Tropical Cyclone Pam - SW Pacific

[Manukau heads obs]

eye visible now on IR sat image
still moving slowly south on the 170 line

[Nev]

Nadi upgraded Pam to Cat 4 earlier this morning and according to their track-map will become a 'Cat 6' tomorrow?

The nicely developed eye last night has also begun 'corkscrewing' this morning, with the bulk of convection offset to her west flank. I wonder if she's going through an eye-wall replacement?

TROPICAL DISTURBANCE ADVISORY NUMBER A18 ISSUED FROM RSMC NADI
Mar 11/1402 UTC 2015 UTC.

SEVERE TROPICAL CYCLONE PAM CENTRE 946HPA CATEGORY 4 WAS LOCATED NEAR
11.4S 169.7E AT 111200 UTC. POSITION POOR BASED ON HR GMS EIR IMAGERY
AND PERIPHERAL SURFACE REPORTS. CYCLONE MOVING SOUTHEAST AT ABOUT 4
KNOTS. MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT
ABOUT 90 KNOTS. EXPECT WINDS ABOVE 63 KNOTS WITHIN 30 NAUTICAL MILES
OF CENTRE, ABOVE 47 KNOTS WITHIN 60 NAUTICAL MILES OF CENTRE AND
ABOVE 33 KNOTS WITHIN 300 NAUTICAL MILES IN N SEMICIRCLE AND WITHIN
180 NAUTICAL MILES ELSEWHERE.

ORGANISATION REMAINS GOOD. DEEP CONVECTION REMAINS PESISTENT. SYSTEM
LIES IN A HIGH SHEARED ENVIRONMENT. OUTFLOW GOOD. CYCLONIC
CIRCULATION EXTENDS TO 300HPA. SST AROUND 30 DEGREES CELSIUS. PAM IS
BEING STEERED SOUTHWARDS BY A NORTHERLY DEEP LAYER MEAN FLOW. DVORAK
ANALYSIS BASED ON EYE PATTERN WITH LG EYE EMBD IN W SURROUND, YEILDS
DT=6.0, MET= 5.5,PT=5.5. FT BASED ON MET. THUS YIELDING
T5.5/5.5/D1.0/24HRS

GLOBAL MODEL HAVE PICKED THE SYSTEM AND MOVE IT SOUTHWARDS WITH
FURTHER INTENSIFICATION.
...

WTPS31 PGTW 111500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 17P (PAM) WARNING NR 008//
RMKS/
1. TROPICAL CYCLONE 17P (PAM) WARNING NR 008
02 ACTIVE TROPICAL CYCLONES IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
111200Z --- NEAR 11.5S 169.7E
MOVEMENT PAST SIX HOURS - 180 DEGREES AT 03 KTS
POSITION ACCURATE TO WITHIN 030 NM
POSITION BASED ON EYE FIXED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 115 KT, GUSTS 140 KT
...
REMARKS:
111500Z POSITION NEAR 11.8S 169.7E.
TROPICAL CYCLONE (TC) 17P (PAM), LOCATED APPROXIMATELY 641 NM
NORTHWEST OF SUVA, FIJI, HAS TRACKED SOUTHWARD AT 03 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED IR SATELLITE
IMAGERY DEPICTS A WELL CONSOLIDATED SYSTEM WITH A DEVELOPING
EYE AND INTENSE DEEP CONVECTIVE BANDING. A 111058Z AMSU-B AND
111013Z TRMM PARTIAL IMAGE SHOWS A WELL CURVED BANDING WRAPPING INTO
A DEVELOPING MICROWAVE EYE FEATURE WITH THE BULK OF THE DEEP
CONVECTION IN THE NORTHWESTERN QUADRANT. THE INITIAL INTENSITY IS
BASED ON DVORAK DT ESTIMATES OF 6.0 FROM KNES AND PTGW.
UPPER-LEVEL ANALYSIS INDICATES A CONTINUED FAVORABLE ENVIRONMENT
REGARDLESS OF THE HIGH VERTICAL WIND SHEAR (VWS) DUE TO THE RADIAL
VIGOROUS OUTFLOW. ADDITIONALLY, THE OCEAN HEAT CONTENT REMAINS
FAVORABLE FOR CONTINUED DEVELOPMENT. TC PAM IS TRACKING ALONG THE
WESTERN EXTENSION OF THE SUBTROPICAL RIDGE (STR) TO THE EAST. AS THE
STR CONTINUES TO BUILD INTO THE WEST, TC PAM WILL CONTINUE TO
INTENSIFY OVER THE NEXT 48 HOURS DUE TO THE FAVORABLE ENVIRONMENT
AND SEA SURFACE TEMPERATURES (SSTS). AS THE SYSTEM ROUNDS THE AXIS
OF THE STR, INCREASED VWS AND DECREASING SSTS WILL CAUSE THE SYSTEM
TO BEGIN TO WEAKEN. ADDITIONALLY, BY TAU 72, THE SYSTEM WILL BEGIN
EXTRA-TROPICAL TRANSITION (ETT) AS IT INTERACTS WITH THE BAROCLINIC
ZONE AND IS EXPECTED TO COMPLETE ETT BY TAU 96. DYNAMIC MODEL
GUIDANCE CONTINUES TO BE IN GOOD AGREEMENT WITH THE TRACK, LENDING
TO A HIGH CONFIDENCE IN THE JTWC OFFICIAL FORECAST. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 111200Z IS 35 FEET.
…

[Manukau heads obs]

JTWC track map has it further east more again for NZ...hummmm

[Nev]

JTWC track map has it further east more again for NZ...hummmm

I think that's just an optical illusion as the area of uncertainty shrinks. If anything, it's marginally more west.

[Manukau heads obs]

ah, OK, you might be right (I had not had my coffee at that stage, LOL)

[David]

Not looking too good for a decent rainfall anymore in more recent model runs

[harleyb]

A couple of model runs I saw this morning suggest the possibility of a slight westward hook in the track by the time Pam gets to NZ latitudes, hinting at weak blocking to the east. Hard to tell but can't rule it out just yet.

[Manukau heads obs]

its forward speed has increased heaps last couple of hours

[Nev]

Latest from JTWC…

WTPS31 PGTW 112100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 17P (PAM) WARNING NR 009//
RMKS/
1. TROPICAL CYCLONE 17P (PAM) WARNING NR 009
02 ACTIVE TROPICAL CYCLONES IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
111800Z --- NEAR 11.9S 170.1E
MOVEMENT PAST SIX HOURS - 135 DEGREES AT 06 KTS
POSITION ACCURATE TO WITHIN 030 NM
POSITION BASED ON EYE FIXED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 115 KT, GUSTS 140 KT
...
REMARKS:
112100Z POSITION NEAR 12.3S 170.1E.
TROPICAL CYCLONE (TC) 17P (PAM), LOCATED APPROXIMATELY 608 NM
NORTHWEST OF SUVA, FIJI, HAS TRACKED SOUTHEASTWARD AT 06 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY DEPICTS TIGHTLY CURVED BANDING WRAPPING INTO A 30 NM RAGGED
EYE. AN 111534Z SSMI MICROWAVE IMAGE REVEALS EXTENSIVE DEEP
CONVECTION OVER THE EASTERN PERIPHERY AND AN APPARENT MICROWAVE EYE.
THE CURRENT POSITION IS BASED ON THE EYE FEATURE WITH HIGH
CONFIDENCE. THE INITIAL INTENSITY REMAINS AT 115 KNOTS BASED ON AN
OVERALL ASSESSMENT OF DVORAK INTENSITY ESTIMATES FROM ALL REPORTING
AGENCIES. UPPER-LEVEL ANALYSIS INDICATES A POINT SOURCE LOCATED
DIRECTLY OVER THE SYSTEM SUSTAINING THE CONVECTION AND PROVIDING
ROBUST OUTFLOW. TC PAM IS CURRENTLY TRACKING ALONG THE WESTERN
EXTENSION OF THE SUBTROPICAL RIDGE (STR) TO THE EAST. OVER THE NEXT
48 HOURS, FAVORABLE CONDITIONS ARE EXPECTED TO PERSIST ALLOWING THE
SYSTEM TO FURTHER INTENSIFY LEADING TO A PEAK INTENSITY OF 140
KNOTS. BY TAU 72, THE SYSTEM WILL BEGIN EXTRA-TROPICAL TRANSITION
(ETT) AS IT INTERACTS WITH THE BAROCLINIC ZONE AND IS EXPECTED TO
COMPLETE ETT BY TAU 96. AVAILABLE MODEL GUIDANCE REMAINS IN GOOD
AGREEMENT, LENDING TO HIGH CONFIDENCE IN THE JTWC OFFICIAL FORECAST.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 111800Z IS 36 FEET. NEXT WARNINGS
AT 120300Z, 120900Z, 121500Z AND 122100Z.
…

[Manukau heads obs]

you have Nathan's text there Nev..

[Nev]

Oops! Thanks… amended now. Been meaning to update Nathan, but bit short on time.

[Manukau heads obs]

jogged now more SW latest sat image sequence...

[Manukau heads obs]

latest BOM has it a bit closer again..and very intense!

[Nev]

JTWC has inched her very slightly to the east of NZ this time.

I have a friend attending a conference in Noumea atm. Hopefully she arrives back to Akld on Saturday... just in time for round two… lol

[Manukau heads obs]

Pam is wobbling alot , like a spinning top...and loves the 170 longitude line!

[Nev]

Latest RSMC Nadi remarks…

TROPICAL DISTURBANCE ADVISORY NUMBER A20 ISSUED FROM RSMC NADI
Mar 12/0145 UTC 2015 UTC.

SEVERE TROPICAL CYCLONE PAM CENTRE 935HPA CATEGORY 4 WAS LOCATED NEAR
12.5S 170.2E AT 120000 UTC. POSITION FAIR BASED ON HR GMS VIS IMAGERY
AND PERIPHERAL SURFACE REPORTS. CYCLONE MOVING SOUTH AT ABOUT 2
KNOTS. MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT
ABOUT 100 KNOTS.

EXPECT WINDS OVER 63 KNOTS WITHIN 45 NAUTICAL MILES OF CENTRE.
EXPECT WINDS OVER 47 KNOTS WITHIN 60 NAUTICAL MILES OF CENTRE.
EXPECT WINDS OVER 33 KNOTS WITHIN 300 NAUTICAL MILES IN NORTHEAST
QUADRANT,
AND WITHIN 210 NAUTICAL MILES IN NORTHWEST
QUADRANT,
AND WITHIN 120 NAUTICAL MILES ELSEWHERE.

ORGANISATION REMAINS GOOD. DEEP CONVECTION REMAINS PESISTENT. SYSTEM
LIES IN A MODERATE SHEARED ENVIRONMENT. OUTFLOW GOOD. CYCLONIC
CIRCULATION EXTENDS TO 300HPA. SST AROUND 30 DEGREES CELSIUS. PAM IS
BEING STEERED SOUTHWARDS BY A NORTHERLY DEEP LAYER MEAN FLOW. DVORAK
ANALYSIS BASED ON EYE PATTERN WITH DG EYE EMBD IN W, YIELDS DT=6.0,
MET AND PAT AGREE. THUS YIELDING T6.0/6.0/D1.0/24HRS.

GLOBAL MODELS MOVE THE SYSTEM SOUTHWARDS WITH FURTHER
INTENSIFICATION.

[Manukau heads obs]

wow
935hpa
100kts average windspeed
intense!

[Nev]

Yeah, and she's almost as wide as the North island. From JTWC…

WTPS31 PGTW 120300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 17P (PAM) WARNING NR 010//
RMKS/
1. TROPICAL CYCLONE 17P (PAM) WARNING NR 010
02 ACTIVE TROPICAL CYCLONES IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
120000Z --- NEAR 12.6S 170.2E
MOVEMENT PAST SIX HOURS - 170 DEGREES AT 07 KTS
POSITION ACCURATE TO WITHIN 030 NM
POSITION BASED ON EYE FIXED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 115 KT, GUSTS 140 KT
...
REMARKS:
120300Z POSITION NEAR 13.0S 170.2E.
TROPICAL CYCLONE (TC) 17P (PAM), LOCATED APPROXIMATELY 578 NM
NORTHWEST OF SUVA, FIJI, HAS TRACKED SOUTHWARD AT 07 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI)
CONTINUES TO DEPICT DEEPENED CENTRAL CONVECTION WITH TIGHLY-CURVED
BANDING WRAPPING INTO A 30 NM RAGGED EYE. AN 112204Z METOP-A
MICROWAVE IMAGE REVEALS EXTENSIVE DEEP CONVECTION OVER THE EASTERN
PERIPHERY AND AN APPARENT MICROWAVE EYE. THE CURRENT POSITION IS
BASED ON THE EYE FEATURE WITH HIGH CONFIDENCE. THE INITIAL INTENSITY
REMAINS AT 115 KNOTS BASED ON CONSENSUS DVORAK INTENSITY ESTIMATES
OF T6.0 FROM PGTW, KNES AND NFFN. UPPER-LEVEL ANALYSIS INDICATES THE
SYSTEM REMAINS IN A FAVORABLE ENVIRONMENT WITH LOW TO MODERATE (10
TO 20 KNOT) VERTICAL WIND SHEAR OFFSET BY RADIAL OUTFLOW, AS EVIDENT
ON THE WATER VAPOR IMAGERY. TC PAM IS CURRENTLY TRACKING ALONG THE
WESTERN EXTENSION OF THE SUBTROPICAL RIDGE (STR) TO THE EAST. OVER
THE NEXT 48 HOURS, FAVORABLE CONDITIONS ARE EXPECTED TO PERSIST
ALLOWING THE SYSTEM TO FURTHER INTENSIFY LEADING TO A PEAK INTENSITY
OF 140 KNOTS. BY TAU 72, THE SYSTEM IS EXPECTED TO START ITS
WEAKENING TREND AND BEGIN EXTRA-TROPICAL TRANSITION (ETT) AS IT
INTERACTS WITH THE BAROCLINIC ZONE. TC PAM IS EXPECTED TO COMPLETE
ETT BY TAU 96. AVAILABLE MODEL GUIDANCE REMAINS IN GOOD AGREEMENT,
LENDING TO HIGH CONFIDENCE IN THE JTWC OFFICIAL FORECAST. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 120000Z IS 36 FEET.
...

[Manukau heads obs]

would be great to see a high resolution visible sat image
the JTWC cone of uncertainty has shifted a bit further west again I see

[NZ Thunderstorm Soc]

Another "Bola" maybe?? ECMWF have it looking quite intense as it leaves the tropics ?

[David]

Latest GFS (00Z) brings it in a little closer again

[Manukau heads obs]

its amazing how the eye is "corkscrewing" around like it is
(I suspect its like leaning over a bit?)

[David]

Latest GFS (00Z) brings it in a little closer again

If that holds true Gisborne will be blown away! Checkout windfinder forecast for Gisborne, based on GFS I believe
http://www.windfinder.com/forecast/gisborne

[Manukau heads obs]

and yet the UKMet model, that the Met Service use, has moved it further east and has done away with the turn to the south all together

[Nev]

From RSMC Nadi this evening…

TROPICAL DISTURBANCE ADVISORY NUMBER A21 ISSUED FROM RSMC NADI
Mar 12/0802 UTC 2015 UTC.

SEVERE TROPICAL CYCLONE PAM CENTRE 920HPA CATEGORY 4 WAS LOCATED NEAR
13.4S 170.1E AT 120600 UTC. POSITION POOR BASED ON HR GMS EIR/VIS
IMAGERY AND PERIPHERAL SURFACE REPORTS. CYCLONE MOVING
SOUTH-SOUTHEAST AT ABOUT 06 KNOTS. MAXIMUM 10-MINUTE AVERAGE WINDS
NEAR THE CENTRE ESTIMATED AT ABOUT 105 KNOTS.
…
EYE WARMING AND CONVECTIVE TOPS COOLING FURTHER PAST 6 HOURS. SYSTEM
LIES IN A MODERATE SHEARED ENVIRONMENT WITH MODERATE TO HIGH UPPER
DIVERGENCE. OUTFLOW GOOD. CYCLONIC CIRCULATION EXTENDS TO 250HPA. SST
AROUND 30 DEGREES CELSIUS. SYSTEM TRACKING ALONG THE WESTERN
PERIPHERY OF THE SUB-TROPICAL RIDGE LOCATED TO THE EAST. DVORAK
ANALYSIS BASED ON EYE PATTERN WITH OW EYE SURROUNDED IN WHITE, YEILDS
DT=6.0, MET AND PT AGREE. THUS YIELDING T6.0/6.0/D1.0/24HRS.
…