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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General Question..
Anyone know why this isn't updating every 7 days like it's supposed to?..
Last update was 10 days ago..
NWS CPC..ENSO


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Quoting Tazmanian:




you are vary vary late i posted that vary early this AM and sid yuck i wish they had the old one back

Taz I saw it there from like 2AM this morn but I did not get the chance to mention it till now so no I'm not late

Quoting Bluestorm5:
Not everybody is on blog 24/7 Taz... we all got life.


That is true I didn't get the chance to mention it earlier till now
Member Since: June 13, 2009 Posts: 2 Comments: 12140
Quoting Tazmanian:




you are vary vary late i posted that vary early this AM and sid yuck i wish they had the old one back
Yeah I saw where u said that.

I like the larger format too, but all the wind roses seem much bigger / more intrusive than before.
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Quoting Tazmanian:




you are vary vary late i posted that vary early this AM and sid yuck i wish they had the old one back
Not everybody is on blog 24/7 Taz... we all got life.
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Quoting wunderkidcayman:
Hey guys I was meaning to ask why the TWD has a new surface map I kinda miss the old one





you are vary vary late i posted that vary early this AM and sid yuck i wish they had the old one back
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Member Since: July 17, 2009 Posts: 71 Comments: 26418
Quoting Levi32:
Forecasting TC genesis >10 days out is impossible. We can only predict the setup for it.
...
TC genesis is something for the 3-5 day forecast.
eh.

You can forecast anything, it's not impossible. Skillfully forecasting is another story. What one considers "skillful" is also subjective. Finally, the time frame at which one can skillfully forecast TC genesis varies with the confidence in the pattern. Sometimes we can skillfully predict genesis well beyond 5 days. All depends on the confidence in the pattern. I won't say we can skillfully predict genesis with the wcarib situation right now, cause we can't, but I don't think we'll have to wait till 3-5 days before either.
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Quoting Skyepony:
Mahasen~ peak 80-90kts maybe..


emanuel


Coupled Hurricane Intensity Prediction System

have not seen that before. Got some reading to do. Thanks - take care
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Link for #413

http://www.wired.com/dangerroom/2013/05/haarp-fra ud/
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In the history of U.S. military research, there’s never been a project with such a combination of big science, high sleaze, and pure conspiratorial strangeness. Yet somehow, some way, the story of the High Frequency Active Auroral Research Program, or HAARP, just got sleazier and stranger — all thanks to an elderly physicist named Alfred Wong.

Wong was an early proponent of HAARP, who used the facility in his studies of the ionosphere, the electrically-charged portion of the atmosphere. He also was something of a serial con man, according to a federal plea agreement provided to Danger Room. (.pdf) On Thursday, Wong agreed to pay nearly $1.7 million in damages for falsely billing Darpa and the Interior Department. He also plead guilty to a host of fraud charges.

HAARP was originally pitched back in the Cold War as a way for plasma physicists to study the ionosphere by blasting it with radio frequency emissions. If you build this series of RF antennas in remote Alaska, the scientists told the Pentagon, HAARP wound not only advance our understanding of this crucial field. It could also be used to fry incoming Soviet missiles and spy on underground bunkers. One physicist working for the Arco oil-and-gas conglomerate even suggested that HAARP could be used to weaponize hurricanes — that is, if Arco’s natural gas fields were used to power the thing.

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Quoting TropicalAnalystwx13:

That's what anticyclones are for.


You know

I been trying to tell people that is why I agree with GFS in that situation
Member Since: June 13, 2009 Posts: 2 Comments: 12140
Hey guys I was meaning to ask why the TWD has a new surface map I kinda miss the old one

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409. Skyepony (Mod)
Mahasen~ peak 80-90kts maybe..


emanuel
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Quoting Bluestorm5:
Another thing that made me doubt about formation in May... high shear winds in tropics. It's just too early.

That's what anticyclones are for.
Member Since: July 6, 2010 Posts: 113 Comments: 32251
Quoting CybrTeddy:


Not as rare as it used to be.

2003, 2007, 2008, 2009 and 2012 all had May tropical cyclones develop.


2003 had no tropical cyclones developed on May, but the first named storm (Ana) developed on April.
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Another thing that made me doubt about formation in May... high shear winds in tropics. It's just too early.
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Cybr, what do the 1990's look like for May cyclogenesis?
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Quoting Bluestorm5:
I really doubt it... it's still May. I know two tropical cyclones formed last May, but that was very rare.


Not as rare as it used to be.

2003, 2007, 2008, 2009 and 2012 all had May tropical cyclones develop.
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the big warmer up coming soon.
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Month-to-date temperature anomalies across the USA:



Still predominantly blue and green across the image.
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Quoting Levi32:


Well they are. The equations are integrated at each grid point, but sometimes the data is scaled up a bit because often people don't really need to see the full resolution data, and the file size is smaller.

Yeah CFS is T126 and disseminated by NOMADS on a 1.0 lat/lon grid, which is a very slight interpolation from the T126 grid but essentially the same resolution.
Yeah it makes sense that the do it, its just not something one realizes right away. In fact, if you polled this blog and asked everyone what resolution the first leg of a gfs 500mb plot was displayed at Id bet 99% would say t574/27km or they wouldn't know. Reality is what we see is less than half the native (27km) resolution.

And thanks for the CFS info. I'm assuming all models get interpolated to some extent then. ECMWF UKMET and mesoscale models seem to be the only ones immune to this. Even then, I think most the UKMET and ECMWF plots found on the web are not at full resolution.
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400. HadesGodWyvern (Mod)
India Meteorological Department
Tropical Cyclone Advisory #11
CYCLONIC STORM MAHASEN (BOB01-2013)
2:30 AM IST May 12 2013
==========================================

At 21:00 PM UTC, The Cyclonic Storm Mahasen over southeast Bay of Bengal moved northwestward and now lays near 9.5N 88.0E, about 530 km west of Car Nicobar, 750 km east of Trincomalee, Sri Lanka, 940 km southeast of Chennai, India, and 1480 km south southwest of Chittagong, Bangladesh.

The system would intensify further into a severe cyclonic storm during the next 24 hours. It would move initially northwestward during the next 36 hours and recurve thereafter northeastward towards Bangladesh-Myanmar coast.

According to satellite imagery, the Dvorak intensity of Cyclonic Storm Mahasen is T2.5. It has a central dense overcast cloud pattern. Intense to very intense convection is seen over southern Bay of Bengal, adjoining Indian Ocean between 5.0N to 12.5N and 82.0E to 90.0E. The lowest cloud top temperature due to convection is about -70C.

3 minute sustained winds 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 12.0N and is providing poleward outflow in association with the anticyclonic circulation over southern Andaman Sea. Upper level divergence is favorable for intensification. The low level convergence along with low level relative vorticity remained unchange during the past 12 hours. The sea surface temperature is around 30-32C. Ocean thermal energy is more than 100 kj/cm2 over the storm area. The vertical wind shear of horizontal wind is about 10-20 knots (MODERATE) in the northwest sector. The MJO now lays over phase 3 with amplitude greater than 2. It is favorable for intensification.

Most of the numerical weather predication models suggest initial northwestward movement during the next 36 hours and then recurving northeastward towards Bangladesh-Myanmar coast. However, ECMWF models show slow movement and doe not show landfall. There is a large divergence in the numerical weather prediction models guidance with respect to intensification of the system. While some models like JMA suggest intensification of the system to severe cyclonic storm, the models like ECMWF, UKMO, and GFS do not suggest such severity in intensify. Rather they suggest gradual weakening during recurvature of the system. Climatologically, the system is likely to intensify further.
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Interesting feature near 24N/65W. waiting for invest 90L TO COME SOON.
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Quoting Tropicsweatherpr:
Hi Levi. Is Alvin a better possibility to develop rather than the Western Caribbean or we may see development in both basins as the MJO kicks into the area?


You should not be able to have an Alvin, without a Simon and Theodore in the same list...
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Quoting KEEPEROFTHEGATE:


Southern cell appears to be exhibiting Bunkers (right-turning) storm motion, often associated with strong intensifying supercells.
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One could see the low-level center of this disturbance becoming exposed and unstacked from the upper-level low/trough right before sunset.

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Blog Hole
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Quoting Minnemike:
i got the perfect vid for the 'ice age is coming' folks!!
i know it's irrelevant, and i'm not starting anything, but man is this wild :o
here come the glaciers ;)


That was cool, literally.

MesoWest Jurupa Valley CA US SGXWFO, Riverside, California (PWS)
Updated: 4:49 PM PDT on May 11, 2013
Scattered Clouds
93 °F
Scattered Clouds
Humidity: 27%
Dew Point: 54 °F
Wind: 5 mph from the WSW
Wind Gust: 15.0 mph
Pressure: 29.91 in (Steady)
Heat Index: 91 °F
Visibility: 10.0 miles
UV: 3 out of 16
Pollen: 5.10 out of 12
Pollen Forecast new!
Clouds:
Scattered Clouds 12000 ft
(Above Ground Level)
Elevation: 794 ft

This would fix it.
Member Since: February 29, 2012 Posts: 0 Comments: 5899
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I actually like the model run the gfs has been CONSISTANTLY showing for the past week+.
Member Since: April 30, 2013 Posts: 5 Comments: 4316


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Hi Levi. Is Alvin a better possibility to develop rather than the Western Caribbean or we may see development in both basins as the MJO kicks into the area?
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Quoting Andrebrooks:
Tropical developments in the next two weeks,watch out United States.Possible tropical Storm or maybe hurricane Andrea.
I really doubt it... it's still May. I know two tropical cyclones formed last May, but that was very rare.
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Member Since: July 15, 2006 Posts: 173 Comments: 54282
Tropical developments in the next two weeks,watch out United States.Possible tropical Storm or maybe hurricane Andrea.
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i got the perfect vid for the 'ice age is coming' folks!!
i know it's irrelevant, and i'm not starting anything, but man is this wild :o
here come the glaciers ;)
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Forecasting TC genesis >10 days out is impossible. We can only predict the setup for it. The GFS is almost always too aggressive with the monsoon lows.

What does matter here is that the western Caribbean is likely to descend into a very wet pattern near the end of May and early June, and if a longwave trough taps into that, Cuba, Florida, and the Bahamas may be in for copious amounts of rainfall, which will be significant with or without a tropical storm embedded in all of that. Forecasting the wet pattern is the important part. TC genesis is something for the 3-5 day forecast.
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Cyclone Mahasen


The areas in the north-central BOB must monitor the progress of Mahasen, regardless of the intensity during impact..this storm could bring deadly rainfalls for the area, mudslides are a major threat out of this storm.
The storm could impact anywhere in the orange-shaded area with over hurricane intensity (equivalent), places in the yellow-shade could see some impacts from Mahasen when it reaches the northern Bay of Bengal... more updates later as we go


click image for larger view..

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Quoting JTDailyUpdate:
You Gotta be Kidding Me






I vote this for best post of the year so far :p
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Member Since: July 15, 2006 Posts: 173 Comments: 54282
Quoting SLU:


If Isaac formed in 2010 it would have been a cat 4 tracking through the Caribbean and entering the Gulf. Expect in 2013 that the storms which died midway across the Atlantic and those which barely strengthened will probably be in with a good chance of some serious development.
and see SLU i try to tell people why Isaac wasn't that bad but they always argue me down that we will never see a big storm again. Boy I tell ya some people need a wake up call out here. I think this year will wake em up!
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376. HadesGodWyvern (Mod)
India Meteorological Department
Tropical Cyclone Advisory #10
CYCLONIC STORM MAHASEN (BOB01-2013)
23:30 PM IST May 11 2013
==========================================

At 18:00 PM UTC, The Cyclonic Storm Mahasen over southeast Bay of Bengal moved northwestward and now lays near 9.0N 88.5E, about 470 km west of Car Nicobar, 800 km east of Trincomalee, Sri Lanka, 1010 km southeast of Chennai, India, and 1520 km south southwest of Chittagong, Bangladesh.

The system would intensify further into a severe cyclonic storm during next 24 hours. It would move initially northwestwards during next 36 hours and recurve thereafter northeastwards towards Bangladesh-Myanmar coast.

According to satellite imagery, the Dvorak intensity of Cyclonic Storm Mahasen is T2.5. It is a curved band pattern. Intense to very intense convection seen over southern Bay of Bengal, adjoining Indian Ocean between 4.5N and 13.0N east of 82.0E. The lowest cloud top temperature due to convection is about -70C.

3 minute sustained winds 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 12.0N and is providing poleward outflow in association with the anticyclonic circulation over southern Andaman Sea. Upper level divergence is favorable for intensification. The low level convergence along with low level relative vorticity remained unchanged during the past 12 hours. The sea surface temperature is about 30-32C. Ocean thermal is more than 100 kj/cm2 over the storm area. The vertical wind shear of horizontal wind is about 10-20 knots (MODERATE) in the northwest sector. The MJO now lies over phase 3 with amplitude greater than 2. It is favorable for intensification.

Forecast and Intensity
======================
12 HRS: 10.0N 86.5E - 45 knots (Cyclonic Storm)
24 HRS: 11.5N 85.8E - 50 knots (Severe Cyclonic Storm)
48 HRS: 14.5N 85.8E - 55 knots (Severe Cyclonic Storm)
72 HRS: 17.0N 86.8E - 60 knots (Severe Cyclonic Storm)
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Member Since: July 15, 2006 Posts: 173 Comments: 54282
Quoting KEEPEROFTHEGATE:
hey wash looky here

They've been scattered all day long.We just had a heavy downpour in N.W D.C while my sister in Hyattsville had nothing which is about 5 miles from where I live.
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hey wash looky here

Member Since: July 15, 2006 Posts: 173 Comments: 54282

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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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