Tropical Storm Debby has formed in the Gulf of Mexico

By: angelafritz , 9:18 PM GMT on June 23, 2012

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Tropical Storm Debby has been named by the National Hurricane Center this afternoon after hurricane hunters investigated Invest 96L and found a solid closed circulation, with maximum winds of 50mph and gusts up to 65mph. All interests along the Gulf of Mexico coast should pay attention to the progress of Debby. Debby is drifting north at 5mph. The storm has brought heavy rains to Western Cuba, South Florida, and Mexico's Yucatan Peninsula over the past two days, but the disturbance's heaviest rains are located well offshore over the Eastern Gulf of Mexico, where heavy thunderstorms are generating winds near tropical storm-force. A buoy 243 miles west of Naples, FL measured sustained winds of 31 mph, gusting to 38 mph, with 10-foot waves, at 8 am EDT Saturday morning. Our Wundermap for the surrounding ocean areas shows a large region of the northern and eastern Gulf of Mexico is experiencing winds of 20 - 30 mph.

Visible satellite loops show an unorganized tropical cyclone with an obvious surface circulation, though the thunderstorm activity is well displaced to the east. The heavy thunderstorm activity is slowly expanding and growing more intense. Upper-level winds out of the west continue to create moderate 10 - 20 knots of wind shear over the region, though that is expected to increase over the next few days. Water vapor satellite loops show a region of dry air over the central Gulf of Mexico, which will continue to interfere with Debby's development and make it hard for the west side of the circulation to maintain heavy thunderstorms. Ocean temperatures are about 28.5°C (83°F) in the Central Gulf of Mexico, which is about 1°F above average.


Figure 1. Saturday afternoon satellite image of Tropical Storm Debby in the Gulf of Mexico.


Figure 2. Saturday afternoon forecast track for Tropical Storm Debby.

Forecast for Debby
The National Hurricane Center is forecasting Debby to remain a tropical cyclone over the next 5 days as it drifts north and then west toward Texas. The Hurricane Center is forecasting a very slow progression of the storm, with a potential landfall not occurring until Friday. However, most of the models that predict the turn to the west suggest landfall will happen before or around Wednesday. The models are still generally split on the forecast for Debby; by Monday, the majority of the reliable models, including the ECMWF, NOGAPS, HWRF, and UKMET, agree that a ridge of high pressure will build in over the Southern U.S., forcing Debby west across the Gulf of Mexico and into South Texas by Wednesday. However, the GFS model, which has been our 2nd most reliable track model over the past two years (behind the ECMWF), has consistently been predicting that a trough of low pressure pushing off of the U.S. East Coast will be capable of grabbing the disturbance and accelerating it to the northeast across Florida north of Tampa Bay on Monday. The GFDL model splits the difference between these extremes and takes Debby north to a landfall near the Alabama/Florida border on Tuesday. The predicted track west to Texas is still the most likely outcome, though it remains a low-confidence forecast. In terms of intensity, none of the models is predicting Debby will become a hurricane, nor is the Hurricane Center. Though sea surface temperature is warm (and around 1°F above average), the actual heat content of the Gulf is relatively low. Wind shear is predicted to remain moderately strong through Sunday, but will increase to 30+ knots by Tuesday.

Debby's place in history (by Jeff Masters)
Remarkably, Debby's formation on June 23 comes a full two months ahead of the usual formation date of the season's fourth storm in the Atlantic, August 23. Debby's formation beats by twelve days the previous record for formation of the fourth named storm of the year in the Atlantic, set in 2005, when Hurricane Dennis was named on July 5. An early start to the Atlantic hurricane season has been increasingly common in recent years. In 2008, I blogged about the research of Dr. Jim Kossin of the University of Wisconsin, who published a 2008 paper in Geophysical Research Letters, titled "Is the North Atlantic hurricane season getting longer?" He concluded that yes, there is a "apparent tendency toward more common early- and late-season storms that correlates with warming Sea Surface Temperature but the uncertainty in these relationships is high". Three out of four of this year's early quartet of storms--Alberto, Beryl, and Debby--formed in ocean areas that were more than 1°F above average, which is an unusually high amount of warmth. We should expect to see more early-season Atlantic tropical storms as a consequence of global warming, since cool ocean temperatures are a key impediment to formation of such storms. However, this assumes that factors such as wind shear and atmospheric stability won't grow more hostile for tropical cyclone formation during the early part of hurricane season, and this is uncertain. If we do end up seeing a substantial increase in early-season tropical storms as a consequence of global warming, this is not necessarily a bad thing. Early-season tropical storms are often more boon than bane, bringing much-needed drought-busting rains, like Tropical Storm Beryl did for North Florida last month. With drought frequency and intensity predicted to increase for much of the Gulf Coastal states in coming decades, an increase in rainfall from early-season tropical storms may do more good than the damages inflicted by the high winds and flooding these storms may bring. There is typically a lot of wind shear around in May, June, and July, making it difficult for early season storms to reach major hurricane status. According to Wunderground's list of major early-season hurricanes, since record keeping began in 1851, there has been only one major hurricane in May, two in June, and nine in July. Three of these occurred in the past ten years, so there has not as yet been a large increase in early-season major hurricanes due to global warming.

References
Kossin, J., 2008, "Is the North Atlantic hurricane season getting longer?", Geophysical Research Letters, Vol. 35, L23705, doi:10.1029/2008GL036012, 2008.

Angela and Jeff

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Irene, and the other Irene, and the other other Irene were all overrated.
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Thanks Dr. You need all the factors (SST's - temps, etc.) to click at the same time for cyclogenesis so unless June-July sheer values also decrease over time, we may get a lot of sheered storms like Debby or a tropical/subtropical mix in these months in the future. In terms of Debby; kudos to NHC for sticking with the overall model guidance.........Westward Ho.
Member Since: August 8, 2006 Posts: 0 Comments: 9314
3 or 4 more Meso type cells moving into the keys and south Florida. Anybody there needs to watch for tornado or water spouts spinning up.

Also a ~50kts cell moving to Ft. Meyers. The warning box has not been updated yet.
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Quoting Hurricanes101:


Yea I saw it when I went there, so they are discounting the GFS and GFDL completely; which is interesting


I wouldn't say discounting them completely. They've acknowledged that there is a split in guidance (covering there is a possiblilty of a different outcome in track even if it is not likely), but they've made it clear they're not using data from those models for intensity.
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Quoting washingtonian115:
I wanted to see Doc use "Unprecedented" in his title....


He hasn't called Debby dangerous in the title yet so that means he isn't expecting anything on the scales of Irene etc. I remember hearing from somewhere that when he calls a particular storm dangerous, he means it.
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Concerning the operational GFS note the NHC discussion on this: "...EVEN THOUGH THE DETERMINISTIC GFS SHOWS AN EASTWARD TRACK...MORE THAN HALF OF THE GFS ENSEMBLE MEMBERS ARE INAGREEMENT WITH THE WESTWARD-MOVING MODELS...MAKING THE WESTWARD SCENARIO SEEM MORE LIKELY..."
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Angela is certainly downcasting here. The statement that the shear will rise to 30+ knots is absolutely bogus. It's just a futile attempt at antisensationalism and getting people to calm down.

But at the same time it's 100% pure, farm-raised horse dung, considering all signs (including the NHC) point to the shear dropping to low to very low in the next few days.
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Quoting charlottefl:
THE GFS FIELDS USED
BY THE SHIPS AND LGEM MODELS ARE NOT LIKELY TO BE REPRESENTATIVE OF
THE CONDITIONS ENCOUNTERED BY DEBBY. THE NHC FORECAST THEREFORE
SHOWS MORE STRENGTHENING THAN INDICATED BY THE INTENSITY GUIDANCE.


Yea I saw it when I went there, so they are discounting the GFS and GFDL completely; which is interesting
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Quoting nigel20:

Hey Levi...what is your forecast for Debby?


Texas. Watch his Tidbit. He goes into great detail.
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Quoting washingtonian115:
You might have to take that welcome mat away if Debby becomes to strong.


Tal vez. Point taken.
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It appears Debby has stalled.

Debby Long Floater - Visible Imagery Loop
Member Since: August 31, 2009 Posts: 0 Comments: 5628
Quoting CybrTeddy:


It makes perfect sense.

How many of the models are showing the convection from Debby splitting off and developing into another Tropical Cyclone? None. That's why it pulls Debby NE, the low from an equally as strong system on the GFS pulls and influences Debby into the trough and over Florida. This is a classic example of the GFS's flaw of convective feedback with so much moisture and energy, it doesn't know what to do with it so it strings it out and splits low after low.


maybe but I have seen the GFS be right on a few occasions when it predicted multiple lows
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Quoting Hurricanes101:


Is it interesting that they are using the GFS to determine the intensity but they are completely discounting its track...does not really make sense to me
IMO i think it is premature to rule out NHC #2 most reliable model!
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I wanted to see Doc use "Unprecedented" in his title....
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THE GFS FIELDS USED
BY THE SHIPS AND LGEM MODELS ARE NOT LIKELY TO BE REPRESENTATIVE OF
THE CONDITIONS ENCOUNTERED BY DEBBY. THE NHC FORECAST THEREFORE
SHOWS MORE STRENGTHENING THAN INDICATED BY THE INTENSITY GUIDANCE.
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the ULL is forcast too move in too TX wish this will help lower the wind shear



i wish they learn too look at the nhc site be for post a blog update
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Quoting Hurricanes101:


Is it interesting that they are using the GFS to determine the intensity but they are completely discounting its track...does not really make sense to me


It makes perfect sense.

How many of the models are showing the convection from Debby splitting off and developing into another Tropical Cyclone? None. That's why it pulls Debby NE, the low from an equally as strong system on the GFS pulls and influences Debby into the trough and over Florida. This is a classic example of the GFS's flaw of convective feedback with so much moisture and energy, it doesn't know what to do with it so it strings it out and splits low after low.
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I'm 50 miles inland and we are forecast to not get a drop of rain from Debby. Our NWS says ridging will be too strong. I have to believe with Debby being so large that we could get one or two stray bands through here.
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Tornado threat will probably be higher the next 2 days along the FL west coast given the increase in rotation from the storm, and then after that along the northern Gulf coast. We've already had 3 tornado warnings in this area today.
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Quoting MiamiHurricanes09:
It was written by Angela Fritz; she was going off of intensity models which use the GFS track for guidance. And as you know the GFS is the outlier and thus unreliable.

The discussion went over this already...

Well somebody didn't read it.

*points at Angela!*

Lol.
Member Since: July 6, 2010 Posts: 113 Comments: 32501
18z GFS 18 hours... Now begins the stalling

Member Since: February 11, 2012 Posts: 84 Comments: 7922
Quoting katadman:
Debbie,

We have put out the welcome mat for you here in Texas.
You might have to take that welcome mat away if Debby becomes to strong.
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.
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Quoting TropicalAnalystwx13:

They didn't use the GFS to determine intensity.


unless I read it wrong, read post #35 from chaser07
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Quoting Hurricanes101:


Is it interesting that they are using the GFS to determine the intensity but they are completely discounting its track...does not really make sense to me
They aren't using the GFS' intensity. They clearly said that they were discounting intensity models that use the GFS for guidance.
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I am really surprised at the NHC forecast track, not for my personal sake, but for the fact that they discounted several models (including the major model GFS) that had the system going east instead (and they left no margin of error in the cone for a potential Eastern Gulf Strike) and if this storm goes to Texas, then this will be a most surprising continuation of the unusually high Texas/Mexico/Louisiana (Western Gulf) Activity the past 5 years. Remember that the western gulf has had 4 hurricane landfalls the past 5 years (Alex, Ike, Gustav, Humberto). These were significant storms, and also not to mention this region also had 5 tropical storms in addition to these hurricanes (Erin, Edouard, Hermine, Lee, Don) while the Eastern Gulf has experienced no hurricanes in this time period, with only one tropical storm being significant (Fay), and the other 4 tropical storms impacting the Eastern Gulf (Barry, Claudette, Ida, and Bonnie) were piddly things. It will be interesting to see if this continuation of Texas/Louisiana/Mexico landfalls continues the rest of the season or if there will be a return to more Eastern gulf activity.
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Quoting Hurricanes101:


Is it interesting that they are using the GFS to determine the intensity but they are completely discounting its track...does not really make sense to me


They don't have a choice. They can't just switch all of the intensity guidance over to assimilating another global model's environmental data. The NHC recognized in the discussion that the GFS information is useless and thus adjusted their intensity forecast upward.
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Arent they calling for more strength than the GFS predicts?
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Quoting Hurricanes101:


Is it interesting that they are using the GFS to determine the intensity but they are completely discounting its track...does not really make sense to me

They didn't use the GFS to determine intensity. They knew it showed a weaker storm than it's likely to be because it shows an unfavorable environment, and they went higher than that.
Member Since: July 6, 2010 Posts: 113 Comments: 32501
Quoting Levi32:
The Gulf of Mexico is soupy right now. There's no reason to worry about dry air for the moment.


Hey Levi...what is your forecast for Debby?
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Quoting RTSplayer:



I guess Dr. M. disagrees on the direction the ULL will move and it's strength?

Completely different theory on environmental conditions.
It was written by Angela Fritz; she was going off of intensity models which use the GFS track for guidance. And as you know the GFS is the outlier and thus unreliable.

The discussion went over this already...
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Debbie,

We have put out the welcome mat for you here in Texas.
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Quoting Stormchaser2007:
Current intensity estimates are using the GFS for environmental details.

Not sure why that needed to be repeated. I thought the NHC disco was pretty obvious.


Is it interesting that they are using the GFS to determine the intensity but they are completely discounting its track...does not really make sense to me
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great; a slow mover predicted to meander west along the gulf coast, as for myself i hope it gets real close to the coast or really far out their is a path that does not bold well for us.

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Quoting TropicalAnalystwx13:
"Upper-level winds out of the west continue to create moderate 10 - 20 knots of wind shear over the region, though that is expected to increase over the next few days."

*cough* NHC discussion *cough*

"DEBBY IS CURRENTLY A SHEARED CYCLONE WITH NEARLY ALL OF THE DEEP
CONVECTION LOCATED IN A CURVED BAND TO THE EAST OF THE CENTER.
HOWEVER...AN UPPER-LEVEL LOW OVER THE NORTHWESTERN GULF OF MEXICO
IS FORECAST TO DIG SOUTHWESTWARD...WHICH WILL RESULT IN A DECREASE
OF VERTICAL SHEAR AFFECTING THE SYSTEM...AND A GREATER CHANCE OF
INTENSIFICATION OVER THE NEXT FEW DAYS. BECAUSE THE OFFICIAL TRACK
FORECAST IS SO DIFFERENT FROM THE GFS SOLUTION...THE GFS FIELDS USED
BY THE SHIPS AND LGEM MODELS ARE NOT LIKELY TO BE REPRESENTATIVE OF
THE CONDITIONS ENCOUNTERED BY DEBBY. THE NHC FORECAST THEREFORE
SHOWS MORE STRENGTHENING THAN INDICATED BY THE INTENSITY GUIDANCE."



I guess Dr. M. disagrees on the direction the ULL will move and it's strength?

Completely different theory on environmental conditions.
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Thank you, Dr Masters.
Member Since: July 18, 2005 Posts: 9 Comments: 4146
i see dr m is being a downcaster like all ways
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Chris became a cane north of 30N in cool water, once the shear in the GOM relaxes, Debby would become a full blown hurricane herself if the time allows.
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The Gulf of Mexico is soupy right now. There's no reason to worry about dry air for the moment.

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Thanks Angela and DRM. I'm hoping she stays a disorganized mess. Especially with family on Matagorda Bay.
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Quoting AllStar17:
Both Beryl and Chris surpassed the initial NHC intensity forecast by quite a bit.
I remember when he was not suppose to intensify and just stay a weak Tropical storm...what a whack hurricane season thus far.
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Thanks for the update.
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Quoting duajones78413:
I am from Corpus Christi and the forecast brings Debby near our neck of the woods.
Dr Masters said that the NHC doesnt think Debby will become a hurricane.
I sure hope not


Master's thought that north of Tampa had the highest chance of impact a few days ago....
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Goodbye Florida,

Watch out Texas!!



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The circulation of Debby continues to become better-defined and is clearly strong enough to resist leaping northeast into the sheared convection the way the GFS has been insisting on for so long.

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**REPOST FROM LAST BLOG**


Member Since: July 14, 2009 Posts: 51 Comments: 1731
Quoting turtlehurricane:
This forecast looks to be intractable for the next several days, not surprising given the multiple vortex nature of the circulation and the weak steering currents in the Gulf of Mexico. I think it's going to be moving erratically for the next few days at least and mostly drifting, which may give it time to develop. I'm surprised the NHC has latched onto the western models, I myself would've drawn a circle! I made a full analysis on my blog Meteorological Phenomena

The NHC forecasters call this a squished spider when the models get like this btw lol http://www.sfwmd.gov/portal/page/portal/xweb%2520 weather/hurricane%2520model%2520plots




Nice to see you on the blog.
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Quoting MississippiWx:


Dry air is not the issue.


I hope it doesnt pull a Don on Texas and can get some decent rain that they need
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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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