WPAC: RAI - Post-Tropical

[mrbagyo]

[Sciencerocks]

[InfernoFlameCat]

https://imagizer.imageshack.com/img922/69/fcPyMv.gif

It’s started for real now. If it can maintain the ccc/possible CDO we could easily see RI soon.

[doomhaMwx]

All that deep convection is actually being slightly displaced north of the LLCC, which may limit short-term intensification.




That said, a ship recently recorded a SLP of 1000mb some 350km from 96W's center (so central pressure is likely lower than that), suggesting that it could be a TS now. TS-force winds probably occurring underneath the deep convection.

[InfernoFlameCat]

Llc is clearly exposed atm but it will soon be relocated under the deeper convection IMO.

[doomhaMwx]

Now TD 28W from JTWC

28W TWENTYEIGH 211213 0000 5.1N 141.7E WPAC 25 1002

[mrbagyo]

[Hayabusa]

85 kt peak before landfall

WDPN31 PGTW 130300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 28W (TWENTYEIGHT)
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 5.1N 141.7E
INITIAL INTENSITY: 25 KTS
GEOGRAPHIC REFERENCE: 340 NM SOUTHEAST OF YAP
MOVEMENT PAST 6 HOURS: WESTWARD AT 10 KTS
SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY
EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC), DISPLACED JUST SOUTH
OF AN EXPANSIVE AREA OF DEEP, PERSISTENT CONVECTION. THE MOST
RECENT MICROWAVE IMAGE, A 122144Z 89GHZ SSMIS IMAGE, DEPICTED THE
DISORGANIZED STRUCTURE OF THE SYSTEM CONVECTIVE CORE, WITH THE LLCC
DISPLACED TO THE SOUTH. THE INITIAL POSITION IN ASSESSED WITH HIGH
CONFIDENCE BASED ON A SPIRAL BAND ANALYSIS OF THE EXPOSED LOW LEVEL
CLOUD LINES TO THE SOUTH OF THE CENTER. THE INITIAL INTENSITY OF 25
KNOTS IS ASSESSED WITH MEDIUM CONFIDENCE, BASED ON THE AVERAGE OF
MULTI-AGENCY DVORAK CURRENT INTENSITY ESTIMATES. THE WIND FIELD
REMAINS HIGHLY ASYMMETRIC, WITH EARLIER 121925Z SCATTEROMETER DATA
SHOWING 25-30 KNOTS TO THE NORTH, WITH EVEN HIGHER LIKELY OCCURRING
UNDER THE DEEPEST CONVECTION, WHILE WINDS WERE MEASURED AT 15-20
KNOTS ALONG THE SOUTHERN PORTIONS OF THE CIRCULATION. ENVIRONMENTAL
ANALYSIS REVEALS DIVERGENT EASTERLY FLOW OVER TOP OF THE SYSTEM,
AIDING THE CONVECTIVE ACTIVITY CURRENTLY BEING SEEN, THOUGH OVERALL
OUTFLOW REMAINS RELATIVELY WEAK AT PRESENT, BOTH POLEWARD AN
EQUATORWARD. SSTS ARE VERY WARM (29-30C) AND VWS IS LOW, LEADING TO
AN OVERALL FAVORABLE ENVIRONMENTAL ASSESSMENT.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T1.5 - 25 KTS
RJTD: T1.5 - 25 KTS
KNES: T2.5 - 35 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 5-10 KTS
SST: 29-30 CELSIUS
OUTFLOW: WEAK POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: TROPICAL DEPRESSION 28W IS EXPECTED TO TRACK
WEST-NORTHWESTWARD THROUGH THE DURATION OF THE FORECAST PERIOD
ALONG THE SOUTHERN SIDE OF AN EXTENSIVE STR ENTRENCHED TO THE
NORTH. TRACK SPEEDS ARE FORECAST TO REMAIN RELATIVELY STEADY EXCEPT
FOR A BRIEF SLOWDOWN BETWEEN TAU 48 AND 72, IN RESPONSE TO A SLIGHT
WEAKENING OF THE STEERING GRADIENT DUE TO DEVELOPMENT OF A WEAKNESS
IN THE RIDGE TO THE NORTH. TD 28W IS EXPECTED TO CROSS THROUGH THE
SOUTHERN PHILIPPINE ISLANDS AFTER TAU 72, AND ULTIMATELY EMERGE INTO
THE SULU SEA AND TRACK TO NEAR PALAWAN BY TAU 120. OVER THE NEXT 12
TO 18 HOURS, THE LLCC IS EXPECTED TO FURTHER CONSOLIDATE WHILE
MOVING UNDER THE DEEP CONVECTION, ESTABLISHING A WELL DEFINED CORE.
THIS WILL MARK THE START OF A PERIOD OF STEADY INTENSIFICATION TO A
PEAK OF 85 KNOTS BY TAU 72. THE BULK OF THE INTENSIFICATION IS
EXPECTED IN THE FIRST 48 HOURS AS VWS REMAINS BELOW 15 KNOTS AND
OUTFLOW REMAINS RELATIVELY HIGH. BY TAU 72, SHEAR IS EXPECTED TO
INCREASE ABOVE 15 KNOTS AND THE OUTFLOW WILL DECREASE AS THE UPPER-
LEVEL FLOW SHIFTS TO A MORE EASTERLY DIRECTION, CUTTING OFF THE
POLEWARD OUTFLOW CHANNEL. THE SYSTEM WILL WEAKEN AS IT CROSSES
THROUGH THE PHILIPPINES DUE TO INFLOW AND CORE DISRUPTION CAUSED BY
INTERACTION WITH THE COMPLEX TERRAIN FEATURES. ONCE BACK OVER WATER,
THE SYSTEM WILL QUICKLY INTENSIFY ONCE MORE AS THE POLEWARD OUTFLOW
CHANNEL IS REESTABLISHED

MODEL DISCUSSION: TRACK GUIDANCE IS IN GOOD AGREEMENT THROUGH THE
DURATION OF THE FORECAST WITH A 90NM SPREAD AT TAU 48 INCREASING TO
210NM AT TAU 120, BUT ONLY 110NM IF THE NAVGEM TRACKER IS
DISCOUNTED AS THE SINGLE MAJOR OUTLIER. THE JTWC FORECAST LIES
AMONGST THE TIGHTEST PACKING OF CONSENSUS MEMBERS AND JUST SOUTH OF
THE CONSENSUS MEAN WITH HIGH CONFIDENCE THROUGH TAU 72, AND MEDIUM
CONFIDENCE THEREAFTER. INTENSITY GUIDANCE IS MIXED WITH TWO
DISTINCT PEAKS WITHIN THE FORECAST PERIOD. THE ENVELOPE OF PEAK
INTENSITIES RANGES FROM A LOW OF 65KNOTS TO A HIGH OF 110 KNOTS FOR
THE FIRST PEAK EAST OF THE PHILIPPINES, AND 65 KNOTS TO 135 KNOTS
FOR THE SECOND PEAK AT TAU 120. THE COAMPS-TC MODELS ARE THE MOST
AGGRESSIVE THROUGH THE FORECAST PERIOD, WITH THE SHIPS GUIDANCE
MARKING THE LOW END AND HWRF VERY AGGRESSIVE THROUGH TAU 24, BUT
THEREAFTER MORE MODEST, THOUGH THE HWRF DOES NOT WEAKEN THE SYSTEM
THROUGH THE PHILIPPINES. BASED ON ANALYSIS OF THE GLOBAL FIELDS,
THE COAMPS-TC AND HWRF TRACKERS ARE DETERMINED TO BE TOO AGGRESSIVE
WHILE THE GFS IS TOO BEARISH. THE JTWC FORECAST LIES AMONGST MOST
OF THE GUIDANCE THROUGH TAU 48, THEN DIVERGES LOWER THAN THE MOST
AGGRESSIVE MODELS THROUGH THE REMAINDER OF THE FORECAST. IN LIGHT
OF THE EXTREME UNCERTAINTY EXHIBITED BY THE MODEL GUIDANCE, AT THIS
TIME THERE IS LOW CONFIDENCE IN THE JTWC FORECAST INTENSITY.

FORECAST CONFIDENCE:
TRACK 0 - 72 HR: HIGH
TRACK 72-120 HR: MEDIUM
INTENSITY 0 - 72 HR: LOW
INTENSITY 72-120 HR: LOW//
NNNN

[Hayabusa]

WTPQ50 RJTD 130600
RSMC TROPICAL CYCLONE ADVISORY
NAME TS 2122 RAI (2122) UPGRADED FROM TD
ANALYSIS
PSTN 130600UTC 06.0N 140.8E FAIR
MOVE W 17KT
PRES 998HPA
MXWD 035KT
GUST 050KT
30KT 240NM NORTHWEST 150NM SOUTHEAST
FORECAST
24HF 140600UTC 08.0N 136.7E 65NM 70%
MOVE WNW 11KT
PRES 990HPA
MXWD 050KT
GUST 070KT
48HF 150600UTC 09.0N 132.0E 90NM 70%
MOVE W 12KT
PRES 965HPA
MXWD 070KT
GUST 100KT
72HF 160600UTC 09.5N 126.8E 140NM 70%
MOVE W 13KT
PRES 945HPA
MXWD 085KT
GUST 120KT
96HF 170600UTC 09.9N 121.5E 200NM 70%
MOVE W 13KT
PRES 965HPA
MXWD 070KT
GUST 100KT
120HF 180600UTC 11.3N 116.7E 280NM 70%
MOVE WNW 12KT
PRES 950HPA
MXWD 080KT
GUST 115KT =

[Hayabusa]

Latest 00Z HWRF, NAVGEM northern group, while Euro, UK, CMC southern group. GFS in the middle.

[Sciencerocks]

[mrbagyo]

If Rai builds a decent CDO tonight, intensity forecast will be bumped up.

[xtyphooncyclonex]

Haven't been here in a while and I've been through lots of busts but... the Metro Cebu LGUs are really taking this thing seriously. Rescue vehicles, equipment, tents and hotline numbers are set. The mayors of the three "big" cities in the metro are holding special sessions to prepare for the storm... and the mayor asserted that forced evacuations will likely begin as it approaches land. Hoping we ride this out safe.

[dexterlabio]

Looks like a go-time for Rai with that tiny and compact core developing plus that curved banding

[mrbagyo]

I would say Rai has a good chance of becoming a Typhoon before it reaches the longitude of Palau (134°35'E)
Rai is developing a core

[Hayabusa]

06Z HWRF almost super typhoon.

[aspen]

An absolutely fantastic microwave pass… /s

[Iceresistance]

An absolutely fantastic microwave pass… /s
https://rammb-data.cira.colostate.edu/tc_realtime/products/storms/2021wp28/amsusr89/2021wp28_amsusr89_202112130824.gif

Perfectly Cut core, LOL

[mrbagyo]

CCC or CDO?

[InfernoFlameCat]

If it is a CDO the Philippines are in trouble. That thing looks like its RI towards a true monster.