Mahasen not Strengthening; Eastern Pacific's First Tropical Depression Forming

By: Dr. Jeff Masters , 1:34 PM GMT on May 15, 2013

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Tropical Cyclone Mahasen in the Bay of Bengal continues to show little change as it steams north-northeastward at 14 mph towards the Bangladesh coast just north of the border with Myanmar. Though the storm is no longer expected to reach hurricane strength, Mahasen's storm surge and heavy rains represent a significant threat to people living in low-lying areas along the Bangladesh and Myanmar coasts. At least 70,000 people have been asked to evacuate, and a boat carrying refugees capsized on Monday, killing eight and leaving 50 missing. The ocean bottom is shallow and allows storm surges to pile up to great depths on the Bangladeshi coast, and Mahasen is expected to bring a storm surge of 3 - 5 feet (1 - 1.5 meters) to the Bangladesh coast on Thursday, according to the Regional Specialized Meteorological Center in Delhi, India. The Bangladesh Meteorological Department is warning of a 5 - 7 foot (2 meter) storm surge for their coastal districts. The greatest storm surge will occur to the right of where the center crosses the coast, in northern Myanmar. The Myanmar Department of Meteorology and Hydrology is warning of a 6 - 10 foot (2 - 3 meter) storm surge there. Accompanying the surge will be torrential rains of 3 - 7 inches that have the potential to cause dangerous flooding. At least seven people have been killed in Sri Lanka due to landslides triggered by Mahasen's heavy rains.


Figure 1. MODIS image of Tropical Cyclone Mahasen taken at 07:45 UTC Wednesday May 15, 2013. At the time, Mahasen was a tropical storm with 50 mph winds. The storm appears disorganized due to wind shear keeping the heavy thunderstorms to the west of the center. Image credit: NASA.

The 10 am EDT Wednesday advisory from the Joint Typhoon Warning Center put Mahasen's top sustained winds near 50 mph. Satellite loops show that Mahasen continues to struggle with wind shear. The low-level circulation center has become exposed to view several times, with an intense area of thunderstorms with very cold cloud tops just to the west of the center. The cloud pattern is not well-organized, with little spiral banding. Wind shear remains a moderate 10 - 15 knots, but Mahasen is now over cooler waters with a much reduced total heat content, and it appears unlikely that the storm will change much in intensity before landfall. Landfall is expected to occur near 18 UTC on Thursday.


Figure 2. Storm-total rainfall from Tropical Cyclone Mahasen as predicted by the 12 UTC May 14, 2013 run of the HWRF model. Rainfall amounts of 3 - 7" are expected along a wide swath of Bangladesh and Myanmar. Image credit: India Meteorological Department.


Figure 3. Bathymetry of the Bay of Bengal. The shallow waters of the Continental Shelf (mostly shallower than 200 meters) are shaded whitish-grey. From Kolkata, India to Cox's Bazar, Bangladesh, the ocean bottom is shallow and allows storm surges to pile up to great depths. Fifteen of the twenty deadliest tropical cyclones in world history have been Bay of Bengal storms that have hit Bangladesh, India, or Myanmar, bringing catastrophic storm surges. Image credit: geomapapp.org.

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


Figure 4. Latest satellite image of Invest 90E.

First tropical depression of the year forming in the Eastern Pacific
The official start of hurricane season in the Eastern Pacific is Wednesday, May 15 (today!), and Mother Nature is playing along with this idea. The first "Invest" of the year, Invest 90E, has become well-organized on satellite loops, and NHC has set in motion the process to name this system Tropical Depression One-E (or possibly Tropical Storm Alvin) at 11 am EDT. Wind shear is a low 5 -10 knots, and is predicted to remain low for the next five days. Ocean temperatures are a warm 29 - 30°C, and it is possible that this could become Hurricane Alvin late this week. The storm is moving west-northwest into the Central Pacific, and is not a threat to any land areas.

I'll have a new post late this morning or early this afternoon on yesterday's remarkable heat wave in the Midwest. Can you believe 106° in Iowa and 108° in Nebraska, after unprecedented May snows were falling less than two weeks ago? Unbelievable!

Jeff Masters

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176. moonlightcowboy
9:48 PM GMT on May 15, 2013
Quoting MississippiWx:
The MDR just can't make up its mind. Significant cooling has occurred over the past 7 days. Of course, this is probably something that happens every year, but this year Levi has given us the luxury of the daily change in the anomalies.





Good point. I can't remember ever taking continuous looks at SST anomalies. You're likely right in that these fluctuations are probably quite normal, i.e., clouds, sunshine, dust, currents, etc. The bottom line would be are SSTs thresholds able to support cyclogenesis. My guess would be yes, even now in the seemingly more than usual anomalously cool GoM.
Member Since: July 9, 2006 Posts: 184 Comments: 29594
175. Andrebrooks
8:55 PM GMT on May 15, 2013
It's now Tropical Storm Alvin.
Member Since: March 25, 2013 Posts: 29 Comments: 991
174. nrtiwlnvragn
5:49 PM GMT on May 15, 2013
Both cyclone specific models like 01E.

GFDL

HOUR: 84.0 LONG: -112.96 LAT: 13.99 MIN PRESS (hPa): 954.98 MAX SURF WIND (KNOTS):100.73

HWRF

HOUR: 72.0 LONG: -111.70 LAT: 11.80 MIN PRESS (hPa): 965.00 MAX SURF WIND (KNOTS): 94.00
Member Since: September 23, 2005 Posts: 14 Comments: 10872
173. WunderAlertBot (Admin)
5:48 PM GMT on May 15, 2013
JeffMasters has created a new entry.
172. ncstorm
5:47 PM GMT on May 15, 2013
Quoting MississippiWx:


Thanks for your very beneficial comment to the blog. Glad that you could grab yourself a little attention. Please don't post again.

Regards,

The entire blog


thank you Miss!!

Member Since: August 19, 2006 Posts: 13 Comments: 14412
171. nigel20
5:46 PM GMT on May 15, 2013
Good afternoon Friends!
Member Since: November 6, 2010 Posts: 11 Comments: 7819
170. wunderkidcayman
5:46 PM GMT on May 15, 2013
Quoting ncstorm:
the 12z Navgem got two area of low pressures entering the caribbean..180 hours..looks like everything wants to head due north..





Now we got models forecasting development

Member Since: June 13, 2009 Posts: 2 Comments: 10915
169. MississippiWx
5:45 PM GMT on May 15, 2013
Quoting Wiiilbur:
I've always gotten a good chuckle out of the range of comments on this blog. Posters drooling over every thunderstorm that pops up in the tropics - complete with predictions that it will reach Category 4 or 5 strengh sometime in the next 12 minutes, invests being referred to as though they have names, gleeful pronouncements of excitement over waves, etc. All at the same time there is the hand wringing, "Oh gee, I hope that everyone gets out of the way." Make up your minds.

Despite all of the predictions, arguments and agreements over the next big storm, or complaints that the NHC didn't upgrade it to a Category 4 storm when the winds are still at 25 kts, what will happen will happen. Prepare for the worst, hope for the best and get your forecasts from the professionals. Copy and paste of 10,000 word forecasts that are readily available on the web doesn't make you a climatological or meteorological genius.

By the way, while I am working on getting myself banned or ignored for not making a big deal over every freaking cloud over a tropical ocean, "canes" are for walking, "nados" or "naders" are non-words (at least not in English) and a "cat" is a feline that in general is not a big fan of water.


Thanks for your very beneficial comment to the blog. Glad that you could grab a little attention for yourself. Please don't post again.

Regards,

The entire blog
Member Since: July 15, 2006 Posts: 17 Comments: 10159
168. KeysieLife
5:45 PM GMT on May 15, 2013
@Wiiilbur

How could you not enjoy the "Season"

Quoting weathermanwannabe:
Pre-Alvin might have some issues with some dry air injection out of the Southern quadrant as the bands start to wrap around but the coc is in a nice little pocket of moisture otherwise at the moment.

Link


SSTs will be on the upswing!
Member Since: September 10, 2010 Posts: 3 Comments: 409
166. MississippiWx
5:36 PM GMT on May 15, 2013
The MDR just can't make up its mind. Significant cooling has occurred over the past 7 days. Of course, this is probably something that happens every year, but this year Levi has given us the luxury of the daily change in the anomalies.



Member Since: July 15, 2006 Posts: 17 Comments: 10159
165. ncstorm
5:35 PM GMT on May 15, 2013
Quoting washingtonian115:
I see nothing but blobs of rain.


I never said they were hurricanes or even tropical depressions..I was just pointing out the potential of development..
Member Since: August 19, 2006 Posts: 13 Comments: 14412
164. MississippiWx
5:33 PM GMT on May 15, 2013
Quoting CybrTeddy:


I'm not seeing much in the way of model support. Looks too close to land.


Looks to be in association with the semi-permanent low that is there this time of the year.
Member Since: July 15, 2006 Posts: 17 Comments: 10159
163. stormchaser19
5:33 PM GMT on May 15, 2013
Quoting Gearsts:




Member Since: June 20, 2012 Posts: 0 Comments: 2150
162. KEEPEROFTHEGATE (Mod)
5:31 PM GMT on May 15, 2013
Toronto Pearson Int'l Airport
Date: 1:10 PM EDT Wednesday 15 May 2013
Condition:Mainly Sunny
Pressure:29.5 inches
Tendency:falling
Visibility:15 miles
Temperature:77.5°F
Dewpoint:55.6°F
Humidity:60%
Wind:W 26 gust 36 mph
Humidex: 83


nice temp change over 24 hrs 48 yesterday 77.5 today
almost 30 degree temp change in 24hrs
Member Since: July 15, 2006 Posts: 169 Comments: 53296
161. Gearsts
5:29 PM GMT on May 15, 2013
Quoting ncstorm:
nice wave coming off Africa, east coast system, and trouble heading in the GOM..last frame of the GFS looks to cover it all..

Alex Déjà vu.
Member Since: August 2, 2010 Posts: 0 Comments: 1413
160. weathermanwannabe
5:28 PM GMT on May 15, 2013
Pre-Alvin might have some issues with some dry air injection out of the Southern quadrant as the bands start to wrap around but the coc is in a nice little pocket of moisture otherwise at the moment.

Link
Member Since: August 8, 2006 Posts: 0 Comments: 8768
159. ncstorm
5:28 PM GMT on May 15, 2013
im not a big fan of the epac but the GFS had this on the 12z run at 240 hours but it looks to impact Mexico





Member Since: August 19, 2006 Posts: 13 Comments: 14412
158. KEEPEROFTHEGATE (Mod)
5:27 PM GMT on May 15, 2013
T.C.F.W.
01E/TD/XX/CX

Member Since: July 15, 2006 Posts: 169 Comments: 53296
157. CybrTeddy
5:27 PM GMT on May 15, 2013
Quoting Tazmanian:



dos this have a ch too fourm in too any thing ???? I all so wounder if this was one of the gfs that was forcasting TD two E a few days a go





I'm not seeing much in the way of model support. Looks too close to land.
Member Since: July 8, 2005 Posts: 259 Comments: 23562
156. washingtonian115
5:27 PM GMT on May 15, 2013
Quoting ncstorm:
nice wave coming off Africa, east coast system, and trouble heading in the GOM..last frame of the GFS looks to cover it all..

I see nothing but blobs of rain.
Member Since: August 14, 2010 Posts: 10 Comments: 16383
155. ncstorm
5:26 PM GMT on May 15, 2013
the 12z Navgem got two area of low pressures entering the caribbean..180 hours..looks like everything wants to head due north..



Member Since: August 19, 2006 Posts: 13 Comments: 14412
154. Thrawst
5:22 PM GMT on May 15, 2013
Well well well...

Nice chance to see a tornado today!

Member Since: July 18, 2010 Posts: 50 Comments: 1793
153. VR46L
5:20 PM GMT on May 15, 2013
Quoting Gearsts:
Celia


Thank You !!
Member Since: March 1, 2012 Posts: 0 Comments: 6820
152. ncstorm
5:19 PM GMT on May 15, 2013
nice wave coming off Africa, east coast system, and trouble heading in the GOM..last frame of the GFS looks to cover it all..

Member Since: August 19, 2006 Posts: 13 Comments: 14412
151. Gearsts
5:19 PM GMT on May 15, 2013
Quoting VR46L:


What storm is that ?
Celia
Member Since: August 2, 2010 Posts: 0 Comments: 1413
150. wxchaser97
5:17 PM GMT on May 15, 2013
Quoting VR46L:


What storm is that ?

My guess is Hurricane Celia from 2010 in the EPAC.
Member Since: March 16, 2012 Posts: 127 Comments: 7927
149. VR46L
5:14 PM GMT on May 15, 2013
Quoting Gearsts:


What storm is that ?
Member Since: March 1, 2012 Posts: 0 Comments: 6820
148. MississippiWx
5:11 PM GMT on May 15, 2013
Quoting wunderkidcayman:
Ok we have first tropical wave



And 90E is now TD1E

and someone said you can't have invest get stronger with it being in the monsoon trough we this proves them wrong


It is no longer embedded in the monsoon trough. The trough dissipated, thus allowing development. This is something that was forecast to happen.
Member Since: July 15, 2006 Posts: 17 Comments: 10159
147. Tazmanian
5:04 PM GMT on May 15, 2013
Quoting CybrTeddy:
Well organized, should have no problem with approaching hurricane status in the next few days. Certainly rare to have two consecutive years with hurricanes developing in the month of May in the Eastern Pacific.



dos this have a ch too fourm in too any thing ???? I all so wounder if this was one of the gfs that was forcasting TD two E a few days a go



Member Since: May 21, 2006 Posts: 5091 Comments: 114703
146. Civicane49
5:04 PM GMT on May 15, 2013
TD 1-E has formed. Just in time for the start of East Pacific hurricane season.

Member Since: July 21, 2011 Posts: 83 Comments: 7167
145. nrtiwlnvragn
5:02 PM GMT on May 15, 2013
Popocatépetl Volcano in Mexico Continues to Show Signs of Activity
After an eruption last week that spewed ash and lava, the Popocatépetl Volcano just southeast of Mexico City is again showing signs of activity. NOAA's Washington Volcanic Ash Advisory Center is monitoring the status of the volcano for any potential impacts on air traffic using a variety of satellite sensors, including the Ozone Monitoring Instrument (OMI) found on the NASA Aura spacecraft. Though OMI is intended primarily for ozone measurements, it can also detect sulfur dioxide - one of the many gases released by volcanoes before and during eruption. This image shows the sulfur dioxide measurements from two consecutive passes over the area on May 12th and 13th.





Link
Member Since: September 23, 2005 Posts: 14 Comments: 10872
144. Gearsts
5:02 PM GMT on May 15, 2013
Member Since: August 2, 2010 Posts: 0 Comments: 1413
143. stormchaser19
5:02 PM GMT on May 15, 2013
Quoting bigwes6844:
Manhassen is struggling. the MJO left and now its the east Pac turn to show what its made of.

Starting to believe this graph maybe right.

The MJO hasn't left the zone at all(second box), but soon will do,if you see the first box, the velocity potential is not good in the Region, is the same thing that happened with Ernesto last year...

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142. bigwes6844
5:00 PM GMT on May 15, 2013
Member Since: July 25, 2010 Posts: 0 Comments: 2510
141. CaribBoy
4:56 PM GMT on May 15, 2013


I prefer this one. But I know it will change *unfavorably* (drier) for my area... as usual.
Member Since: October 6, 2007 Posts: 0 Comments: 5923
140. bigwes6844
4:56 PM GMT on May 15, 2013
Quoting Torito:


The main reason why it cant get stronger is because of the storm bands hitting land while it is being sheared at the same time.... Nothing lasts long when that happens.
exactly! but its almost over for them. we learned alot from the twins
Member Since: July 25, 2010 Posts: 0 Comments: 2510
139. Torito
4:55 PM GMT on May 15, 2013
Quoting Gearsts:



LOL
Member Since: April 30, 2013 Posts: 5 Comments: 4316
138. Gearsts
4:55 PM GMT on May 15, 2013
Quoting Torito:



you can kinda see the monsoon wrapped INSIDE of the TD. xD
Member Since: August 2, 2010 Posts: 0 Comments: 1413
137. bigwes6844
4:53 PM GMT on May 15, 2013
Quoting wunderkidcayman:

Then the Caribbean and Atlantic after
right! huge MJO pulse!
Member Since: July 25, 2010 Posts: 0 Comments: 2510
136. Torito
4:53 PM GMT on May 15, 2013
Quoting bigwes6844:
yeah i even doubt if it goes past 60 the way its looking


The main reason why it cant get stronger is because of the storm bands hitting land while it is being sheared at the same time.... Nothing lasts long when that happens.
Member Since: April 30, 2013 Posts: 5 Comments: 4316
135. bigwes6844
4:52 PM GMT on May 15, 2013
Quoting Torito:


May get up to 65-70MPH winds but i seriously doubt it will make it to Cat1.
yeah i even doubt if it goes past 60 the way its looking
Member Since: July 25, 2010 Posts: 0 Comments: 2510
134. Torito
4:52 PM GMT on May 15, 2013
Quoting CybrTeddy:
Well organized, should have no problem with approaching hurricane status in the next few days. Certainly rare to have two consecutive years with hurricanes developing in the month of May in the Eastern Pacific.


Look at that little circle right behind the TD, diddnt see that yet...
Member Since: April 30, 2013 Posts: 5 Comments: 4316
133. wunderkidcayman
4:51 PM GMT on May 15, 2013
Quoting bigwes6844:
Manhassen is struggling. the MJO left and now its the east Pac turn to show what its made of.

Then the Caribbean and Atlantic after
Member Since: June 13, 2009 Posts: 2 Comments: 10915
132. Torito
4:50 PM GMT on May 15, 2013



you can kinda see the monsoon wrapped INSIDE of the TD. xD
Member Since: April 30, 2013 Posts: 5 Comments: 4316
131. CybrTeddy
4:50 PM GMT on May 15, 2013
Well organized, should have no problem with approaching hurricane status in the next few days. Certainly rare to have two consecutive years with hurricanes developing in the month of May in the Eastern Pacific.
Member Since: July 8, 2005 Posts: 259 Comments: 23562
130. Torito
4:49 PM GMT on May 15, 2013
Quoting bigwes6844:
Manhassen is struggling. the MJO left and now its the east Pac turn to show what its made of.


May get up to 65-70MPH winds but i seriously doubt it will make it to Cat1.
Member Since: April 30, 2013 Posts: 5 Comments: 4316
129. wunderkidcayman
4:48 PM GMT on May 15, 2013
Quoting Torito:


TCFP still shows possible formation there :]

Yep I could remember a few times a storm developed and models did not pick it up till father it became a TD
Member Since: June 13, 2009 Posts: 2 Comments: 10915
128. bigwes6844
4:48 PM GMT on May 15, 2013
Manhassen is struggling. the MJO left and now its the east Pac turn to show what its made of.

Starting to believe this graph maybe right.
Member Since: July 25, 2010 Posts: 0 Comments: 2510
127. Gearsts
4:46 PM GMT on May 15, 2013
Quoting Tropicsweatherpr:


The May MSLP is out and show near normal pressure in the MDR and Caribbean and that is different from the April one that had higher pressures.



Link
Oh wow can't wait what Levi has to say about it.
Member Since: August 2, 2010 Posts: 0 Comments: 1413
126. Torito
4:46 PM GMT on May 15, 2013
TD1 looks more like a TS now. First image of the loop compared to last image really shows the strengthening it is having right now.


Member Since: April 30, 2013 Posts: 5 Comments: 4316

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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.