Tropical Storm Don forms in the Gulf of Mexico

By: Dr. Jeff Masters , 9:29 PM GMT on July 27, 2011

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Tropical Storm Don, the fourth tropical cyclone of the 2011 season, has formed in the Gulf of Mexico just north of the Yucatan Peninsula. Hurricane Hunters began investigating the system earlier this afternoon and quickly found a closed surface circulation. As the mission continued to gather data from what was thought to be a tropical depression at the time, winds of around 39 mph were found, as well as a 1001 mb central pressure, bringing the system up to tropical storm strength.


Figure 1. Satellite loop of Tropical Storm Don. This loop will stay current.

The official forecast for Don agrees with what most of the models have been suggesting over the past 24 hours. Don will make its way toward the northwest over the next 48 hours before making landfall somewhere between Brownsville and Galveston. The statistical models tend to suggest a more southerly track toward Brownsville, and the dynamical models are forecasting anything from Corpus Christi to Galveston. They all tend to agree landfall will occur late on the 29th (Friday night). Whether or not Don will reach hurricane status is still in question. The Hurricane Center's initial forecast is that Don will remain a tropical storm until landfall. Today some models were intensifying Don to a strong tropical storm, but none crossed the hurricane threshold. Now that we have data from aircraft reconnaissance, the models will be able to get a better handle on potential intensity. The runs that occur later tonight and early tomorrow will have much less uncertainty than those from today.


Figure 2. Model forecast tracks for Tropical Storm Don as of Wednesday afternoon.

I believe Jeff will be back tomorrow for an update.

Angela

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1476. jpsb
Quoting dan77539:
Our local (Houston) NWS office shows us with a 50% chance of rain on Friday. I think the Texas drought map was on the blog a couple days ago--it showed that central areas of the state need the rain more than the Corpus-Brownsville area, so the southward shift is not very welcome news on that front.
Yeah, I am thinking we in South East Texas are not going to get much rain out of Don. Very bad news for us, hope they need it in South Texas would be a real shame to waste this rain on folks that don't need it.
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1475. Gearsts
Quoting MahFL:


TS can have CDO's, you don't need an eye for a CDO.....
Trust me Don doesnt have a CDO, what you see is just convection.For CDO to form it needs very low shear and i think shear is a little highter that what the map are saying by looking at Don.
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Don needs to seperate form that convection thing over the NW carribean its preventing outflow to the east but it wont have that much to the east due to the big ridge although its trying to become more circular and strong convection is builiding by the center
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Dubuque, Iowa, has received around 3.0" of rain since midnight, atop the nearly 7.5" it received yesterday. There's a whole lot of flooding going on there right now. The radar-based storm total precipitation estimate is very telling.
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Time: 11:47:30Z
Coordinates: 23.8333N 89.9W
Acft. Static Air Press: 843.2 mb (~ 24.90 inHg)
Acft. Geopotential Hgt: 1,548 meters (~ 5,079 feet)
Extrap. Sfc. Press: 1007.9 mb (~ 29.76 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 38° at 11 knots (From the NE at ~ 12.6 mph)
Air Temp: 17.4°C (~ 63.3°F)
Dew Pt: 4.1°C (~ 39.4°F)
Peak (10s) Flt. Lvl. Wind: 12 knots (~ 13.8 mph)
SFMR Peak (10s) Sfc. Wind: 17 knots (~ 19.5 mph)
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1471. MahFL
Quoting Gearsts:
CDO central dense overcast? Don doesnt have any CDO yet is just a TS or a TD.


TS can have CDO's, you don't need an eye for a CDO.....
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1470. Gearsts
Quoting MahFL:
"Tropical cyclones that have nearly circular CDO's are indicative of favorable, low vertical shear environments"

Don is becoming circular.
No Don is actually getting shear and push by the high, thats why the convection looks like that.
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1468. HCW
Quoting HimacaneBrees:
Don kind of went down over night. Dry air?


It felt some cold water but should make a come back later today
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don looks ragged this am, but i suspect the HHs will find a 60mph storm by time the mission is completed.
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1465. Gearsts
Quoting MahFL:


You are watching the sat pics right ?
CDO central dense overcast? Don doesnt have any CDO yet is just a TS or a TD.
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hurricane hunters are in don. anyone have information from them?
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1463. MahFL
"Tropical cyclones that have nearly circular CDO's are indicative of favorable, low vertical shear environments"

Don is becoming circular.
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Quoting MahFL:


You are watching the sat pics right ?

I think you mean that big blowup of convection near the center.
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1461. MahFL
Quoting Gearsts:
What CDO?lol


You are watching the sat pics right ?
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1460. WxLogic
Quoting floridaboy14:

Do you think the HH will find don stronger? and do you think don is getting its act together now?


Possibly... we shall see.
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1458. Gearsts
Quoting MahFL:
The cdo is getting bigger and more circular by the frame :)
What CDO?lol
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Quoting Neapolitan:

I've been scouring the NHC's official glossary, and I can't find the term "fish storm"; I'm beginning to think it's not part of their official nomenclature. No, looking at that ECWMF run, I'd definitely say that modeled cyclone is "off the SE US coast". ;-)


The term "Fish Storm" is used on here fairly often by people who think that any system that does not endanger the CONUS is irrelevant. Lose of life or vessels to them doesn't really count, if its not from the CONUS.

P.S. You have no idea how peeved I get when I see that term used.
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Don doesnt look like he is going to become a hurricane. Though conditions are becoming more favorable, I dont think he has the time.
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1455. MahFL
The cdo is getting bigger and more circular by the frame :)
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Quoting WxLogic:


Typically not... unless there's some major change, so a status change from Invest to TD, TD to TS, etc...

Do you think the HH will find don stronger? and do you think don is getting its act together now?
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Complete Update

TS BUSTED FORECAST ALIBI





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1452. WxLogic
Quoting floridaboy14:
Will we get an earlier advisory than the 11pm one if the HH find stronger winds in don?


Typically not... unless there's some major change, so a status change from Invest to TD, TD to TS, etc...
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Will we get an earlier advisory than the 11pm one if the HH find stronger winds in don?
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Quoting Chicklit:
There is flooding in Seoul.
Link


Big time. The heaviest rains the area has seen in at least 100 years--that is, since official recordkeeping began.
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1449. barbamz
Quoting Chicklit:
There is flooding in Seoul.
Link



Good morning everyone. Chicklit, you've been a bit faster ...
Up to German media unfortunately already 67 are confirmed to be dead in Seoul. You've recently been there, do you?

RAW-Video BBC
http://www.bbc.co.uk/news/world-asia-pacific-1432 7024

Century-Worst Deluge Kills Dozens in South Korea
South Korean officials say dozens of people have died as a result of mudslides triggered by the heaviest rains to hit the nation's capital in a century.

Soldiers and police were called out Thursday to assist with rescue and clean-up efforts as the rain continued into a third day.

Thirteen people were killed and 24 were injured Wednesday when a landslide crashed into a mountain resort in Chuncheon, located about 100 kilometers east of Seoul. The victims include 10 college students who were staying at the resort while doing volunteer work at a local elementary school.

At least 15 others died later Wednesday when a landslide buried dozens of houses in southern Seoul. Authorities say 10 more people died in landslides and a floods in separate incidents near the capital.

Emergency officials say more than 400 millimeters of rain have fallen on Seoul and surrounding areas since Tuesday, making it the worst storm to hit the area since 1907.

The storm, which has closed roads and disrupted subway service, is expected to dump more heavy rain on Seoul through Friday.
Source: http://blogs.voanews.com/breaking-news/2011/07/28 /century-worst-deluge-kills-dozens-in-south-korea/
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1448. ncstorm
Rain for Texas-Days 1-2 QPF

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Quoting NOLALawyer:


I would call that a fish storm, not "off the SE US coast." That is way out to sea.

I've been scouring the NHC's official glossary, and I can't find the term "fish storm"; I'm beginning to think it's not part of their official nomenclature. No, looking at that ECWMF run, I'd definitely say that modeled cyclone is "off the SE US coast". ;-)
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1446. WxLogic
Current steering:



Favoring a WNW for quite a while.
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Quoting floridaboy14:
8am adivsory
40mph
pressure 1000mb center relocated farther north

...DON MOVING WEST-NORTHWESTWARD ACROSS THE SOUTHERN GULF OF MEXICO...HURRICANE HUNTER PLANE APPROACHING THE SYSTEM...
7:00 AM CDT Thu Jul 28
Location: 24.0°N 89.8°W
Max sustained: 40 mph
Moving: WNW at 10 mph
Min pressure: 1000 mb
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Don kind of went down over night. Dry air?
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1443. ncstorm
Quoting floridaboy14:

looks like a recurvuture. wont help the drought in the south east lets hope there is no trough


the ECWMF actually has two storms off the SE Coast..one is pounding Fl/GA and then the the other storm recurving possibly due to that storm off of Fl/GA
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Quoting ncstorm:
I'm glad Texas is getting some much needed rain..

Both the CMC and the ECWMF have the tropical wave off that came off africa a couple of days ago off the SE US coast by next sunday..long range but its interesting to see the model support..

CMC


ECWMF
Link


I would call that a fish storm, not "off the SE US coast." That is way out to sea.
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1441. jdb777
HH en route:

roduct: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 28th day of the month at 11:27Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 303)
Storm Number: 04
Storm Name: Don (flight in the North Atlantic basin)
Mission Number: 2
Observation Number: 02

Mandatory Data...

Observation Time: Thursday, 11:23Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 24.7N 90.9W
Location: 368 miles (593 km) to the S (188°) from New Orleans, LA, USA.
Turbulence: None
Conditions Along Flight Route: In the clear
Pressure Altitude: 1,520 meters
Flight Level Wind: From 60° at 15 knots (From the ENE at ~ 17.2 mph)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: 18°C
Flight Level Dew Point: 6°C
Weather (within 30 nautical miles): Clear
850 mb Surface Altitude: 1,497 geopotential meters

Remarks Section...

Surface Wind Speed (likely by SFMR): 19 knots (~ 21.9mph)
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8am adivsory
40mph
pressure 1000mb center relocated farther north
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Quoting WxLogic:


Had some indigestion issues.

Oh. Poor thing.
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Good morning, everyone. Just read through the last two pages. So Don is now heading towards the Valley? (Brownsville to Raymondville area) About the same territory as last years TS's then.
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There is flooding in Seoul.
Link

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Quoting ncstorm:
I'm glad Texas is getting some much needed rain..

Both the CMC and the ECWMF have the tropical wave off that came off africa a couple of days ago off the SE US coast by next sunday..long range but its interesting to see the model support..

CMC


ECWMF
Link

looks like a recurvuture. wont help the drought in the south east lets hope there is no trough
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Looks like Don got pinched in the middle by the Yucatan. He needs to gain more of a northward component. I am sure the Texans will be very upset if Don finds himself visiting South of the Border.
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1434. WxLogic
Quoting WeatherNerdPR:
Good Morning. What happened to Don?


Had some indigestion issues.
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1433. ncstorm
I'm glad Texas is getting some much needed rain..

Both the CMC and the ECWMF have the tropical wave off that came off africa a couple of days ago off the SE US coast by next sunday..long range but its interesting to see the model support..

CMC


ECWMF
Link
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Good Morning. What happened to Don?
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good AM i see are low out there has go in stronger overe night it was 1010-1012mb now its 1008mb this one needs to be watch for sure do we have the most up todate photo of the low with t-storms?

Member Since: May 21, 2006 Posts: 5091 Comments: 114956
1429. WxLogic
Quoting MahFL:


No I think they are actually going to Don, not just where he is lol......


LOL that's funny how translations sometimes come out to be.
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Our local (Houston) NWS office shows us with a 50% chance of rain on Friday. I think the Texas drought map was on the blog a couple days ago--it showed that central areas of the state need the rain more than the Corpus-Brownsville area, so the southward shift is not very welcome news on that front.
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1427. HCW
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1426. WxLogic
Quoting floridaboy14:

starting to look better organized. doesnt have to look pretty to be strong. 8am advisory should be unchanged or 45mph


Agree with the look part to some degree. In regards the advisory well... I wouldn't say 45MPH yet but 40MPH as it currently stands:

4:00 AM CDT Thu Jul 28
Location: 23.0°N 88.7°W
Max sustained: 40 mph
Moving: WNW at 10 mph
Min pressure: 1000 mb

If indeed it increased some... then the HH will validate that for us shortly and validate DVORAK numbers also.
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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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