BoB: AMPHAN - Post-Tropical

[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

[FireRat]

This storm feels so ominous.

completely agree!
This thing could be huge and strong, storm surge in this part of the world could be a huge concern if indeed the cyclone develops and becomes a large monster. Definitely gotta watch this situation closely into next week.

[SouthDadeFish]

I am quite concerned about this system. It is appearing increasingly likely somewhere along the Bay of Bengal coastline is going to be impacted by a significant TC.

 https://twitter.com/MikeFischerWx/status/1261386527147343873

[1900hurricane]

Technically, 91B is a tropical depression per JTWC's b-deck, but JTWC only renumbers once a system reaches tropical storm intensity outside the WPac. That moment is probably coming sooner than later.

IO, 91, 2020051518, , BEST, 0, 104N, 864E, 25, 1003, TD, 34, NEQ, 0, 0, 0, 0, 1006, 150, 50, 0, 0, B, 0, , 0, 0, INVEST, S,

[aspen]

SSTs are insanely high in the BOB and just about all the models are calling for at least a Cat 4 system....but are other environmental factors favorable? Could they be overblowing a possible Cat 1/2? The reason I have a bit of doubts is because some model runs have been showing an asymmetrical structure that would suggest wind shear acting on the system, preventing it from going nuclear like the GFS, NAVGEM, ICON, and HWRF want it to.

[aspen]

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=

[TropicalAnalystwx13]

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.

[Abdullah]

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?

[Abdullah]

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=

What's more important right now, I think, is the wind shear tendency, because over the last few hours a blob where wind shear is decreasing has been moving into the path of the storm and on the storm, at least that's what it looks like to me. You can see the change on that same website when you click on "Shear Tendency".

Here's an image right now as of 21Z (even though we'll have a new one within an hour):

https://i.imgur.com/YY8vL2y

[aspen]

Even if shear will be decreasing and changing to a more favorable pattern for 91B to take advantage of the plentiful warm waters in the BOB, something just seems off. That asymmetrical structure on the GFS and Euro just makes me skeptical of the 930-950 mbar peak they forecast. Why do such a lopsided structure and such an aggressive intensity forecast coincide together in both models?

[1900hurricane]

I'm ready to pull a renumber now just based on subjective Dvorak. It's really looking good for this part of its development cycle.

 https://twitter.com/1900hurricane/status/1261446503798718466

[StruThiO]

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=

looks to me like the shear depicted is associated with the anticyclone of 91B.

[1900hurricane]

Yeah, give me 35 kt for 00Z.

[aspen]

I think this might be the strongest convection associated with a newly formed storm since Halong, which is certainly saying something. Let’s see how it puts itself together.

[1900hurricane]

Extensive, cold convection yields extensive outflow. There is an upper level jet draped across the northern Bay of Bengal region at the moment, but I imagine that's going to get displaced northward just due to the ever expanding outflow pushing on it.

[aspen]

Extensive, cold convection yields extensive outflow. There is an upper level jet draped across the northern Bay of Bengal region at the moment, but I imagine that's going to get displaced northward just due to the ever expanding outflow pushing on it.

https://i.imgur.com/lw8cBji.gif

Do you think 91B could fight off any potentially present shear, or could it’s development/intensification be (somewhat) stalled by it?

[1900hurricane]

Extensive, cold convection yields extensive outflow. There is an upper level jet draped across the northern Bay of Bengal region at the moment, but I imagine that's going to get displaced northward just due to the ever expanding outflow pushing on it.

https://i.imgur.com/lw8cBji.gif

Do you think 91B could fight off any potentially present shear, or could it’s development/intensification be (somewhat) stalled by it?

Hard to tell for sure. The intensity of and outflow from the convection make me think it would be more resilient to at least upper level shear than most. If I'm looking for a disruptive layer of shear, I'd look for something undercutting: below anvil level to mid level. Some of the guidance depictions of shifting the 200 mb anticyclone a little upstream of the TC is a little unusual, and I'm not quite sure what to make of it. It almost looks like it ends up getting sheared by its own outflow, which doesn't make sense to me. Maybe it's another feature entirely.

[1900hurricane]

Still firmly believe this is a tropical storm right now.



Also, keep an eye on the dry air hook.

[Chris90]

Based off its structure and the convection it's been producing, wouldn't surprise me if this was a stronger tropical storm, maybe on the order of 50-55kts.

I enjoy watching intensifying tropical cyclones like so many others here, obviously, but I don't want to see impacts, especially not in this region. There can be astronomical death tolls associated with intense cyclones in this part of the world. I feel like there's enough going on in the world with the current pandemic. I'm really hoping this system dies off and doesn't even come close to the intensity some of the guidance has suggested.

[aspen]

Still firmly believe this is a tropical storm right now.

https://i.imgur.com/l1EKTJ4.jpg

Also, keep an eye on the dry air hook.

JTWC: looks like a well marked low pressure system with the potential for development.

Last year, there was a tropical storm that should’ve been named Amphan, but for some reason it was though to be an undeveloped disturbance while it was at peak intensity.