT.ORGANIZATION REMAINS GOOD. SST AROUND 29-30
DEGREES CELSIUS. SYSTEM LIES IN A STRONG UPPER DIVERGENCE REGION AND
IN A MODERATE SHEARED ENVIRONMENT. OUTFLOW GOOD. DVORAK ANALYSIS
BASED ON OW EYE MG SURROUND YIELDS DT=4.5, MET AND PT AGREE, FT BASED
ON DT. THUS YIELDING T4.5/5.0/W1.0/24HRS.

FORECASTS :
AT 12 HRS VALID AT 230000 UTC 19.4S 172.8E MOV SSE AT 06KT WITH 80 KT
CLOSE TO CENTRE
AT 24 HRS VALID AT 231200 UTC 20.9S 173.8E MOV SSE AT 08KT WITH 80 KT
CLOSE TO CENTRE

OUTLOOK :
AT 36 HRS VALID AT 240000 UTC 22.5S 174.7E MOV SSE AT 09KT WITH 75 KT
CLOSE TO CENTRE
AT 48 HRS VALID AT 241200 UTC 24.0S 174.6E MOV SSE AT 08KT WITH 70
KT CLOSE TO CENTRE

WTPS31 PGTW 221500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TROPICAL CYCLONE 11P (WINSTON) WARNING NR 038
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 18.2S 172.3E
MOVEMENT PAST SIX HOURS - 180 DEGREES AT 03 KTS
POSITION ACCURATE TO WITHIN 020 NM
POSITION BASED ON EYE FIXED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT
…
REMARKS:
221500Z POSITION NEAR 18.5S 172.4E.
TROPICAL CYCLONE 11P (WINSTON), LOCATED APPROXIMATELY 348 NM WEST
OF SUVA, FIJI, HAS TRACKED SOUTHWARD AT 03 KNOTS OVER THE PAST
SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS
A RAGGED 20NM EYE THAT HAS CHANGED LITTLE IN STRUCTURE OVER THE LAST
SIX HOURS GIVING HIGH CONFIDENCE TO THE INITIAL POSITION. THE
CURRENT INTENSITY IS ASSESSED TO BE 90 KNOTS WHICH IS
BASED ON DVORAK ESTIMATES FROM ALL AGENCIES REPORTING CURRENT
INTENSITIES OF T5.0 (90 KNOTS). SEA SURFACE TEMPERATURES ARE WARM
(29 CELSIUS), AND A STRONG POLEWARD OUTFLOW CHANNEL EXISTS WHICH IS
HELPING TO MAINTAIN THE CURRENT INTENSITY. HOWEVER, THE EQUATORWARD
OUTFLOW CHANNEL IS SHOWING SIGNS OF WEAKENING DUE TO CONVERGENCE
OBSERVED NORTH OF THE CYCLONE, EVIDENT ON RECENT WATER VAPOR
IMAGERY. THE CIMSS MICROWAVE TPW LOOP ALSO INDICATES A BAND OF DRY
AIR CURRENTLY BEING ENTRAINED INTO THE CYCLONE HINDERING FURTHER
INTENSIFICATION. WINSTON SHOULD MAINTAIN ITS CURRENT INTENSITY FOR
THE NEXT 12 HOURS, BEFORE WEAKENING SIGNIFICANTLY DUE TO THE
DISRUPTION OF THE EQUATORWARD EXHAUST CHANNEL AND INCREASED VERTICAL
WIND SHEAR ASSOCIATED WITH A DEEPENING TROUGH TO THE WEST. THE
CURRENT MOVEMENT IS QUASI-STATIONARY AS THE PRIMARY STEERING
MECHANISM IS SHIFTING FROM A RIDGE RETROGRADING WESTWARD TO A RIDGE
BUILDING IN TO THE EAST. TC WINSTON WILL SOON ACCELERATE ALONG A
SOUTHEASTWARD TRACK, GUIDED BY THE BUILDING RIDGE TO THE EAST. BY
TAU 72, AS THE SYSTEM WEAKENS, THE DOMINANT STEERING MECHANISM WILL
SHIFT TO A LOW TO MID-LEVEL RIDGE TO THE SOUTH WHICH WILL STEER TC
WINSTON WESTWARD UNDER AN UPPER-LEVEL TROUGH. THE SUBSIDENCE
ASSOCIATED WITH THE TROUGH AND SSTS DROPPING BELOW 26 CELSIUS WILL
BEGIN SUBTROPICAL TRANSITION INTO A COLD CORE SYSTEM. TC WINSTON IS
FORECAST TO COMPLETE SUBTROPICAL TRANSITION BY TAU 96. DYNAMIC MODEL
GUIDANCE IS IN GOOD AGREEMENT PROVIDING HIGH CONFIDENCE TO THE
JTWC FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 221200Z IS
34 FEET. NEXT WARNINGS AT 222100Z, 230300Z, 230900Z AND 231500Z.//

[Razor]

Saddening to hear up to 25 dead in Fiji. Thoughts with those affected

[Nev]

Yes, latest toll is at least 29…

Winstone was downgraded to Cat 2 this morning. He's taken a bit of a battering over the last 24 hrs, with convection being sheared to the SE of LLCC overnight and a no longer discernible eye in recent hrs…

TROPICAL DISTURBANCE ADVISORY NUMBER A55 ISSUED FROM RSMC NADI
Feb 231936 UTC.

TROPICAL CYCLONE WINSTON CENTRE 975HPA CATEGORY 2 WAS LOCATED NEAR
22.1 SOUTH 174.9 EAST AT 231800 UTC. POSITION FAIR. CYCLONE MOVING
SOUTH-SOUTHEAST AT 10 KNOTS.
EXPECT SUSTAINED WINDS OF 60 KNOTS CLOSE TO THE CENTRE.
…
CONVECTION REMAINS PERSISTENT.CONVECTIVE BAND WRAPPING AROUND LLCC.
ORGANIZATION REMAINS GOOD. SST AROUND 28 DEGREES CELSIUS. SYSTEM LIES
IN A MODERATE TO STRONG UPPER DIVERGENCE REGION AND IN A LOW TO
MODERATE SHEARED ENVIRONMENT. OUTFLOW GOOD TO THE SOUTH. SYSTEM IS
BEING STEERED TO THE SOUTH-SOUTHEAST BY THE DEEP LAYER MEAN
NORTH-NORTHWEST WIND FLOW. DVORAK ANALYSIS BASED ON 0.70 WRAP YIELDS
DT=3.0, MET AND PT AGREE, FT BASED ON DT. THUS YIELDING
T3./4.0/W1.0/24HRS.

FORECASTS :
AT 12 HRS VALID AT 240600 UTC 23.6S 175.0E MOV S AT 08KT WITH 60 KT
CLOSE TO CENTRE
AT 24 HRS VALID AT 241800 UTC 25.0S 173.9E MOV SW AT 08KT WITH 55 KT
CLOSE TO CENTRE

OUTLOOK :
AT 36 HRS VALID AT 250600 UTC 26.1S 171.7E MOV WSW AT 12KT WITH 50 KT
CLOSE TO CENTRE
AT 48 HRS VALID AT 251800 UTC 27.1S 168.7E MOV WSW AT 14KT WITH 45 KT
CLOSE TO CENTRE

Earlier JTWC remarks...

WTPS31 PGTW 221500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TROPICAL CYCLONE 11P (WINSTON) WARNING NR 038
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 18.2S 172.3E
MOVEMENT PAST SIX HOURS - 180 DEGREES AT 03 KTS
POSITION ACCURATE TO WITHIN 020 NM
POSITION BASED ON EYE FIXED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT
…
REMARKS:
221500Z POSITION NEAR 18.5S 172.4E.
TROPICAL CYCLONE 11P (WINSTON), LOCATED APPROXIMATELY 348 NM WEST
OF SUVA, FIJI, HAS TRACKED SOUTHWARD AT 03 KNOTS OVER THE PAST
SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS
A RAGGED 20NM EYE THAT HAS CHANGED LITTLE IN STRUCTURE OVER THE LAST
SIX HOURS GIVING HIGH CONFIDENCE TO THE INITIAL POSITION. THE
CURRENT INTENSITY IS ASSESSED TO BE 90 KNOTS WHICH IS
BASED ON DVORAK ESTIMATES FROM ALL AGENCIES REPORTING CURRENT
INTENSITIES OF T5.0 (90 KNOTS). SEA SURFACE TEMPERATURES ARE WARM
(29 CELSIUS), AND A STRONG POLEWARD OUTFLOW CHANNEL EXISTS WHICH IS
HELPING TO MAINTAIN THE CURRENT INTENSITY. HOWEVER, THE EQUATORWARD
OUTFLOW CHANNEL IS SHOWING SIGNS OF WEAKENING DUE TO CONVERGENCE
OBSERVED NORTH OF THE CYCLONE, EVIDENT ON RECENT WATER VAPOR
IMAGERY. THE CIMSS MICROWAVE TPW LOOP ALSO INDICATES A BAND OF DRY
AIR CURRENTLY BEING ENTRAINED INTO THE CYCLONE HINDERING FURTHER
INTENSIFICATION. WINSTON SHOULD MAINTAIN ITS CURRENT INTENSITY FOR
THE NEXT 12 HOURS, BEFORE WEAKENING SIGNIFICANTLY DUE TO THE
DISRUPTION OF THE EQUATORWARD EXHAUST CHANNEL AND INCREASED VERTICAL
WIND SHEAR ASSOCIATED WITH A DEEPENING TROUGH TO THE WEST. THE
CURRENT MOVEMENT IS QUASI-STATIONARY AS THE PRIMARY STEERING
MECHANISM IS SHIFTING FROM A RIDGE RETROGRADING WESTWARD TO A RIDGE
BUILDING IN TO THE EAST. TC WINSTON WILL SOON ACCELERATE ALONG A
SOUTHEASTWARD TRACK, GUIDED BY THE BUILDING RIDGE TO THE EAST. BY
TAU 72, AS THE SYSTEM WEAKENS, THE DOMINANT STEERING MECHANISM WILL
SHIFT TO A LOW TO MID-LEVEL RIDGE TO THE SOUTH WHICH WILL STEER TC
WINSTON WESTWARD UNDER AN UPPER-LEVEL TROUGH. THE SUBSIDENCE
ASSOCIATED WITH THE TROUGH AND SSTS DROPPING BELOW 26 CELSIUS WILL
BEGIN SUBTROPICAL TRANSITION INTO A COLD CORE SYSTEM. TC WINSTON IS
FORECAST TO COMPLETE SUBTROPICAL TRANSITION BY TAU 96. DYNAMIC MODEL
GUIDANCE IS IN GOOD AGREEMENT PROVIDING HIGH CONFIDENCE TO THE
JTWC FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 221200Z IS
34 FEET. NEXT WARNINGS AT 222100Z, 230300Z, 230900Z AND 231500Z.//

[Nev]

Winston has weakened rapidly today and with a fully exposed LLCC thanks to strong shear; along with dry air and cold SST's, it looks like he may even be lucky to last the night...

TROPICAL DISTURBANCE ADVISORY NUMBER A56 ISSUED FROM RSMC NADI
Feb 240129 UTC.

TROPICAL CYCLONE WINSTON CENTRE 975HPA CATEGORY 2 WAS LOCATED NEAR
23.3 SOUTH 176.5 EAST AT 240000 UTC. POSITION FAIR. CYCLONE MOVING
SOUTH-SOUTHEAST AT 13 KNOTS.
EXPECT SUSTAINED WINDS OF 60 KNOTS CLOSE TO THE CENTRE.
EXPECT WINDS OVER 47 KNOTS WITHIN 80 NAUTICAL MILES OF CENTR
…
CONVECTION REMAINS PERSISTENT.CONVECTIVE BAND WRAPPING AROUND LLCC.
ORGANIZATION REMAINS GOOD. SST AROUND 28 DEGREES CELSIUS. SYSTEM LIES
IN A MODERATE TO STRONG UPPER DIVERGENCE REGION AND IN A LOW TO
MODERATE SHEARED ENVIRONMENT. OUTFLOW GOOD TO THE SOUTH. SYSTEM IS
BEING STEERED TO THE SOUTH-SOUTHEAST BY THE DEEP LAYER MEAN
NORTH-NORTHWEST WIND FLOW. DVORAK ANALYSIS BASED ON 0.60 WRAP YIELDS
DT=3.0, MET AND PT AGREE, FT BASED ON DT. THUS YIELDING
T3./4.0/W1.0/24HRS.

FORECASTS :
AT 12 HRS VALID AT 241200 UTC 24.9S 175.9E MOV S AT 08KT WITH 50 KT
CLOSE TO CENTRE
AT 24 HRS VALID AT 250000 UTC 26.2S 174.0E MOV SW AT 08KT WITH 50 KT
CLOSE TO CENTRE

OUTLOOK :
AT 36 HRS VALID AT 251200 UTC 27.5S 170.7E MOV WSW AT 12KT WITH 45 KT
CLOSE TO CENTRE
AT 48 HRS VALID AT 251800 UTC 28.2S 167.2E MOV WSW AT 14KT WITH 40 KT
CLOSE TO CENTRE

THE NEXT TROPICAL DISTURBANCE ADVISORY ON WINSTON WILL BE ISSUED
AROUND 240800 UTC.

WTPS31 PGTW 240300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 11P (WINSTON) WARNING NR 044//
RMKS/
1. TROPICAL CYCLONE 11P (WINSTON) WARNING NR 044
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
240000Z --- NEAR 22.7S 174.3E
MOVEMENT PAST SIX HOURS - 180 DEGREES AT 11 KTS
POSITION ACCURATE TO WITHIN 050 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
…
REMARKS:
240300Z POSITION NEAR 23.0S 174.1E.
TROPICAL CYCLONE 11P (WINSTON), LOCATED APPROXIMATELY 360 NM
SOUTHWEST OF SUVA, FIJI, HAS TRACKED SOUTHWARD AT 11 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
DEPICTS AN ELONGATED AND FULLY EXPOSED LOW-LEVEL CIRCULATION CENTER
(LLCC) WITH DEEP CONVECTION SHEARED TO THE SOUTH. A 232156Z GPM 36
GHZ IMAGE REVEALS A BROAD BUT DEFINED CENTER WITH DEEP CONVECTION
CONSTRAINED TO THE SOUTHERN SEMI-CIRCLE. THE INITIAL INTENSITY IS
ASSESSED AT 50 KNOTS BASED ON DVORAK CURRENT INTENSITY ESTIMATES
OF T3.0 (45 KNOTS) FROM PGTW AND KNES, AND ROUNDING UP TO ACCOUNT
FOR A 232125Z ASCAT PARTIAL PASS. UPPER-LEVEL ANALYSIS REVEALS
AN INCREASINGLY UNFAVORABLE ENVIRONMENT WITH STRONG (40 TO 50 KNOTS)
VERTICAL WIND SHEAR (VWS) AND DRY AIR ENTRAINMENT. TC 11P IS
TRACKING ALONG THE WESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR)
AND IS FORECAST TO BEGIN TURNING SOUTHWESTWARD BY TAU 12 AND WEST-
SOUTHWESTWARD BY TAU 24, AS THE STEERING MECHANISM TRANSITIONS TO A
BUILDING STR TO THE SOUTH. TC WINSTON IS FORECAST TO CONTINUE
WEAKENING RAPIDLY THROUGH THE FORECAST PERIOD DUE TO HIGH VWS, DRY
AIR ENTRAINMENT, AND COLD SSTS. TC WINSTON IS ALSO INTERACTING WITH
AN UPPER-LEVEL LOW TO THE WEST. TC 11P WILL TRANSITION INTO A
SUBTROPICAL SYSTEM BY TAU 36, HOWEVER, IT IS POSSIBLE WINSTON MAY
DISSIPATE PRIOR TO THAT TIME. DYNAMIC MODEL GUIDANCE REMAINS IN GOOD
AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST
TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 240000Z IS 17 FEET. NEXT
WARNINGS AT 240900Z, 241500Z, 242100Z AND 250300Z.//

[Nev]

Winstone was downgraded to Cat 1 earlier this morning, as he continues to rapidly weaken and will likely be declared extratropical today (maybe even this morn)…

ROPICAL DISTURBANCE ADVISORY NUMBER A58 ISSUED FROM RSMC NADI
Feb 241330 UTC.

TROPICAL CYCLONE WINSTON CENTRE 987HPA CATEGORY 1 WAS LOCATED NEAR
24.6S 173.8E AT 241200 UTC. POSITION FAIR BASED ON HR MTSAT EIR
IMAGERY. CYCLONE MOVING SOUTH- SOUTHWEST AT ABOUT 10 KNOTS. MAXIMUM
10-MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT ABOUT 45 KNOTS.
…
DEEP CONVECTION HAS DECREASED SIGNIFICANTLY AND IS DISPLACED TO THE
SOUTH. SST AROUND 26 DEGREES CELSIUS. SYSTEM LIES IN A HIGH SHEARED
ENVIRONMENT. DRY AIR ENTRAINMENT FROM THE NORTHWEST. DVORAK ANALYSIS
BASED ON SHEAR PATTERN WITH LLCC GREATER THEN 5/4 DEGREES FROM
CONVECTION YEILDS DT=1.5, MET=2.0 AND PT=1.5, FT BASED ON MET. THUS
YIELDING T2.0/3.0/W1.5/24HRS.

FORECASTS :
AT 12 HRS VALID AT 250000 UTC 25.8S 171.6E MOV WSW AT 12KT WITH 40 KT
CLOSE TO CENTRE
AT 24 HRS VALID AT 251200 UTC 27.0S 168.1E MOV WSW AT 15KT WITH 35 KT
CLOSE TO CENTRE

THIS WILL BE THE FINAL TROPICAL DISTURBANCE ADVISORY ON WINSTON.

WTPS31 PGTW 240900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 11P (WINSTON) WARNING NR 045//
RMKS/
1. TROPICAL CYCLONE 11P (WINSTON) WARNING NR 045
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
…
REMARKS:
240900Z POSITION NEAR 23.9S 173.7E.
TROPICAL CYCLONE (TC) 11P (WINSTON), LOCATED APPROXIMATELY 404 NM
SOUTHWEST OF SUVA, FIJI, HAS TRACKED SOUTH-SOUTHWESTWARD AT 08 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
DEPICTS AN EXPOSED, BROAD LOW-LEVEL CIRCULATION CENTER WITH DEEP
CONVECTION SHEARED TO THE SOUTH. A 240439Z SSMIS 91 GHZ IMAGE
REVEALS SHALLOW BANDING WRAPPING AROUND A DEFINED BUT BROAD CENTER,
WHICH PROVIDES GOOD CONFIDENCE IN THE CURRENT POSITION. THE INITIAL
INTENSITY IS ASSESSED AT 50 KNOTS, HEDGED SLIGHTLY HIGHER THAN THE
PGTW DVORAK CURRENT INTENSITY ESTIMATE OF 3.0 (45 KNOTS), BASED ON
RECENT ASCAT DATA. UPPER-LEVEL ANALYSIS SHOWS AN UNFAVORABLE
ENVIRONMENT WITH STRONG (30 TO 40 KNOTS) VERTICAL WIND SHEAR (VWS).
TC 11P IS TRACKING ALONG THE WESTERN PERIPHERY OF THE SUBTROPICAL
RIDGE (STR) AND IS FORECAST TO TURN SOUTHWESTWARD TO WEST-
SOUTHWESTWARD AS IT TRANSITIONS TO THE STEERING INFLUENCE OF A
BUILDING STR TO THE SOUTH. TC 11P IS EXPECTED TO CONTINUE WEAKENING
AS IT ENCOUNTERS INCREASING VWS AND COOLER SST. NEAR TAU 24, THE
SYSTEM WILL BEGIN TO INTERACT WITH AN UPPER-LEVEL SUBTROPICAL LOW.
BY TAU 36, 11P WILL TRANSITION FULLY INTO A SUBTROPICAL LOW BUT IS
EXPECTED TO MAINTAIN GALE-FORCE WINDS. DYNAMIC MODEL GUIDANCE
REMAINS IN GOOD AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN
THE JTWC FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 240600Z
IS 17 FEET. NEXT WARNINGS AT 241500Z, 242100Z, 250300Z AND 250900Z.//

[Manukau heads obs]

video showing how its like a bomb had gone off for some of the islands
https://youtu.be/AmT2JVNOGPw

[Orion]

Grievous damage indeed.

[Nev]

Yes, heart-breaking looking at some of the images. Toll currently stands at 44 and expected to increase.

Fiji's previous deadliest TC's were Cat 3 Kina in 1993 and Cat 3 Eric in 1985. Kina passed between Fiji's Fiji's two main islands of Viti Levu and Vanua Levu from WNW to ESE in Jan 1993 as a Cat 2, causing 23 deaths. And Cat 3 Eric at its peak crossed the main Island of Viti Levu in Jan 1985, also from WNW to ESE, making a direct hit on Suva, causing 25 deaths. Eric was followed less than 2 days later by Cat 3 Nigel making landfall near its peak and crossing northern areas of Viti Levu.

Also just an update on the earlier claim that Winston was the strongest TC in the S.H. and 2nd strongest in the world to make landfall. It would appear that JTWC's initial estimates have been downgraded slightly according to a follow-up comment made by BoM climatologist, Blair Trewin a couple of days ago…

Latest talk I'm seeing in tropical cyclone quarters (although I haven't confirmed this directly with the sources) is that the landfall intensity of Winston has been downgraded slightly and it is no longer assessed as clearly the strongest South Pacific cyclone, although it's clearly amongst the top few, along with Pam, Zoe and Monica. (As I've noted earlier, the uncertainties in tropical cyclone intensity measurement are such that trying to do a ranking amongst those top few is fairly meaningless).

I've also heard a second-hand report of a measured AWS gust of 296 km/h in Fiji.

[Nev]

Winston was downgraded to an Ex-TC this afternoon, and JTWC issued its Final Warning earlier this morning...

WTPS31 PGTW 242100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 11P (WINSTON) WARNING NR 047//
RMKS/
1. TROPICAL CYCLONE 11P (WINSTON) WARNING NR 047
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
241800Z --- NEAR 25.2S 172.8E
MOVEMENT PAST SIX HOURS - 225 DEGREES AT 11 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
…
REMARKS:
242100Z POSITION NEAR 25.5S 172.0E. TROPICAL CYCLONE 11P (WINSTON),
LOCATED APPROXIMATELY 367 NM NORTHEAST OF KINGSTON IS., HAS TRACKED
SOUTHWESTWARD AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED
INFRARED SATELLITE IMAGERY DEPICTS AN EXPOSED, BROAD LOW-LEVEL
CIRCULATION CENTER (LLCC) WITH SHALLOW CONVECTION SHEARED TO THE
SOUTH. A 241514Z SSMI 89 GHZ IMAGE REVEALS SHALLOW BANDING WRAPPING
AROUND THE BROAD LLCC, WHICH PROVIDES GOOD CONFIDENCE IN THE CURRENT
POSITION. THE INITIAL INTENSITY IS SLIGHTLY HIGHER, ASSESSED AT 40
KNOTS, THAN DVORAK INTENSITY ESTIMATES WOULD SUGGEST DUE TO THE
HIGHLY SHEARED NATURE OF THE SYSTEM. A ASCAT PASS FROM APPROXIMATELY
10 HOURS AGO ALSO INDICATED A BROAD REGION OF 30-40 KNOT WINDS
AROUND THE SYSTEM. ENVIRONMENTAL ANALYSIS INDICATES THAT TC WINSTON
IS TRACKING THROUGH A HIGHLY UNFAVORABLE REGION WITH STRONG (30 TO
40 KNOTS) VERTICAL WIND SHEAR (VWS) AND LOW SEA SURFACE TEMPERATURES
OF 26 CELSIUS. TC WINSTON HAS WEAKENED TO THE POINT THAT THE PRIMARY
STEERING MECHANISM IS NOW THE RELATIVELY SHALLOW SUBTROPICAL RIDGE
(STR) TO THE SOUTH, STEERING THE SYSTEM WESTWARD. TC WINSTON IS
ALREADY EXHIBITING SIGNS OF BEING SUBTROPICAL, WITH THE MID-LEVEL
WARM CORE WEAKENING AND THE WIND FIELD EXPANDING. THE SYSTEM IS
FORECAST TO COMPLETE SUBTROPICAL TRANSITION BY TAU 12, BUT IS
EXPECTED TO MAINTAIN GALE-FORCE WINDS. DYNAMIC MODEL GUIDANCE
REMAINS IN GOOD AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN
THE JTWC FORECAST TRACK. THIS IS THE FINAL WARNING ON THIS SYSTEM BY
THE JOINT TYPHOON WRNCEN PEARL HARBOR HI. THE SYSTEM WILL BE CLOSELY
MONITORED FOR SIGNS OF REGENERATION. MAXIMUM SIGNIFICANT WAVE HEIGHT
AT 241800Z IS 18 FEET.//

MetService - Subtropic high seas forecast

TROPICAL CYCLONE GALE WARNING 376
This affects ocean area: SUBTROPIC
Tropical Cyclone WINSTON [987hPa] centre was located near 25.0 South 172.5 East at 241800 UTC.
Position Fair.
Repeat position 25.0S 172.5E at 241800 UTC.
Cyclone is moving southwest 10 knots.
Expect sustained winds of 45 knots close to the centre with very rough sea and moderate to heavy swell.
Expect winds over 33 knots within 400 nautical miles of centre in the southeast quadrant and within 320 nautical miles of centre in the southwest quadrant and within 150 nautical miles of centre in the northern semicircle.

Forecast position near 26.3S 169.3E at 250600 UTC
and near 27.8S 165.0E at 251800 UTC.
This warning cancels and replaces warning 375.

Issued at 8:15am Thursday 25 Feb 2016

MetService - Subtropic high seas forecast

STORM WARNING 383
This affects ocean area: SUBTROPIC
AT 250000UTC
Over waters south of 25S.
Low 992hPa, former Cyclone WINSTON, near 26S 171E moving westsouthwest 15kt.
1. Within 120 nautical miles of low in southern quadrant: Clockwise 50kt easing to 40kt next 6-12 hours.
2. Outside area 1 and within 240 nautical miles of low in southern semicircle: Clockwise 40kt.
3. Outside areas 1 and 2 and within 120 nautical miles of low in northern semicircle: Clockwise 35kt.
Storm and gale areas moving with low.
This warning cancels and replaces warning 376.

Issued at 1:43pm Thursday 25 Feb 2016

[Nev]

Just for posterity, I thought I'd include MeSerivce's first (and only?) decent track-map…

TC Winston - MetService Track-map - Feb 24, 1800z.jpg

[Manukau heads obs]

https://www.climate.gov/news-features/e ... l-paradise

[Nev]

https://www.climate.gov/news-features/e ... l-paradise

According to JTWC's revised track-file, those figures for Winston are already out of date. JTWC have reduced Winston's estimated peak 1-minute mean-winds to 155 kts (about 178 mph or 287 km/h). That also equates to 10-minute mean-winds of about 253 km (160 mph), compared to RSMC Nadi's peak 10-minute mean-winds of about 232 km/h (144 mph).

Also note that JTWC had winds peaking after the island of Vanua Balvau recorded max mean-winds of 220 km/h as Winston's eye passed directly over it. I would have thought some weakening due to land interaction with Fiji's main islands would have occurred between then and Winston making landfall on the main island of Viti Levu about 12 hrs later. So I'm more inclined to believe RSMC Nadi's estimated peak winds of about 230 km/h.

For comparison:

In 2015, TC Pam's peak 10-minute mean-winds were estimated by RSMC Nadi at 250 km/h (155 mph), while JTWC had peak 1-minute mean-winds of 270 km/h (160 mph).

In 2006, TC Monica's peak 10-minute mean-winds were estimated by the BoM at 250 km/h (155 mph), while JTWC had peak 1-minute mean-winds of 285 km/h (180 mph).

And in 2002, TC Zoe's peak 10-minute mean-winds were estimated by RSMC Nadi at 240 km/h (150 mph), while JTWC had peak 1-minute mean-winds of 285 km/h (180 mph).

[Manukau heads obs]

mouse over the photos...Koro island destruction
http://www.abc.net.au/news/2016-03-07/f ... on/7220784

[jamie]

Gob smacked! That to me is jaw dropping!

[Nev]

That second sat-pic is amazing… buildings vanished… washed out to sea.

The last pic is of southern Yasawa Islands group, just NW of Viti Levu.

This image from the Suomi NPP satellite's VIIRS instrument shows Winston's eye directly over Koro Island.