Bay of Bengal Tropical Storm Mahasen remains a dangerous threat

By: Dr. Jeff Masters , 2:39 PM GMT on May 13, 2013

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It's always a nervous time when a tropical cyclone with the potential to intensify marches through the Indian Ocean's Bay of Bengal. That's because fifteen of the twenty deadliest tropical cyclones in world history have been Bay of Bengal storms that have hit Bangladesh, India, or Myanmar. The most recent of these horrifying storms was 2008's Cyclone Nargis, which killed 146,000 people in Myanmar. The Bay of Bengal's notorious history is why hurricane forecasters are watching Tropical Cyclone Mahasen a little nervously today. Even though there has been little change to the 55 mph tropical storm over the past two days, the storm remains a potential threat to undergo rapid intensification into a dangerous major hurricane. The 11 am EDT Monday advisory from the Joint Typhoon Warning Center put Mahasen's top sustained winds at 55 mph, with a motion northwest at 11 mph towards India. Satellite loops show that Mahasen has a large area of intense thunderstorms with very cold cloud tops that reach high into the atmosphere. The cloud pattern is not well-organized, with little spiral banding. This lack of organization is also apparent on radar out of Chennai. However, the cyclone has developed a respectable upper-level outflow channel to the northwest. Wind shear has decreased to a moderate 10 - 20 knots, and is continuing to decrease. Ocean waters that are an exceptionally warm 31°C (88°F), about 1°C warmer than average for this time of year. The warm ocean waters extend to great depth, and the Tropical Cyclone Heat Potential (TCHP) is over 90 J/kg/cm^2, which is favorable for rapid intensification.


Figure 1. MODIS image of Tropical Cyclone Mahasen taken at 07:55 UTC Monday May 13, 2013. At the time, Mahasen was a tropical storm with 55 mph winds. Image credit: NASA.


Figure 2. Storm-total rainfall from Tropical Cyclone Mahasen as predicted by the 00 UTC May 13, 2013 run of the HWRF model. Rainfall amounts of 16 - 30 cm (6 - 12") are expected along a wide swath just to the right of where the storm makes landfall. Bangladesh's two largest cities, Dhaka and Chittagong, are shown. If Mahasen's track occurs farther to the left, as suggested by some models, these two cities will receive Mahasen's heaviest rains. Image credit: India Meteorological Department.

Forecast for Mahasen
The official forecast brings Mahasen to Category 1 strength before landfall occurs in Bangladesh near the Myanmar border on Thursday near 18 UTC. However, the model forecasts of Mahasen from the GFS, ECMWF, UKMET, GEM, NAVGEM, and FIM models continue to show wide disagreement on the future intensity, speed, and landfall location of the storm. It is possible that wind shear will keep the storm disorganized and below hurricane strength until landfall, as suggested by the ECMWF model. However, other model guidance, such as the 00 UTC May 13 forecast from the HWRF model, bring Mahasen to Category 2 strength by Tuesday. Mahasen is currently approaching a trough of low pressure to its northwest that is expected to recurve the storm to the northeast into Bangladesh. As the recurvature process progresses today through Tuesday, wind shear should relax to a low to moderate 5 - 15 knots, and a strong upper-level outflow channel will intensify to the storm's north, aiding intensification. There is a lot of hot, dry air to the storm's northwest over India, and if this dry air gets wrapped into Mahasen's circulation, it could put the brakes on rapid intensification, though. Considering all these factors, I give a 30% chance that Mahasen will undergo rapid intensification to a Category 3 or stronger storm by Wednesday. The storm should experience higher wind shear and less oceanic heat content in the waters beneath it in the 12 hours before landfall, which should cause some weakening. But even a weakening Category 1 storm has the potential to bring a devastating storm surge to the coast of Bangladesh, and torrential rainfall will be a major flooding threat regardless of the storm's final intensity at landfall. The 00Z May 13 run of the HWRF model predicts that the Mahasen will dump a significant area of heavy rains of 16 - 30 cm (6 - 12") over Maynmar and Bangladesh. The storm surge, high winds, and heavy rains of Mahasen are a particular concern for the thousands of Myanmar refugees living near the coast in makeshift camps, as reported by the New York Times.

MJO pulse that spawned Mahasen headed towards the Atlantic
Mahasen spun up in response to an active phase of the Madden Julian Oscillation (MJO) that has been moving through the Indian Ocean during the past week. The MJO is a pattern of increased thunderstorm activity near the Equator that moves around the globe in 30 - 60 days. The strong MJO pulse coincided with a convectively coupled atmospheric Kelvin wave (CCKW), a wave of increased heat and moisture propagating along the Equator, which helped increase thunderstorm activity. The active pulse of the Madden Julian Oscillation is expected to reach the Western Caribbean (in a somewhat weakened state) May 21 - 25, and there will be a heightened chance of an early-season tropical storm forming in the Eastern Pacific and Western Caribbean during that time period.

Resources
Comparative model forecasts of Mahasen from the GFS, ECMWF, UKMET, GEM, NAVGEM, and FIM models

India Meteorological Department's tropical cyclone page

Radar out of Chennai, India

Bangladesh Meteorological Department Warning

Myanmar Dept. of Meteorology and Hydrology Warning

Jeff Masters

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I brought out the thick comforter from the cedar chest tonight. Cool in here.
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90E/INV/XX

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LOL, this blog is buzzing tonight. I love it
Member Since: July 18, 2010 Posts: 50 Comments: 1912
Quoting trHUrrIXC5MMX:


cos tan is sin!

so are permutations/combinations, line/parabolas transformations/shifts, functions, inverses, radians, degrees, pi, sigma values, standard deviations and so much more!!!

sorry for the off-topic matter



Our deviations insofar as our interest in weather are not standard. They are off the chart!
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The Mothers' Day shootings? I heard about those. Ick.
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reminder...

Only a little more than a day left for the first NHC TWO...

On May 15 expect the first TWO to be issued for the Eastern Pacific Basin at 8 AM EDT or 5 AM PDT.

No 2 AM because it's 11 PM PDT May 14.
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Member Since: July 6, 2010 Posts: 113 Comments: 33600
Quoting FunnelVortex:
Where is this invest 90E?


must be one of these two
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Where is this invest 90E?
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Quoting BaltimoreBrian:
Cos tan is a sin?

Skin cancer, ya know.


cos tan is sin!

so are permutations/combinations, line/parabolas transformations/shifts, functions, inverses, radians, degrees, pi, sigma values, standard deviations and so much more!!!

sorry for the off-topic matter
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Quoting BaltimoreBrian:
Sounds like a fun time Kori.


There was actually a shooting literally right after I left, and less than a mile from where I was. Talk about a certain stroke of luck.
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Cos tan is a sin?

Skin cancer, ya know.
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Quoting Grothar:


How dare you. I would never use a y=mx b equation.

I'm strictly and ax by=c guy myself.


LOL...

Trust me I'll take that rather than sin-cos-tan crap...
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i had a bad dream that a hurricane came through tampa because the gulf at my house was a picture of a big hurricane with a big eye
lol
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Sounds like a fun time Kori.
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Quoting trHUrrIXC5MMX:


oops, at first sight I thought that was a simple y=mx+b equation line...jk

well, these intensities are for are for 90E?? nuts!, not buying none of that though.


How dare you. I would never use a y=mx+b equation.

I'm strictly and ax+by=c guy myself.
Member Since: July 17, 2009 Posts: 71 Comments: 27518
Quoting Grothar:


Until it reaches the top of the page, I would presume.


That's no fun. We need a legal pad!
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Quoting BaltimoreBrian:
What's the story Kori? Did you make that tie-dye yourself?


Nah. There was a friendly meetup in the French Quarter in New Orleans over the weekend; one of the people in the Facebook group (she didn't show) made customized shirts for all the participants. I chose to have that one. I found out about the event through AwakeInMaryland, whom I haven't seen post here in quite some time.

Of note, I had the pleasure of meeting a couple of people from this website, namely auburn (the moderator) and Isle(sp?)Watcher. David (auburn) and I talked a lot, we all had a really good time. I wanna go back again already, lol.
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In 2005 the pattern of April- May,was almost the same in the hard of the season, with the high shifting to the west...


In May 2013 the pattern looks like this:


Lets see what happens....
Member Since: June 20, 2012 Posts: 0 Comments: 2178
Quoting BaltimoreBrian:
Grothar how linear. How long is that trend forecast to be maintained?


Until it reaches the top of the page, I would presume.
Member Since: July 17, 2009 Posts: 71 Comments: 27518
Quoting Grothar:
Intensity graph for 90E



oops, at first sight I thought that was a simple y=mx b equation line...jk

well, these intensities are for 90E?? nuts!, not buying none of that though.
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What's the story Kori? Did you make that tie-dye yourself?
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Grothar how linear. How long is that trend forecast to be maintained?
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Quoting KoritheMan:


There is usually very little run to run consistency until we actually get a cyclone.

Or at least a definitive, well-organized low-level center for that matter. We'll have to see how it goes over the coming days. I'm just glad to be tracking something. [I] Missed this.
Member Since: July 6, 2010 Posts: 113 Comments: 33600
Intensity graph for 90E

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Quoting cyclonekid:
Is this for Mahasen or for 90E?


90E, only NHC basins these apply to as far as I know.

Do note, not all the time the ATCF's data seals the intensity for the storm nor any other information regarding it for the NHC advisory issued after.
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Quoting TropicalAnalystwx13:
Latest statistical model guidance isn't as enthusiastic about intensification as the previous cycle was. As I said earlier, the first runs typically like to be bullish.



There is usually very little run to run consistency until we actually get a cyclone.
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Latest statistical model guidance isn't as enthusiastic about intensification as the previous cycle was. As I said earlier, the first runs typically like to be bullish.

Member Since: July 6, 2010 Posts: 113 Comments: 33600
Quoting TropicalAnalystwx13:
This is the highest I have ever seen the 25-kt RI probability.

Prob of RI for 25 kt RI threshold= 95% is 8.5 times the sample mean(11.7%)


Ironically, it's more likely to land on that 5% of not RI'ing.
Member Since: July 18, 2010 Posts: 50 Comments: 1912
Quoting cyclonekid:
Is this for Mahasen or for 90E?

Invest 90E. Unless I'm extremely oblivious, there isn't an ATCF system for the Indian Ocean.
Member Since: July 6, 2010 Posts: 113 Comments: 33600
Quoting TropicalAnalystwx13:
This is the highest I have ever seen the 25-kt RI probability.

Prob of RI for 25 kt RI threshold= 95% is 8.5 times the sample mean(11.7%)
Is this for Mahasen or for 90E?
Member Since: July 14, 2009 Posts: 51 Comments: 1731
Quoting trHUrrIXC5MMX:


This is how I put it... in descending order

East coast
FL. Keys up to Tampa and Panhandle
North of Tampa to Appalachicola
It's more like South Fl., Panhandle,Central & NE Fl.
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Wow. The flare has peaked at X3.2, the strongest of the three that have occurred within 24 hours, and by Solarham.com's count, the third strongest of Solar Cycle 24 so far.

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This is the highest I have ever seen the 25-kt RI probability.

Prob of RI for 25 kt RI threshold= 95% is 8.5 times the sample mean(11.7%)
Member Since: July 6, 2010 Posts: 113 Comments: 33600
X class solar flare in progress.
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90E just before night takes over

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SHIPS is less bullish--and more reasonable--this run.

V (KT) NO LAND 25 27 29 32 34 37 47 52 55 57 56 52 51
Member Since: July 6, 2010 Posts: 113 Comments: 33600
Where, oh where, is the first Special Tropical Weather Outlook (STWO)?
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Quoting Sangria:



You do realize, he asked specifically, about Florida?????


Oh wait, yeah. derp
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00z ATCF update drops 90E's pressure to 1007 mb; winds up to 30 mph; changed from "DB" (disturbance) to "LO" (low) again.

EP, 90, 2013051400, , BEST, 0, 69N, 956W, 25, 1007, LO,
Member Since: July 6, 2010 Posts: 113 Comments: 33600
Quoting Tropicsweatherpr:


It was very deep so it wont cause damage in the islands.


I know, Im just brining it up here for all of you to know it happened.
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Quoting trHUrrIXC5MMX:
preliminary...

darn! USGS removed their map..

Tsunami Information Bulletin
05/13/2013 08:39 PM EDT

000
WEPA42 PHEB 140039
TIBPAC

TSUNAMI BULLETIN NUMBER 001
PACIFIC TSUNAMI WARNING CENTER/NOAA/NWS
ISSUED AT 0039Z 14 MAY 2013

THIS BULLETIN APPLIES TO AREAS WITHIN AND BORDERING THE PACIFIC
OCEAN AND ADJACENT SEAS...EXCEPT ALASKA...BRITISH COLUMBIA...
WASHINGTON...OREGON AND CALIFORNIA.

... TSUNAMI INFORMATION BULLETIN ...

THIS BULLETIN IS FOR INFORMATION ONLY.

THIS BULLETIN IS ISSUED AS ADVICE TO GOVERNMENT AGENCIES. ONLY
NATIONAL AND LOCAL GOVERNMENT AGENCIES HAVE THE AUTHORITY TO MAKE
DECISIONS REGARDING THE OFFICIAL STATE OF ALERT IN THEIR AREA AND
ANY ACTIONS TO BE TAKEN IN RESPONSE.

AN EARTHQUAKE HAS OCCURRED WITH THESE PRELIMINARY PARAMETERS

ORIGIN TIME - 0032Z 14 MAY 2013
COORDINATES - 18.8 NORTH 145.4 EAST
DEPTH - 566 KM
LOCATION - MARIANA ISLANDS
MAGNITUDE - 7.0


It was very deep so it wont cause damage in the islands.
Member Since: April 29, 2009 Posts: 75 Comments: 15379
preliminary...

darn! USGS removed their map..

Tsunami Information Bulletin
05/13/2013 08:39 PM EDT

000
WEPA42 PHEB 140039
TIBPAC

TSUNAMI BULLETIN NUMBER 001
PACIFIC TSUNAMI WARNING CENTER/NOAA/NWS
ISSUED AT 0039Z 14 MAY 2013

THIS BULLETIN APPLIES TO AREAS WITHIN AND BORDERING THE PACIFIC
OCEAN AND ADJACENT SEAS...EXCEPT ALASKA...BRITISH COLUMBIA...
WASHINGTON...OREGON AND CALIFORNIA.

... TSUNAMI INFORMATION BULLETIN ...

THIS BULLETIN IS FOR INFORMATION ONLY.

THIS BULLETIN IS ISSUED AS ADVICE TO GOVERNMENT AGENCIES. ONLY
NATIONAL AND LOCAL GOVERNMENT AGENCIES HAVE THE AUTHORITY TO MAKE
DECISIONS REGARDING THE OFFICIAL STATE OF ALERT IN THEIR AREA AND
ANY ACTIONS TO BE TAKEN IN RESPONSE.

AN EARTHQUAKE HAS OCCURRED WITH THESE PRELIMINARY PARAMETERS

ORIGIN TIME - 0032Z 14 MAY 2013
COORDINATES - 18.8 NORTH 145.4 EAST
DEPTH - 566 KM
LOCATION - MARIANA ISLANDS
MAGNITUDE - 7.0
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breaking...

Strong 7.0 quake hits near the Northern Mariana Islands

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Quoting Sangria:



You do realize, he asked specifically, about Florida?????


do you realize I mentioned specifically about which places of Florida??
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Well now...
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Quoting Doppler22:

Remain warm: Failed
Avoid Shivering: Failed Miserably


purposely done so...

I always say feel as fell... Idk why... sorry
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Quoting psetas23:
which side of florida has the greater chance of a hurricane or is it the same odds
Quoting trHUrrIXC5MMX:


This is how I put it... in descending order

East coast
FL. Keys up to Tampa and Panhandle
North of Tampa to Appalachicola
Quoting KoritheMan:


No mention of the western Gulf at all? Not even Mexico?



You do realize, he asked specifically, about Florida?????
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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