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 Articuno:

Good afternoon.

Hey guys, long time no see.
(Sorry I've been so inactive..Grades getting a grip on me being on the internet and videogames and stuff)


Hey Articuno, nice to see you.

Grades...shoot, gotta go study, bye guys.
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Quoting Thrawst:
I am so grateful for air conditioning. It is 88 right now with a 74 dew point.


I am so grateful for heating, 60 outside right now, a bit on the chilly side.
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Quoting Articuno:

Good afternoon.

Hey guys, long time no see.
(Sorry I've been so inactive..Grades getting a grip on me being on the internet and videogames and stuff)

I've been pretty busy as well...this is about the third time I've been on over the last two months
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Quoting nigel20:

Hey!
How have you been?

Pretty good. Just really busy lately.
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I am so grateful for air conditioning. It is 88 right now with a 74 dew point.
Member Since: July 18, 2010 Posts: 50 Comments: 1915
can't wait to see what 18Z GFS has to offer
Member Since: June 13, 2009 Posts: 2 Comments: 13577
Quoting SFLWeatherman:
I love the 6Z GFS!:) lol


so did I
Member Since: June 13, 2009 Posts: 2 Comments: 13577
I love the 6Z GFS!:) lol
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Quoting nigel20:
Good afternoon fellow bloggers!

Good afternoon.

Hey guys, long time no see.
(Sorry I've been so inactive..Grades getting a grip on me being on the internet and videogames and stuff)
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Here is the weather history for the nearest airport where the winds blew that ice into the lake resort. Strong winds as you can see.
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Quoting TropicalAnalystwx13:

Not yet. The NHC says it is "tropical wave-like"; however, if it was an actual tropical wave, it would say so on the surface analysis map.

Example:



where you get this does NHC have an archive that has it please post link if yes
Member Since: June 13, 2009 Posts: 2 Comments: 13577
Quoting HurricaneDean07:

Hey Nigel

Hey!
How have you been?
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Quoting HurricaneDean07:

I just got annoyed by the fact that he states something, and then automatically he thinks he's the "Weather Expert" here and that everything he posts about is 100% correct. Ex. The Tropical Wave off Africa. If the ignorance wasn't present, someone would notice that Tropical Waves don't start rolling off of Africa until May.

People like that, to me, are close to as bad as trolls.

Oh I know it is pretty bad, but I'll just keep him off ignore for now.

Quoting nigel20:
Good afternoon fellow bloggers!

Afternoon Nigel!
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Went out on the boat today...Caught a few Lane Snapper.... Oh my, Summer is coming.
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Member Since: July 25, 2010 Posts: 0 Comments: 2764
Quoting nigel20:
Good afternoon fellow bloggers!

Hey Nigel
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Good afternoon fellow bloggers!
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Quoting wxchaser97:

I'm trying to be different this year and not ignore anybody unless I really have to. I'll stop correcting every post though.

I just got annoyed by the fact that he states something, and then automatically he thinks he's the "Weather Expert" here and that everything he posts about is 100% correct. Ex. The "Tropical Wave" (Not at all one) off Africa a month ago. If the ignorance wasn't present, someone would notice that Tropical Waves don't start rolling off of Africa until May.

People like that, to me, are close to as bad as trolls.
Member Since: Posts: Comments:
Hm surface trough in east Atl. Mentioned last night there was a disturbance coming off the coast which could be designated as the first t-wave but I didn't think it was going to happen though. NHC has labeled it a surface trough here so looks like it won't be getting the t-wave designation. Never know though, they could change their mind.



After all, it is a wave...just a weak one.

Member Since: August 24, 2010 Posts: 19 Comments: 4358
Quoting HurricaneDean07:


I ignored him. Don't feel like correcting every post of his.

If you feel like correcting him all the time, go ahead.

I'm trying to be different this year and not ignore anybody unless I really have to. I'll stop correcting every post though.
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Quoting KEEPEROFTHEGATE:


nice shot of the lakes low
Yeah, I felt that west wind on my walk today.
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Quoting beell:


Thanks, nrt. Like...I'm happy you like...caught that.


Ya man.... groovy...
Member Since: September 23, 2005 Posts: 16 Comments: 11634
Quoting wxchaser97:

Tropical waves form over Africa only, not in the middle of the Atlantic, lol.


I ignored him/her. Don't feel like correcting every post of his.

If you feel like correcting him/her all the time, go ahead.
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Quoting Torito:


out of africa, yes, but i seem to recall one forming just off of africa closer to the equator... wish i remembered exactly when it was..

Tropical waves form over Africa only, not in the middle of the Atlantic, lol.
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000
AXNT20 KNHC 121735
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN MAY 12 2013


TROPICAL WAVE-LIKE HAS MOVED OUT OF AFRICA. A SURFACE TROUGH IS
ANALYZED ALONG 17W FROM 2N TO 9N ON THE 1200 UTC SURFACE MAP.
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION WAS NOTED THIS
MORNING IN ASSOCIATION WITH THIS SYSTEM...BUT CONVECTION IS NOW
DIMINISHING. AN AREA OF SAHARAN DUST IS OBSERVED ON VIS AND
SAHARAN AIR LAYER SATELLITE IMAGERY REACHING 55W. THE REMNANTS
OF A SHEAR AXIS IS STILL EVIDENT ON THE SAME SATELLITE IMAGERY
ACROSS THE TROPICAL ATLC JUST N OF THE AREA OF SAHARAN DUST.

Member Since: July 15, 2006 Posts: 189 Comments: 59031
696. beell
Quoting nrtiwlnvragn:
TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN MAY 12 2013



Excerpt:

A TROPICAL WAVE-LIKE HAS MOVED OUT OF AFRICA.


Thanks, nrt. Like...I'm happy you like...caught that.
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Quoting TropicalAnalystwx13:

I wasn't talking about the one currently. I was referring to the disturbance off Africa about a month ago.

oh. My bad. Carry on about that... lol. That definitely wasn't one.
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Quoting wunderkidcayman:

why would I need that when I live in a massive concrete bunker on a sea side property in Grand Cayman



no we have not well not till now


yeah I remember but we thought it was but it was not
Quoting HurricaneDean07:

No. The thing off Africa is a tropical wave, man.

Link
Quoting TropicalAnalystwx13:

It was just an area of disturbed weather everybody was freaking out about because it had deep convection. It did not have the wind shift characteristic of a tropical wave.



Ok thanks guys, i was confused, like normal...
Member Since: April 30, 2013 Posts: 6 Comments: 4467
Quoting HurricaneDean07:

No. The thing off Africa is a tropical wave, man.

Link

I wasn't talking about the one currently. I was referring to the disturbance off Africa about a month ago.
Member Since: July 6, 2010 Posts: 113 Comments: 34095
Quoting HurricaneDean07:
SCREW IT. 4000 Comments

FIRST TROPICAL WAVE OF THE SEASON
http://www.nhc.noaa.gov/tafb/USA_12Z.gif


Not yet. The NHC says it is "tropical wave-like"; however, if it was an actual tropical wave, it would say so on the surface analysis map.

Example:

Member Since: July 6, 2010 Posts: 113 Comments: 34095
Quoting TropicalAnalystwx13:

It was just an area of disturbed weather everybody was freaking out about because it had deep convection. It did not have the wind shift characteristic of a tropical wave.

No. The thing off Africa is a tropical wave, man.

Link
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Quoting beell:


Would you like to buy some ocean front property in Arizona?

why would I need that when I live in a massive concrete bunker on a sea side property in Grand Cayman

Quoting Torito:



We already have had tropical waves this year.... I'm assuming you mean tropical depression/storm?


no we have not well
Quoting nrtiwlnvragn:
TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN MAY 12 2013



Excerpt:

A TROPICAL WAVE-LIKE HAS MOVED OUT OF AFRICA.
not till now

Quoting Torito:


I seem to recall the blog filled with images of it like a month or so ago...

yeah I remember but we thought it was but it was not
Member Since: June 13, 2009 Posts: 2 Comments: 13577
Quoting Torito:


out of africa, yes, but i seem to recall one forming just off of africa closer to the equator... wish i remembered exactly when it was..

It was just an area of disturbed weather everybody was freaking out about because it had deep convection. It did not have the wind shift characteristic of a tropical wave.
Member Since: July 6, 2010 Posts: 113 Comments: 34095
Since i havent been here for a day and a half, anyone wanna tell me what is going on with the GFS? I really can't do much with my WIFI connection atm...
Member Since: April 30, 2013 Posts: 6 Comments: 4467
Quoting wxchaser97:

Not sure where you're getting that from as there have been no waves yet. Nothing has came off Africa that has had the structure and spin to be a tropical wave. In the next couple weeks there should be one though.


out of africa, yes, but i seem to recall one forming just off of africa closer to the equator... wish i remembered exactly when it was..
Member Since: April 30, 2013 Posts: 6 Comments: 4467
SCREW IT. 4000 Comments

FIRST TROPICAL WAVE OF THE SEASON
http://www.nhc.noaa.gov/tafb/USA_12Z.gif

Member Since: Posts: Comments:
Quoting TropicalAnalystwx13:

No we haven't.


Time to get our globes out, TA!

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Quoting Torito:



We already have had tropical waves this year.... I'm assuming you mean tropical depression/storm?

Not sure where you're getting that from as there have been no waves yet. Nothing has came off Africa that has had the structure and spin to be a tropical wave. In the next couple weeks there should be one though.
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Quoting TropicalAnalystwx13:

No we haven't.


I seem to recall the blog filled with images of it like a month or so ago...
Member Since: April 30, 2013 Posts: 6 Comments: 4467
TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN MAY 12 2013



Excerpt:

A TROPICAL WAVE-LIKE HAS MOVED OUT OF AFRICA.
Member Since: September 23, 2005 Posts: 16 Comments: 11634
Quoting Torito:



We already have had tropical waves this year.... I'm assuming you mean tropical depression/storm?

No we haven't.
Member Since: July 6, 2010 Posts: 113 Comments: 34095
Quoting wunderkidcayman:
hmm could that over the W coast of africa be the first tropical wave







We already have had tropical waves this year.... I'm assuming you mean tropical depression/storm?
Member Since: April 30, 2013 Posts: 6 Comments: 4467
Quoting FunnelVortex:


Ah yes. The same low that gave me gusty winds and rain/snow showers yesterday.

Also the same low that has made my high temps 20 below average and lows tonight near record territory. Of course, on Wednesday the high will be in the low 80s, that's Michigan for you.
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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.......


Congratulations! May you and your family enjoy this wonderful day and remember it always.
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677. beell
Quoting wunderkidcayman:
hmm could that over the W coast of africa be the first tropical wave




Worth keeping en eye on at least.



Tropical IR Hovmoller Series 6° - 18° N
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XX/XX/XXE
Member Since: July 15, 2006 Posts: 189 Comments: 59031
675. beell
Quoting wunderkidcayman:


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


Would you like to buy some ocean front property in Arizona?
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674. VR46L
As well as storms in the Indian ocean theres lots of moisture Question is how much will make it out of Africa....



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Quoting KEEPEROFTHEGATE:


nice shot of the lakes low


Ah yes. The same low that gave me gusty winds and rain/snow showers yesterday.
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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: 13577

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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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