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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Here's from an article in the Guardian this week. These so called scientists predicted five years ago that the ice cap wouldn't melt until 2035. Well, the ice cap is set to melt completely this year, so I have a few less rosy predictions not sponsored by the "don't panic" government: there will be open water within 100 miles of the north pole within 6 weeks. Mass extinctions will take place beginning next year. All species will be "at risk" within five years. And, I predict, that people will fire off their guns as their "solution" to the problem.

"One-third of common land animals could see dramatic losses this century because of climate change, scientists predict.

More than half of plants could be hit the same way as habitats become unsuitable for numerous species.

The collapse of ecosystems would have major economic impacts on agriculture, air quality, clean water access, and tourism.

Global temperatures are set to rise 4C above preindustrial levels by 2100 if nothing is done to stem greenhouse gas emissions.

This could have a hugely destructive effect on thousands of common as well as rare and endangered species around the world, according to the researchers.

An estimated 57% of plants and 34% of animals were likely to lose half or more of their habitat range."
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gna
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This was a terrible tragedy. I hope never to be repeated.


1970 Bhola cyclone
From Wikipedia, the free encyclopedia

The 1970 Bhola cyclone was a devastating tropical cyclone that struck East Pakistan (now Bangladesh) and India's West Bengal on November 11, 1970. It was the deadliest tropical cyclone ever recorded, and one of the deadliest natural disasters in modern times.[2] Up to 500,000 people lost their lives in the storm, primarily as a result of the storm surge that flooded much of the low-lying islands of the Ganges Delta.[1] This cyclone was the sixth cyclonic storm of the 1970 North Indian Ocean cyclone season, and also the season's strongest, reaching a strength equivalent to a strong Category 3 hurricane.

The cyclone formed over the central Bay of Bengal on November 8 and travelled north, intensifying as it did so. It reached its peak with winds of 185 km/h (115 mph) on November 11, and made landfall on the coast of East Pakistan (now Bangladesh) that night. The storm surge devastated many of the offshore islands, wiping out villages and destroying crops throughout the region. In the most severely affected upazila, Tazumuddin, over 45% of the population of 167,000 was killed by the storm.



Member Since: July 17, 2009 Posts: 71 Comments: 27479
what happened to this potential TD in the atlantic on the model runs? It seems that it has dissapeared.
Member Since: April 30, 2013 Posts: 6 Comments: 4319
Quoting AussieStorm:

Hey Torito.
I better get to bed. Almost 2am here and I've been sick all day.
Night all


L8rs
Member Since: April 30, 2013 Posts: 6 Comments: 4319
Quoting Torito:


Hey Aussie :D

Hey Torito.
I better get to bed. Almost 2am here and I've been sick all day.
Night all
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12Z is coming out now!!:) 72HR
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Quoting Torito:
It looks like a TD in this satellite....



Any area of low pressure is actually north of the biggest area of convection. The NHC stated in their discussion that the weak low was around 9N. Most of the convection is at 5N and further south towards the equator.
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Quoting AussieStorm:


Gotta fight off the dry air.


Hey Aussie :D
Member Since: April 30, 2013 Posts: 6 Comments: 4319
Quoting Torito:
It looks like a TD in this satellite....



Gotta fight off the dry air.
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Quoting Grothar:
I looks like it is getting close to India.





Yup, pretty close



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Quoting hydrus:
Geritol is delicious..:)


Congratulations, you just received the first "twit" of the season from me. :)
Member Since: July 17, 2009 Posts: 71 Comments: 27479
It looks like a TD in this satellite....

Member Since: April 30, 2013 Posts: 6 Comments: 4319
I looks like it is getting close to India.




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Quoting Grothar:
Geritol is delicious..:)
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Rotation easy to see in the satellite when no enhancements are added to it...


Member Since: April 30, 2013 Posts: 6 Comments: 4319
The NHC hurricane specialists would have to be called in [while on vacation] in order to designate it an invest or give it a circle. When hurricane season starts on May 15 and there are two forecasters on shift at all times, it may warrant a mention, but for now, it's no immediate concern.
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Member Since: July 17, 2009 Posts: 71 Comments: 27479
Morning all. Weather here is kinda like the image below. Not much going on. No rain, not cold, not warm. Just um... Bland.


Some info on TS MAHASEN

TXIO28 KNES 131238
TCSNIO

A. 01B (MAHASEN)

B. 13/1230Z

C. 12.7N

D. 85.5E

E. THREE/MET-7

F. T2.5/2.5/W0.5/18HRS

G. IR/EIR/SSMIS

H. REMARKS...5/10 BANDING FOR DT=2.5. MET AND PT AGREE. FT IS BASED
ON DT. BULLETIN ISSUED EARLY DUE TO SCHEDULED NETWORK MAINTENANCE.

I. ADDL POSITIONS

13/1116Z 12.5N 85.7E SSMIS


...SALEMI

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 13 MAY 2013 Time : 143000 UTC
Lat : 12:44:09 N Lon : 85:41:54 E


CI# /Pressure/ Vmax
3.2 / 993.7mb/ 49.0kt


Final T# Adj T# Raw T#
2.9 3.1 3.1

Center Temp : -72.8C Cloud Region Temp : -69.0C

Scene Type : UNIFORM CDO CLOUD REGION

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : INDIAN
Dvorak CI > MSLP Conversion Used : PACIFIC

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : ON
Rapid Dissipation Flag : OFF

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 72km
- Environmental MSLP : 1005mb

Satellite Viewing Angle : 36.3 degrees























Goodnight, Stay safe.
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Quoting yonzabam:


Ssshh. You'll waken the HAARP nutters.


OK. I won't harp on it anymore.
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Quoting Tazmanian:




i think you need new eys or some in this storm has a ton of spin and its geting better and better


Link


learn too look closer and see it has lots and lots of spin


Nope, eyes are fine. In fact, I have better than 20/20 vision.
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You all have been warned

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Quoting Tropicsweatherpr:


At least qualifies to be invest.


Anything can qualify to be an invest, really. It's still embedded within the monsoon trough/ITCZ. It's no threat for a few days. The EPac season starts in 2 days, so if it's still around then they will have a circle around it. Should be the system that the CMC has been developing for a while now.
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Quoting MississippiWx:


This system has a long way to go before it develops, if it ever does. Hardly any spin with it yet.





i think you need new eys or some in this storm has a ton of spin and its geting better and better


Link


learn too look closer and see it has lots and lots of spin
Member Since: May 21, 2006 Posts: 5091 Comments: 115610
Looks like just any old ITCZ disturbance to me. That's not to say it won't develop - far from it, ITCZ disturbances can and often do develop if they manage to separate from the ITCZ.


Here's the NHC's take on it.
THE WEAK LOW EMBEDDED WITHIN THE MONSOON TROUGH NEAR 8N93W IS
INDUCING NLY WINDS TO 30 KT THROUGH THE GULF OF TEHUANTEPEC MON.

A very weak and broad area of 850mb vorticity.
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Quoting MississippiWx:


This system has a long way to go before it develops, if it ever does. Hardly any spin with it yet.



At least qualifies to be invest.
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Quoting Tazmanian:
it would be nic if the the NHC would do a SPECIAL TROPICAL WEATHER OUTLOOK on are E pac storm has it all most seem like we may have are 1st TD fourming


Yes, but i think the disturbance in the pacific will be in time for May 15... :)
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Quoting Grothar:


Hey, anybody in South Florida, Lauderdale or Miami, just go outside and look at the gigantic halo around the sun. I haven't seen anything like it in years. The brightest I have ever seen.


Got nothing here Gro.. :(
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Quoting Tazmanian:
it would be nic if the the NHC would do a SPECIAL TROPICAL WEATHER OUTLOOK on are E pac storm has it all most seem like we may have are 1st TD fourming


This system has a long way to go before it develops, if it ever does. Hardly any spin with it yet.

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Quoting Tazmanian:
it would be nice if the the NHC would do a SPECIAL TROPICAL WEATHER OUTLOOK on are E pac storm has it all most seem like we may have are 1st TD fourming


All i can find...

000
AXPZ20 KNHC 131518
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON MAY 13 2013

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0900 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH 9N84W TO LOW PRES NEAR 8N93W 1010 MB TO
10N110W TO 8N120W. ITCZ FROM 8N120W TO 6N140W. NUMEROUS
MODERATE TO STRONG CONVECTION FROM 5N-10N BETWEEN 90W-98W.


...DISCUSSION...

AN UPPER LEVEL TROUGH ACROSS THE FAR NW PORTION OF THE
DISCUSSION AREA FROM 32N132W TO 28N140W WITH DOWNSTREAM RIDGE
EXTENDING FROM 32N122W TO 21N127W. MODERATE TO STRONG SUBSIDENCE
WITH DRY STABLE AIR AT THE MIDDLE AND UPPER LEVELS IS N OF 20N
BETWEEN 115W-130W.

AN UPPER LEVEL TROUGH EXTENDS FROM CYCLONIC
CIRCULATION CENTERED OVER THE GULF OF CALIFORNIA NEAR 28N111WTO 24N124W
.

A 70-90 KT JETSTREAM FROM THE SOUTHERN TIP OF THE
BAJA PENISULA ACROSS NORTHEN MEXICO. UPPER LEVEL DIFFULENT FLOW
IS ENHANCING CONVECTION ALONG A SURFACE 1010 MB LOW CENTERED
NEAR 8N93W.


THE WEAK LOW EMBEDDED WITHIN THE MONSOON TROUGH NEAR 8N93W IS
INDUCING NLY WINDS TO 30 KT THROUGH THE GULF OF TEHUANTEPEC MON.


A HIGH PRES RIDGE EXTENDS ACROSS NORTHERN PORTION OF AREA N OF
12N W OF 110W. PRES GRADIENT BETWEEN THE RIDGE AND LOWER PRES
IN THE ITCZ IS MAINTAINING FRESH TRADES N OF THE CONVERGENCE
ZONE TO 15N W OF 135W WITH SEAS TO 8 FT.

ELY WINDS 20-25 KT ARE BLOWING THROUGH THE GULF OF PAPAGAYO
ARE EXPECTED TO CONTINUE THROUGH THE MIDDLE OF THE WEEK.

$$
DGS

Member Since: April 30, 2013 Posts: 6 Comments: 4319
it would be nic if the the NHC would do a SPECIAL TROPICAL WEATHER OUTLOOK on are E pac storm has it all most seem like we may have are 1st TD fourming
Member Since: May 21, 2006 Posts: 5091 Comments: 115610
Quoting Grothar:


Hey, anybody in South Florida, Lauderdale or Miami, just go outside and look at the gigantic halo around the sun. I haven't seen anything like it in years. The brightest I have ever seen.


Ssshh. You'll waken the HAARP nutters.
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Quoting Neapolitan:
That's a pretty amazing statistic. One can only image how much worse things will become there as sea level rise puts more people at risk. And, of course, as saltwater intrusion from those rising seas lays waste to sources of fresh water and low-lying agricultural areas in those three nations, societal upheaval and political unrest are certain to follow. Add that to the already near-a-breaking-point religious, political, and cultural strife in the region, and it doesn't take much imagination to envision any of a dozen worst-case scenarios coming to pass...


According to Wikipedia if the sea level rose 1 meter, Bangladesh would lose 10% of it's land area.

LINK

Bangladesh



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Quoting Grothar:


Hey, anybody in South Florida, Lauderdale or Miami, just go outside and look at the gigantic halo around the sun. I haven't seen anything like it in years. The brightest I have ever seen.


We can kinda see it here in MD too..

Looks kinda like this to me, but smaller.

Member Since: April 30, 2013 Posts: 6 Comments: 4319


Hey, anybody in South Florida, Lauderdale or Miami, just go outside and look at the gigantic halo around the sun. I haven't seen anything like it in years. The brightest I have ever seen.
Member Since: July 17, 2009 Posts: 71 Comments: 27479
looks like are 1st TD is fourming in the E pac but it looks like it still needs a few more days but its looking better and better it is likey we will have 90E any day now and looks like about a 30 too 40% ch of some in fourming on the 1st two for the E pac
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Quoting SFLWeatherman:





will likey have 90E vary soon
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GFS taking TS Mahasen as Cat.2 Saffir Simpson scale at 51 hours...Note: GFS full resolution
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TCFP SHORT RANGE




Pacific spot looking nice on satellite.(bottom left)

Member Since: April 30, 2013 Posts: 6 Comments: 4319
Quoting JeffMatsers:
[F]ifteen of the twenty deadliest tropical cyclones in world history have been Bay of Bengal storms that have hit Bangladesh, India, or Myanmar.
That's a pretty amazing statistic. One can only image how much worse things will become there as sea level rise puts more people at risk. And, of course, as saltwater intrusion from those rising seas lays waste to sources of fresh water and low-lying agricultural areas in those three nations, societal upheaval and political unrest are certain to follow. Add that to the already near-a-breaking-point religious, political, and cultural strife in the region, and it doesn't take much imagination to envision any of a dozen worst-case scenarios coming to pass...
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with the lac of severe weather this season it more then likey that will end up paying for it next year this look at 2010 was this like this year and then BOOM 2011 we ended up paying for with a lot of EF4 and EF5 nados
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11:00 Update

Mahasan



Jamala (looks like it has become extatropical to me now... It wont last too much longer.)

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Arctic Ocean. North pole is in the upper left. People who can't change their ways; nature will change it for you. I feel it getting hotter already.

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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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