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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1675. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Cyclone Advisory #29
TROPICAL STORM NOCK-TEN (T1108)
21:00 PM JST July 28 2011
==========================================

SUBJECT: Category One Typhoon In South China Sea

At 12:00 PM UTC, Tropical Storm Nock-Ten (992 hPa) located at 18.2N 113.8E has 10 minute sustained winds of 40 knots with gusts of 60 knots. The cyclone is reported as moving west at 12 knots

Dvorak Intensity: T2.5

Gale Force Winds
================
240 NM from the center in north quadrant
160 NM from the center in south quadrant

Forecast and Intensity
========================
24 HRS: 19.8N 110.9E - 50 knots (CAT 2/Severe Tropical Storm)
48 HRS: 20.1N 107.7E - 55 knots (CAT 2/Severe Tropical Storm)
72 HRS: 20.5N 104.9E - 45 knots (CAT 1/Tropical Storm)
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1674. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Cyclone Advisory #21
TROPICAL STORM MUIFA (T1109)
21:00 PM JST July 28 2011
==========================================

SUBJECT: Category One Typhoon In Sea East Of The Philippines

At 12:00 PM UTC, Tropical Storm Muifa (996 hPa) located at 12.3N 134.0E has 10 minute sustained winds of 35 knots with gusts of 50 knots. The cyclone is reported as moving west at 11 knots

Dvorak Intensity: T2.5

Gale Force Winds
=================
200 NM from the center

Forecast and Intensity
========================
24 HRS: 14.3N 131.9E - 45 knots (CAT 1/Tropical Storm)
48 HRS: 16.7N 131.2E - 55 knots (CAT 2/Severe Tropical Storm)
72 HRS: 18.9N 130.7E - 65 knots (CAT 3/Strong Typhoon)
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1673. HadesGodWyvern (Mod)
Philippines Atmospheric Geophysical Astronomical Services and Administration
Tropical Cyclone Bulletin #1
TROPICAL STORM KABAYAN (MUIFA)
5:00 PM PhST July 28 2011
==============================

The Tropical Depression East of Visayas has entered the Philippine Area of Responsibility and intensified into a Tropical Storm and was named "KABAYAN"

At 4:00 PM PhST, Tropical Storm Kabayan (Muifa) located at 12.3°N 134.7°E or 1,000 km east southeast of Catarman, Northern Samar has 10 minute sustained winds of 35 knots with gusts of 50 knots. The cyclone is reported as moving northwest at 7 knots.

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

This weather disturbance is too far to directly affect any part of the country.

The public and the disaster coordinating councils concerned are advised to take appropriate actions and watch for the next bulletin to be issued at 11 PM today.
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Don running with a starboard bias.


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1671. Jax82
There are plenty of hurricane wishcasters in here this morning, but lets not forget the storm intensity forecast from NWS this morning. It does not appear at the moment that Don will reach Hurricane status.

FORECAST POSITIONS AND MAX WINDS

INIT 28/0900Z 23.0N 88.7W 35 KT 40 MPH
12H 28/1800Z 23.9N 90.3W 40 KT 45 MPH
24H 29/0600Z 25.1N 92.5W 45 KT 50 MPH
36H 29/1800Z 26.3N 94.7W 50 KT 60 MPH
48H 30/0600Z 27.3N 97.1W 50 KT 60 MPH
72H 31/0600Z 29.0N 101.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 01/0600Z...DISSIPATED

THE INTENSITY FORECAST IS TRICKY. WHILE THE LARGE-SCALE ENVIRONMENT
DOES NOT APPEAR TO HAVE MUCH SHEAR...THE LOW- AND MID-LEVEL CENTERS
ARE NOT WELL-ALIGNED INITIALLY...WHICH WAS APPARENT ON A 2316Z
SSMIS MICROWAVE IMAGE. THE GFS/ECMWF MODELS HAVE A REASONABLE
REPRESENTATION OF THIS INITIAL STRUCTURE AND KEEP THE CENTERS FROM
VERTICALLY STACKING...POSSIBLY WHY THESE MODELS DO NOT SHOW
MUCH INTENSIFICATION. WHILE THE STATISTICALLY MODELS STILL
FORECAST STEADY STRENGTHENING...THE HWRF/GFDL MODELS FORECAST A
SLOW DECLINE. ANOTHER FACTOR TO CONSIDER IS THAT THE SIZE OF DON
MAKES IT SUSCEPTIBLE TO RAPID CHANGES IN STRENGTH...BOTH UP AND
DOWN...THAT ARE NEARLY IMPOSSIBLE TO FORECAST. GIVEN THE REDUCED
ORGANIZATION...THE NHC INTENSITY FORECAST IS LOWERED SOMEWHAT FROM
THE PREVIOUS FORECAST...BUT IS STILL ON THE UPPER END OF THE
GUIDANCE ENVELOPE NEAR A COMPOSITE OF THE SHIPS/LGEM MODELS.



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1669. hydrus
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Visible always reveals the true location of center of circulation. Right now Don's main convection is displaced to South of the circulation.
Member Since: November 13, 2009 Posts: 2 Comments: 728
1666. snotly
Yep it looks to be sw of center. I wonder if the convection will become the new center.

Quoting P451:
Don's expanded floater imagery page. SSD

Don's rammb floater imagery page.


Using rainbow, and creating a rocking loop, you can see the lower level clouds. In the NW quadrant you can see them real well. Convection is not stacked directly overhead - displaced to the S and SE of the surface circulation. You can also note the direction of the surface circulation - appears NW as of now.



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Quoting NICycloneChaser:
HH approaching the centre again. Interesting to see what pressure they find this time.

Poll anyone?....

No poll...let's just wait and see. Sounds like a better plan to me.
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Is it me, or did post 1615 mess up the blog formatting? Avatars are missing for me and every post looks like it is a quote. (Using IE and not by choice)
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Quoting NICycloneChaser:
HH approaching the centre again. Interesting to see what pressure they find this time.

Poll anyone?....


999mb-1002mb pressure
Uncontaminated winds between 40-50 kts
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1660. Levi32
Good morning.

Blog update:

Tropical Tidbit for Thursday, July 28th, with Video
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HH approaching the centre again. Interesting to see what pressure they find this time.

Poll anyone?....
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1636. HurricaneDevo

They are determining the wind field. They will typically fly out from the center to the edge of 34 kt surface winds.
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1657. hydrus
Should be at least some rain for Texas..
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Quoting NotCircumventing:
Blog is oddly slow ... we've become TC snobs around here, anything less than hurricane doesn't warrant the time I guess.


I know you meant it as a joke, but I think that is sadly a true statement.
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1654. fmbill
Good morning all,

This may have already been discussed, but it looks like we are well on our way to having a well-above average season.

Doing a little research, over the past 30 years there have been only 6 other years that we have seen 4 or more tropical systems form prior to the month of August. 2008 (4), 2005 (7), 2003, (4), 1997 (5), 1995 (5), and 1989 (4).

If the wave in the east/central atlantic forms within the next couple of days, we will be in a season where only 3 other years saw 5 of more storms.
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IMAO, Don= Freeport, Strong Cat 1
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1651. hydrus
Better shot of Atlantic wave...
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1650. hydrus
Don has a tail...
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1649. snotly
My guess is it hits 75 miles SW of Galveston as a Cat 2 with winds of 100 mph. Early guess so lets hope I'm wrong on the weak side of things and not the strong side.
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1647. jpsb
Quoting nrtiwlnvragn:


Situation does change


Thanks, based on what I saw in 1595 I am going to assume a serious jog-move north plus a bit of strengthening so I'd say I'm 50-50 for TS winds. See ya all in a while got to go do stuff. thanks again.
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Quoting NavarreMark:
The group of clouds known as Don is lookin a little sickly. Kinda pale and wan.

Wishcasters are attempting CPR in an attempt to revive.


Not really, it is clearly them most organized we have seen this since we lost visible images last night.
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1645. hydrus
The big blob will move north across Panama..Possible development with Pacific blob...Possible heavy rain for Central America again..
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1644. HCW
They are out in front of it sampling the environment and that will give us more accurate model runs once it's ingested into the models
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1642. hydrus
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this is not a poll but next advisory 11pm how strong do u think don will be
Member Since: July 25, 2011 Posts: 0 Comments: 1102
Quoting Floodman:
Okay, so let me get this straight: Don is weakening/strengthening, dissipating/organizing with a 1-100% chance of making it to hurricane strength and making landfall from Lake Charles to Brownsville. Have I hit the high points?

That's what I love about the blog; there's something for everyone!

i see we have the same reading on it, only different ;)
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Will Corpus Christi get any rain from Don?
Member Since: August 30, 2008 Posts: 0 Comments: 287
Is it just me, or does it look like recon is flying around about 50-100 miles in front of the storm?

13:15:30Z 25.050N 91.033W 843.3 mb
(~ 24.90 inHg) 1,590 meters
(~ 5,217 feet) 1012.8 mb
(~ 29.91 inHg) - From 67° at 15 knots
(From the ENE at ~ 17.2 mph) 17.1°C
(~ 62.8°F) 6.6°C
(~ 43.9°F) 16 knots
(~ 18.4 mph) 27 knots
(~ 31.0 mph) 2 mm/hr
(~ 0.08 in/hr) 25.3 knots (~ 29.1 mph)
168.8%
13:16:00Z 25.033N 91.017W 844.2 mb
(~ 24.93 inHg) 1,582 meters
(~ 5,190 feet) 1012.9 mb
(~ 29.91 inHg) - From 68° at 12 knots
(From the ENE at ~ 13.8 mph) 17.0°C
(~ 62.6°F) 6.5°C
(~ 43.7°F) 15 knots
(~ 17.2 mph) 24 knots*
(~ 27.6 mph*) 1 mm/hr*
(~ 0.04 in/hr*) 19.2 knots* (~ 22.1 mph*)
160.0%*
13:16:30Z 25.017N 90.983W 842.8 mb
(~ 24.89 inHg) 1,594 meters
(~ 5,230 feet) 1012.9 mb
(~ 29.91 inHg) - From 70° at 14 knots
(From the ENE at ~ 16.1 mph) 16.7°C
(~ 62.1°F) 6.3°C
(~ 43.3°F) 14 knots
(~ 16.1 mph) 24 knots
(~ 27.6 mph) 0 mm/hr
(~ 0 in/hr) 24.0 knots (~ 27.6 mph)
171.4%
13:17:00Z 25.000N 90.967W 843.2 mb
(~ 24.90 inHg) 1,590 meters
(~ 5,217 feet) 1012.9 mb
(~ 29.91 inHg) - From 78° at 15 knots
(From the ENE at ~ 17.2 mph) 16.8°C
(~ 62.2°F) 6.2°C
(~ 43.2°F) 16 knots
(~ 18.4 mph) 24 knots
(~ 27.6 mph) 1 mm/hr
(~ 0.04 in/hr) 22.5 knots (~ 25.9 mph)
150.0%
13:17:30Z 24.983N 90.950W 842.8 mb
(~ 24.89 inHg) 1,591 meters
(~ 5,220 feet) 1012.6 mb
(~ 29.90 inHg) - From 79° at 16 knots
(From between the ENE and E at ~ 18.4 mph) 17.1°C
(~ 62.8°F) 6.1°C
(~ 43.0°F) 16 knots
(~ 18.4 mph) 24 knots
(~ 27.6 mph) 0 mm/hr
(~ 0 in/hr) 24.0 knots (~ 27.6 mph)
150.0%
Time Coordinates Aircraft
Static Air Pressure Aircraft
Geopotential Height Extrapolated
Surface Pressure D-value Flight Level Wind (30 sec. Avg.) Air Temp. Dew Point Peak (10 sec. Avg.)
Flight Level Wind SFMR
Peak (10s Avg.) Sfc. Wind SFMR
Rain Rate Estimated Surface Wind (30 sec. Avg.)
Using Estimated Reduction Factor Peak Wind at Flight Level to
Est. Surface Reduction Factor
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1635. ackee
which wave does the model devlop the one at 35 west now ? I think the one in the EASTERN carrb bare watching once its reach the westrn carrb
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1634. hydrus
Caribbean wave and Atlantic wave..
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okay, got to get working...back soon!
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Quoting hydrus:
Hello Floodman......storms gonna getcha........:)


I certainly hope so
Member Since: August 2, 2006 Posts: 10 Comments: 9922
1629. hydrus
Some convection flaring up...
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Quoting NEwxguy:
Don't forget Flood, this will not help break the drought/this will be a drought buster.


LOL...you are correct sir!
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Quoting jpsb:
Well if I am going to anything to prepare for Don when the time to get started is now. What are the odds of Don sending TS strength winds to the Galveston Bay area? If greater the 1 in 3 then I will take action to protect my properties.


Situation does change


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1626. hydrus
Quoting Floodman:
Okay, so let me get this straight: Don is weakening/strengthening, dissipating/organizing with a 1-100% chance of making it to hurricane strength and making landfall from Lake Charles to Brownsville. Have I hit the high points?

That's what I love about the blog; there's something for everyone!

Hello Floodman......storms gonna getcha........:)
Member Since: Posts: Comments:

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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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