Storm Australian Severe Weather Forum
Severe Weather Discussion => Tornado Alley Outbreaks and Severe Weather Worldwide => Topic started by: Michael Thomas on 27 March 2010, 04:01:56 PM
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Bangladesh and adjacent parts of India could see some severe storms over the next week. The latest GFS runs have forecast LI's down to -10 and CAPEs to 3000 j/kg as southerly low-level flow off the Bay of Bangal ramps up. Mid-level winds should be around 30-50 knots over Bangladesh for the entire week. In addition, the exit region of quite strong upper-level jet will be over Bangladesh part of the week.
The present date is close to the climatological peak for tornadoes in Bangladesh which is the 10-14th of April. Certainly worth keeping an eye on.
Michael
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This mornings sounding from Dhaka-
http://weather.uwyo.edu/cgi-bin/sounding?region=seasia&TYPE=GIF%3ASKEWT&YEAR=2010&MONTH=03&FROM=2700&TO=2700&STNM=41923 (http://weather.uwyo.edu/cgi-bin/sounding?region=seasia&TYPE=GIF%3ASKEWT&YEAR=2010&MONTH=03&FROM=2700&TO=2700&STNM=41923)
Impressive CAPE with nice turning in the lower levels and moderately strong deep layer shear. Pretty strong cap in place but I guess that it is still breakable. I would think that very large hail is likely with any isolated storms that form (if the cap breaks). In addition, with low LCL's and strong low level turning I think there is also a possibility of tornadoes.
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John,
You might be right. I will say however that very large hail does occur in Bangladesh and that this sounding is quite typical of those associated with severe weather in Bangladesh (although the 300 mbar temperature is a little on the warm side). I don't think you will find soundings from Bangladesh with the -10 to -30 layer much lower than this (outside of winter anyway). Regarding the shear...well we can't really expect a sounding taken in the morning, at once specific location, to represent the conditions in the afternoon, particularly along boundaries, such as a warm front or an outflow boundary, where storms are likely to fire.
Edit: I think that I should be careful not to speculate too much. I have access to very little meteorological data from the area so I am relying only on GFS model output and a single sounding.
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I think today may have the greatest probability of severe weather over Bangladesh/East India. Very strong mid and upper level winds are present over Bangladesh. 500 mbar winds are 50 knots over northern Bangladesh and increase to 60 knots to the north into India. GFS has a strong SW'ly low level jet over eastern Bangladesh and into eastern India with 850 mbar to 40 knots. High CAPE is also present and with very rich low level moisture leading to low LCL's.
The sounding for Dhaka-
http://weather.uwyo.edu/cgi-bin/sounding?region=seasia&TYPE=GIF%3ASKEWT&YEAR=2010&MONTH=03&FROM=3100&TO=3100&STNM=41923 (http://weather.uwyo.edu/cgi-bin/sounding?region=seasia&TYPE=GIF%3ASKEWT&YEAR=2010&MONTH=03&FROM=3100&TO=3100&STNM=41923)
Wish I could find some reports or satellite and radar images.
Michael
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Storms occurred in NE India on Tuesday night. There are reports of around 120 people being killed unfortunately.
Here is a link to a Stormtrack discussion-
http://www.stormtrack.org/forum/showthread.php?s=28e5ec937f9da200621cbe3e800fa44d&t=23617 (http://www.stormtrack.org/forum/showthread.php?s=28e5ec937f9da200621cbe3e800fa44d&t=23617)
ABC news-
http://www.abc.net.au/news/stories/2010/04/16/2874326.htm?section=world (http://www.abc.net.au/news/stories/2010/04/16/2874326.htm?section=world)
There are a few youtube videos of the damage if you search for 'bangladesh cyclone'
To be honest, I don't really know what happened. A few articles are calling it a cyclone, media always get confused. Whether the damage was caused by a squall line or supercells is not clear to me. I am not sure whether the damage was from straight line winds or a tornado.
Michael
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To be honest, I don't really know what happened. A few articles are calling it a cyclone, media always get confused. Whether the damage was caused by a squall line or supercells is not clear to me. I am not sure whether the damage was from straight line winds or a tornado.
Michael
There is a satellite picture on Stormtrack and it looks very much like 3 discreet SC's to me.
Would love to see the storm from ground, but I think chasing there would be a logistic nightmare and given roads and population density a potential life threatening situation.
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Mike
I think from memory, the Bangledeshi's like to use cyclone as a term to discribe tornadoes, adn SLW storms, as they don't have the word Tornado in their vocabulary....
Looks to be to be a possible tornado event, but it could have been similar to the Qld event of 2008.
Peter J
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Yeah agree, it did look like a couple of discrete storms (probable supercells) in the satellite image. I think these may of transitioned later into a squall line capable of damaging winds. This doesn't help the straight-line vs tornado question though.
About the cyclone naming, I have heard something along those lines. I think they also call these big damaging storms they get Nor'westers.
Michael