ARB: SHAHEEN (Gulab) - Post-Tropical

[Subtrop]

96B INVEST 210924 0000 18.0N 93.0E IO 15 1010

[Subtrop]

03B THREE 210924 0600 18.8N 92.1E IO 35 1005

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[doomhaMwx]

Glad that JTWC wasted no time upgrading this obvious TC. ASCAT a few hours ago also found a well-defined LLCC with 30-35kt winds underneath the deep convection.
Very rare to see JTWC quickly upgrade a system that's not even mentioned in their TWO.

[doomhaMwx]

First JTWC warning has the system peaking at 60kts before hitting India. There is low confidence in the intensity forecast though given how models are poorly handling this system at the moment.



On a side note, JTWC seems to be now issuing prognostic reasonings for systems outside the WPAC. They usually only placed a brief discussion under the "TC Warning Text" for non-WPAC systems.

WDIO31 PGTW 240900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 03B (THREE) WARNING
NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 18.8N 92.1E
INITIAL INTENSITY: 35 KTS
GEOGRAPHIC REFERENCE: 211 NM SOUTH OF CHITTAGONG
MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 15 KTS
SIGNIFICANT WAVE HEIGHT: 10 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY
EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION
IS PLACED WITH MEDIUM CONFIDENCE BASED ON A 240550Z GMI 89GHZ
MICROWAVE IMAGE SHOWING DEEP CONVECTION OFFSET TO THE SOUTHWEST OF
THE LLCC. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH MEDIUM
CONFIDENCE BASED ON A 240229Z METOP-A ASCAT PASS SHOWING A SWATH OF
30-35KT WINDS WRAPPED AROUND THE LLCC. THE ENVIRONMENT IS OVERALL
FAVORABLE WITH AN ANTICYCLONE ALOFT, LOW VERTICAL WIND SHEAR AND
WARM SEA SURFACE TEMPERATURES.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: NO CURRENT ESTIMATE

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

ANALYSIS CONFIDENCE:
INITIAL POSITION: MEDIUM
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: MEDIUM

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 03B WILL GENERALLY CONTINUE ON ITS CURRENT
WESTWARD
TRACK UNTIL DISSIPATION OVER INDIA BEFORE TAU 96. THE FAVORABLE
ENVIRONMENT OF SUSTAINED WARM SEA SURFACE TEMPERATURES (28-29
DEGREES CELSIUS), MODERATE UPPER LEVEL DIVERGENCE AND LOW SHEAR
(10-15 KNOTS) WILL FUEL GRADUAL INTENSIFICATION TO A PEAK OF 60KTS
BY TAU 48. A SLIGHT WEAKENING IS EXPECTED BEFORE LANDFALL DUE TO
MODERATE SHEAR. AFTERWARDS, LAND INTERACTION ACROSS THE RUGGED
TERRAIN OF INDIA WILL CAUSE RAPID WEAKENING.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN LOOSE AGREEMENT ON TRACK
AND INTENSITY AS TC 03B HAS RECENTLY MOVED OFFSHORE AND INTENSIFIED
IN THE BAY OF BENGAL. THE ENVIRONMENT IS FAVORABLE FOR CONTINUED
INTENSIFICATION, HOWEVER, MODELS ARE STRUGGLING TO GRASP ITS
CURRENT VORTEX. DESPITE THE ENVIRONMENT, THERE IS LOW CONFIDENCE IN
THE TRACK AND INTENSITY OF TC 03B.

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

[Extratropical94]

Latest TWO by the official RSMC. 0% chance of TC formation

BAY OF BENGAL:

UNDER THE INFLUENCE OF THE CYCLONIC CIRCULATION, A LOW PRESSURE AREA HAS
FORMED OVER EASTCENTRAL BAY OF BENGAL & NEIGHBOURHOOD . IT IS LIKELY TO
BECOME MORE MARKED AND MOVE WEST­NORTHWESTWARDS TOWARDS ODISHA COAST
DURING THE SUBSEQUENT 48 HOURS.

LOW PRESSURE AREA LAY OVER EAST­CENTRAL BAY OF BENGAL & NEIGHBOURHOOD.
ASSOCIATED BROKEN LOW AND MEDIUM CLOUDS WITH EMBEDDED INTENSE TO VERY
INTENSE CONVECTION LAY OVER EAST­CENTRAL ADJOINING NORTHEAST BAY OF
BENGAL, ARAKAN COAST & NEIGHBOURHOOD. MINIMUM CLOUD TOP TEMPERATURE IS
­930C.

SCATTERED TO BROKEN LOW AND MEDIUM CLOUDS WITH EMBEDDED INTENSE TO VERY
INTENSE CONVECTION LAY OVER NORTHEAST ADJOINING CENTRAL BAY OF
BENGAL,ARAKAN COAST.SCATTERED LOW AND MEDIUM CLOUDS WITH EMBEDDED
MODERATE TO INTENSE CONVECTION LAY OVER SOUTHWEST BAY OF BENGAL OFF
NORTH TAMILNADU COAST, SOUTHEAST BAY OF BENGAL & SOUTH ANDAMAN SEA.

PROBABILITY OF CYCLOGENESIS (FORMATION OF DEPRESSION) DURING NEXT 120 HRS:

24 HOURS 24-48 HOURS 48-72 HOURS 72-96 HOURS 96-120 HOURS
NIL NIL NIL NIL NIL

[Sciencerocks]

[Sciencerocks]

Latest TWO by the official RSMC. 0% chance of TC formation

BAY OF BENGAL:

UNDER THE INFLUENCE OF THE CYCLONIC CIRCULATION, A LOW PRESSURE AREA HAS
FORMED OVER EASTCENTRAL BAY OF BENGAL & NEIGHBOURHOOD . IT IS LIKELY TO
BECOME MORE MARKED AND MOVE WEST­NORTHWESTWARDS TOWARDS ODISHA COAST
DURING THE SUBSEQUENT 48 HOURS.

LOW PRESSURE AREA LAY OVER EAST­CENTRAL BAY OF BENGAL & NEIGHBOURHOOD.
ASSOCIATED BROKEN LOW AND MEDIUM CLOUDS WITH EMBEDDED INTENSE TO VERY
INTENSE CONVECTION LAY OVER EAST­CENTRAL ADJOINING NORTHEAST BAY OF
BENGAL, ARAKAN COAST & NEIGHBOURHOOD. MINIMUM CLOUD TOP TEMPERATURE IS
­930C.

SCATTERED TO BROKEN LOW AND MEDIUM CLOUDS WITH EMBEDDED INTENSE TO VERY
INTENSE CONVECTION LAY OVER NORTHEAST ADJOINING CENTRAL BAY OF
BENGAL,ARAKAN COAST.SCATTERED LOW AND MEDIUM CLOUDS WITH EMBEDDED
MODERATE TO INTENSE CONVECTION LAY OVER SOUTHWEST BAY OF BENGAL OFF
NORTH TAMILNADU COAST, SOUTHEAST BAY OF BENGAL & SOUTH ANDAMAN SEA.

PROBABILITY OF CYCLOGENESIS (FORMATION OF DEPRESSION) DURING NEXT 120 HRS:

24 HOURS 24-48 HOURS 48-72 HOURS 72-96 HOURS 96-120 HOURS
NIL NIL NIL NIL NIL

There must be good drugs in India.

[Subtrop]

THE DEPRESSION OVER NORTHEAST AND ADJOINING EASTCENTRAL BAY OF BENGAL
MOVED WESTWARDS WITH A SPEED OF 12 KMPH IN LAST 6 HOURS, INTENSIFIED INTO A
DEEP DEPRESSION AND LAY CENTERED AT 0000 UTC OF 25TH SEPTEMBER 2021, OVER
NORTH AND ADJOINING EASTCENTRAL BAY OF BENGAL NEAR LAT. 18.4°N AND LONG.
89.7°E, ABOUT 510 KM EAST-SOUTHEAST OF GOPALPUR (43049) & 590 KM EASTNORTHEAST OF KALINGAPATNAM (43105).
IT IS LIKELY TO INTENSIFY INTO A CYCLONIC STORM DURING NEXT 12 HOURS. IT
IS LIKELY TO MOVE NEARLY WESTWARDS AND CROSS NORTH ANDHRA PRADESH - SOUTH
ODISHA COASTS BETWEEN VISHAKHAPATNAM (43149) & GOPALPUR (43049) AROUND
KALINGAPATNAM (43105) BY EVENING OF 26TH SEPTEMBER, 2021.

[Subtrop]

The Deep Depression over northwest & adjoining westcentral Bay of Bengal moved
nearly westwards with a speed of 07 kmph in last 6 hours, intensified into Cyclonic Storm
‘Gulab’ (pronounced as Gul-Aab) and lay centered at 1730 hrs IST of 25
th September 2021,
over northwest and adjoining westcentral Bay of Bengal near Lat. 18.3°N and Long. 88.3°E,
about 370 km east-southeast of Gopalpur (Odisha) & 440 km east of Kalingapatnam (Andhra
Pradesh).
It is likely to move nearly westwards and cross north Andhra Pradesh - south Odisha
coasts between Kalingapatnam & Gopalpur around evening of 26th September, 2021.

[underthwx]

Is the storm forecast to be a Tropical Storm until a landfall occurs?...

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[shah83]

Hey guys, check out what the 12z Euro has this storm doing in the Arabian Sea!

[doomhaMwx]

The remnants of TC Gulab are starting to emerge over the northern Arabian Sea. With the system already looking good in terms of vorticity and low-level structure + favorable conditions in the Arabian Sea, redevelopment to a tropical storm (or stronger) will be an easy task as shown by models.





Depending on Gulab's proximity, heavy rainfall and gale-force winds could be an issue to the coastal areas of Pakistan as the system meanders just off the country's coast over the next few days (landfall uncertain).

[doomhaMwx]

WTIO21 PGTW 291730

REMARKS: THE AREA OF CONVECTION (REMNANTS OF TC 03B) PREVIOUSLY
LOCATED NEAR 22.1N 72.4E IS NOW LOCATED NEAR 22.6N 71.4E,
APPROXIMATELY 103 NM NORTH OF JAFARABAD, INDIA. ANIMATED ENHANCED
INFRARED (EIR) SATELLITE IMAGERY AND A 291314Z SSMIS 91GHZ SATELLITE
IMAGE DEPICT FORMATIVE BAND OF DEEP CONVECTION DEVELOPING ALONG THE
WESTERN PERIPHERY OF A LOW LEVEL CIRCULATION CENTER AT THE EDGE OF
THE INDIAN SHORELINE. ENVIRONMENTAL ANALYSIS INDICATES AN OVERALL
FAVORABLE ENVIRONMENT CHARACTERIZED BY VERY WARM (30-31C) SEA
SURFACE TEMPERATURES (SST) AND AN UPPER LEVEL ANTICYCLONE THAT IS
ENHANCING EQUATORWARD OUTFLOW. THE CIRCULATION ALSO IS MOVING
TOWARDS AN AREA OF LOW VERTICAL WIND SHEAR (VWS). GLOBAL MODELS ARE
GOOD IN AGREEMENT THAT THE REMNANTS OF TC 03B WILL STRENGTHEN AND
CONSOLIDATE AS IT EMERGES OVER THE ARABIAN SEA AND PROPAGATES WEST
NORTHWESTWARD. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20
TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004
MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL
CYCLONE WITHIN THE NEXT 24 HOURS IS HIGH.

[Sciencerocks]

[doomhaMwx]

IMD now refers to the remnants of Gulab as an unnamed depression and thus, it would receive a new name when it becomes a cyclonic storm (although they indeed acknowledged this as Gulab's remnants earlier). OTOH, JTWC will likely keep its 03B designation, which may cause confusion.

SUB: DEPRESSION OVER NORTHEAST ARABIAN SEA OFF GUJARAT COAST.

THE DEPRESSION OVER NORTHEAST ARABIAN SEA & ADJOINING KUTCH MOVED NEARLY WESTWARDS WITH A SPEED OF ABOUT 28 KMPH DURING PAST 3 HOURS AND LAY CENTRED AT 0300 UTC OF TODAY, THE 30TH SEPTEMBER, 2021, OVER NORTHEAST ARABIAN SEA OFF GUJARAT COAST, NEAR LATITUDE 22.7°N AND LONGITUDE 68.6°E, ABOUT 60 KM WEST-NORTHWEST OF DEVBHOOMI DWARKA (42731), 280 KM EAST-
SOUTHEAST OF KARACHI (41780) AND 860 KM EAST-SOUTHEAST OF CHABAHAR PORT (IRAN).

IT IS VERY LIKELY TO MOVE WEST-NORTHWESTWARDS AND INTENSIFY INTO A DEEP DEPRESSION OVER NORTHEAST ARABIAN SEA OFF NORTH GUJARAT COAST DURING NEXT 12 HOURS. THEN IT IS VERY LIKELY TO MOVE FURTHER WEST-NORTHWESTWARDS AND INTENSIFY INTO A CYCLONIC STORM DURING THE
SUBSEQUENT 24 HOURS. THEREAFTER IT IS LIKELY TO CONTINUE TO MOVE WEST-NORTHWESTWARDS TOWARDS PAKISTAN – MAKRAN COASTS, MOVING AWAY FROM THE INDIAN COAST.

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