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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Downhearted

Long Live the King
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Member Since: September 30, 2007 Posts: 9 Comments: 15932
Quoting SouthernIllinois:

It's got a longer way to go than you think. Have you looked at the latest infrared?

I'm white aware of how far it has to go. But it's in a favourable environment and most models show development by the time I mentioned.
Member Since: July 6, 2010 Posts: 113 Comments: 31502
Quoting StormTrackerScott:


Alkright Taz. Misspelling is intentional by the waoy;) LOL




you been reported for the commet you made
Member Since: May 21, 2006 Posts: 5091 Comments: 114750
712. WunderAlertBot (Admin)
JeffMasters has created a new entry.
Quoting AussieStorm:
90E looks like a typical Monsoon low, It may take a lot of time to get it's act together since it's very large. Lets hope if/when it does get it's act together and consolidate, it keeps heading west and stays fish.


Just as is the case with early season Caribbean disturbances. Remember TS Debby?
Member Since: February 28, 2013 Posts: 4 Comments: 2323
Quoting SouthernIllinois:
LMAO. Scott---YOU'RE WRONG BUDDY. 90E DOES HAVE A CHANCE. IT WAS BECOME A MONSTER CATEGORY 5 STORM!!! BELIEVE!!!!!!!!!!!!!!!!!!!!!!!!!!!!

:P




reported for yelling
Member Since: May 21, 2006 Posts: 5091 Comments: 114750
Quoting SouthernIllinois:
LMAO. Scott---YOU'RE WRONG BUDDY. 90E DOES HAVE A CHANCE. IT WAS BECOME A MONSTER CATEGORY 5 STORM!!! BELIEVE!!!!!!!!!!!!!!!!!!!!!!!!!!!!

:P


Alkright Taz. Misspelling is intentional by the waoy;) LOL
Member Since: February 28, 2013 Posts: 4 Comments: 2323
90E looks like a typical Monsoon low, It may take a lot of time to get it's act together since it's very large. Lets hope if/when it does get it's act together and consolidate, it keeps heading west and stays fish.
Member Since: September 30, 2007 Posts: 9 Comments: 15932
Quoting SouthernIllinois:
I had one in my yard in Grand Rapids as a kid in the 80s. We ain't scared of hairless nuts anyhow!
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Quoting SouthernIllinois:

Nnnnnnnoooooooooooo...................
Quoting washingtonian115:
I think the storm Taz and Teddy are referring to is Felix..it looked absolutely hideous and worthless when it was a swirl between Africa and the Leeward Islands only to have found a more favorable environment and turn into a monster..That Felix was surely something and a lesson learned.I hope we won't have to be tracking nothing like that this year in the caribbean.No Ivan's,Gustav's,Ike's,or Dean's this year please or Wilma's..

Also Michael from last year went from a 1015mb swirl to a major hurricane in just 4 days.
Member Since: March 16, 2012 Posts: 127 Comments: 7928
703. VR46L
Quoting StormTrackerScott:


No chance in that. 90E has a very long way to go right now.


I would tend to agree with ya ... seems glued to the Monsoon trough at the moment

Rammb Imagery

Member Since: March 1, 2012 Posts: 0 Comments: 6834
Quoting SouthernIllinois:

It's got a longer way to go than you think. Have you looked at the latest infrared?




have you even been following ???? I guss not



some time invest dos this then they find a more favorable environment it could all so be its Dmin or or it could no longer be hock up with the INTERTROPICAL CONVERGENCE ZONE so wish means 90E is now on its own and this needs to find a more favorable environment and its olny tuesday
Member Since: May 21, 2006 Posts: 5091 Comments: 114750
Quoting StormTrackerScott:


Wishcasting?




have you even been following ???? I guss not



some time invest dos this then they find a more favorable environment it could all so be its Dmin or or it could no longer be hock up with the INTERTROPICAL CONVERGENCE ZONE so wish means 90E is now on its own and this needs to find a more favorable environment and its olny tuesday
Member Since: May 21, 2006 Posts: 5091 Comments: 114750
I think the storm Taz and Teddy are referring to is Felix..it looked absolutely hideous and worthless when it was a swirl between Africa and the Leeward Islands only to have found a more favorable environment and turn into a monster..That Felix was surely something and a lesson learned.I hope we won't have to be tracking nothing like that this year in the caribbean.No Ivan's,Gustav's,Ike's,or Dean's this year please or Wilma's..
Member Since: Posts: Comments:
Quoting TropicalAnalystwx13:
My best guess is we'll see classification sometime late Thursday or early Friday.


Wishcasting?

Member Since: February 28, 2013 Posts: 4 Comments: 2323
My best guess is we'll see classification sometime late Thursday or early Friday.
Member Since: July 6, 2010 Posts: 113 Comments: 31502
Quoting KEEPEROFTHEGATE:
90e will be first named system of the 2013 east pacific season it will get named after 8 am tomorrow morning


No chance in that. 90E has a very long way to go right now.
Member Since: February 28, 2013 Posts: 4 Comments: 2323
Quoting KEEPEROFTHEGATE:
90e will be first named system of the 2013 east pacific season it will get named after 8 am tomorrow morning


I hope for a 'poof-less' start to the season so it can add credibility for the season.
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Quoting GeoffreyWPB:


Grothar posted it first.



he seen nothing 1st
Member Since: May 21, 2006 Posts: 5091 Comments: 114750
Quoting Grothar:


Don't let Taz see that!




you seen nothing 1st
Member Since: May 21, 2006 Posts: 5091 Comments: 114750
Quoting GeoffreyWPB:


Grothar posted it first.


Don't let Taz see that!
Member Since: July 17, 2009 Posts: 69 Comments: 25371
Quoting KEEPEROFTHEGATE:
90e will be first named system of the 2013 east pacific season it will get named after 8 am tomorrow morning

Member Since: September 9, 2010 Posts: 5 Comments: 1034
Quoting StormTrackerScott:


I posted it earlier.


Grothar posted it first.
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Quoting SFLWeatherman:
Did you all see the 0Z CMC and GFS Ensemble have it too!:)


I posted it earlier.
Member Since: February 28, 2013 Posts: 4 Comments: 2323
Quoting StormTrackerScott:


90E going POOF? Could this be the first POOF of the season?
90e will be first named system of the 2013 east pacific season it will get named after 8 am tomorrow morning
Member Since: Posts: Comments:
Quoting Tazmanian:



right i re rember one i think it was 94L it look this like 90E and then it turned in two a big cat 5 hurricane and made land fall in MX


Correct, we've seen naked swirls eventually become major hurricanes in a few days time.
Member Since: July 8, 2005 Posts: 259 Comments: 23590
Quoting CybrTeddy:
If you think 90E is dead you haven't seen many invests.



right i re rember one i think it was 94L it look this like 90E and then it turned in two a big cat 5 hurricane and made land fall in MX
Member Since: May 21, 2006 Posts: 5091 Comments: 114750
Did you all see the 0Z CMC and GFS Ensemble have it too!:)
Member Since: May 23, 2012 Posts: 0 Comments: 4392
If you think 90E is dead you haven't seen many invests.
Member Since: July 8, 2005 Posts: 259 Comments: 23590
Solar activity last peaked in 2001, in Cycle #23. Solar Cycle 24 should be peaking now but so far it's been a fizzle.

http://http://solarscience.msfc.nasa.gov/predict. shtml
Quoting SouthernIllinois:

Lots of big flares lately. Could the warming be attributed to these?

Member Since: Posts: Comments:
90E ROTATION :D




29KT wind speed, compared to 26 yesterday.
Member Since: April 30, 2013 Posts: 5 Comments: 4316
Tropics really got active in the last 24 hours...

Member Since: April 30, 2013 Posts: 5 Comments: 4316


Cant even tell this was once jamala anymore.
Member Since: April 30, 2013 Posts: 5 Comments: 4316
Quoting JNCali:
Shhhhhhhh, just let her rest as long as she can....



whats not whats wake here up
Member Since: May 21, 2006 Posts: 5091 Comments: 114750


Member Since: July 17, 2009 Posts: 69 Comments: 25371
ISS crew members safely return to Earth this Morning..



Explanation: The Soyuz TMA-07M spacecraft is seen as it lands with Expedition 35 Commander Chris Hadfield of the Canadian Space Agency (CSA), NASA Flight Engineer Tom Marshburn and Russian Flight Engineer Roman Romanenko of the Russian Federal Space Agency (Roscosmos) in a remote area near the town of Zhezkazgan, Kazakhstan, on Tuesday, May 14, 2013. Hadfield, Marshburn and Romanenko returned from five months onboard the International Space Station where they served as members of the Expedition 34 and 35 crews. Image Credit: NASA/Carla Cioffi
Member Since: August 13, 2009 Posts: 13 Comments: 6770
Quoting Luisport:
Triple X-Class Solar Flares - May 14, 2013 Link


Yeah this is from the 3 day Solar X-ray Flux, Really Weird Plot



Also, Here is The Ark's help files for embedding YouTube videos into the blog, hope it helps you

Link
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TXPZ21 KNES 141227
TCSENP

A. TROPICAL DISTURBANCE (90E)

B. 14/1145Z

C. 6.0N

D. 99.8W

E. FIVE/GOES-E

F. TOO WEAK

G. IR/EIR/SWIR

H. REMARKS...NO CLOSED LOW LEVEL CIRCULATION WAS DETECTED IN 1026Z AMSU
DATA. LOW CONFIDENCE IN CENTER FIX WHICH WAS BASED IN PART ON ROTATION
IN CONVECTIVE CLOUD TOPS WITH SOME CONTRIBUTION FROM 0634Z OSCAT. THIS
SYSTEM IS TOO WEAK TO CLASSIFY DUE TO BANDING OF LESS THAN 2/10.

I. ADDL POSITIONS

NIL


...MCCARTHY

Member Since: April 30, 2013 Posts: 5 Comments: 4316
Jamala pretty much dissipated.



Not really anything there anymore other than winds and clouds.
Member Since: April 30, 2013 Posts: 5 Comments: 4316
Carribbean

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE COAST OF GUINEA-BISSAU NEAR
12N16W TO 9N21W. THE ITCZ BEGINS FROM 9N21W AND CONTINUES ALONG
5N30W 2N47W EQ51W. SCATTERED MODERATE CONVECTION IS WITHIN 150
NM SOUTH OF THE AXIS BETWEEN 24W-33W...AND WITHIN 120 NM NORTH
OF THE AXIS BETWEEN 33W-45W. SCATTERED MODERATE/STRONG
CONVECTION IS FROM EQ-3N BETWEEN 45W-51W.

Quoting JNCali:
Shhhhhhhh, just let her rest as long as she can....




Member Since: April 30, 2013 Posts: 5 Comments: 4316
Shhhhhhhh, just let her rest as long as she can....
Member Since: September 9, 2010 Posts: 5 Comments: 1034
NHC


...DISCUSSION...

ASCAT SCATTEROMETER PASS OVER THE GULF OF TEHUANTEPEC AT 0400
UTC REVEALED SMALL AREA OF 35 KT GALE-FORCE WINDS NEAR 15.5N95W.
FOR THIS REASON A GALE WARNING IS IN EFFECT...FOR THE GULF OF
TEHUANTEPEC N OF 15N...THROUGH THE EARLY MORNING MAX UNTIL ABOUT
1500 UTC. MODEL GUIDANCE INDICATES WINDS WILL BE BELOW GALE BY
18Z. EXPECT 20-30 KT WINDS TO PERSIST THROUGH WED MORNING.

LOW PRES EMBEDDED IN AN ACTIVE EARLY SEASON MONSOON TROUGH NEAR
07N96W HAS STRENGTHENED OVER THE PAST 24 HOURS...WITH THE HELP
OF SHEAR VORTICITY ASSOCIATED WITH GAP WINDS FROM THE GULFS OF
TEHUANTEPEC AND PAPAGAYO. CONVECTIVE ORGANIZATION HAS DECREASED
SOMEWHAT OVER THE PAST 6-9 HOURS...BUT ACTIVE CONVECTION REMAINS
SOUTH AND WEST OF THE LOW. THE LOW IS WITHIN A BAROTROPICALLY
UNSTABLE ENVIRONMENT WHICH IS FAVORABLE FOR CONTINUED GROWTH OF
THIS FEATURE...LEADING TO A BREAKDOWN OF THE MONSOON TROUGH...
WHICH MODEL GUIDANCE IS DEPICTING BY WED. THE BREAKDOWN OF THE
MONSOON TROUGH ASSOCIATED WITH A WEST-PROPAGATING DISTURBANCE...
IN THIS CASE A CARIBBEAN WAVE THAT MOVED INTO THE EASTERN NORTH
PACIFIC...HAS BEEN ASSOCIATED WITH TROPICAL CYCLOGENESIS IN SOME
CASES. GLOBAL MODELS ARE BULLISH ON THIS DISTURBANCE BECOMING A
TROPICAL CYCLONE SOMEWHERE BETWEEN 105W AND 110W WITHIN THE NEXT
2-3 DAYS.

ELSEWHERE...HIGH PRES NNW OF THE AREA WITH SFC RIDGE EXTENDING
SE TO NEAR 20N114W. THE GRADIENT BETWEEN THIS RIDGE AND LOWER
PRESSURE NEAR THE ITCZ IS MAINTAINING MODERATE TO LOCALLY FRESH
TRADES N OF THE ITCZ W OF 130W. THE HIGH WILL SHIFT NE OVER THE
NEXT 24 HOURS AND DECREASE THE PRESSURE GRADIENT TO WEAKEN THE
TRADES AND ALLOW SEAS TO SUBSIDE TO 6-7 FT THROUGH THU.

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90E Intensity graph

Member Since: July 17, 2009 Posts: 69 Comments: 25371
This TCFP has been so consistant with the potential formation of a TD for so long now above south america...


Member Since: April 30, 2013 Posts: 5 Comments: 4316

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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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