Dangerous Cyclone Mahasen gathering strength in the Bay of Bengal

By: Dr. Jeff Masters , 4:25 PM GMT on May 11, 2013

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Dangerous Tropical Cyclone Mahasen is gathering strength over the Indian Ocean's Bay of Bengal, and is a potential major threat to Bangladesh and Myanmar. The 11 am EDT Saturday advisory from the Joint Typhoon Warning Center put Mahasen's top sustained winds at 55 mph, with a motion northwest at 19 mph into the center of the Bay of Bengal. 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. However, the cyclone has developed respectable upper-level outflow channels to the north and east, which are ventilating the storm by carrying away air converging to the center near the surface. High wind shear of 20 - 25 knots is affecting the storm, which is keeping the system disorganized. However, wind shear has declined about 5 knots since Friday, and is predicted to fall to the moderate range, 10 - 20 knots, by Sunday. This should allow organization into a Category 1 storm on Sunday. Aiding this process will be Mahasen's motion away from the Equator, which will help the cyclone leverage the Earth's spin to get itself spinning faster. Also aiding the intensification process will be ocean waters that are an exceptionally warm 31°C (88°F). This is about 1°C warmer than average for this time of year.


Figure 1. Latest satellite image of Tropical Cyclone Mahasen gathering strength over the Indian Ocean's Bay of Bengal.

Forecast for Mahasen
The official forecast brings Mahasen to Category 1 strength before landfall occurs in Bangladesh near the Myanmar border on Wednesday. Comparative model forecasts of Mahasen from the GFS, ECMWF, UKMET, GEM, NAVGEM, and FIM models show wide disagreement on the future intensity and speed of the storm, though. It is possible that wind shear will keep the storm disorganized and below hurricane strength until landfall, as suggested by the GFS and ECMWF models. The 06 UTC forecast from the HWRF model brings Mahasen to Category 3 strength on Monday, but weakens the storm to tropical storm strength at landfall. The model predicts that the storm will dump a significant area of heavy rains of 32 cm (12.6") over Maynmar and Bangladesh. The storm surge, high winds, and heavy rains of Mahasen are a huge concern for the thousands of Myanmar refugees living near the coast in makeshift camps, as reported by the New York Times.


Figure 2. Double trouble: Tropical Cyclone Jamala (lower) and Tropical Cyclone Mahasen (upper storm) spin on opposite sides of the Equator in this in this MODIS image taken at 04:25 UTC May 10, 2013. Mahasen is the name of a King of Sri Lanka from the 3rd century. Image credit: NASA.

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 sometime May 22 - 26, 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.

There is a small disturbance a few hundred miles north of Puerto Rico today that has developed some spin and a bit of heavy thunderstorm activity. This system is over cool waters of 77 - 79°F, and will likely be torn apart by high wind shear on Sunday.

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

India Meteorological Department's tropical cyclone page

Bangladesh Meteorological Department Warning

Myanmar Dept. of Meteorology and Hydrology Warning

Tutorial on Equatorial Waves in the COMET program's Introduction to Tropical Meteorology, plus their case exercise built around the May 2002 "twin twins" case, for use in a tropical synoptic course.

Jeff Masters

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Quoting beell:
The monsoon circulation is still evident in today's 12Z GFS by the presence of lower tropospheric westerly winds in the eastern Pacific at or about the latitude of Central America.

Contrary to a few previous model runs, a longwave trough is late, weak, or non-existent As a reult, the monsoon is suppressed by ridging over the Caribbean and Gulf-which could favor an EPAC system.

We are not DOOM yet.



05/12 12Z GFS 700mb @ 264 hrs


if, GFS was showing that kinda set up and forecasted this consistently for the past couple of days I would buy it. but that is not the case here. I don't buy it. what I am buying, is the idea what GFS been forecasting for day with almost perfect consistency (except for the few times it either pushed back the timing and/or hardly or did not develop the system at all, which is very few times) however, if GFS continues then I'd be inclined to buy that idea that is now presented before us now on the 12Z run
Member Since: June 13, 2009 Posts: 2 Comments: 11277
I guess it's time to start checking in with the good ole Weather Underground Hurricane Blog, just a few weeks away ! Things will start getting cranked up around these parts for sure !

Long time lurker, little time poster .

Pompano Beach,Fl
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oops wrong quote but u get what im saying
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Quoting VR46L:


Congratulations Largo !!!:)


again congrats largo fl
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nice shot of the lakes low
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Quoting LargoFl:
yesssssssssss, just GOT THE CALL...its a BOY!!!!!!!!!!!!!!!..8lbs 6 ounces and healthy!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ! and on Mothers Day...I just had the feeling it was going to be today..wow..ok ive got things to do now lol...have a great day everyone!!!!!!!!!!!!!!!!!!!!!!...now..do they have a GrandParents day i wonder LOLOLOL.......


Congrats Largo....
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666. VR46L
Quoting LargoFl:
yesssssssssss, just GOT THE CALL...its a BOY!!!!!!!!!!!!!!!..8lbs 6 ounces and healthy!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ! and on Mothers Day...I just had the feeling it was going to be today..wow..ok ive got things to do now lol...have a great day everyone!!!!!!!!!!!!!!!!!!!!!!...now..do they have a GrandParents day i wonder LOLOLOL.......


Congratulations Largo !!!:)
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hmm could that over the W coast of africa be the first tropical wave




Member Since: June 13, 2009 Posts: 2 Comments: 11277
Sunday, September 8,2013 is grandparents day.
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Quoting LargoFl:
yesssssssssss, just GOT THE CALL...its a BOY!!!!!!!!!!!!!!!..8lbs 6 ounces and healthy!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ! and on Mothers Day...I just had the feeling it was going to be today..wow..ok ive got things to do now lol...have a great day everyone!!!!!!!!!!!!!!!!!!!!!!...now..do they have a GrandParents day i wonder LOLOLOL.......



Alright!!!! I bet you didn't know you could smile that much. Congrats to you and your family.
Member Since: July 17, 2009 Posts: 69 Comments: 25575
Quoting Thrawst:
Our Alvin producer??

I was thinking the same thing this morning when I see it.
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I just want to wish a Happy mother`s day to every mom in the blog and to my mom that is her birthday to.Hope everyone have a happy and beautiful day.
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Quoting LargoFl:
yesssssssssss, just GOT THE CALL...its a BOY!!!!!!!!!!!!!!!..8lbs 6 ounces and healthy!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ! and on Mothers Day...I just had the feeling it was going to be today..wow..ok ive got things to do now lol...have a great day everyone!!!!!!!!!!!!!!!!!!!!!!...now..do they have a GrandParents day i wonder LOLOLOL.......


WOW!!!!! CONGRATS!!!!
Member Since: March 10, 2006 Posts: 0 Comments: 10034
Quoting Grothar:


Get out there and put that new siding up.


Why? You want a Cat 5 to come roaring thru Miami?
Member Since: March 10, 2006 Posts: 0 Comments: 10034
658. beell
The monsoon circulation is still evident in today's 12Z GFS by the presence of lower tropospheric westerly winds in the eastern Pacific at or about the latitude of Central America.

Contrary to a few previous model runs, a longwave trough is late, weak, or non-existent As a result, the monsoon is suppressed by ridging over the Caribbean and Gulf-which could favor an EPAC system.

We are not DOOM yet.



05/12 12Z GFS 700mb @ 264 hrs
Member Since: September 11, 2007 Posts: 142 Comments: 16295
Quoting Dakster:
KOTG - Still jealous, it is so hot outside I can't stand it. And this is just the beginning.

Even though I don't like the heavy rain, it is nice that the rain still cools things off a bit. Thank changes in the heart of the summer when it just adds humidity and no relief.


Get out there and put that new siding up.
Member Since: July 17, 2009 Posts: 69 Comments: 25575
yesssssssssss, just GOT THE CALL...its a BOY!!!!!!!!!!!!!!!..8lbs 6 ounces and healthy!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ! and on Mothers Day...I just had the feeling it was going to be today..wow..ok ive got things to do now lol...have a great day everyone!!!!!!!!!!!!!!!!!!!!!!...now..do they have a GrandParents day i wonder LOLOLOL.......
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Hey guys don't pull the plug for Carib storm just yet yeah 00Z wasn't great and 12Z a little worse and 06Z yesterday was that great either but other times it did great so just wait for next few runs
Member Since: June 13, 2009 Posts: 2 Comments: 11277
KOTG - Still jealous, it is so hot outside I can't stand it. And this is just the beginning.

Even though I don't like the heavy rain, it is nice that the rain still cools things off a bit. Thank changes in the heart of the summer when it just adds humidity and no relief.
Member Since: March 10, 2006 Posts: 0 Comments: 10034
Our Alvin producer??

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Shear is really hurting Mahasen, most of the convection is west of the center:



I think it's unlikely the storm will ever organize much, but it still presents a serious rain threat for the northern BOB coast.

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Got good rain yesterday!:)
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IMO,we may have to wait until early to mid June as the MJO kicks into the Caribbean. EPAC will form it's first named storm as models are more bullish for Alvin.GFS has been too fast with the MJO progression.
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You can tell the GFS is trying to back off with development, the 0z run showed very little and now 12z is almost blank. The Caribbean system could very well happen, but it won't be within 2 weeks like the GFS has been suggesting.
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Quoting TropicalAnalystwx13:

The days look chaseable perhaps, but far from significant outbreak days. The slowest tornado season in recent decades continues.


Hahahah I say significant for a reason! It's been so horrid that anything slightly leaning towards a potential tornado is significant.
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12Z GFS at 312H show pretty much nothing I think it's safe to say that for this run 12Z is dead we will have to see if this continues in the 18Z run
Member Since: June 13, 2009 Posts: 2 Comments: 11277
looks like the GFS is taking the storm into the EPAC

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If anything even develops, it will be very weak this run.

Member Since: July 6, 2010 Posts: 113 Comments: 31608
312HR
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Hmm 12Z GFS shows pretty much non-existence with the Caribbean system either that or they pushed it way back
Member Since: June 13, 2009 Posts: 2 Comments: 11277
Any of the models picking up on the Carribean storm?
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252 hours
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Quoting Thrawst:
I guess people are too focused on the potential for our first tropical storm of the season in the Caribbean that they haven't realized that severe weather potential, per the SPC, is supposed to increase significantly in the next 6-8 days.

SPC 4-8 Outlook:

NWS STORM PREDICTION CENTER NORMAN OK
0346 AM CDT SUN MAY 12 2013

VALID 151200Z - 201200Z

...DISCUSSION...
GFS AND ECMWF IN DECENT AGREEMENT THROUGH THE FIRST HALF OF THE
PERIOD -- WITH ONLY LOCAL/LIMITED SEVERE POTENTIAL EVIDENT AS THE
UPPER GREAT LAKES TROUGH SHIFTS NEWD ACROSS ONTARIO INTO QUEBEC AND
A SECOND/MUCH WEAKER UPPER SYSTEM EXITS THE SRN PLAINS AND MOVES
SLOWLY ACROSS THE MID-SOUTH/SOUTHEAST.

MORE APPRECIABLE SEVERE THREAT COULD EVENTUALLY EVOLVE ACROSS THE
CENTRAL U.S. AS AN ERN PACIFIC TROUGH -- MOVING ONSHORE DAY 5 /THU.
5-16/ -- CROSSES THE WRN U.S. AND APPROACHES THE PLAINS.
HOWEVER...THE MODELS DIFFER WITH RESPECT TO TIMING AND EVOLUTION OF
THIS TROUGH -- THE GFS BEING FASTER AND STRONGER WITH THE
PROGRESSION OF THE SYSTEM WHILE THE ECMWF EJECTS A MUCH
SLOWER/WEAKER TROUGH.

OVERALL...IT WOULD APPEAR THAT SOME SEVERE POTENTIAL COULD BE
POSSIBLE INVOF THE LEE TROUGH DAY 7 /SAT. 5-18/...WITH PERHAPS
GREATER THREAT -- PARTICULARLY PER THE GFS SOLUTION -- FOR DAY 8
/SUN. 5-19/. WHILE INDICATIONS ATTM ARE THAT OUTLOOK AREAS WILL
LIKELY BE REQUIRED IN LATER FORECASTS -- POSSIBLY FOR MULTIPLE
CONSECUTIVE DAYS...DEGREE OF UNCERTAINTY WITHIN THE MODEL SOLUTIONS
PRECLUDES A CONFIDENT AREAL DELINEATION OF THREAT AREAS ATTM.

..GOSS.. 05/12/2013

The days look chaseable perhaps, but far from significant outbreak days. The slowest tornado season in recent decades continues.
Member Since: July 6, 2010 Posts: 113 Comments: 31608
Why is the 12Z GFS not out??
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12z GFS is running..nice low there off the african coast..

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Riverside, California (Airport)
Updated: 8:53 AM PDT on May 12, 2013
Clear
80 °F
Clear
Humidity: 32%
Dew Point: 48 °F
Wind: Calm
Pressure: 30.01 in (Steady)
Visibility: 10.0 miles
UV: 4 out of 16
Pollen: 5.50 out of 12
Pollen Forecast new!
Clouds:
Clear -
(Above Ground Level)
Elevation: 817 ft

75.8 here, gonna be UGLY.
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Quoting Dakster:


I am jealous.
yeah earlier this am ice pellets were mixing with rain here as well


Toronto Pearson Int'l Airport
Date: 12:00 PM EDT Sunday 12 May 2013
Condition:Light Rainshower
Pressure:29.7 inches
Tendency:falling
Visibility:10 miles
Temperature:44.4°F
Dewpoint:35.4°F
Humidity:70%
Wind:W 17 gust 31 mph
Member Since: July 15, 2006 Posts: 169 Comments: 53308
I guess people are too focused on the potential for our first tropical storm of the season in the Caribbean that they haven't realized that severe weather potential, per the SPC, is supposed to increase significantly in the next 6-8 days.

SPC 4-8 Outlook:

NWS STORM PREDICTION CENTER NORMAN OK
0346 AM CDT SUN MAY 12 2013

VALID 151200Z - 201200Z

...DISCUSSION...
GFS AND ECMWF IN DECENT AGREEMENT THROUGH THE FIRST HALF OF THE
PERIOD -- WITH ONLY LOCAL/LIMITED SEVERE POTENTIAL EVIDENT AS THE
UPPER GREAT LAKES TROUGH SHIFTS NEWD ACROSS ONTARIO INTO QUEBEC AND
A SECOND/MUCH WEAKER UPPER SYSTEM EXITS THE SRN PLAINS AND MOVES
SLOWLY ACROSS THE MID-SOUTH/SOUTHEAST.

MORE APPRECIABLE SEVERE THREAT COULD EVENTUALLY EVOLVE ACROSS THE
CENTRAL U.S. AS AN ERN PACIFIC TROUGH -- MOVING ONSHORE DAY 5 /THU.
5-16/ -- CROSSES THE WRN U.S. AND APPROACHES THE PLAINS.
HOWEVER...THE MODELS DIFFER WITH RESPECT TO TIMING AND EVOLUTION OF
THIS TROUGH -- THE GFS BEING FASTER AND STRONGER WITH THE
PROGRESSION OF THE SYSTEM WHILE THE ECMWF EJECTS A MUCH
SLOWER/WEAKER TROUGH.

OVERALL...IT WOULD APPEAR THAT SOME SEVERE POTENTIAL COULD BE
POSSIBLE INVOF THE LEE TROUGH DAY 7 /SAT. 5-18/...WITH PERHAPS
GREATER THREAT -- PARTICULARLY PER THE GFS SOLUTION -- FOR DAY 8
/SUN. 5-19/. WHILE INDICATIONS ATTM ARE THAT OUTLOOK AREAS WILL
LIKELY BE REQUIRED IN LATER FORECASTS -- POSSIBLY FOR MULTIPLE
CONSECUTIVE DAYS...DEGREE OF UNCERTAINTY WITHIN THE MODEL SOLUTIONS
PRECLUDES A CONFIDENT AREAL DELINEATION OF THREAT AREAS ATTM.

..GOSS.. 05/12/2013
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Quoting AstroHurricane001:
It's snowing here!

Well, almost. We're seeing a steady stream of ice pellets.

--Newmarket, ON, 6.5C (43.7F)


I am jealous.
Member Since: March 10, 2006 Posts: 0 Comments: 10034
Quoting AstroHurricane001:


Are you sure it's not "Information Unavailable"?


I will pass on the link so you can explore and answer the questions you have..Click HERE
Member Since: August 13, 2009 Posts: 13 Comments: 6779
Quoting AstroHurricane001:


Manitoba: piles of ice NINE METRES HIGH (that's 30 ft!) threaten homes, cottages on Dauphin Lake


That is just SICK. I wouldn't have wanted to have been there.
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Quoting pcola57:


It's an experimental format product using current GOES data..
The gray areas are less than 20 degrees C and have not been assigned a coinciding color..
If they every will be..


Are you sure it's not "Information Unavailable"?
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Quoting JupiterKen:


What is SST represented by the gray areas?


It's an experimental format product using current GOES data..
The gray areas are less than 20 degrees C and have not been assigned a coinciding color..
If they every will be..
Member Since: August 13, 2009 Posts: 13 Comments: 6779
May....
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Quoting pcola57:







What is SST represented by the gray areas?
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Quoting Grothar:





They are rare, but here is a list beginning in 1953:

1953 - 1
1959 - 1
1969 - 1
1970 - 1
1971 - 1
1972 - 1
1974 - 1
1976 - 1
1981 - 1
1987 - 1
1988 - 1
1990 - 1
1993 - 1
2007 - 1
2008 - 1
2009 - 1
2012 - 2

Note: 2004 and 2005 the first storm to form was not until June or July.
I will remember those years forever.
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geez its humid here,come on dry weather and cool front......
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It's snowing here!

Well, almost. We're seeing a steady stream of ice pellets.

--Newmarket, ON, 6.5C (43.7F)
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Thanks folks still waiting for the call lol
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Quoting PedleyCA:


Saw that posted somewhere on WU yesterday. Very interesting.


Manitoba: piles of ice NINE METRES HIGH (that's 30 ft!) threaten homes, cottages on Dauphin Lake
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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.