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 TxHurricanedude11:
sorry to some people that when I said the people are getting overselves....yes prepare early better safe than sorry.But like I said earlier I think tx/la will be safe.


It may be safe this time, I hope so if it's more than a tropical storm. But many got caught by surprise by Rita. I was teaching school and by the time school was out we were told not to evacuate as we would be caught out in our cars. There were no supplies to be bought. I had my stash for my family, but took in another single mom and her two kids, doubling the number of people for the supplies. No one who lives in hurricane country should wait until the storm is coming at them to begin getting ready.
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Quoting TxHurricanedude11:
sorry to some people that when I said the people are getting overselves....yes prepare early better safe than sorry.But like I said earlier I think tx/la will be safe.
Yeah a gutless call would be CCTX, but I have to go with that. That high dome over Texas stretching to the east is going to block it from significant northerly turns. I like the track that takes it over SATX (where I am) only because we need big time rain. That being said, the best for us would be a minimal TS with moderate forward motion. For awhile there will be some flash flooding with the ground baked as hard as it has been since May. But the aquifers will be replenished. Not sure it is a drought-buster unless it really bogs down and gets blocked from the west after landfall - but that doesn't appear likely at all.
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Quoting Tazmanian:
too me it seen like DON is weaking tonight



then am not sure any more lol
Member Since: May 21, 2006 Posts: 5091 Comments: 114776
Quoting cat5hurricane:
I'm still thinking that Mexican landfall.



sorry no mode runs are pointing at MX any more
Member Since: May 21, 2006 Posts: 5091 Comments: 114776
Quoting hurricaneben:
What will Don be at landfall?

a)TD
b)TS
c)CAT1
d)CAT2
e)CAT3-5


I still say a Category 1, the current organization notwithstanding.
Member Since: March 7, 2007 Posts: 558 Comments: 20010
Member Since: August 2, 2010 Posts: 21 Comments: 9737
Quoting PortABeachBum:


You would be due West 25 miles!


Technically, SW. I live in SE Corpus not far from the Oso. But close enough, neighbor!
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too me it seen like DON is weaking tonight
Member Since: May 21, 2006 Posts: 5091 Comments: 114776
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Member Since: July 3, 2005 Posts: 421 Comments: 127664
Quoting BrockBerlin:
Levi in your opinion what is the approximate probability that Don will reach Hurricane status?


Low.
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What will Don be at landfall?

a)TD
b)TS
c)CAT1
d)CAT2
e)CAT3-5
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Quoting centex:
But the weakness to north increases over time next day or two. Also weaker systems more likey to track west and stronger storms more N. I must be missing something.


The only reason that rule of thumb exists is because the most common situation is having the deeper steering currents point more poleward. That's all. Nothing about that guideline says that it is always true, and it far from is. You are correct about the ridge moving east and allowing a window for more northerly movement over time, but the low-level flow right now has more of a northerly component to it than the mid-level flow ever will during the next 3 days.
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GOM 120 Hour Surface Current Forecast Model, (HYCOM)
Member Since: July 3, 2005 Posts: 421 Comments: 127664
Quoting Levi32:


How? That has to do with thermal equilibrium between objects.


Nerd joke. :)

I remember when I heard that law thinking: "only one of us could ever come up with something so logical". Us being an engr.
Member Since: September 3, 2007 Posts: 0 Comments: 523
Quoting atmoaggie:
Besides the ocean heat content for the last ~8 hours, what else would cause the seeming collapse? I don't see DMIN having this much an effect.

Though before you say it laughed in the face of DMIN yesterday, remember that it was aided by convergence in the western Caribbean due the the slowing easterlies and land-forced convergence.

My guess is that it is a combination of DMIN and land interaction. During the day, it is more unstable over the land, so that is robbing Don of instability in his core. Notice how the band begins the flourish over land as the core loses intensity.
Member Since: August 2, 2006 Posts: 46 Comments: 11666
Quoting atmoaggie:
Besides the ocean heat content for the last ~8 hours, what else would cause the seeming collapse? I don't see DMIN having this much an effect.

Though before you say it laughed in the face of DMIN yesterday, remember that it was aided by convergence in the western Caribbean due the the slowing easterlies and land-forced convergence.


Hey Atmo....yes the two coming together caused the Convergence for a short time. I remember saying that may the Convergence will now pick up. Then the Graphic map has not showed much in Convergence since. I can't remember seeing a TS without Convergence of winds in the Lower Levels. Am i wrong.
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Quoting nopepper:


I was thinking the same thing about the vodka.


You guys have me laughing. Oh man.
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Atmo - did that graph srsly say the GFS basically uses zero dropsnodes?? (kind of hard to read even with my newly Lasik'ed 20/15 vision)
Member Since: September 3, 2007 Posts: 0 Comments: 523
Quoting nopepper:


Don't mention the plywood! Just south of you in CC and I haven't put mine up in so long it's buried behind a lot of junk in the garage. Watching this closely to see if I need to go start moving stuff ...


You would be due West 25 miles!
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Quoting atmoaggie:
Besides the ocean heat content for the last ~8 hours, what else would cause the seeming collapse? I don't see DMIN having this much an effect.

Though before you say it laughed in the face of DMIN yesterday, remember that it was aided by convergence in the western Caribbean due the the slowing easterlies and land-forced convergence.


Exactly...it had more support yesterday. I suspect the cold shelf water along and south of 22N may have played a small role in depressing the convection near the coast of the Yucatan as well, though that's only part of it. There is also some dry air nearby to the west. I think it's an indicator that overall conditions just aren't "great," in that they aren't allowing sustainable deep convection over the center at this time.
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Quoting baywader:
Hi Everybody, my son is a member of the Coast Guard A.N.T's team stationed in Galveston. They just called him back to base to make ready. I usually just lurk and learn on here and try to pass what info i can on to him. so thanks to everyone for all the info that you post.


Semper Paratus and we thank Him for his service to America
Member Since: July 3, 2005 Posts: 421 Comments: 127664
Quoting 1900hurricane:

I was looking at that earlier. It looks like it corresponds with the really warm patch of water from this satellite derived SST analysis:

Hmm, could be.

L8R, gotta go.
Member Since: August 16, 2007 Posts: 6 Comments: 12461
Quoting sunlinepr:
You having a lot of rain again ?
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Besides the ocean heat content for the last ~8 hours, what else would cause the seeming collapse? I don't see DMIN having this much an effect.

Though before you say it laughed in the face of DMIN yesterday, remember that it was aided by convergence in the western Caribbean due the the slowing easterlies and land-forced convergence.
Member Since: August 16, 2007 Posts: 6 Comments: 12461
Quoting CanesfanatUT:


Wouldn't that violate the zeroth law of thermodynamics?


How? That has to do with thermal equilibrium between objects.
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Quoting PortABeachBum:
And so, the Gulf season starts!!!
Tomorrow I'll have to start bringing the ply-wood up the stairs!


Don't mention the plywood! Just south of you in CC and I haven't put mine up in so long it's buried behind a lot of junk in the garage. Watching this closely to see if I need to go start moving stuff ...
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GOM 120 Hour Water Surface Temperature Forecast Model (HYCOM)
Member Since: July 3, 2005 Posts: 421 Comments: 127664
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Quoting centex:
But the weakness to north increases over time next day or two. Also weaker systems more likey to track west and stronger storms more N. I must be missing something.


That is what I thought....
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Quoting BahaHurican:
Evening everybody... does anyone remember if Doc M. went on vacation during 2006? LOL

Don is there, but still working on getting it all together, it seems. Hope it ends up solely as a much needed rainmaker for TX....


Evening, Baha!
Member Since: March 7, 2007 Posts: 558 Comments: 20010
Hi Everybody, my son is a member of the Coast Guard A.N.T's team stationed in Galveston. They just called him back to base to make ready. I usually just lurk and learn on here and try to pass what info i can on to him. so thanks to everyone for all the info that you post.
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Member Since: August 2, 2010 Posts: 21 Comments: 9737
Don could also be temporarily suffering from cooler SSTs:

Member Since: July 15, 2006 Posts: 17 Comments: 10160
935. DFWjc
Quoting atmoaggie:
Yeah, I think it does...or gets close to violation.


Are you forgetting to think 4th dimensionally ?
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Member Since: July 3, 2005 Posts: 421 Comments: 127664
Quoting atmoaggie:
This is just odd. not sure if it is real, or not.

Look at the 84F+ dewpoints in the gulf:


Exhibited by all sorts of analyses all over the web in multiple ways.

Wonder if it just one bad buoy ob...but the plot above is the NCEP analysis. After quality controls.

I was looking at that earlier. It looks like it corresponds with the really warm patch of water from this satellite derived SST analysis:

Member Since: August 2, 2006 Posts: 46 Comments: 11666
Quoting lovemamatus:
Vegas Odds Update:

At landfall:
TS 8-1
Cat1 3-1
Cat2 even
Cat3 5-1
Cat4 12-1
Cat5 30-1
Cat6 80-1
Dog7 125-1



haha, I got that one.
Member Since: July 6, 2010 Posts: 113 Comments: 31554
i believe recon found 1000mb? i think 40mph maybe 45 but i will pick up tomorrow morning and afternoon
Member Since: July 25, 2011 Posts: 0 Comments: 1102
Quoting Levi32:


Up and under is most likely correct if the system is strengthening as it goes, as the steering turns it more westerly as the system grows deeper.
But the weakness to north increases over time next day or two. Also weaker systems more likey to track west and stronger storms more N. I must be missing something.
Member Since: August 10, 2007 Posts: 0 Comments: 3232
Quoting angelafritz:


Absolutely! Many of us had given up on this system, although I do think I remember mentioning that I didn't quite understand why the models were disliking it so much. The environment was there. Like I say, this will make a nice little masters thesis for someone looking into tropical cyclone generation forecasts and/or data assimilation.
What data assimilation?
(Just kidding, really. I know data is being assimilated, we just don't have access to GFDL and HWRF statistics.)
Member Since: August 16, 2007 Posts: 6 Comments: 12461
928. DFWjc
Quoting lovemamatus:
Vegas Odds Update:

At landfall:
TS 8-1
Cat1 3-1
Cat2 even
Cat3 5-1
Cat4 12-1
Cat5 30-1
Cat6 80-1
Dog7 125-1



I got Cat 1 @ Aransas Pass
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Quoting CanesfanatUT:


Wouldn't that violate the zeroth law of thermodynamics?
Yeah, I think it does...or gets close to violation.
Member Since: August 16, 2007 Posts: 6 Comments: 12461

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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.