WPAC: BANYAN - Post-Tropical

[Hayabusa]

94W.INVEST

94W INVEST 221026 0600 7.5N 146.2E WPAC 15 1010

[Hayabusa]

ECMWF, GFS has some development, but better watch it could be a sleeper.

[Hayabusa]

ABPW10 PGTW 280000
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS REISSUED/280000Z-280600ZOCT2022//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/271951ZOCT2022//
AMPN/REF A IS A TROPICAL CYCLONE WARNING.//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
A. TROPICAL CYCLONE SUMMARY:
(1) AT 27OCT22 1800Z, TROPICAL STORM 26W (NALGAE) WAS LOCATED NEAR
12.1N 129.6E, APPROXIMATELY 524 NM EAST-SOUTHEAST OF MANILA, PHILIPPINES,
AND HAD TRACKED WESTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. MAXIMUM
SUSTAINED SURFACE WINDS WERE ESTIMATED AT 40 KNOTS GUSTING TO 50 KNOTS.
SEE REF A (WTPN31 PGTW 272100) FOR FURTHER DETAILS.
(2) NO OTHER TROPICAL CYCLONES.
B. TROPICAL DISTURBANCE SUMMARY:
(1) AN AREA OF CONVECTION (INVEST 94W) HAS PERSISTED NEAR 8.9N
141.3E, APPROXIMATELY 191 NM EAST OF YAP. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY DEPICTS A BROAD AREA OF TURNING ASSOCIATED WITH FLARING
CONVECTION. UPPER-LEVEL ANALYSIS INDICATES INVEST 94W IS IN MARGINALLY
UNFAVORABLE CONDITIONS DUE TO HIGH VWS (25-40KTS) BUT IS OFFSET BY GOOD
DIVERGENCE ALOFT. THE ENVIRONMENTAL ANALYSIS SHOWS FAVORABLE CONDITIONS
WITH WARM SEA SURFACE TEMPERATURES (28-30C). GLOBAL MODEL GUIDANCE
INDICATES A MORE GRADUAL INTENSIFICATION OF INVEST 94W, AS IT MEANDERS IN
THE PHILIPPINE SEA THROUGH TAU 72. PREVIOUS MODEL RUNS WERE INDICATING A
MORE AGGRESSIVE INTENSITY BUT HAVE SINCE BACKED OFF. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA LEVEL PRESSURE
IS ESTIMATED TO BE NEAR 1006 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS LOW.

[Hayabusa]

00Z, navgem excited but navgem

[mrbagyo]

now subject to a TCFA

[Hayabusa]

06Z EPS

[underthwx]

Hopefully 94W is a no show, the track scenario would result in an area sustaining 2 cyclones in a short period of time.

[Hayabusa]

Latest Euro intensifies it significantly in the long range

EPS without Nalgae

[Hayabusa]

WWJP27 RJTD 281800
WARNING AND SUMMARY 281800.
WARNING VALID 291800.
WARNING IS UPDATED EVERY 6 HOURS.
TROPICAL DEPRESSION 1006 HPA AT 08N 139E ALMOST STATIONARY.

[Hayabusa]

Back to TCFA again after it was downgraded to low

WTPN21 PGTW 292300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 94W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
160 NM EITHER SIDE OF A LINE FROM 9.0N 139.4E TO 8.0N 132.7E
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 18 TO 23 KNOTS. METSAT
IMAGERY AT 292300Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 9.0N 138.9E. THE SYSTEM IS MOVING WESTWARD AT 06 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 94W) PREVIOUS LOCATED NEAR
8.8N 139.4E IS NOW LOCATED NEAR 9.0N 138.9E APPROXIMATELY 53 NM EAST-
SOUTHEAST OF YAP. ANIMATED MULTISPECTRAL SATELLITE AND ENHANCED INFRARED
IMAGERY DEPICT A CONSOLIDATING LOW LEVEL CIRCULATION COVERED BY DENSE
CONVECTION. A 291849 SSMIS 91GHZ PASS CONFIRMED THE TIGHTLY CONSOLIDATED
LLCC TO THE SE OF YAP, CENTERED ON THE NORTHEAST EDGE OF THE DEEP
CONVECTIVE MASS. UPPER LEVEL ANALYSIS INDICATES THAT WHILE THE STRONG
UPPER LEVEL NORTHEASTERLY FLOW UP TO 40-50 KNOTS IS PRESENT ACROSS THE
REGION, 94W IS COCOONED WITHIN A FAVORABLE BUBBLE OF LOW (5-10KT) VWS,
NESTLED UNDER A REGION OF HIGHLY DIVERGENT FLOW ALOFT. THE SYSTEM HAS
GOOD EQUATORWARD OUTFLOW AND A GOOD FUEL SOURCE OF 30C SST AND 125KJ
OCEAN HEAT CONTENT. THE 850MB VORTICITY CHART ALSO DEPICTS A STRONG,
SYMMETRICAL VORTICITY SIGNATURE ASSOCIATED WITH 94W. GLOBAL MODELS JUMPED
BACK ON BOARD WITH DEVELOPMENT OF THE SYSTEM, SHOWING A SLOW AND GRADUAL
INTENSIFICATION OVER THE NEXT 24-36 HOURS WITH A WOBBLY TRACK WEST-
NORTHWEST TOWARDS THE PHILIPPINES. MAXIMUM SUSTAINED SURFACE WINDS ARE
ESTIMATED AT 18 TO 23 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO
BE NEAR 1005 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT
TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
302300Z.//
NNNN

[Hayabusa]

EPS 18Z

[doomhaMwx]

The LLCC has become exposed again this morning as it passes near Yap, but this is likely a TD (under JTWC standards) for a while now. HY-2B recently found 25-30kt winds in western-half of the LLCC before it got exposed. Yap Airport recorded a min SLP of around 1003mb (not even directly in the center) but the strongest winds are probably not affecting the island. Highest observed winds so far are ~15kts sustained with ~25kts gust.

[mrbagyo]

[Hayabusa]

WDPN32 PGTW 302100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 27W (TWENTYSEVEN)
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 8.2N 135.3E
INITIAL INTENSITY: 30 KTS
GEOGRAPHIC REFERENCE: 76 NM NORTHEAST OF KOROR
MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 08 KTS
SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) AND PROXY VISIBLE SATELLITE
IMAGERY DEPICTS A COMPACT, WELL-DEFINED AND VERY TIGHTLY WRAPPING
LOW LEVEL CIRCULATION CENTER (LLCC), WITH FLARING, DISORGANIZED
CONVECTION TO THE SOUTHWEST. THE LLCC HAS ALTERNATIVELY BEEN
EXPOSED COVERED BY CONVECTIVE BLOWOFF OVER THE PAST DAY AS
CONVECTION HAS CONTINUALLY CYCLED, ONLY TO BE SHEARED OFF TO THE
SOUTHWEST IN THE FACE OF PERSISTENT NORTHEASTERLY FLOW ALOFT.
HOWEVER, WHILE THE CONVECTIVE STRUCTURE HAS REMAINED DISORGANIZED,
THE STRUCTURE OF THE LOW-LEVEL CIRCULATION HAS STEADILY IMPROVED,
AND LOW-LEVEL WIND FIELD HAS CONTINUED TO STRENGTHEN. RECENT
SCATTEROMETER DATA INDICATED A COMPACT WIND FIELD WITH WINDS UP TO
30-35 KNOTS IN THE WEST-NORTHWEST SECTOR OF THE CIRCULATION.
ADDITIONALLY, AGENCY FIXES HAVE BEEN IN THE T1.5-T2.0 FOR MORE THAN
24 HOURS, AND KNES HAS BEEN AT T2.5 FOR THE LAST COUPLE OF FIXES.
THE CONGRUENCE OF THE ABOVE DATA LENDS INCREASED CONFIDENCE THAT
WHILE THE SYSTEM DOES NOT LOOK ALL THAT IMPRESSIVE, THE WINDS ARE
ABOVE THE WARNING THRESHOLD. THE ENVIRONMENT IS MARGINAL AT BEST,
WITH WARM SSTS AND GOOD EQUATORWARD OUTFLOW BEING OFFSET BY
PERSISTENT, STRONG NORTHEASTERLY FLOW ALOFT. THE 301200Z SOUNDING
FROM YAP SHOWED 40-50 KNOT NORTHEASTERLIES ABOVE THE 300MB LEVEL,
WHILE THE KOROR SOUNDING SHOWED THE WINDS ARE A BIT DIVERGENT AND
WEAKER THAN AT YAP. CIMSS ANALYSIS REVEALS HIGHLY DIVERGENT FLOW IN
THE IMMEDIATE VICINITY OF TD 27W, WHICH EXPLAINS THE REPEATED
CYCLING OF THE CONVECTIVE FLARE-UPS. THE SYSTEM IS TRACKING
WEST-SOUTHWEST ALONG THE SOUTHERN SIDE OF A DEEP SUBTROPICAL RIDGE
TO THE NORTH.

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

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

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T2.0 - 30 KTS
RJTD: T1.5 - 25 KTS
KNES: T2.5 - 35 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
VWS: 20-25 KTS
SST: 29-30 CELSIUS
OUTFLOW: STRONG EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TD 27W WILL CONTINUE TRACKING TO THE WEST
THROUGH THE FIRST 24 HOURS, THEN GRADUALLY TURN TO A MORE
NORTHWESTWARD HEADING AFTER TAU 36 AS THE STEERING RIDGE PULLS AWAY
TO THE NORTHEAST AND THE LOWER LEVEL FLOW BECOMES ORIENTED TO A
NORTHWEST TO SOUTHEAST DIRECTION. WHILE THE SYSTEM HAS BEEN ABLE TO
BECOME BETTER SYMMETRIZED AND INTENSIFY OVER THE PAST DAY OR SO,
IT CANNOT CONTINUE THIS TREND IN THE FACE OF THE STRONG AND
PERSISTENT NORTHEASTERLY SHEAR. THE LATEST CIMSS ANALYSIS ALSO
SHOWS AN AREA OF CONVERGENCE UPSTREAM, WHICH IS EXPECTED TO PUSH
DOWN ON TOP OF THE SYSTEM OVER THE NEXT 24 HOURS. THIS, ALONG A
PUSH OF MID-LEVEL DRY AIR, AS REVEALED IN THE YAP SOUNDING, WILL
KILL ANY POSSIBILITY OF INTENSIFICATION. THUS, THE FORECAST CALLS
FOR A SLOW, STEADY DECLINE IN INTENSITY THROUGH THE FORECAST
PERIOD, WITH THE SYSTEM FULLY DISSIPATING NO LATER THAN TAU 48, AND
POTENTIALLY AS EARLY AS TAU 36, TO THE EAST OF THE PHILIPPINES.

MODEL DISCUSSION: TRACK GUIDANCE IS IN GOOD AGREEMENT THROUGH THE
FORECAST PERIOD, WITH ALL AVAILABLE CONSENSUS MEMBERS CONFINED TO A
TIGHT, 70NM ENVELOPE, LENDING HIGH CONFIDENCE TO THE JTWC TRACK
FORECAST. INTENSITY GUIDANCE IS SURPRISINGLY MIXED, WITH THE
MESOSCALE HWRF AND COAMPS-TC ALONG WITH THE GFS, INDICATING SLOW,
STEADY WEAKENING WHILE THE DECAY-SHIPS BEING VERY AGGRESSIVE WITH
INTENSIFYING THE SYSTEM UP TO 50 KNOTS IN THE CASE OF THE GFS
VERSION. FOR THE REASONS OUTLINED ABOVE, THE INTENSIFICATION
SCENARIO IS DEEMED HIGHLY UNLIKELY, THUS THE JTWC FORECAST ALIGNS
WITH THE MESOSCALE MODELS, WITH HIGH CONFIDENCE.

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

[Hayabusa]

TS from JTWC

27W TWENTYSEVE 221031 0000 7.8N 134.1E WPAC 35 1000

[dexterlabio]

If not for Nalgae’s insanely huge outflow, this one could’ve had a chance to develop into a potent system. What a tenacity to maintain convection at the center amid very strong VWS

[dexterlabio]

Now TS Banyan….forecast to dissipate within 1 or 2 days

[doomhaMwx]

Some interesting obs from Palau when Banyan passed over there earlier. An impressive gust of 66.7kts (~124kph) was recorded at Ongingiang in southern Palau. Nearby Koror Airport recorded max gust of 48kts (89kph) with conditions described as "thunderstorm, heavy rain and windy". Satellite and MW images at that time show that while 17W's exposed LLCC passed to the north, areas south were under very intense convection.






Kayangel to the north, where the LLCC passed over, recorded max wind speeds of 33kts gusting to 45.7kts and a min pressure of 996mb.



 https://twitter.com/doomhaMwx/status/1586982129845514241

[Hayabusa]

ACCESS model keeps it alive for the next 162 hours