Winter rains ease Southeast U.S. drought; Brazilian storm could go subtropical

By: Dr. Jeff Masters , 5:59 PM GMT on February 29, 2008

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The winter of 2007-2008 is in the books, as today marks the last day of meteorological winter (December, January, and February). Winter rains have eased the drought gripping the Southeast U.S., where the area covered by extreme to exceptional drought has shrunk by about 50% since the beginning of the year (Figure 1). Some regions of southern Georgia and southern Alabama, where winter rains have been more than six inches above average (Figure 2), are no longer suffering drought conditions at all.


Figure 1. Drought categories for the Southeast U.S. from December 25, 2007, and February 28, 2007. Image credit: U.S. Drought Monitor.

However, A large swath of the Southeast U.S., including Atlanta, Charlotte, and Huntsville, have received 1-4 inches of precipitation below usual for this time of year. The shortfall is particularly acute in northern Alabama, where Huntsville has received only 6.77" this year, compared to the normal 10.47". The below average rains during this winter rainy season bode ill for the summer, when drought conditions could easily return to last year's extreme levels. The Southeast badly needs one or two landfalling tropical storms or hurricanes in 2008 to help break the drought.

Central Florida surrounding Lake Okeechobee is also suffering from below average rains this winter. The lake, which reached its all-time low water mark of 8.82 feet on July 2, 2007, has risen to 10.02 feet, but this is still a record low for this time of year. The surface area of the lake has shrunk to about 2/3 of normal, and the water level is more than four feet below normal. Part of the reason for the record low lake levels is the fact that the lake was deliberately drawn down before the 2006 hurricane season, in anticipation of another very active hurricane season.


Figure 2. Departure of precipitation from average for January and February 2008. Image credit: NOAA Advanced Hydrologic Prediction Service.

The forecast
The short-range rainfall forecast is good for the Southeast, with significant rainstorms possible both Tuesday and Thursday. The longer range three-month forecast calls for a continuation of below average precipitation for the spring season, thanks to the continued presence of a strong La Niña event in the Equatorial East Pacific. La Niña events usually deflect the jet stream into a pattern that takes the Southeast U.S. out of the the usual storm track needed to bring typical spring rains. However, for the summer months of June, July, and August, NOAA's CFS Climate Forecast System Model is predicting a return to normal levels of rainfall over the Southeast U.S.

Severe weather outbreak coming on Monday
A strong low pressure system is forecast to develop over Texas on Sunday, bringing a slight chance of severe weather to eastern Texas Sunday afternoon. By Monday afternoon, the storm is expected to track northeastwards over the Ohio Valley, dragging a strong cold front across the south. A significant severe weather outbreak is possible Monday afternoon in advance of this cold front.

Interesting South Atlantic storm could become subtropical
An extratropical storm centered near 31S 30W, a few hundred miles east of the Brazil-Uruguay border, has begun to acquire subtropical characteristics and could become a subtropical storm this weekend. The storm is not expected to hit land. NASA/MSFC has a clickable satellite image of Southern Hemisphere one can use to zoom in on the storm. An ASCAT pass at 5:29am EST this morning showed winds of 50 mph near the center of the storm. Water temperatures are about 26°C, which is right at the boundary where tropical storm formation can occur. Subtropical and tropical storms are quite rare in the South Atlantic. I'll update this section of the blog through the weekend if the storm develops. There is no naming system in place to name any tropical or subtropical storm that may form in the South Atlantic. It would be up to the World Meteorological Organization (WMO) to institute such a scheme. The last time I checked into this, they had no plans to consider a naming system. Here's nice MODIS image of the storm from 15:30 GMT today.



Figure 3. Visible satellite image of extratropical low off the coast of Brazil that is beginning to acquire some subtropical characteristics. Image credit: NASA/MSFC.

Jeff Masters

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260. weatherbro
12:44 AM GMT on March 04, 2008
doesn't feel humid in Orlando with dewpoints in the 50's
Member Since: May 26, 2007 Posts: 47 Comments: 1463
259. atmoaggie
4:46 PM GMT on March 03, 2008
Nice low level convergence and the resulting lightning, of course:

Member Since: August 16, 2007 Posts: 6 Comments: 12463
258. weathermanwannabe
4:26 PM GMT on March 03, 2008
At least it looks like the sytem is moving down at pretty fast clip (the potentially damaging straight line winds) so it will not (Thank God) be an extended event, but, the tornado potential seems to be on target right now..............
Member Since: August 8, 2006 Posts: 0 Comments: 9981
256. weathermanwannabe
4:12 PM GMT on March 03, 2008
Getting pretty warm and humid in Florida Panhandle and that low swinging down into Texas from NM is looking better organized this morning........Looks like a pretty warm and unstable air mass will be meeting up with the front later today/this evening as the system approches South TX/LA/MISS/AL.......How is the weather looking right now (in terms of heat and moisture) from some of our friends in those parts?.............
Member Since: August 8, 2006 Posts: 0 Comments: 9981
255. cajunkid
3:27 PM GMT on March 03, 2008
Link

PUCKER TIME!
Member Since: July 10, 2005 Posts: 3 Comments: 1281
254. weathermanwannabe
2:34 PM GMT on March 03, 2008
NATIONAL WEATHER SERVICE TALLAHASSEE FL
421 AM EST MON MAR 3 2008

500 MB CHART AT 00 UTC SHOWED A DEEP POSITIVELY TILTED TROF JUST PREPARING TO EXIT THE ROCKIES AND MOVE INTO THE HIGH PLAINS. A
CLOSED LOW OF 546 DM IS ANALYZED JUST SOUTH OF GRAND JUNCTION CO. 500 MB TEMPS ARE QUITE COLD WITH THIS FEATURE...AS COLD AS -34C. SHORTWAVE RIDGING IS MOVING OFF THE U.S. EAST COAST. VAPOR IMAGERY INDICATES THIS UPPER TROF AND CLOSED LOW IS MOVING SSE INTO CENTRAL
NEW MEXICO. THE FUTURE MOVEMENT OF THIS FEATURE WILL BE KEY IN THE DEVELOPMENT OF AND MAINTENANCE OF EXPECTED SEVERE WEATHER IN THE
SOUTHEAST.


Good Morning Folks.........

Things are relatively quiet in the Gulf/SE right now, but, as the closed low drops down into Texas from New Mexico later today, we'll have to wait and see how the potential for severe weather develops as the front interacts with the warm flow and moisture coming up from the Gulf..........It will be interesting later this evening and into tommorow and interests around the Gulf will need to keep a close eye on their NOAA products and local weather alerts...................

See Yall Later this evening as the situation unfolds..........
Member Since: August 8, 2006 Posts: 0 Comments: 9981
253. surfmom
2:32 PM GMT on March 03, 2008
Wow a week of EXCITING weather perhaps! More fun watching this unfold then TV Frankly, I am praying for rain - for several reasons,1. to change my yard from a dust bowl back to a tropical garden and get my rain barrels filled, 2. to replenish water holes and pasture land out east of I75 and remove the "tinderbox" situation we have out there now 3. get a rain day off from work and lastly I sure love to ride some waves and take a break from riding horses.

I am wishing for Sarasota,FL to get a good soaking. Off to work, see you all in the PM
Member Since: July 18, 2007 Posts: 30 Comments: 26536
252. NEwxguy
2:30 PM GMT on March 03, 2008
By the looks of that line of storms so early in the morning,its only going to get worse,Arkansas and Louisianna,better prepare.
Member Since: September 6, 2007 Posts: 896 Comments: 16202
251. IKE
2:24 PM GMT on March 03, 2008
It's already starting...

" Tornado Warning

Statement as of 8:09 AM CST on March 03, 2008

The National Weather Service in Shreveport has issued a

* Tornado Warning for...
Bowie County in northeast Texas...
this includes the cities of... Wake Village... Texarkana... New
Boston...
southern Little River County in southwest Arkansas...
this includes the city of Ashdown...

* until 915 am CST

* at 807 am CST... National Weather Service Doppler radar indicated a
severe thunderstorm capable of producing a tornado near New
Boston... moving northeast at 25 mph.

* The tornado will be near...
New Boston by 820 am CST...
Hooks by 835 am CST...
Ogden by 915 am CST...

The safest place to be during a tornado is in a basement. Get under a
workbench or other piece of sturdy furniture. If no basement is
available... seek shelter on the lowest floor of the building in an
interior hallway or room such as a closet. Use blankets or pillows to
cover your body and always stay away from windows.

If in Mobile homes or vehicles... evacuate them and get inside a
substantial shelter. If no shelter is available... lie flat in the
nearest ditch or other low spot and cover your head with your hands.

A Severe Thunderstorm Watch remains in effect until 100 PM CST Monday
afternoon for southwestern Arkansas and northwestern Louisiana and
northeastern Texas."
Member Since: June 9, 2005 Posts: 23 Comments: 37860
250. Ivansrvivr
2:15 PM GMT on March 03, 2008
CC, with winter systems so infrequent here, it is natural for the models to have a hard time picking up systems like storm#2
249. NEwxguy
2:13 PM GMT on March 03, 2008
Thanks Storm,Wednesday storm is g oing to be a wet one and windy.
Member Since: September 6, 2007 Posts: 896 Comments: 16202
248. Ivansrvivr
2:12 PM GMT on March 03, 2008
The CPC 6-10 day precip forecast is good indicator when the 3 day forecast models are blinded by current storm. When it's too early for the specific models, look at the big picture forecast. The CPC is leaning towards a very wet pattern for the Central and southern Peninsula over the next 10 days.
245. cchsweatherman
2:01 PM GMT on March 03, 2008
Just completed my forecast for Southern Florida on my site. Will publish my forecast discussion later on, but have included possible severe storms in the forecast for Friday and Saturday with high rain chances for both days. Just hoping the heavy rains sit over Lake Okeechobee over the next week. But, all in all, it seems like this is great news with tropical moisture coming much earlier than usual over the region bringing early spring rains.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
244. cchsweatherman
1:59 PM GMT on March 03, 2008
Agreed Ivansrvivr. As is customary with the weather, we will have to hope for the best and prepare for the worst since there is such a high degree of uncertainty in the forecast.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
243. Ivansrvivr
1:54 PM GMT on March 03, 2008
CC, the NAO's tilt is the key to storm #2, if it continues to go more neg. #2 becomes bigger deal. If NAO goes back pos., 2nd storm will be non-event.
242. Ivansrvivr
1:48 PM GMT on March 03, 2008
CC, the models won't get a handle on storm#2 until storm#1 gets out of the picture.
241. biff4ugo
1:41 PM GMT on March 03, 2008
North Central Florida has two more rainy days on our weekly forecast. I know the humidity has been a little low, but the dried out lakes have made a shallow return, detention ponds are fuller than they have been all year, thing are looking good.
So why do they keep putting out fire weather warnings in the rain? We had a sunny dry weekend and finally my county doesn't have a sever warning over it.
Member Since: December 28, 2006 Posts: 117 Comments: 1630
240. cchsweatherman
1:22 PM GMT on March 03, 2008
Taking a look at the latest models, it appears that they don't have any handle on the second system as of this time. There is no agreement in the models which makes me worried also. It makes forecasting this system tougher.

While I was looking at the models, they all seem to agree on a well-defined surface low developing in the Central Atlantic within the next few days. I'll be watching this area.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
239. cchsweatherman
1:18 PM GMT on March 03, 2008
Good morning all! Been getting drenched with some much needed rainfall here in Cooper City. Looks like there is some training occuring in the Southern Broward county.

I'll be in and out all day. Going to take a look at the latest models and see what they're up to now.

Any thoughts regarding Friday and Saturday here in South Florida? I agree with your ideas Ivansrvivr. It has me worried for a flooding event, but hopefully Lake Okeechobee gets the most rain.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
238. Cavin Rawlins
1:14 PM GMT on March 03, 2008
237. surfmom 9:10 AM AST on March 03, 2008
Morning Weather 456 - you are really rockin' these days, thanks for the picture - post 231 - helps me to understand the technical reports better!


ur welcome and no problem
Member Since: July 24, 2005 Posts: 407 Comments: 19076
237. surfmom
1:10 PM GMT on March 03, 2008
Morning Weather 456 - you are really rockin' these days, thanks for the picture - post 231 - helps me to understand the technical reports better!

StormW morning to you too! Looks like the weather will be interesting this week - you know I'll be checking in. Thanks for ALL weather warning - have alerted non-weather-aware friends in those areas this AM
Member Since: July 18, 2007 Posts: 30 Comments: 26536
236. Cavin Rawlins
1:09 PM GMT on March 03, 2008
233. BahaHurican 7:56 AM AST on March 03, 2008
Morning guys.

It's actually cold outside (for Nassau, Bahamas) this morning. Looks like 456 was correct in characterizing the frontal boundary as just that, and not as a surface trough as was analysed yesterday.


Morning, yeah.....and in addition to that, winds clearly veered from southwest to north-northwest in Bermuda and during the passage rain fell followed by a sudden increase in sustain winds. The obs from Bermuda clearly supports the passage of a front.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
235. surfmom
1:07 PM GMT on March 03, 2008
Morning Weather 456 - you are really rockin' these days, thanks for the picture - post 231 - helps me to understand the technical reports better!

StormW morning to you too! Looks like the weather will be interesting this week - you know I'll be checking in.
Member Since: July 18, 2007 Posts: 30 Comments: 26536
233. BahaHurican
11:56 AM GMT on March 03, 2008
Morning guys.

It's actually cold outside (for Nassau, Bahamas) this morning. Looks like 456 was correct in characterizing the frontal boundary as just that, and not as a surface trough as was analysed yesterday.
Member Since: October 25, 2005 Posts: 19 Comments: 22844
231. Cavin Rawlins
10:07 AM GMT on March 03, 2008
Morning,

Member Since: July 24, 2005 Posts: 407 Comments: 19076
230. KoritheMan
8:07 AM GMT on March 03, 2008
The line seems to have weakened considerably. It should built back up though, what with MUCAPE values in excess of 2000 J/KG.
Member Since: March 7, 2007 Posts: 602 Comments: 21780
229. KoritheMan
7:01 AM GMT on March 03, 2008
Wouldn't be surprised to see some strong winds with that cell by Dallas.

If this line can hold together, it looks like I'll be getting some severe weather today.
Member Since: March 7, 2007 Posts: 602 Comments: 21780
226. quasigeostropic
6:07 AM GMT on March 03, 2008
MUCAPE is very ominous in the most threatened region for tomorrow!(click on thermo fields then MUCAPE) Readings of 2000-3000 J/kg!

Member Since: November 20, 2007 Posts: 21 Comments: 192
224. Ivansrvivr
5:03 AM GMT on March 03, 2008
The models wont get a good read on the 2nd storm until the first one gets out of the way. If the Atlantic ridge is so weak, why is storm #1 taking a NNE track west of the Appalachians? This path will take it north too quickly to push the trailing front out of the area. Storm #2 will (as all are here) be an all or nothing deal. We either get flooding or nothing in S.FL.
223. BahaHurican
4:05 AM GMT on March 03, 2008
Wow! Thunder! First I've heard in months.
Member Since: October 25, 2005 Posts: 19 Comments: 22844
222. KoritheMan
3:58 AM GMT on March 03, 2008
STL, reading that kinda scared me. And I'm not usually frightened by weather, no matter how extreme.

I definitely hope no significant tornadoes occur, but it's very likely they will somewhere.
Member Since: March 7, 2007 Posts: 602 Comments: 21780
221. BahaHurican
3:53 AM GMT on March 03, 2008
Hmmm . . . looks like this week is going to be a bumpy ride . . .
Member Since: October 25, 2005 Posts: 19 Comments: 22844
220. M1HS
3:51 AM GMT on March 03, 2008
Hi. I wonder if that S. Atlantic storm still has potential to become a SS>
219. BahaHurican
3:48 AM GMT on March 03, 2008
We're finally getting some substantial rain from the front that has been lingering the last 3-4 days. Sounds more like late May than early March lol. I guess this means that stalled-out boundary is finally on the move, trailing its parent low out to sea. . .
Member Since: October 25, 2005 Posts: 19 Comments: 22844
217. surfmom
1:53 AM GMT on March 03, 2008
dog walking bbl
Member Since: July 18, 2007 Posts: 30 Comments: 26536
215. KoritheMan
1:32 AM GMT on March 03, 2008
Dang, even if we don't get the severe weather here in Louisiana, it is bound to be windy. I'd say minimal tropical storm force gusts can't be ruled out even as far inland as I am (Prairieville). One heck of a storm coming. Wouldn't be surprised to see us under a Wind Advisory soon, Pat.
Member Since: March 7, 2007 Posts: 602 Comments: 21780
214. surfmom
1:28 AM GMT on March 03, 2008
Well I am ready to deal with a bit of rough weather inorder to get some RAIN! SRQ needs rain. We are so dry my backyard looks like a dust bowl, and I so want our pastures, and dried up water holes to get replenished. I am hoping this front will bring the waves all surfers are anticipating, but mostly I know we need rain. Depending on you all to keep me updated, so if I have to do any extra prep work to keep the horses safe I'll have plenty of time.
Member Since: July 18, 2007 Posts: 30 Comments: 26536
212. KoritheMan
12:13 AM GMT on March 03, 2008
New tornado watch just issued by the SPC:

Member Since: March 7, 2007 Posts: 602 Comments: 21780
211. BahaHurican
11:46 PM GMT on March 02, 2008
Looks like EUMETSAT is updating its website presentation.

EUMETSAT has developed a new, improved interface to view Near Real Time Derived Products on the website. The new web visualisation has several enhancements to improve interactive use, including a new download feature, overlapping segments to avoid slicing countries in two, as well as the possibility to zoom in and out of an image.

The Derived Products that are available are: Dust, Fog, Airmass, MPE, Fire, Volcanic Ash, Global Instability Index (GII) and Europe seen with the High Resolution Visible channel (E-View).

Two Metop RGB products are also available, based on AVHRR channels 1, 2 and 4. The Orbitview is a composition made by the concatenation of subsequential images. The EPSFlight displays two AVHRR PDUs with orbit information attached.

Member Since: October 25, 2005 Posts: 19 Comments: 22844
210. BahaHurican
11:21 PM GMT on March 02, 2008
Also noticed this area in the S. Indian, which looks like it may be of interest in the ensuing week.

Member Since: October 25, 2005 Posts: 19 Comments: 22844

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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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