BoB: AMPHAN - Post-Tropical

[Hayabusa]

[ColdMiser123]

The latest wind shear graphic shows a bunch of high (20-30 kt) shear in the path of 91B. I’m starting to doubt it’ll get past Cat 2 status.

http://tropic.ssec.wisc.edu/real-time/w ... oom=&time=

The current wind shear map is for just that, current conditions. It does not show how upper-level winds will evolve over the coming days. In this case, the shear environment looks favorable for significant intensification.

Also important to keep in mind that upper level outflow from convection will inherently create a difference in wind with height surrounding the storm, so often surrounding shear will appear to be higher on these kinds of maps than it actually is for the storm.

[doomhaMwx]

The well marked low pressure area over southeast Bay of Bengal concentrated into
depression has formed over Southeast Bay of Bengal and lay centred at 0530 hrs IST of today, the
16th May, 2020 near latitude 10.4°N and longitude 87.0°E, about 1100 km south of Paradip (Odisha),
1250 km south of Digha (West Bengal) and 1330 km south-southwest of Khepupara (Bangladesh). It
is very likely to intensify rapidly into a Cyclonic Storm by today evening and further into a severe
cyclonic storm during subsequent 24 hours. It is very likely to move north-northwestwards initially till
17th May and then re-curve north-northeastwards across northwest Bay of Bengal towards West
Bengal coast during 18th to 20th May 2020.

[Hayabusa]

Upgraded, now we wait if this one becomes the models are hyping

01B ONE 200516 0600 9.8N 86.4E IO 35 998

[Hayabusa]

[doomhaMwx]

REMARKS:
160900Z POSITION NEAR 10.0N 86.4E.
16MAY20. TROPICAL CYCLONE 01B (ONE), LOCATED APPROXIMATELY 392 NM
EAST-SOUTHEAST OF CHENNAI, INDIA, HAS TRACKED NORTH-NORTHWESTWARD AT
03 KNOTS OVER THE PAST SIX HOURS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT
160600Z IS 12 FEET. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI)
SHOWS A MONSOON DEPRESSION THAT CONTINUES TO CONSOLIDATE,
CHARACTERIZED BY EXPANSIVE (OVER 600NM ACROSS) RAIN BANDS. THE
INITIAL POSITION IS PLACED WITH LOW CONFIDENCE BASED ON THE MSI LOOP.
THE INITIAL INTENSITY IS EXTRAPOLATED FR0M A 160309Z PARTIAL ASCAT
PASS AND CONSISTENT WITH NEARBY BUOY WIND OBSERVATIONS. TC 01B IS IN
A FAVORABLE ENVIRONMENT WITH LOW (10-15KT) VERTICAL WIND SHEAR (VWS),
STRONG RADIAL OUTFLOW, AND VERY WARM (31C) SSTS. THE CYCLONE WILL
TRACK NORTHWARD UNDER THE STEERING INFLUENCE OF A SUBTROPICAL RIDGE
(STR) TO THE EAST. BY TAU 48, THE TC WILL TRACK MORE NORTH-
NORTHEASTWARD AS THE STR WEAKENS. VWS WILL INCREASE AS THE TC MOVES
POLEWARD, HOWEVER, STRONG RADIAL OUTFLOW AND THE STORM MOTION BEING
IN-PHASE WITH THE UPPER LEVEL WIND FLOW WILL EASILY OFFSET THE VWS.
THIS, COMBINED WITH VERY WARM SST WILL PROMOTED STEADY
INTENSIFICATION TO A PEAK OF 90KTS. AFTERWARD, TC 01B WILL MAKE
LANDFALL JUST SOUTHEAST OF KOLKATA AROUND TAU 96. LAND INTERACTION
WILL PRIMARILY CAUSE ITS RAPID DECAY AND BY TAU 120, WILL BE REDUCED
TO 30KTS AS IT MOVES FURTHER INLAND. NUMERIC MODELS ARE IN GOOD
AGREEMENT, HOWEVER, GIVEN THE FORMATIVE NATURE OF THE CYCLONE, THERE
IS LOW CONFIDENCE IN THIS INITIAL TRACK FORECAST FROM JTWC.

[aspen]

https://i.imgur.com/nXGyINr.jpg

Is that actually 912 mbar from the Euro model?!

The last two storms it was this aggressive with were Hagibis and Kammuri. The former likely became one of the top 10 strongest tropical cyclones ever recorded, while the latter failed to live up to the model hype despite becoming a Cat 4. Only time will tell which one Amphan ends up like.

[1900hurricane]

2.0 DT, really? Looks like an easy 3.0 at the time and probably 3.5 now. Again, I'd probably out the door it at 3.0 currently given where it was yesterday (though 3.5 is also valid given the apparent rate of intensification/using the 1.5 MET increase), but JTWC seems behind the curve. Loos like 8/10 banding at minimum to me, not 3/10.

TPIO10 PGTW 160953

A. TROPICAL CYCLONE 01B (E OF INDIA)

B. 16/0845Z

C. 10.11N

D. 86.10E

E. FIVE/GOES-IO

F. T2.0/2.0 STT: S0.0/03HRS

G. IR/EIR/VIS/MSI

H. REMARKS: 40A/PBO SBC/ANMTN. .30 WRAP ON LOG10 SPIRAL YIELDS
A 2.0 DT. MET AND PT YIELD A 2.0. DBO DT.

I. ADDITIONAL POSITIONS: NONE


BERMEA

[1900hurricane]

 https://twitter.com/1900hurricane/status/1261633476463394822

[aspen]

2.0 DT, really? Looks like an easy 3.0 at the time and probably 3.5 now. Again, I'd probably out the door it at 3.0 currently given where it was yesterday (though 3.5 is also valid given the apparent rate of intensification/using the 1.5 MET increase), but JTWC seems behind the curve. Loos like 8/10 banding at minimum to me, not 3/10.

TPIO10 PGTW 160953

A. TROPICAL CYCLONE 01B (E OF INDIA)

B. 16/0845Z

C. 10.11N

D. 86.10E

E. FIVE/GOES-IO

F. T2.0/2.0 STT: S0.0/03HRS

G. IR/EIR/VIS/MSI

H. REMARKS: 40A/PBO SBC/ANMTN. .30 WRAP ON LOG10 SPIRAL YIELDS
A 2.0 DT. MET AND PT YIELD A 2.0. DBO DT.

I. ADDITIONAL POSITIONS: NONE


BERMEA

https://i.imgur.com/UXuspRr.gif

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

They’ve been terrible with NIO cyclones since October, from not upgrading Kyarr to a Cat 5 despite plenty of Dvorak evidence to not even classifying or naming a fully fledged tropical cyclone.

[1900hurricane]

I don't know, maybe I'm way off base, especially since I'm not actually using a log10 spiral and just estimating visually, but I just don't know why JTWC is an entire half wrap lower than me using the curved band pattern.

TPIO10 PGTW 161220

A. TROPICAL CYCLONE 01B (E OF INDIA)

B. 16/1145Z

C. 10.06N

D. 86.22E

E. FIVE/GOES-IO

F. T2.0/2.0/D2.0/24HRS STT: S0.0/03HRS

G. IR/EIR/VIS/MSI

H. REMARKS: 40A/PBO SBC/ANMTN. .35 WRAP ON LOG10 SPIRAL YIELDS
A 2.0 DT. MET AND PT YIELD A 2.0. DBO DT.

I. ADDITIONAL POSITIONS:
16/0654Z 10.38N 86.07E MMHS
16/0743Z 10.30N 85.98E ATMS
16/0749Z 9.97N 86.22E AMS2
16/1038Z 9.98N 86.07E SSMS
16/1109Z 9.98N 86.38E SSMS


BERMEA

[TorSkk]

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

You can find them here, on the RSMC New Delhi's website. Advisories are issued every three hours at at 00, 03, 06, 09, 12, 15, 18 and 21 UTC

http://www.rsmcnewdelhi.imd.gov.in/index.php?lang=en

Thanks for the link! I assume the three hour update is for full cyclones, though, right? For the invest, no update has been published since 6:00 UTC using data from 3:00 UTC of May 15. How often do we receive updates for invests?

A Tropical Weather Outlook is issued once a day at 6Z when there is no cyclone in the AOR. A Special Tropical Weather Outlook is issued twice a day (6Z and 15Z) when there is a Depression, and five times a day (3Z, 6Z, 9Z, 15Z, 21Z) when the Depression has intensified into a Deep Depression or is expected to intensify into one shortly. The previously mentioned Advisories are issued when it reaches cyclonic storm (TS) intensity

[wxman57]

Officially, this is classified as a depression, not even a "deep depression" by IMD. I believe a "deep depression" has winds around 35 mph. They're not the best RSMC, but they're the official agency of the NIO. We have it as a rapidly-strengthening 40 kt TS on our advisories.

[TorSkk]

Officially, this is classified as a depression, not even a "deep depression" by IMD. I believe a "deep depression" has winds around 35 mph. They're not the best RSMC, but they're the official agency of the NIO. We have it as a rapidly-strengthening 40 kt TS on our advisories.

It's a Deep Depression as per the latest outlook

[wxman57]

Officially, this is classified as a depression, not even a "deep depression" by IMD. I believe a "deep depression" has winds around 35 mph. They're not the best RSMC, but they're the official agency of the NIO. We have it as a rapidly-strengthening 40 kt TS on our advisories.

It's a Deep Depression as per the latest outlook

I'm deeply depressed with IMD's analysis skills...

[Nancy Smar]

VORTEX OVER SE BAY & N/HOOD HAS FURTHER INTENSIFIED AND NOW LAY CENTERED
NEAR 10.5N/86.1E (.) INTENSITY T2.5 RPT T2.5 CURVED BAND PATTERN MINIMUM CTT MINUS
93 DEG C (.) ASSTD BKN LOW/MED CLOUDS WITH EMBDD INT TO V INT CONVTN OVER BAY
BET LAT 6.0N TO 16.0N LONG 81.0E TO 91.0E (.)

The latest Dvorak analysis from IMD is T2.5 so that it will be named Amphan at 15Z.

[aspen]

VORTEX OVER SE BAY & N/HOOD HAS FURTHER INTENSIFIED AND NOW LAY CENTERED
NEAR 10.5N/86.1E (.) INTENSITY T2.5 RPT T2.5 CURVED BAND PATTERN MINIMUM CTT MINUS
93 DEG C (.) ASSTD BKN LOW/MED CLOUDS WITH EMBDD INT TO V INT CONVTN OVER BAY
BET LAT 6.0N TO 16.0N LONG 81.0E TO 91.0E (.)

Dvorak analysis from IMD is T2.5.
And it will be named Amphan at 15Z.

Maybe they’ll assess it as a 3.0 once that eye fully clears out within a CDG CDO.

[Highteeld]

https://i.imgur.com/nXGyINr.jpg

Is that actually 912 mbar from the Euro model?!

The last two storms it was this aggressive with were Hagibis and Kammuri. The former likely became one of the top 10 strongest tropical cyclones ever recorded, while the latter failed to live up to the model hype despite becoming a Cat 4. Only time will tell which one Amphan ends up like.

Ukmet and HWRF both going under 900 mb

IO, 91, 2020051600, 03, UKM, 84, 190N, 865E, 108, 898, TC, 34, NEQ, 195, 197, 115, 88, , , 23, , , B, , , , , 91B

[doomhaMwx]

WPAC-feels

[Highteeld]