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 VR46L:
384 ...
Storm in both Epac and Caribbean and possible developing storm in Atlantic .... Think its getting high on the possibility of MJO in the area

oh my this run has it close to Nicaragua.yep maybe I get rain.
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Quoting HurricaneDean07:

GFS pushed the storm back in the Timeline again. Which means two things...
Its a Ghost storm, or its coming into more agreement with the other models about the approach of the MJO and the Timeframe... Time will tell, of coarse.

I'll wait for 00Z run to come out
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Quoting Dakster:


Probably a Cat 5 thru Tampa..

only you want a cat 5 thru tampa
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Quoting VR46L:
384 ...
Storm in both Epac and Caribbean and possible developing storm in Atlantic .... Think its getting high on the possibility of MJO in the area


GFS pushed the storm back in the Timeline again. Which means two things...
Its a Ghost storm, or its coming into more agreement with the other models about the approach of the MJO and the Timeframe... Time will tell, of coarse.
Member Since: October 3, 2010 Posts: 40 Comments: 4129
Take that Wikipedia! My february blog just surpassed wiki in results for 2013 Huricane Season only news posts from last weak are ahead of me. :P

Booyah

Search Results
Member Since: October 3, 2010 Posts: 40 Comments: 4129
XXE/AOI/XX
MARK
9.56N/92.63W
Member Since: July 15, 2006 Posts: 171 Comments: 53806
I can't believe how fast the MDR is cooling after its big spike a couple days ago, it may even have a negative anomaly soon:



The Caribbean anomaly is also dropping fast, to borderline negative:

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865. HadesGodWyvern (Mod)
India Meteorological Department
Tropical Cyclone Advisory #18
CYCLONIC STORM MAHASEN (BOB01-2013)
23:30 PM IST May 12 2013
==========================================

At 18:00 PM UTC, The cyclonic storm Mahasen over southeast Bay of Bengal moved northward and now lays centered near 11.0N 86.5E, about 700 km northwest of Car Nicobar, 630 km northeast of Trincomalee, Sri Lanka, 720 km southeast of Chennai, India, and 1380 km south southwest of Chittagong, Bangladesh.

It would move initially northward during the next 18 hours and recurve thereafter northeastward towards Bangladesh-Myanmar coast.

According to satellite imagery, Satellite estimate Dvorak intensity is T2.5. Associated intense to very intense convection over southern Bay of Bengal, adjoining Indian Ocean between 7.0N to 14.0N and 81.0E to 88.0E, adjoining Sri Lanka, and Palk Strait. The lowest cloud top temperature due to convection is -70C.

3 minutes sustained wind near the center is 40 knots with gusts of 50 knots. The central pressure of the system is 996 hPa. The state of the sea is high around the center of the system.

The upper tropospheric ridge runs along 15.0N and is providing poleward out flow in association with the anticyclonic circulation over southern Andaman Sea. Upper level divergence is favorable for maintaining the intensity. The low level convergence along with low level relative vorticity shows no change during past 12 hrs. The sea surface temperature is about 30-32c. Ocean thermal energy is more than 100 kj/cm square over storm area. The vertical wind shear of horizontal wind continues to be about 5-10 knots (low to moderate) in the northeast sector. The MJO now lays in the border of phase 3 with amplitude greater than 2. It is favorable for intensification and northward movement of the system. Dynamical parameters show the intensification of the system after recurvature.

Most of the numerical weather prediction models suggest initial northwestward movement during next 12-24 hrs and then recurving northeastwards towards Bangladesh adjoining Myanmar coast. However, there is large divergence in the numerical weather prediction guidance with respect to intensification of the system. ECMWF and HWRF model maintain intensity until recurvature and weakening thereafter. UKMO maintains intensity until landfall. While JMA and GFS indicate weakening of the system. Dynamical statistical models of India Meteorological Department suggest slight weakening during next 36 hrs and then intensification further during subsequent 24 hrs.

Forecast and Intensity
=======================
12 HRS: 11.8N 86.2E - 40 knots (Cyclonic Storm)
24 HRS: 13.8N 86.5E - 40 knots (Cyclonic Storm)
48 HRS: 16.4N 87.5E - 40 knots (Cyclonic Storm)
72 HRS: 19.4N 90.0E - 40 knots (Cyclonic Storm)
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Quoting PedleyCA:


Get any Snow this morning. My Sister said it was snowing this morning in Northeast Wisconsin.


some ice mixed with the rain off and on all day may switch over to wet snow before midnight then end

its only tonight and tomorrow night then it warms back up
Member Since: July 15, 2006 Posts: 171 Comments: 53806
Quoting KEEPEROFTHEGATE:
Toronto Pearson Int'l Airport
Date: 7:00 PM EDT Sunday 12 May 2013
Condition:Light Rainshower
Pressure:29.9 inches
Tendency:rising
Visibility:12 miles
Temperature:39.4°F
Dewpoint:31.1°F
Humidity:72%
Wind:W 25 gust 44 mph


Get any Snow this morning. My Sister said it was snowing this morning in Northeast Wisconsin.
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Quoting Thrawst:


Have you visited any in Florida? I highly recommend visiting University of Florida, Florida Tech, Florida State University, and the one I will be attending, University of Miami.


Sorry for late response, had to do some studying, tried out Khan Academy, not bad, just a little bit long.

I haven't done Florida, mainly because my interest does not lie with hurricanes. I might visit one or two this summer, we'll see.
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Toronto Pearson Int'l Airport
Date: 7:00 PM EDT Sunday 12 May 2013
Condition:Light Rainshower
Pressure:29.9 inches
Tendency:rising
Visibility:12 miles
Temperature:39.4°F
Dewpoint:31.1°F
Humidity:72%
Wind:W 25 gust 44 mph
Member Since: July 15, 2006 Posts: 171 Comments: 53806
Got My Mojo Working
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859. VR46L
Quoting Dakster:


Probably a Cat 5 thru Tampa..


LOL ... thats what is the kick with models ... at that timeframe its basically fantasyland but its still interesting ...
Member Since: March 1, 2012 Posts: 0 Comments: 6898
Member Since: July 17, 2009 Posts: 71 Comments: 26118
Quoting BaltimoreBrian:


Must....resist....urge....to...post....Alvin & the Chipmunks vids....


Me too....
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Quoting wunderkidcayman:

yeah at 12Z run but 18Z brought it back though later in time line let see what 00Z does


Probably a Cat 5 thru Tampa..
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Quoting xcool:
GFsss dropped development in the Caribbean

yeah at 12Z run but 18Z brought it back though later in time line let see what 00Z does
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hey guys its back
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853. VR46L
Quoting Dakster:
GFS getting its MOJO?


Seems to be .....
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384HR 18Z GFS today
Member Since: May 23, 2012 Posts: 0 Comments: 4516
GFS getting its MOJO?
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850. VR46L
384 ...
Storm in both Epac and Caribbean and possible developing storm in Atlantic .... Think its getting high on the possibility of MJO in the area

Member Since: March 1, 2012 Posts: 0 Comments: 6898
hmm nice 18Z GFS is get back to its former self now Has storm developing and back in the caribbean though later in time I think that maybe 00Z GFS coming up tonight may show a stronger storm and further up the time line by the looks of it it just seems like on the last few runs GFS was feeling a little sick maybe it is getting better and maybe it will continue let watch and see what happens
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I see you are still sizzling PedleyCA.
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I don't know what to think, GFS is in bluff mode!!!
Member Since: June 20, 2012 Posts: 0 Comments: 2159
MesoWest Jurupa Valley CA US SGXWFO, Riverside, California (PWS)
Updated: 2:49 PM PDT on May 12, 2013
Scattered Clouds
99 °F
Scattered Clouds
Humidity: 18%
Dew Point: 48 °F
Wind: 4 mph from the West
Wind Gust: 12.0 mph
Pressure: 29.90 in (Falling)
Heat Index: 96 °F
Visibility: 10.0 miles
UV: 7 out of 16
Pollen: 5.50 out of 12
Pollen Forecast new!
Clouds:
Scattered Clouds 12000 ft
(Above Ground Level)
Elevation: 794 ft

96.5 here.
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845. VR46L
I know its the 18z @348 but .....quite interesting

Member Since: March 1, 2012 Posts: 0 Comments: 6898
How does it know, exactly where to not get?
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Too bad MODIS couldn't nab the latest on our AOI

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latest as of 10 mins ago

Member Since: July 15, 2006 Posts: 171 Comments: 53806
Ocean Prediction Center updated their maps, which move the wave westward and now have the dashed line.

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Quoting BaltimoreBrian:


Hurricane Felix was a BEAST. I'm still amazed at how quickly it went from a tropical depression to a Category 5 hurricane.
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839. VR46L
Quoting Doppler22:
Is that a potential Alvin I see?


I think its a possibility ...
Member Since: March 1, 2012 Posts: 0 Comments: 6898
Quoting Doppler22:
Is that a potential Alvin I see?


Must....resist....urge....to...post....Alvin & the Chipmunks vids....
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Is that a potential Alvin I see?
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836. VR46L
Quoting Dakster:


Cool now if it will just stay gone.


Only about an hour to find out if its gone on the 18z too..
Member Since: March 1, 2012 Posts: 0 Comments: 6898
If anyone was particularly interested in the trek of the Atlantic swirl see this image:

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834. Skyepony (Mod)
OSCAT caught a partial of that low. ASCAT had a nice pass earlier.

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Quoting xcool:
GFsss dropped development in the Caribbean


Cool now if it will just stay gone.
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832. Skyepony (Mod)
em>Flood in Kenya on Sunday, 12 May, 2013 at 16:01 (04:01 PM) UTC.
Description
The flood situation along the River Nyando Basin in Nyanza has worsened after the river burst its banks, displacing more than 1,000 people. Three schools have been closed indefinitely after River Nyando burst its banks following heavy down pour that pounded most parts of Nyanza province last night. Learning was paralyzed in Ahero Girls Secondary School, Kokwach Primary and Apondo Primary Schools after their classrooms, toilets and kitchen were submerged. The Kisumu County Director of Education, Beatrice Adu said they decided to close schools to avoid a catastrophe. Area District Commissioner, Isaiah Tanui says that more schools affected by floods are likely to be closed down due the situation because the environment is not conducive for learning. Western Kenya Red Cross coordinator Emmanuel Owako said the situation was pathetic and their response was overwhelmed as they were faced with difficulties in ensuring the safety of the affected families. In response to the floods, the Kenya Red Cross Western branch has organized a free medical camp for the displaced families as an outbreak of water borne diseases is imminent.
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831. xcool
GFsss dropped development in the Caribbean
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Toronto Pearson Int'l Airport
Date: 5:30 PM EDT Sunday 12 May 2013
Condition:Mostly Cloudy
Pressure:29.8 inches
Tendency:rising
Visibility:10 miles
Temperature:39.9°F
Dewpoint:35.1°F
Humidity:72%
Wind:WNW 23 gust 38 mph
Member Since: July 15, 2006 Posts: 171 Comments: 53806
829. Skyepony (Mod)
Extreme Weather in Canada on Sunday, 12 May, 2013 at 10:36 (10:36 AM) UTC.

em>Hundreds of local residents arrived Saturday with backhoes, bulldozers and wheelbarrows, helping to chip away massive ice floes that destroyed 12 homes and damaged another 15 Friday night along Ochre Beach, located 20 kilometres east of Dauphin. According to provincial Emergency Measures Organization officials, seven permanent homes were literally crushed by the ice that rose up within minutes from Lake Dauphin around suppertime Friday, pushed by north winds gusting up to 60 kilometres an hour. In all, 27 homes and cottages were damaged or destroyed -- but no injuries were reported. A local state of emergency was declared in the municipality and residents along the beach were evacuated Friday night. The provincial Emergency Social Services were called to the scene Friday night to assist residents in finding temporary lodging. Structural experts from the Office of the Fire Commissioner were also on hand to determine whether some residents could be allowed to attempt a cleanup or collect belongings. On Saturday, the residents and volunteers were allowed to return to the area and begin digging into the ice on homes that were declared structurally stable.
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Member Since: July 21, 2011 Posts: 83 Comments: 7167
Looks like the Greater Antilles swirl had enough merit to receive a mention on today's ATL marine graphicast.

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The wind shear is somewhat favorable for some intensification...For the E.Pacific Low


And the tendency is decreasing

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Member Since: July 21, 2011 Posts: 83 Comments: 7167
Uh Oh, Patrap better get cracking then. Someone pass him a Fresca.
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Quoting cg2916:
New AOI? That was quick! Looks like the tropics are looking for an early start, at least invest-wise.


Though also note the predecessor to Tropical Storm Aletta formed around this time of year as well, on May 11, 2012.
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Quoting BaltimoreBrian:
Tazmanian if you post 2 more comments you'll tie Patrap for the most comments here. 3 more to be the champ!



wow cool
Member Since: May 21, 2006 Posts: 5091 Comments: 115079

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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.