WPAC: RAI - Post-Tropical

[dexterlabio]

I don't think it's a mere warm spot at this point because the feature has been visible for more than 6 hours now. Shear impacts are obvious, particularly on the eastern side,.but I think its core is getting established regardless.

[doomhaMwx]

Typhoon warning for Palau

PMZ161-141245-
KOROR PALAU-
939 AM ChST Tue Dec 14 2021

...TYPHOON WARNING NOW IN EFFECT...
...MARINE CONDITIONS HAZARDOUS FOR SMALL CRAFT OPERATIONS...
...COASTAL INUNDATION OF 2 TO 4 FT POSSIBLE THROUGH WEDNESDAY...

.TODAY...Strong tropical storm is intensifying to typhoon strength.
Northwest to west wind 20 to 30 kt with gusts to 40 kt increasing 35
to 45 kt around noon with gusts of 65 kt likely. Combined seas 14 to
16 ft. Cloudy with showers and isolated thunderstorms. Locally heavy
showers likely.
.TONIGHT...Typhoon conditions expected. Northwest to west wind 40 to
50 kt with gusts to 65 kt likely. Combined seas 14 to 16 ft. Cloudy
with showers and isolated thunderstorms. Locally heavy showers
likely. Wind speeds are expected to peak around midnight, then
decrease.

Rai's center is forecast to pass very close to Palau's northernmost state — Kayangel — by tonight at/near typhoon intensity.

[doomhaMwx]

WDPN31 PGTW 140300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 28W (RAI) WARNING NR
005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 7.4N 136.9E
INITIAL INTENSITY: 50 KTS
GEOGRAPHIC REFERENCE: 149 NM EAST OF KOROR
MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 18 KTS
SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A CENTRAL
COLD COVER (CCC) WITH A SINGLE, NON-ROTATING UPDRAFT AND
OVERSHOOTING TOPS WITH CLOUD TOP TEMPERATURE NEAR -100C. THE
HORIZONTAL EXTENT OF THE CIRRUS SHIELD HAS DECREASED AND BECOME
ELONGATED NORTH TO SOUTH OVER THE PAST FEW HOURS. UNFORTUNATELY,
THERE HAS BEEN ONLY ONE GOOD MICROWAVE PASS IN THE PAST 18 HOURS,
FROM 131946Z AND THUS THERE IS LITTLE IN THE WAY TO REFINE THE
INITIAL POSITION, WHICH IS CURRENTLY PLACED UNDER THE CENTER OF THE
MAIN UPDRAFT AS SEEN IN VISIBLE IMAGERY, WITH LOW CONFIDENCE.
FORWARD TRACK SPEED HAS INCREASED AS WELL, BUT THIS IS ALSO VERY
LOW CONFIDENCE DUE TO THE UNCERTAINTY IN THE INITIAL POSITION. ALL
AGENCIES ARE USING THE CCC SCENE TYPE IN THEIR DVORAK ANALYSIS,
THUS THE CURRENT INTENSITIES ARE BEING HELD AT T3.0 OR T3.5 DUE TO
THE ASSOCIATED CONSTRAINTS. THE INITIAL INTENSITY HAS BEEN
INCREASED TO 50 KNOTS, RIGHT AT THE MEAN BETWEEN T3.0 AND T3.5.
ADDITIONALLY, A PARTIAL SCATTEROMETER PASS FROM 132236Z SHOWED
40-45 KNOT WIND BARBS ON THE WESTERN SIDE OF THE CIRCULATION,
PROVIDING ADDITIONAL SUPPORT TO AN BUMP UP IN THE INTENSITY.
...

This bullseye ASCAT pass was not yet available at the time of analysis, but JTWC guessed right in placing the center under that overshooting top.

[InfernoFlameCat]

CCC has degraded significantly.

[Sciencerocks]

[xtyphooncyclonex]

This stalling of strengthening was already expected due to some shear. Impressive outflow but the east side is weak. What happens tomorrow is what to look out for.

[Hayabusa]

The coldest mean temp of Rai was

2021DEC13 211000 3.2 996 49 3.2 3.4 3.8 0.7T/6hr OFF OFF OFF OFF -86.66 -90.85 UNIFRM N/A -2.0 7.12 -137.97 FCST HIM-8 8.9

While Kammuri

2019NOV30 041000 4.2 975.3 69.8 4.2 4.2 3.8 MW Adjst ON OFF OFF OFF -86.66 -86.73 UNIFRM N/A 1.2 13.43 -135.53 ARCHER HIM-8 16.8 MWinit=3.8/3.7/3.9

Imagery of the coldest fix

[doomhaMwx]

Here's from the GK-2A satellite on Dec 13 21Z. The minimum cloud top temperature at the time was -100.21°C (172.94 K), with a few other hot towers having cloud top temps of about -98°C.

[dexterlabio]

As the CCC degrades, there's a new blow up of convection at the center which could be an attempt for a CDO (or another CCC)

[mrbagyo]

Easterly shear is very apparent on that visible loop - you can clearly see the upper level cirrus cloud emanating from the east

[aspen]

It does seem like an eyewall is trying to develop, but shear should prevent rapid structural organization over the next day or so. Chances for a major at landfall are thankfully going down.

[dexterlabio]

Banding eye?

[Sciencerocks]

[zzh]

[xtyphooncyclonex]

Appears to have recovered. Much much cleaner looking and the most organized it's ever looked. So it begins...

[mrbagyo]

Banding eye?

[stormstrike]

so much better than yesterday

[stormstrike]

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 9.0
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 14 DEC 2021 Time : 231000 UTC
Lat : 9:00:19 N Lon : 132:15:55 E


CI# /Pressure/ Vmax
4.4 / 978mb / 75kts


Final T# Adj T# Raw T#
4.4 4.4 4.2

Center Temp : -77.4C Cloud Region Temp : -80.6C

Scene Type : EMBEDDED CENTER CLOUD REGION w/ MW EYE

Subtropical Adjustment : OFF

Extratropical Adjustment : OFF

Positioning Method : FORECAST INTERPOLATION

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

Tno/CI Rules : Constraint Limits : MW ON
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 105nmi
- Environmental MSLP : 1005mb

Satellite Name : HIM-8
Satellite Viewing Angle : 14.4 degrees

[xtyphooncyclonex]

Are they going for 65 kts next advisory or straight to 70-75? Looks a typhoon already.

[aspen]

Rai is still dealing with some moderate shear that’s restricting its eastern side, but the development of its inner core indicates that if shear remains at or below its current level, it could peak around 90-100kt before landfall in 36 hours. Any increase, however, will probably be too much.