Arabian Sea: CHAPALA - Post-Tropical

[wxman57]

Note that the JTWC is not the RSMC for any basin. They cannot "officially" upgrade any system. IMD is still calling this a "Deep Depression" so that's its official designation, even though it's likely a 45-50kt TS by now.

[wxman57]

Why do they even do that? Like, do they have access to data that points otherwise? Or do they normally under forecast storms?

The IMD is typically VERY slow to classify a system and almost always low on intensity estimates compared to other agencies. I'm not sure how they estimate intensity or use Dvorak. I heard last year that they estimate intensity first and THEN apply a Dvorak number. I find that hard to believe, but evidence suggests they might be doing that...

[mrbagyo]

Bulls eye by METOP-B @ 2304utc -clearly a TC with those 40 knot wind barbs near the center



45 knots

[Alyono]

ASCAT from 1724 UTC

[Yellow Evan]

T2.0 from IMD. Expect an upgrade to deep depression soon.

Where do you get IMD Dvorak numbers from?

http://www.rsmcnewdelhi.imd.gov.in/images/satelliteImage/description.pdf

Satellite bulletin description page. It shows Dvorak intensity descriptions for the Arabian, Bay of Bengal/Andaman Sea, Southwestern Indian Ocean, and Western Pacific (Philippines westward towards Thailand region)

k, thanks.

[Alyono]

a well defined eye. Makes sense why IMD called this a deep depression

http://www.nrlmry.navy.mil/tc-bin/tc_ho ... egreeticks

[Yellow Evan]

Why do they even do that? Like, do they have access to data that points otherwise? Or do they normally under forecast storms?

The IMD is typically VERY slow to classify a system and almost always low on intensity estimates compared to other agencies. I'm not sure how they estimate intensity or use Dvorak. I heard last year that they estimate intensity first and THEN apply a Dvorak number. I find that hard to believe, but evidence suggests they might be doing that...

I've read in the past they supposedly do Dvorak from visible pictures rather than BD.

[Alyono]

Why do they even do that? Like, do they have access to data that points otherwise? Or do they normally under forecast storms?

The IMD is typically VERY slow to classify a system and almost always low on intensity estimates compared to other agencies. I'm not sure how they estimate intensity or use Dvorak. I heard last year that they estimate intensity first and THEN apply a Dvorak number. I find that hard to believe, but evidence suggests they might be doing that...

I've read in the past they supposedly do Dvorak from visible pictures rather than BD.

You can do Dvoraks from any type of satellite. I do them from microwave imagery. However, the fact is, IMD simply makes awful Dvoraks. A TC with a microwave eye does not have winds less than 50 kts

[Alyono]

ensembles are taking this deep into the Gulf of Aden, possible into the more heavily populated parts of Yemen. Could come in as far west as Al Mukalla or even farther west

[Yellow Evan]

Why would you even bother with IMD Dvorak numbers. Alyono has pointed out many times over in this basin the IMD does not understand dvorak. This system will RI big time.

The fact they are the basis for IMD intensity estimates is why I mentioned them earlier.

[1900hurricane]

ensembles are taking this deep into the Gulf of Aden, possible into the more heavily populated parts of Yemen. Could come in as far west as Al Mukalla or even farther west

That would be a pretty rare track. Just taking a quick glance over at the Wiki page for the region, I can only see one tropical cyclone really make it in there in the 1970-2005 period. Not exactly a tropical cyclone hotbed.

[Alyono]

ensembles are taking this deep into the Gulf of Aden, possible into the more heavily populated parts of Yemen. Could come in as far west as Al Mukalla or even farther west

That would be a pretty rare track. Just taking a quick glance over at the Wiki page for the region, I can only see one tropical cyclone really make it in there in the 1970-2005 period. Not exactly a tropical cyclone hotbed.

I think that one was a mere depression. This one could have winds greater than 100 kts. I wouldn't be surprised at all if this becomes more intense than Gonu was before it starts to weaken

[Alyono]

based upon the microwave eye, I went with 50 kt winds at 3Z, with a peak of 115 kt winds

[Alyono]

huh? what about ignore list immediately after a models post?

as for the models, the ensembles are all well west

[Alyono]

looks like a banding eye is forming now

[mrbagyo]

[Alyono]

IMD named it Chapala and they have now issued a reasonable intensity forecast, with a peak of about 100 kts

Of course, their initial intensity of 35 kts is laughable

[jaguarjace]

Time of issue: 0830 hours
IST Dated: 29.10.2015
Bulletin No.: ARB04/2015/03

Sub: Cyclonic storm ‘Chapala’ over eastcentral and adjoining westcentral & south
Arabian Sea.

The Deep Depression over eastcentral and adjoining areas of westcentral and
south Arabian Sea moved north-northwestwards with a speed of about 10kmph during
past 12 hours and intensified into a Cyclonic storm, ‘Chapala’ and lay centered at 0530
hrs IST of today, the 29th October 2015 over eastcentral and adjoining westcentral and
south Arabian Sea near Latitude 13.7°N and longitude 64.3°E, about 1080 km southwest
of Mumbai and about 1150 km east-southeast of Salalah (Oman). It would move northnorthwestwards
and intensify into a severe cyclonic Storm during next 24 hours. It would
then move westwards towards Yemen and adjoining Oman coast.

http://www.rsmcnewdelhi.imd.gov.in/images/cyclone_pdfs/indian_1446112923.pdf

[Alyono]

if IMD would look at a satellite, they would see it is a severe or a very severe cyclonic storm now

[Alyono]

I'd say winds are at least 65 kts now