BoB: AMPHAN - Post-Tropical

[Nancy Smar]

91B INVEST 200512 0600 6.8N 91.0E IO 15 0

[aspen]

There is complete model agreement on 91B developing into a TC this weekend, and likely reaching hurricane status later on. However, in stark contrast to 01W/Vongfong, all models are showing a very large circulation, and the GFS suggests it will be lopsided. This will probably prevent it from taking full advantage of the warm, untouched waters of the BOB.

[doomhaMwx]

I think this should be merged with the 90B thread since they're basically the same system?
What do the admins/mods/mets here think?

90B INVEST 200510 0000 +8.7 +93.1 15 1007 B

90B INVEST 200510 0600 +8.9 +92.7 15 1007 B

90B INVEST 200510 1200 +9.1 +92.4 15 1007 B

91B INVEST 200511 1800 +6.8 +92.0 15 1010 B

91B INVEST 200512 0000 +6.8 +91.5 15 1010 B

91B INVEST 200512 0600 +7.0 +90.5 15 1010 B

91B INVEST 200512 1200 +7.2 +90.5 15 1010 B

[doomhaMwx]

[doomhaMwx]

This is worrisome. The global models are in tight agreement that 91B will turn north after the next three days or so towards the northern Bay of Bengal while organizing/intensifying at a quicker rate. It might pose a threat to the Ganges Delta in about 7 days time. Kelvin and Rossby waves in the region are forecast to enhance TC formation probabilities according to the CPC discussion as of May 12.

UKMET model

MET OFFICE TROPICAL CYCLONE GUIDANCE FOR NORTH INDIAN OCEAN

GLOBAL MODEL DATA TIME 00UTC 13.05.2020



NEW TROPICAL STORM FORECAST TO DEVELOP AFTER 78 HOURS

FORECAST POSITION AT T+ 78 : 11.1N 84.8E



VERIFYING TIME POSITION STRENGTH TENDENCY

-------------- -------- -------- --------

12UTC 16.05.2020 11.0N 84.2E MODERATE INTENSIFYING RAPIDLY

00UTC 17.05.2020 11.0N 83.4E MODERATE INTENSIFYING SLIGHTLY

12UTC 17.05.2020 11.6N 83.2E STRONG INTENSIFYING SLIGHTLY

00UTC 18.05.2020 12.3N 82.8E STRONG INTENSIFYING RAPIDLY

12UTC 18.05.2020 12.9N 82.3E INTENSE INTENSIFYING RAPIDLY

00UTC 19.05.2020 13.5N 82.0E INTENSE INTENSIFYING RAPIDLY

[aspen]

The GFS is going absolutely nuts with this. It has a TC by Friday, and a sub-940 mbar storm nearing landfall in 120-132 hours. The maximum potential intensity of the region is high enough to support that.

[alan1961]

Looks to be really winding up by the start of next week if the GFS is to be believed

[Nancy Smar]

(1) AN AREA OF CONVECTION (INVEST 91B) HAS PERSISTED NEAR 9.2N
87.1E, APPROXIMATELY 550 NM SOUTHEAST OF VISAKHAPATNAM, INDIA.
ANIMATED ENHANCED INFRARED SATELLITE IMAGERY AND A 131243Z SSMIS 91
GHZ MICROWAVE IMAGE DEPICT A CONSOLIDATING LOW LEVEL CIRCULATION
WITH SOME WEAK FORMATIVE BANDING TO THE SOUTHEAST. INVEST 91B IS IN
A FAVORABLE ENVIRONMENT FOR DEVELOPMENT WITH GOOD EQUATORWARD
OUTFLOW, WARM (28-30C) SEA SURFACE TEMPERATURES, AND LOW (<15 KTS)
VERTICAL WIND SHEAR. GLOBAL MODEL GUIDANCE IS IN GENERAL AGREEMENT
THAT INVEST 91B WILL CONTINUE TO CONSOLIDATE AND INTENSIFY AS IT
TRACKS NORTHWARD IN THE BAY OF BENGAL. MAXIMUM SUSTAINED SURFACE
WINDS ARE ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA LEVEL PRESSURE IS
ESTIMATED TO BE NEAR 1008 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS LOW.

[FireRat]

Oh boy this could be bad stuff, not a good track at all and the storm could be intensifying as it approaches the Ganges delta... a location well known for its historic devastating and deadly cyclone landfalls. Lets hope it doesn't become strong.

[doomhaMwx]

Although convective activity is looking organized on satellite images, recent ASCAT and microwave passes today show that the system remains rather weak and unorganized at the low levels. Convection also appears linear and is displaced east of a broad circulation center.




Global models are showing that monsoonal southwesterly winds in the BOB will strengthen on the next few days and wrap into 91B's circulation. This will not only aid in development but it's also possible that 91B will acquire some monsoonal characteristics during this time — a large system with a wide wind field as advertised by the global models. Such systems typically take more time to organize/intensify so its interesting that model guidance are picking up on rapid development. I imagine the upper-level environment could become excellent once 91B starts heading north. Note that the ECMWF, UKMET, and CMC models develop the system closer to the Indian coast, while the rest are farther east and indicate a higher risk to the Ganges Delta and the west coast of Myanmar.

[aspen]

The GFS is trying to develop a smaller and tighter circulation for 91B once it becomes a TC (likely on Saturday or Sunday), which would support the aggressive intensification into a 940-930 mbar system that most of the models have been pushing for. SSTs and ocean heat content in 91B’s path is high enough to support a max potential intensity of <890 mbar. If shear and moisture are favorable, and if the GFS is correct about a more compact system, then perhaps we could see a very powerful system next week.

[Nancy Smar]

ABIO10 PGTW 141800
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE INDIAN
/OCEAN/141800Z-151800ZMAY2020//
RMKS/
1. NORTH INDIAN OCEAN AREA (MALAY PENINSULA WEST TO COAST OF AFRICA):
A. TROPICAL CYCLONE SUMMARY: NONE.
B. TROPICAL DISTURBANCE SUMMARY:
(1) THE AREA OF CONVECTION (INVEST 91B) PREVIOUSLY LOCATED
NEAR 9.2N 87.1E IS NOW LOCATED NEAR 10.5N 87.6E, APPROXIMATELY 495
NM SOUTHEAST OF VISAKHAPATNAM, INDIA. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY AND A 141230Z SSMIS 91 GHZ MICROWAVE IMAGE DEPICT
A BROAD LOW LEVEL CIRCULATION WITH FLARING CONVECTION OFFSET TO THE
SOUTH. INVEST 91B IS IN A FAVORABLE ENVIRONMENT FOR FURTHER
DEVELOPMENT WITH GOOD POLEWARD OUTFLOW, WARM (28-30C) SEA SURFACE
TEMPERATURES, AND LOW (<15 KTS) VERTICAL WIND SHEAR. GLOBAL MODEL
GUIDANCE IS IN GOOD AGREEMENT THAT INVEST 91B WILL CONTINUE TO
CONSOLIDATE AND INTENSIFY AS IT TRACKS NORTHWARD IN THE BAY OF
BENGAL. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1007 MB.
THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS UPGRADED TO MEDIUM.
(2) NO OTHER SUSPECT AREAS.
C. SUBTROPICAL SYSTEM SUMMARY: NONE.
2. SOUTH INDIAN OCEAN AREA (135E WEST TO COAST OF AFRICA):
A. TROPICAL CYCLONE SUMMARY: NONE.
B. TROPICAL DISTURBANCE SUMMARY: NONE.
C. SUBTROPICAL SYSTEM SUMMARY: NONE.//
NNNN

[1900hurricane]

Starting to look like something that may be classifiable.

[Nancy Smar]

WTIO21 PGTW 151000
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 91B)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
140 NM EITHER SIDE OF A LINE FROM 9.0N 86.3E TO 12.8N 85.0E
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 15 TO 20 KNOTS. METSAT
IMAGERY AT 150900Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 9.4N 86.2E. THE SYSTEM IS MOVING NORTHWESTWARD AT 03 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 91B) PREVIOUSLY LOCATED
NEAR 10.5N 87.6E IS NOW LOCATED NEAR 9.4N 86.2E, APPROXIMATELY 602
NM SOUTH-SOUTHEAST OF VISAKHAPATNAM, INDIA. ANIMATED MULTISPECTRAL
IMAGERY AND A 150746Z GMI 89GHZ SATELLITE IMAGE DEPICT DEEP
CONVECTIVE BANDS IN THE SOUTHERN PERIPHERY WRAPPING INTO AN OBSCURED
LOW LEVEL CIRCULATION CENTER. ENVIRONMENTAL ANALYSES INDICATE A
FAVORABLE ENVIRONMENT FOR DEVELOPMENT WITH LOW (<15KTS) VERTICAL
WIND SHEAR, WARM (30-31C) SEA SURFACE TEMPERATURES, AND GOOD
POLEWARD OUTFLOW. GLOBAL MODELS AGREE THAT 91B WILL TRACK NORTH-
NORTHEASTWARD AS IT STRENGTHENS AND CONSOLIDATES. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1003 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
161000Z.//
NNNN

[Hayabusa]

Holy cow HWRF is going sub 900 mb on this... even major models want it to be an intense system not just only a big TC. If only this was on the wpac

[aspen]

Holy cow HWRF is going sub 900 mb on this... even major models want it to be an intense system not just only a big TC. If only this was on the wpac

https://i.imgur.com/w4grDo9.png

Every model is blowing this thing up. However, I’ve noticed on a few that the wind field or precipitation of the storm comes out asymmetrical, so perhaps it’s going to be somewhat sheared and not nearly as strong as anticipated.

[Hayabusa]

The Indian Ocean is primed theoretically for such one

[mrbagyo]

This storm feels so ominous.

[Hayabusa]

[Abdullah]

Does anyone here know where I can find the latest advisories for this region and how often the agency updates?