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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Quoting texwarhawk:


Lol thanks, I was thinking the high was over the southeastern US and was hearing about it slowly pull off to the northeast, but enough to pull it in to LA/MS/AL. This guy's comment was partially the reason I got off. I'm okay with people asking questions and giving their honest opinion and all but when your opinion is 300-500 miles off of the edge of NHC's cone of uncertainty, chances are you aren't giving the best opinion, and should keep it to yourself lol. Maybe I'm just cynical about all this, but spending just a year in college studying this has made me kinda look down on some people who don't even look at the models. Computer models are forecasting tools (keyword: TOOLS) that help forecasters predict the weather. Someone coming on here and saying "Oh I don't trust computers (or models), it's going to do this..." are just ignorant in my eyes and are giving out misinformation on a blog that many come to for information.


Or anyone saying it'll be a strong hurricane obviously is just hoping it will become one, the conditions and time are just not there for this to become to organized, it looks terrible right now and outlandish statements unfortunately have become the norm of the blog :(
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Quoting VAbeachhurricanes:


>


Lol thanks, I was thinking the high was over the southeastern US and was hearing about it slowly pull off to the northeast, but enough to pull it in to LA/MS/AL. This guy's comment was partially the reason I got off. I'm okay with people asking questions and giving their honest opinion and all but when your opinion is 300-500 miles off of the edge of NHC's cone of uncertainty, chances are you aren't giving the best opinion, and should keep it to yourself lol. Maybe I'm just cynical about all this, but spending just a year in college studying this has made me kinda look down on some people who don't even look at the models. Computer models are forecasting tools (keyword: TOOLS) that help forecasters predict the weather. Someone coming on here and saying "Oh I don't trust computers (or models), it's going to do this..." are just ignorant in my eyes and are giving out misinformation on a blog that many come to for information.
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Quoting texwarhawk:
So what do y'all think about Don? I saw earlier some guy was predicting Louisiana/Mississippi/Alabama, after which I decided to get off. I have absolutely no idea where that came from. If you do please speak up because I am missing something huge lol.


No it wont haha, the high is basically dominating where this thing will go. The high is going to keep this WNW to NW the whole time. As this map shows:


Plus the Storm is already south of most of the model points as seen here:

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Quoting KoritheMan:


I enjoy them, honestly. But that's probably not enough motivation for you.
well I do too, but when I only get a couple of comments I kinda feel like I'm talking to myself lol

Also, when I write up my analysis and forecast I feel like I'm kinda just writing up what's already been said. I don't feel like waking up early before everyone posts nor do I feel like posting during the peak activity. As a result, when I finally post my blog in the late afternoon/nighttime shift I feel like I'm kinda just summarizing the main points already discussed on the blog. I'll bring up a few new points, but the majority of the points have already been written in the main blog.

Knowing my past, although I sound like I don't want to continue, I'll probably still continue with my blogs. Maybe just focus on specific things like just the wave at 30W and write a few paragraphs on that, rather than on what the blog has already been starring at all day long for over a thousand posts now...by that time all that is there to be said has been said lol

Quoting VAbeachhurricanes:


Just keep at it dude, I'm sure Levi didn't have people running over to his blog right away, and now look. People beg him for his blogs and videos. All about just keeping at it and working on up.
thanks, I'll probably continue doing blogs, just losing some enthusiasm at the moment.
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So what do y'all think about Don? I saw earlier some guy was predicting Louisiana/Mississippi/Alabama, after which I decided to get off. I have absolutely no idea where that came from. If you do please speak up because I am missing something huge lol.
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Very nice pop of convection at 6:15 UTC
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Quoting TomTaylor:
Anybody want to read a blog while the main blog is slow?

put quite a bit of time into it. Don't know if I really want to keep up doing blogs unless I get some real support going. I know it sounds a little pathetic, but I'm starting to wonder if its worth the effort, especially when there are others who are already typing up basically the same thing.


Just keep at it dude, I'm sure Levi didn't have people running over to his blog right away, and now look. People beg him for his blogs and videos. All about just keeping at it and working on up.
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Quoting TomTaylor:
Anybody want to read a blog while the main blog is slow?

put quite a bit of time into it. Don't know if I really want to keep up doing blogs unless I get some real support going. I know it sounds a little pathetic, but I'm starting to wonder if its worth the effort, especially when there are others who are already typing up basically the same thing.


I enjoy them, honestly. But that's probably not enough motivation for you.
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Quoting texwarhawk:
When does the NHC put out Forecast Discussions? TIA


Generally every six hours, except for in the instances where the storm is less than 250 miles from land (IIRC), in which case an intermediate advisory will be issued every three hours. The six hour updates comprise the full advisories, meaning the track forecast does not get updated during the intermediate advisories.
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Quoting TomTaylor:
Sure is slow tonight in the wake of a very busy day. So busy in fact, that i decided I'd stay off the blogs and post at night


I honestly hate it when it's that busy.
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When does the NHC put out Forecast Discussions? TIA
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Quoting TxHurricanedude11:

dont really think so look at the outflow its producing..convection is building it'll get there.


All that outflow is really just the tops of now dead thunderstorms, The new convection over the center is tiny, with a curved band of storms about 100 miles to the east that I'm not 100% sure is even connected to Don.
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Anybody want to read a blog while the main blog is slow?

put quite a bit of time into it. Don't know if I really want to keep up doing blogs unless I get some real support going, honestly. I know it sounds a little pathetic, but I'm starting to wonder if its worth the effort, especially when there are others who are already typing up basically the same thing.
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Quoting TomTaylor:
Sure is slow tonight in the wake of a very busy day. So busy in fact, that i decided I'd stay off the blogs and post at night


The amount of incompetency on the blog has just really gotten out of hand...
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Sure is slow tonight in the wake of a very busy day. So busy in fact, that i decided I'd stay off the blogs and post at night
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Quoting OracleDeAtlantis:
The reason this thing is slowing down, is because it is increasing in size, as I've been expecting for the past 24 hours. It's finally begun to turn in on itself.

It's going to double in size in the next 24 hours .... watch.


What makes you think its increasing in size? Looks a lot smaller now than ever.
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The reason this thing is slowing down, is because it is increasing in size, as I've been expecting for the past 24 hours. It's finally begun to turn in on itself.

It's going to double in size in the next 24 hours .... watch.
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Quoting FLWeatherFreak91:
Why not? The storm lost its favorable upper level environment... it's not looking good atm.


No it hasn't. Divergence and convergence should return with the advent of dmax. Notice the direction of the upper-level winds to the north of Don:



That southeasterly to easterly flow should allow for continued development of the equatorial outflow channel, which will allow the system to breathe. The strong northeasterly shear that was plaguing it earlier appears to have diminished somewhat, as the center moved quick enough earlier to effectively outrun the worst of it.

Don isn't going to rapidly intensify, but there is no meteorological reason to expect dissipation.
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Quoting FLWeatherFreak91:
Why not? The storm lost its favorable upper level environment... it's not looking good atm.


No i mean just in the ADT algorithm, a storm could be rapidly weakening, however that doesnt automatically mean its on the way to dissipation. And yes, Don looks horrible with no overshooting tops, and all pop ups of convection rapidly begin to warm.
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As I watch the water vapor imagery over the entire GOM carefully, I can see the shear relaxing and being diverted. The entire environment is also becoming dramatically more moist, all around Don. Every side is experiencing increasing moisture.

I think the thing just got choked off today. pure and simple. When you see those outflow boundaries, you know it's doomed within a few hours, and will only come back if it can get some different air around the COC.

I haven't seen any more outflow boundaries since sunset.
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Quoting VAbeachhurricanes:


Me neither, I think "Rapid Dissipation" is the wrong wording.
Why not? The storm lost its favorable upper level environment... it's not looking good atm.
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This system would be much more beneficial to the drought-stricken areas as an open wave rather than tiny Don
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Quoting KoritheMan:


True.

Mind you, I don't think Don is strengthening at the moment. On the other hand, I doubt he's just going to dissipate.


Me neither, I think "Rapid Dissipation" is the wrong wording.
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Quoting VAbeachhurricanes:


The NHC uses it among with TAFB estimates to tell the strength of a cyclone when there is no plane in the system. I find it is pretty reliable to tell whether or not the system is strengthening or not. However, you must look at trends, since it updates every 30 minutes a hurricane could get a flag every once in a while, usually during EWRC. However itll usually correct itself by the next update.


True.

Mind you, I don't think Don is strengthening at the moment. On the other hand, I doubt he's just going to dissipate.
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Quoting KoritheMan:


That product is not trustworthy in my experience. I've seen intensifying hurricanes get the same treatment.


The NHC uses it among with TAFB estimates to tell the strength of a cyclone when there is no plane in the system. I find it is pretty reliable to tell whether or not the system is strengthening or not. However, you must look at trends, since it updates every 30 minutes a hurricane could get a flag every once in a while, usually during EWRC. However itll usually correct itself by the next update.
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Quoting VAbeachhurricanes:


The NHC does...


That product is not trustworthy in my experience. I've seen intensifying hurricanes get the same treatment.
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Quoting tennisgirl08:


Nice visual. Don is getting crushed by forces from the east. Not sure he'll survive, honestly. That loop is very telling. But, regardless, some nice rains will be headed to TX.
I think you're 100% spot on. There is not much divergence aloft, either. That's liable to improve with DMAX, however.

I'm very surprised there's not more divergence, judging from these photos. It appears to be sitting in between two rivers of air .... almost. Not quite, but it's getting close to where the split is.

The shear is stronger than is predicted tonight, it would appear.
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Quoting tennisgirl08:


Ahhh...here's the real player!


Correct. I'd rather worry about Don in the meantime, though, since the threat is, you know, glaringly obvious.
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Quoting TxHurricanedude11:
who cares about that


The NHC does...
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UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 28 JUL 2011 Time : 044500 UTC
Lat : 22:57:23 N Lon : 88:22:41 W


CI# /Pressure/ Vmax
3.1 / 998.0mb/ 47.0kt


Final T# Adj T# Raw T#
2.6 2.6 2.6

Center Temp : -16.2C Cloud Region Temp : -24.0C

Scene Type : CURVED BAND with 0.38 ARC in LT GRAY

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : ON
Rapid Dissipation Flag : FLAG

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 40km
- Environmental MSLP : 1013mb

Satellite Viewing Angle : 30.8 degrees

Still on.
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1337. JRRP
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Quoting Levi32:
0z CMC shows the potential for mischief with a well-defined area of low pressure in the eastern Atlantic, which will be approaching the eastern Caribbean in several days. This will be monitored closely while Don remains the primary focus.

Goodnight all.



Ahhh...here's the real player!
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Date (UTC) CI MSLP /BiasAdj/(kts) Tno Raw Raw Limit Flag Wkng Region
2011JUL28 051500 2.6 1004.0/ +0.0 / 37.0 2.5 2.5 2.5 NO LIMIT ON OFF -16.06 -26.33
Cloud Type (km) Lat Lon Mthd
CRVBND N/A 22.98 88.44 FCST
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1334. KEEPEROFTHEGATE (Mod)
good night levi from the arctic
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1333. Patrap
Member Since: July 3, 2005 Posts: 428 Comments: 129805
Quoting mynameispaul:
Don's environment.

GOES Atmospheric Animations - Earth Scan Laboratory, LSU


Nice visual. Don is getting crushed by forces from the east. Not sure he'll survive, honestly. That loop is very telling. But, regardless, some nice rains will be headed to TX.
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1331. Levi32
0z CMC shows the potential for mischief with a well-defined area of low pressure in the eastern Atlantic, which will be approaching the eastern Caribbean in several days. This will be monitored closely while Don remains the primary focus.

Goodnight all.

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Wonder when P010L will be invested or get the crayons put over it. 1008mb low embedded in the wave axis. Can really see it spinning away on TPW, but not much in the way of convection.






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Wrote a Lengthy Blog on Don and the Tropical Waves

Please check it out
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1328. KEEPEROFTHEGATE (Mod)
T.C.F.W.
04L/TS/D/CX
MARK
23.11N/88.29W


see all the banding storms to se e ne with central convective cell firing its all coming together now not much longer and we gonna have a storm on our hands here
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Quoting MiamiHurricanes09:
I wouldn't be surprised if Don is downgraded to a tropical depression until it becomes better organized.

hi miami! care to take a crack at this-
no one on here thinks that the current movement of all the storms and clouds are a sign of shift in track and maybe even that don does not have enough power to stay on course? i mean look at wv or even unenhanced. i can't see how don could go against the movement of everything else in the gulf that are around the same area as don or off to the west of don. could someone with more knowledge explain? tia

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If there is any one thing I can say about Don, it is this: As much as we need the rain here in Texas, I just don't have much hope for it being the real drought buster that we all wish for.

Texas Drought > Don

Regardless, we will gladly accept any help we can get!
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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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