Dangerous Cyclone Mahasen gathering strength in the Bay of Bengal

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

Share this Blog
44
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 122 - 72

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22Blog Index

122. JLPR2
Quoting Stormchaser2007:
Really doesn't look terrible.



They are probably going: "nah! it's still the 11th of May" XD
Member Since: Posts: Comments:
Quoting AtHomeInTX:


I'm really wondering if they're going to stop. :)


It's been pretty nice the past few weeks, today is a little warm but otherwise not too bad. I could go for a few more days of moderately warm weather before the summer sauna kicks in.
Member Since: Posts: Comments:
CMC 240HR big rain in the Caribben!
Member Since: Posts: Comments:
192 hours out.........................
Member Since: August 6, 2011 Posts: 4 Comments: 42277
Member Since: July 21, 2011 Posts: 83 Comments: 7167
Quoting VR46L:


The fronts keep on comming...



I'm really wondering if they're going to stop. :)
Member Since: Posts: Comments:
Hot and Humid here,but not a drop so far.................
Member Since: August 6, 2011 Posts: 4 Comments: 42277
folks up on the Nature coast stay alert...................
Member Since: August 6, 2011 Posts: 4 Comments: 42277
Quoting Stormchaser2007:
Really doesn't look terrible.



The NHC must be fairly confident that it won't last much longer. That's really the only thing I can think of that would keep them from at least tagging it an invest.
Member Since: Posts: Comments:
Really doesn't look terrible.

Member Since: Posts: Comments:
Not to take away from the tropics or anything but,

PROBABILITY OF WATCH ISSUANCE...40 PERCENT
Member Since: Posts: Comments:
850 mb vorticity:

Member Since: July 21, 2011 Posts: 83 Comments: 7167
Here is Beryl from last year when it was starting to get its act together.

Beryl:



This year's disturbance:

Member Since: Posts: Comments:
Member Since: July 21, 2011 Posts: 83 Comments: 7167

Mahasen looks pretty good, for a storm below 9N.
Member Since: October 24, 2005 Posts: 0 Comments: 24929
107. VR46L
Nice Image of the Gulf IMO

GulfOfMexico vis_ir_background/goes_lowcloud


Member Since: March 1, 2012 Posts: 0 Comments: 6998
Go little storm go! I don't think that it will develop into a named storm but its fun to have something to watch and think about like that in Early May... Just another reminder that the season is getting close!
Member Since: Posts: Comments:
Member Since: July 21, 2011 Posts: 83 Comments: 7167
104. beell
The western Caribbean disturbance advertised by the GFS seems to share some synoptic similarities with 2010's Tropical Storm Nicole . A broad monsoonal low paired up with an east coast longwave trough that lifted and elongated the monsoon depression out of the Caribbean basin-bringing copious amounts of rainfall along the Atlantic coast of the US.

Looking for a perfectly timed longwave to interact with a monsoon depression continues to be an exercise in random chance at this point.
Member Since: Posts: Comments:
Quoting pcola57:


GFS MSLP Anomaly..Thanks Levi.. :)

From the current run the low (@24-177hrs) is modeled to stick around (the Southern Carribean)..
But what essentially catches my eye is the meadering of the Bermuda High and a ton of Lows all across the Southern Carribean..
GOM is shown as a High pressure refuge..

at the end of the run, is shows a ts steaming towards jamaica....
Member Since: Posts: Comments:
Quoting AtHomeInTX:


I thought maybe all these fronts and the cool gulf so far this year may stop the gulf from getting as warm as it could later. But the other day someone showed the SSTA's for 2005 at this time of year and it showed a cooler gulf so there goes that.

yep thats y i said the Gulf saying "Im tryna warm it up and u keep cooling it off!" LOL!
Member Since: Posts: Comments:
101. VR46L
Quoting bigwes6844:
yep thats y i said the Gulf saying "Im tryna warm it up and u keep cooling it off!" LOL!


The fronts keep on comming...

Member Since: March 1, 2012 Posts: 0 Comments: 6998
CMC continues to be aggressive in predicting a tropical storm developing in the eastern Pacific by late next week.

Member Since: July 21, 2011 Posts: 83 Comments: 7167
Quoting pcola57:


Good afternoon VR46L..
Thats alot of very dry air all around it for sure..
Not a fruitful enviroment..
Have to step away for awhile..
Happy blogging.. :)


Hiya Pcola ,

Looks like you are had some horrid weather this morning



Member Since: March 1, 2012 Posts: 0 Comments: 6998
Quoting AtHomeInTX:


I thought maybe all these fronts and the cool gulf so far this year may stop the gulf from getting as warm as it could later. But the other day someone showed the SSTA's for 2005 at this time of year and it showed a cooler gulf so there goes that.
yep thats y i said the Gulf saying "Im tryna warm it up and u keep cooling it off!" LOL!
Member Since: Posts: Comments:
AOI/XX/XXL
MARK
23.33N65.11W
Member Since: Posts: Comments:
Quoting VR46L:Post# 92
Blob in the Atlantic looks to be getting shredded!

Click on Image to see loop
Rammb Water Vapour


Good afternoon VR46L..
Thats alot of very dry air all around it for sure..
Not a fruitful enviroment..
Have to step away for awhile..
Happy blogging.. :)
Member Since: Posts: Comments:
Member Since: July 21, 2011 Posts: 83 Comments: 7167
Quoting Levi32:
The reason the low is no threat is because 24 hours from now it will have moved from underneath the axis of the upper trough to underneath the convergent flank of it (northwesterly flow), which will create sinking air and kill it off.

NAM 24-hour Upper winds and 850mb vorticity:



agree its a great little test feature just to watch interesting if anything
Member Since: Posts: Comments:
Quoting Levi32:
The reason the low is no threat is because 24 hours from now it will have moved from underneath the axis of the upper trough to underneath the convergent flank of it (northwesterly flow), which will create sinking air and kill it off.

NAM 24-hour Upper winds and 850mb vorticity:



That would be the only reason I could see it falling apart because right now they are stacked almost perfectly. If that can persist longer than forecast, it might be a threat.
Member Since: Posts: Comments:
Blob in the Atlantic looks to be getting shredded!

Click on Image to see loop
Rammb Water Vapour
Member Since: March 1, 2012 Posts: 0 Comments: 6998
Afternoon All.

Active one predicted this year and more favorable patterns for intensification / land falls it would seem thus far. We've been lucky for quite a few years with a few exceptions. With the expected MJO pulse coming around I would bet that the GFS is not depicting a ghost storm.

We all know the drill with the depicted location this time of year. Painfully slow to develop, 70% that it ends up developing in the EPAC, multiple LLC's, typically higher wind shear and walking dangerously close to destructive wind shear in the GOM (Subtropic Jet) etc..
Member Since: Posts: Comments:
The reason the low is no threat is because 24 hours from now it will have moved from underneath the axis of the upper trough to underneath the convergent flank of it (northwesterly flow), which will create sinking air and kill it off.

NAM 24-hour Upper winds and 850mb vorticity:

Member Since: Posts: Comments:
Quoting SouthernIllinois:

You ultimately see the incredibly high TCHP in the Gulf of Mexico later on this year come August, September, and October? It not out of the realm of possibilities, it seems.


I thought maybe all these fronts and the cool gulf so far this year may stop the gulf from getting as warm as it could later. But the other day someone showed the SSTA's for 2005 at this time of year and it showed a cooler gulf so there goes that.
Member Since: Posts: Comments:
Judging by the TWD, the NHC believes this low will drift around and dissipate by tomorrow. I don't expect them to do anything today as far as labeling goes. However, its current pace deserves a little recognition. It certainly doesn't appear to be something that will just dissipate by tomorrow.
Member Since: Posts: Comments:
Quoting Stormchaser2007:
TCHP Comp of the most "active" seasons



Another year I'd like to throw in.
Member Since: Posts: Comments:
Member Since: August 6, 2011 Posts: 4 Comments: 42277
Quoting Stormchaser2007:
TCHP Comp of the most "active" seasons



Interesting comparison. So far this year, the THCP is getting there. Now we need all those other factors to line up as well, if we are to have an active season.

Regarding the FL rainy season, is it coming to a slowly escalating but early start (like last year) rather than the usual abrupt start later in May?
Member Since: Posts: Comments:
Quoting CybrTeddy:
I'd be careful before saying this is an imminent threat to develop, but if it stays in the environment it's in we may have something soon. It would be truly fascinating to have another early May storm two years in a row.
And it would be more impressive if this one and the one the Gfs is portraying develop in the same month Like Alberto and Beryl from last year.
Member Since: Posts: Comments:
Quoting SouthernIllinois:

You ultimately see the incredibly high TCHP in the Gulf of Mexico later on this year come August, September, and October? It not out of the realm of possibilities, it seems.
that is true. i wouldnt be surprised if the TCHP is high around that time the way things are going
Member Since: Posts: Comments:
Member Since: August 6, 2011 Posts: 4 Comments: 42277
I'd be careful before saying this is an imminent threat to develop, but if it stays in the environment it's in we may have something soon. It would be truly fascinating to have another early May storm two years in a row.
Member Since: Posts: Comments:
THE NATIONAL WEATHER SERVICE IN TALLAHASSEE HAS ISSUED A

* SPECIAL MARINE WARNING FOR...
COASTAL WATERS FROM APALACHICOLA TO DESTIN FROM 20 TO 60 NM
OVER GULF OF MEXICO WATERS...

* UNTIL 230 PM CDT

* AT 1228 PM CDT...THE NATIONAL WEATHER SERVICE HAS DETECTED NUMEROUS
THUNDERSTORMS...SOME PRODUCING STRONG WINDS OF 34 KNOTS OR GREATER FROM
ABOUT 40 MILES SOUTH OF DESTIN FL TO 60 NM SOUTH OF APALACHICOLA FL...
MOVING NORTHEAST AT 20 KNOTS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

MARINERS CAN EXPECT STRONG WINDS...HIGH WAVES...DANGEROUS
LIGHTNING...AND HEAVY RAINS. BOATERS SHOULD SEEK SAFE HARBOR
IMMEDIATELY...UNTIL THIS STORM PASSES.

THUNDERSTORMS CAN PRODUCE SUDDEN WATERSPOUTS. WATERSPOUTS CAN EASILY
OVERTURN BOATS AND CREATE LOCALLY HAZARDOUS SEAS. SEEK SAFE HARBOR
IMMEDIATELY. IF CAUGHT AT SEA...MOVE AWAY FROM THE WATERSPOUT AT A 90
DEGREE ANGLE FROM ITS APPARENT MOTION.

&&
Member Since: August 6, 2011 Posts: 4 Comments: 42277
Member Since: Posts: Comments:
Quoting Dakster:


Yes to both of those points.

This is the time of the year where we get a a lot of false tropical cyclone genesis predictions by the models. I still don't think we are all that skillful in predicting genesis out past a week. But we shall see how the models are doing - it is harbinger to how much we can trust them later on in the season.

I hope that Mother Nature doesn't decide to clean the detritus from Florida by sending a strong hurricane across us. But as Grothar pointed out in a previous post, we are now 'due' for one, statistically speaking.


I totally agree Dak..
We have a tendency to get caught up in models and all..
Thats so normal..
But it's different when your looking down a 48hr landfalling window..
I'm glad I had the 120mph film put up on the windows this year..
But anything over that and out comes the plywood..
And then I'm heading out of town..
Getting too old to stay and fight like I used to..
And I have to consider my situation here as well..
I share yours and Gro's concern this year..
We ARE due..
Too long since a major..
But what I find very interesting is that although folks want to find and anomaly year for comparison..
There really aren't any as we are now experiencing a climate influenced by a warming world..
As Dr. Masters pointed out in one of his recent posts, the Jet Stream is/has been all over the place and has directly influenced,( In my opinion since last years T/C season..ie..Hurricaine Sandy and the winter storms anomaly's this year..), our weather to a great degree..
All this is JMO and take it FWIW.. :)

Are you Ready??

Member Since: Posts: Comments:
Quoting SouthernIllinois:

The only thing I can think of is seeding the eyewall with silver iodine. This would break down the inner-structure of the storm and keep it from reaching intense (category 4 or 5) status. Only problem is then the wind field will react and expand exponentially. The subsequent repercussions from that would far outweigh any benefits from this type of geoengineering. I'm definitely not for it. Let's not play God with Mother Nature. She'll ultimately win.


I wonder how much silver iodide costs per ton - in the form suitable for aerial dispersion
Member Since: Posts: Comments:
Member Since: August 6, 2011 Posts: 4 Comments: 42277
Going to be some severe weather up there when this comes ashore..stay alert up there......................
THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST ALABAMA...
SOUTHWEST AND SOUTH CENTRAL GEORGIA...AND THE FLORIDA BIG BEND
AND PANHANDLE...AND ADJACENT COASTAL WATERS.

.DAY ONE...TODAY AND TONIGHT...

NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED TODAY...ESPECIALLY
THIS AFTERNOON. A FEW STRONG TO SEVERE STORMS ARE POSSIBLE...WITH WIND
GUSTS FROM 45 TO 60 MPH AND DIME TO QUARTER SIZE HAIL POSSIBLE.
HEAVY RAIN IS LIKELY WITH SOME STORMS...WHICH COULD PRODUCE LOCALIZED
FLOODING IN LOW LYING...POOR DRAINAGE AREAS...MAINLY IN URBAN
REGIONS. OF COURSE THE MAIN THREAT THAT MOST PEOPLE WILL ENCOUNTER
WITH THUNDERSTORMS IS LIGHTNING...WHICH COULD BE FREQUENT IN THE
STRONGER STORMS.
Member Since: August 6, 2011 Posts: 4 Comments: 42277
AOI/XX/XXL
MARK
23.33N65.11W
Member Since: Posts: Comments:
Member Since: Posts: Comments:
WOW is Jedkins back in Largo yet?...............
Member Since: August 6, 2011 Posts: 4 Comments: 42277

Viewing: 122 - 72

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

JeffMasters's Recent Photos

Lake Effort Snow Shower Over Windsor, Ontario
Sunset on Dunham Lake
Pictured Rocks Sunset
Sunset on Lake Huron