SPAC: PAM - Post-Tropical

[mrbagyo]

Pam's eye sucks
IMO, the only thing Pam can really brag about is her extremely cold cloud tops.

[Yellow Evan]

ADT keeps missing the eye!

[Alyono]

a really good example of the modeling improvements in recent years. Models said this would be one of the world's most powerful cyclones ever. Pam is well on its way to becoming that

[Yellow Evan]

Eye cooling.

[CrazyC83]

It is likely peaking (at least for now) right now. Hard to say, but with some caution, I would go with 140 kt.

[Yellow Evan]

It is likely peaking (at least for now) right now. Hard to say, but with some caution, I would go with 140 kt.

Cloud tops are not warming and Pam is not yet symmetrical.

[somethingfunny]

Levi Cowen (Tropical Tidbits) just posted a tweet comparing the GFS 30-hr and 54-hr forecasts for Pam. Goes from 932mb at 30hrs to 870mb in 24 hours with a very tiny eye.

[cycloneye]

Up to 140kts

17P PAM 150312 1800 15.0S 169.6E SHEM 140 918

[Hypercane_Kyle]

Pam's eye has shrunk considerably in the last few hours.

[Alyono]

Port Vila may not be around much longer. EC has a direct hit

[gatorcane]

wow what a storm! They sure can get some big ones over in that part of the world. Let's see if this RI unfolds over the next 24 hours as the GFS predicts.

[Yellow Evan]

WTPS31 PGTW 122100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 17P (PAM) WARNING NR 013//
RMKS/
1. TROPICAL CYCLONE 17P (PAM) WARNING NR 013
02 ACTIVE TROPICAL CYCLONES IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
121800Z --- NEAR 15.0S 169.6E
MOVEMENT PAST SIX HOURS - 200 DEGREES AT 09 KTS
POSITION ACCURATE TO WITHIN 015 NM
POSITION BASED ON EYE FIXED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 140 KT, GUSTS 170 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT
030 NM SOUTHEAST QUADRANT
030 NM SOUTHWEST QUADRANT
025 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT
080 NM SOUTHEAST QUADRANT
070 NM SOUTHWEST QUADRANT
060 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 170 NM NORTHEAST QUADRANT
180 NM SOUTHEAST QUADRANT
170 NM SOUTHWEST QUADRANT
160 NM NORTHWEST QUADRANT
REPEAT POSIT: 15.0S 169.6E
---
FORECASTS:
12 HRS, VALID AT:
130600Z --- 16.9S 169.5E
MAX SUSTAINED WINDS - 150 KT, GUSTS 180 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT
030 NM SOUTHEAST QUADRANT
030 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 085 NM NORTHEAST QUADRANT
060 NM SOUTHEAST QUADRANT
055 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 170 NM NORTHEAST QUADRANT
155 NM SOUTHEAST QUADRANT
145 NM SOUTHWEST QUADRANT
155 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 165 DEG/ 12 KTS
---
24 HRS, VALID AT:
131800Z --- 19.3S 170.1E
MAX SUSTAINED WINDS - 145 KT, GUSTS 175 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT
035 NM SOUTHEAST QUADRANT
035 NM SOUTHWEST QUADRANT
035 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 090 NM NORTHEAST QUADRANT
070 NM SOUTHEAST QUADRANT
060 NM SOUTHWEST QUADRANT
055 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 175 NM NORTHEAST QUADRANT
160 NM SOUTHEAST QUADRANT
150 NM SOUTHWEST QUADRANT
160 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 155 DEG/ 17 KTS
---
36 HRS, VALID AT:
140600Z --- 22.4S 171.8E
MAX SUSTAINED WINDS - 135 KT, GUSTS 165 KT
WIND RADII VALID OVER OPEN WATER ONLY
BECOMING EXTRATROPICAL
RADIUS OF 064 KT WINDS - 050 NM NORTHEAST QUADRANT
045 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
040 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 090 NM NORTHEAST QUADRANT
080 NM SOUTHEAST QUADRANT
070 NM SOUTHWEST QUADRANT
070 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 180 NM NORTHEAST QUADRANT
165 NM SOUTHEAST QUADRANT
155 NM SOUTHWEST QUADRANT
165 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 145 DEG/ 23 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
141800Z --- 26.1S 174.7E
MAX SUSTAINED WINDS - 105 KT, GUSTS 130 KT
WIND RADII VALID OVER OPEN WATER ONLY
BECOMING EXTRATROPICAL
RADIUS OF 064 KT WINDS - 050 NM NORTHEAST QUADRANT
045 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
040 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 090 NM NORTHEAST QUADRANT
080 NM SOUTHEAST QUADRANT
075 NM SOUTHWEST QUADRANT
070 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 180 NM NORTHEAST QUADRANT
165 NM SOUTHEAST QUADRANT
160 NM SOUTHWEST QUADRANT
165 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 150 DEG/ 26 KTS
---
72 HRS, VALID AT:
151800Z --- 34.8S 178.8W
MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
WIND RADII VALID OVER OPEN WATER ONLY
EXTRATROPICAL
---
REMARKS:
122100Z POSITION NEAR 15.5S 169.6E.
TROPICAL CYCLONE 17P (PAM), LOCATED APPROXIMATELY 470 NM NORTH-
NORTHEAST OF NOUMEA, NEW CALEDONI, HAS TRACKED SOUTH-SOUTHWESTWARD
AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
(EIR) SATELLITE IMAGERY CONTINUES TO DEPICT TIGHTLY CURVED
BANDING SURROUNDING A 15-NM EYE. THE CURRENT POSITION IS BASED ON
THE EYE FEATURE IN THE EIR LOOP WITH HIGH CONFIDENCE. THE INITIAL
INTENSITY OF 140 KNOTS IS BASED ON DVORAK CURRENT INTENSITY
ESTIMATES OF T7.0 FROM PGTW AND KNES. UPPER-LEVEL ANALYSIS INDICATES
THE SYSTEM REMAINS IN A FAVORABLE ENVIRONMENT WITH LOW TO MODERATE
(10 TO 20 KNOT) VERTICAL WIND SHEAR EASILY OFFSET BY RADIAL OUTFLOW,
AS EVIDENT ON ANIMATED WATER VAPOR IMAGERY. TC PAM IS TRACKING ALONG
THE WESTERN EXTENSION OF THE SUBTROPICAL RIDGE TO THE EAST. OVER THE
NEXT 12 HOURS, FAVORABLE CONDITIONS ARE EXPECTED TO PERSIST ALLOWING
THE SYSTEM TO FURTHER INTENSIFY, PEAKING AT 150 KNOTS. AFTERWARDS,
THE SYSTEM IS EXPECTED TO START WEAKENING DUE TO INCREASING VWS AND
COOLING SSTS, AND BEGIN EXTRA-TROPICAL TRANSITION AS IT ENTERS THE
BAROCLINIC ZONE. HOWEVER, IT WILL STILL HAVE VERY INTENSE 65-KNOT
WINDS WHEN IT BECOMES A COLD CORE LOW BY TAU 72. AVAILABLE MODEL
GUIDANCE REMAINS IN TIGHT AGREEMENT, LENDING HIGH CONFIDENCE IN THE
JTWC OFFICIAL FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 121800Z
IS 44 FEET. NEXT WARNINGS AT 130300Z, 130900Z, 131500Z AND 132100Z.
REFER TO TROPICAL CYCLONE 18P (NATHAN) WARNINGS (WTPS32 PGTW)
FOR TWELVE-HOURLY UPDATES.//
NNNN

[CrazyC83]

Not only has the eye become smaller, it has wobbled significantly to the right (west).

[1900hurricane]

Not buying a category 5 intensity at the moment, at least not quite yet. Most of the current intensity estimates rely on some form of the Dvorak technique, which I think at this point is putting too much of an emphasis on the coldness of cloudtops rather than Pam's actual structure. Yes, the cloudtops are very cold, but the lack of a warm eye for this long is a signal that some eyewall weakness still exists, which can be backed up by microwave imagery.



As for current intensity, I'd probably go with a 1 minute sustained of 120-125 kt or so (maybe 130 kt, but I have hesitations), but with a disproportionately low pressure (915 as a random guess?) due to the very large wind field and low background pressures. Then again, I could just as easily be off base (they are the experts after all), but those are just some of my thoughts at the moment.

[euro6208]

Pam is now the 10th category 5 in the south pacific since records began...First one since 2010...

[Alyono]

seeing sustained around 20 kts with about 987mb at Port Vila

[euro6208]

The eye isn't the most classic for a category 5. It has struggle to warm her eye for some reason...

It looks like a monster only because of her deep convection...

[Yellow Evan]

Much better now. Appears to have mixed out the dry air.

[Yellow Evan]

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.2.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 12 MAR 2015 Time : 213000 UTC
Lat : 15:08:02 S Lon : 169:32:33 E


CI# /Pressure/ Vmax
6.4 / 918.7mb/124.6kt


Final T# Adj T# Raw T#
6.4 7.0 7.0

Estimated radius of max. wind based on IR :<10 km

Center Temp : -31.3C Cloud Region Temp : -84.4C

Scene Type : PINHOLE EYE

Positioning Method : SPIRAL ANALYSIS

Ocean Basin : WEST PACIFIC
Dvorak CI > MSLP Conversion Used : PACIFIC

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : ON
Rapid Dissipation Flag : OFF

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 170km
- Environmental MSLP : 994mb

Satellite Name : MTSAT2
Satellite Viewing Angle : 33.3 degrees

[euro6208]

I have a hard time believing this is even a category 5...Looks more like 100 to 125 knots...Eyewall remains open and not as warm as it should be...It's cold cloud tops can really fool anyone which dvorak likes to rate...