Dr. Jeff Masters' WunderBlog

Not a trace of Don; What's next?
Posted by: Dr. Jeff Masters, 7:41 PM GMT op 30 juli 2011 +33
Don is dead

Tropical Storm Don, the fourth named storm of the 2011 season, made landfall near Baffin Bay, Texas yesterday evening around 10pm CDT in less-than-grand fashion. The storm was looking very weak for the 24 hours before landfall, but fizzled rapidly after landfall, and by early Saturday morning, there was barely a trace of the storm to show that it even existed in the first place.

NHC Hurricane Specialist Eric Blake probably said it best in this mornings 5am EDT discussion on the storm:

THE DON IS DEAD. THE CYCLONE LITERALLY EVAPORATED OVER TEXAS ABOUT
AS FAST AS I HAVE EVER SEEN WITHOUT MOUNTAINS INVOLVED. DON HAS NO
CONVECTION...MEAGER RAINFALL...AND ONLY A SLIGHT SIGNATURE IN
SURFACE OBSERVATIONS AND RADAR DATA. THEREFORE...THIS IS THE LAST
ADVISORY ON THIS SYSTEM.


Figure 1. Total precipitation accumulation for the storm, estimated by radar.

The heaviest rainfall was falling south of the storm's center yesterday, so it wasn't surprising that Brownsville saw the most rain, 0.63 inches. KBRO also recorded 18 mph wind gusts. But to the north of the center, where many of the media were located, not a drop of rain fell. Corpus Christi saw zero inches of rain, but did record gale-force wind gusts (39 mph). Harlingen, near Baffin Bay, and close to where the center made landfall, saw 0.20 inches of rain and 18 mph wind gusts. This storm did very, very little to relieve any drought conditions in Southern Texas. And so it continues.

What's next: Invest 91L continues to impress

Invest 91L, which is located near 12°N 48°W in the central Atlantic, continues to impress today, and has shown signs of more organization over the past 24 hours. 91L will probably develop into a tropical cyclone before it reaches the Lesser Antilles, so residents of these islands should remain watchful and prepared. Satellite loops show not only organized thunderstorm activity, but also the makings of a surface circulation. Something this wave has working against it right now is dry air—there's a large mass of Saharan air on the north and east sides of the system, which could at least prevent significant intensification. Also, University of Wisconsin CIMSS analysis shows some strong wind shear (30-40 knots) to the north of the wave. However, I don't expect this to prevent development of the wave. Wind shear out ahead of the system is relatively low (5-15 knots). Moisture is plenty high within the system, and sea surface temperatures are warm and toasty (28°C+) and will only get warmer as 91L moves west into the Caribbean.


Figure 2. Infrared satellite of invest 91L taken at 1:15pm EDT today.

Forecast for 91L
Most of the reliable forecast models (GFS, CMC, FIM, and the ECMWF) have come to agree that 91L will develop, however, they differ on how long-lived that will be. Some of the models are suggesting it will be a short-lived tropical cyclone, not making it out of the Caribbean alive, and some suggest that it will hold together and intensify as it moves north of the Caribbean islands. The forecast track for the system will most likely be to the northwest through the Caribbean, at which point it will take a northeast turn near the Bahamas, never reaching the U.S. coast. HWRF agrees with this track (and also brings the system to category 2 strength by August 3rd). However, there is still some uncertainty that the system could track west, south of the Caribbean islands, and potentially into the Gulf of Mexico. However, none of the models that suggest this solution actually show that the wave will be a tropical cyclone at that point.

The National Hurricane Center is giving this wave an 80% chance of developing into at least Tropical Depression Five over the next 48 hours. Chances are we will see Emily out of this system. A Hurricane Hunter mission is scheduled for tomorrow at 2pm EDT, but I wouldn't be totally surprised to see them call this system this evening, given the threat to the Lesser Antilles.

Watching a northwest Caribbean disturbance

A broad area of disturbed weather is producing some heavy thunderstorms in the northwest Caribbean, southeast of the Yucatan Peninsula. Little to no low-level circulation exists with this feature, and none of the models are picking up on it. The Hurricane Center has "blobbed" this item (as I like to say) with a "near 0%" chance of developing over the next 48 hours. This disturbance could cause major flooding in the region given the amount of thunderstorm activity, and predictability for systems like this (potential Bay of Cempeche tropical cyclones) is very low. Models have a short lead time on development, and they spin up very fast once they enter the Bay of Campeche given the favorable topography of the land surrounding it. The difference between this system, though, and one like Arlene, is that there is very, very little low level circulation already present. Pre-Arlene was a bit more organized before it crossed the Yucatan, and so it's hard to imagine that this disturbance will be able to hold together, should it get that far.

If 91L develops, I'll be back tomorrow with a post.

Angela
Categories: Hurricane
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5951. Bobbyweather 7:25 AM GMT op 01 augustus 2011    
Hello, yesterday I thought 91L was a TD, but i was wrong ;
According to model guidance it is headed for the southeast coast
Although its 4 days away people there should be Aware
P.S. 120 pages? Incredible!
Member Since: 7 september 2006 Posts: 88 Comments: 2487
5954. HadesGodWyvern 7:33 AM GMT op 01 augustus 2011    
Japan Meteorological Agency
Tropical Cyclone Advisory #51
TYPHOON MUIFA (T1109)
15:00 PM JST August 1 2011
==========================================

SUBJECT: Category Four Typhoon In Sea East Of The Philippines

At 6:00 AM UTC, Typhoon Muifa (945 hPa) located at 19.8N 134.0E has 10 minute sustained winds of 85 knots with gusts of 120 knots. The cyclone is reported as moving north at 6 knots

Dvorak Intensity: T5.0

Storm Force Winds
=================
90 NM from the center

Gale Force Winds
=================
300 NM from the center in southeast quadrant
200 NM from the center in northwest quadrant

Forecast and Intensity
========================
24 HRS: 22.4N 133.2E - 85 knots (CAT 4/Very Strong Typhoon) Sea South Of Japan
48 HRS: 24.2N 131.0E - 85 knots (CAT 4/Very Strong Typhoon) Sea South Of Japan
72 HRS: 25.4N 128.3E - 85 knots (CAT 3/Strong Typhoon) Southern Okinawa

Additional Information
======================

Typhoon will move at the same speed for the next 72 hours

Typhoon will move north northwest for the next 24 hours then move northwest

Typhoon will keep present intensity for the next 24 hours

Final initial Dvorak number will be T5.5 after 24 hours
Member Since: 24 mei 2006 Posts: 43 Comments: 36933
5956. FrankZapper 7:34 AM GMT op 01 augustus 2011    
Bloggers please ignore Jason and give him time for a breather. Thanks.
Member Since: 26 mei 2011 Posts: 0 Comments: 1193
5957. NICycloneChaser 7:38 AM GMT op 01 augustus 2011    
Quoting NoVaForecaster:
anyway, 91L looks better-- IMO TD next advisory after HH mission data comes in


HH is scheduled for 12Z, which is at 8 am, so I doubt they'll have the data by the 8 am TWO, if HH finds a TD then the first advisory will likely be 11 am. Eastern time, that is.
Member Since: 10 augustus 2010 Posts: 2 Comments: 1958
5959. KBH 7:43 AM GMT op 01 augustus 2011    
has the present system been classified as a storm as yet? seems to have everything it needs including lots of TS activity
Member Since: 28 augustus 2008 Posts: 0 Comments: 278
5960. Bobbyweather 7:45 AM GMT op 01 augustus 2011    
Quoting KBH:
has the present system been classified as a storm as yet? seems to have everything it needs including lots of TS activity

No not yet, it is still an invest 91L but it is expected to become one soon
Member Since: 7 september 2006 Posts: 88 Comments: 2487
5961. MoltenIce 7:46 AM GMT op 01 augustus 2011    
Quoting SykKid:
91L have limited potential. very boring season to be talking about such weak storm at this time
Tell that to 2010...
Member Since: 11 augustus 2010 Posts: 0 Comments: 552
5962. bigwes6844 7:52 AM GMT op 01 augustus 2011    
Quoting NoVaForecaster:
anyway, 91L looks better-- IMO TD next advisory after HH mission data comes in
u thinking bout 4am or 10am. IMO 10am
Member Since: 25 juli 2010 Posts: 0 Comments: 1594
5964. KBH 7:58 AM GMT op 01 augustus 2011    
Quoting Bobbyweather:

No not yet, it is still an invest 91L but it is expected to become one soon

Perhaps a new system of classifying is needed, slow moving systems with TS activity, high rainfall, but low circulation often pose a greater threat to the islands
Member Since: 28 augustus 2008 Posts: 0 Comments: 278
5965. Vincent4989 7:58 AM GMT op 01 augustus 2011    
TD 5 in the next advisory?
Member Since: 13 november 2009 Posts: 2 Comments: 728
5966. NICycloneChaser 8:00 AM GMT op 01 augustus 2011    
The convection on the west has diminished, and it's slight circulation seems to have vanished. Paves the way for 91L to ramp up.
Member Since: 10 augustus 2010 Posts: 2 Comments: 1958
5967. winter123 8:14 AM GMT op 01 augustus 2011    
Don't feed the trolls... Fact is its still too far out to reliably predict what land areas this will affect besides the islands... On that note I'm going to bed. 91l will probably be a depression when i wake up (ive said that the past 3 nights though so, who knows.
Member Since: 29 juli 2006 Posts: 28 Comments: 1706
5968. Gearsts 8:14 AM GMT op 01 augustus 2011    
Guys just look at it thats a TD.
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5969. farupnorth 8:18 AM GMT op 01 augustus 2011    
Link

around 15n 56 w
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5970. oceanblues32 8:19 AM GMT op 01 augustus 2011    
anyone here on the night shift
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5971. HCW 8:19 AM GMT op 01 augustus 2011    
Quoting Gearsts:
Guys just look at it thats a TD.


Why do you think that is a TD ?
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5972. Vincent4989 8:24 AM GMT op 01 augustus 2011    
91L Floater - Water Vapor Loop shows some dry air, but i think no effect IMO
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5973. Gearsts 8:24 AM GMT op 01 augustus 2011    
Quoting HCW:


Why do you think that is a TD ?
Look at the bands around it and the central convection is a small td.
Member Since: 2 augustus 2010 Posts: 0 Comments: 2155
5974. Yamil1989 8:24 AM GMT op 01 augustus 2011    
Based on satellite imagery, At this time 91L is really ramping up, you can even notice the improvement on the outflow with banding developing in almost all quadrants,it would be interesting to see how it looks on the visible in the next couple of hours,If this trends continue, I'am expecting an special TWO before 8:00 am.
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5975. MoltenIce 8:26 AM GMT op 01 augustus 2011    
91L looks pretty symmetrical.
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5976. Bobbyweather 8:33 AM GMT op 01 augustus 2011    
Quoting Gearsts:
Guys just look at it thats a TD.

And the SAB agrees with you
01/0545 UTC 14.4N 55.6W T2.0/2.0 91L
Member Since: 7 september 2006 Posts: 88 Comments: 2487
5977. NICycloneChaser 8:35 AM GMT op 01 augustus 2011    
Quoting Bobbyweather:

And the SAB agrees with you
01/0545 UTC 14.4N 55.6W T2.0/2.0 91L
Quoting Bobbyweather:

And the SAB agrees with you
01/0545 UTC 14.4N 55.6W T2.0/2.0 91L


Having 30 knot winds (T2.0) isn't the only requirement for it to be a TD, needs a well defined circulation. However, the increase in T number does suggest continued organisation, so shouldn't be too far off.
Member Since: 10 augustus 2010 Posts: 2 Comments: 1958
5978. Vincent4989 8:37 AM GMT op 01 augustus 2011    
Quoting Yamil1989:
Based on satellite imagery, At this time 91L is really ramping up, you can even notice the improvement on the outflow with banding developing in almost all quadrants,it would be interesting to see how it looks on the visible in the next couple of hours,If this trends continue, I'am expecting an special TWO before 8:00 am.

I'm not going to agree with NHC anymore if they still keep it as an invest on the next advisory. 91L looks like a newborn TD.
Member Since: 13 november 2009 Posts: 2 Comments: 728
5979. Stormchaser2007 8:37 AM GMT op 01 augustus 2011    
Recon at 8am

Member Since: 9 juni 2007 Posts: 4 Comments: 15296
5980. wunderkidcayman 8:37 AM GMT op 01 augustus 2011    
91L/PRE-TD5/OR PRE-TS EMILY COC at 14.3N 56.7W
Member Since: 13 juni 2009 Posts: 2 Comments: 5997
5981. robert88 8:39 AM GMT op 01 augustus 2011    
Looks like it's take off time.
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5982. NICycloneChaser 8:40 AM GMT op 01 augustus 2011    
Quoting Vincent4989:

I'm not going to agree with NHC anymore if they still keep it as an invest on the next advisory. 91L looks like a newborn TD.


They'll not move until recon is in. Earliest classification is 8am, more likely 11am, assuming that is that recon do indeed find a good circulation, which is still questionable.
Member Since: 10 augustus 2010 Posts: 2 Comments: 1958
5983. Vincent4989 8:42 AM GMT op 01 augustus 2011    
Quoting Stormchaser2007:
Recon at 8am


That blob to the SE of 91L might be a tap for 91L!
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5985. robert88 8:44 AM GMT op 01 augustus 2011    
Nice consolidation with 91L this morning.
Member Since: 22 mei 2010 Posts: 0 Comments: 877
5986. MiamiHurricanes09 8:46 AM GMT op 01 augustus 2011    
Quoting Stormchaser2007:
Recon at 8am

Probably when the system gets classified.
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5987. wunderkidcayman 8:46 AM GMT op 01 augustus 2011    
yes Emily 2005 I remeber that one

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5988. Vincent4989 8:48 AM GMT op 01 augustus 2011    
Only question for 91L is: Fish or not fish?
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5989. MiamiHurricanes09 8:49 AM GMT op 01 augustus 2011    


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5990. wunderkidcayman 8:49 AM GMT op 01 augustus 2011    
not fish I say Caribbean/gulf storm
Member Since: 13 juni 2009 Posts: 2 Comments: 5997
5992. Bobbyweather 8:53 AM GMT op 01 augustus 2011    
Quoting NICycloneChaser:


Having 30 knot winds (T2.0) isn't the only requirement for it to be a TD, needs a well defined circulation. However, the increase in T number does suggest continued organisation, so shouldn't be too far off.

Sorry; I will keep the fact in mind
Member Since: 7 september 2006 Posts: 88 Comments: 2487
5993. NICycloneChaser 8:56 AM GMT op 01 augustus 2011    
Quoting Bobbyweather:

Sorry; I will keep the fact in mind


It's fine lol, just making note of it.
Member Since: 10 augustus 2010 Posts: 2 Comments: 1958
5994. Cotillion 8:57 AM GMT op 01 augustus 2011    
Shrinking may have been enough to get it together. Just before the East Caribbean, hopefully islanders are aware (you'd suspect they are, it hasn't just arrived over night).
Member Since: 23 augustus 2008 Posts: 7 Comments: 5300
5995. Bobbyweather 9:00 AM GMT op 01 augustus 2011    

Satellite image of 91L
It is on its way to becomimg a tropical cyclone
Member Since: 7 september 2006 Posts: 88 Comments: 2487
5996. PensacolaDoug 9:02 AM GMT op 01 augustus 2011    
About to hit 6000 Posts! Emily well on herway to being born this morn!
Member Since: 25 juli 2006 Posts: 0 Comments: 4831
5997. Cotillion 9:09 AM GMT op 01 augustus 2011    
Quoting wunderkidcayman:
not fish I say Caribbean/gulf storm


Nobody except the most ignorant is calling the storm a fish - it is on the Lesser Antilles' doorstep.

Member Since: 23 augustus 2008 Posts: 7 Comments: 5300
5998. traumaboyy 9:09 AM GMT op 01 augustus 2011    
Quoting Cotillion:
Shrinking may have been enough to get it together. Just before the East Caribbean, hopefully islanders are aware (you'd suspect they are, it hasn't just arrived over night).


Mornin Cotillion....you're right....I hope our island friends don't get a suprise out of this one!!
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5999. Stormchaser2007 9:10 AM GMT op 01 augustus 2011    
4:30



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6000. 7544 9:13 AM GMT op 01 augustus 2011    
looks like 91l is ready for td status at this hour after that all systems aa go go go islands could get watches latter on today , is it 4 days away from fla tia
Member Since: 6 mei 2007 Posts: 0 Comments: 6023

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About JeffMasters
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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