Archive for May 12th, 2012
A heavy rain situation is developing over Central Alabama this evening. Moisture is flowing efficiently northward out of the Gulf of Mexico up and over the warm front that lies over the south central part of the state.
Look at the fire hose of moisture coming northward out of the Gulf near Pensacola. Big thunderstorms are associated with this activity, including one with overshooting cloud tops that is producing a confimed tornado southwest of Pensacola.
Several upper level disturbances moving northeastward in the mid-level flow are helping focus the waves of showers.
NWS Birmingham has issued as areal flood advisory for Greene and Sumter Counties in West Alabama. Doppler radar estimates indicate that a large area of rainfall amounts 1.5-4 inches has fallen over West Alabama. The highest estimates extend just south of I-59 from Livingston to Eutaw. 2 to 4 inches of rain has fallen in this area.
Be alert to the potential for flooding in areas where heavy rain is falling. Flash flood warnings could be required in areas that receive more than 3 inches of rain in 3 hours, which is possible.
At 8:15, the heaviest rain extends from Greene and Sumter Counties southeastward through Selma, south of Montgomery and to near Union Springs in Bullock County.
DAMAGE REPORT – 8:37:
From the NWS Mobile: 12 WSW Pensacola [Escambia Co, FL] law enforcement reports TORNADO at 08:11 PM CDT — unconfirmed tornado damage reported 3252 fenceline rd.pensacola. damage to home…fence…and boat ramp.
LATE REPORT – 7:53:
From the NWS Mobile: Escambia EMA says the tornado lifted briefly, but has touched back down near the Navy base/Gulf Beach Rd. No reports of damage. KEVX radar is stil showing the circulation in the vicinity of Pleasant Grove.
The NWS in Mobile reports that a waterspout moved onshore at Johnson’s Beach, southwest of Pensacola at 7:40 p.m.
it is moving north toward western parts of Pensacola.
A tornado warning is in effect for Escambia County.
Waterspouts driven by tornadic processes, like the one that hit Grand Isle LA earlier this week, are not weak fair weather vortices.
You can see from the Doppler radar presentation showing strong rotation.
The SPC reports that storms along the warm front over South Alabama may be severe over the next few hours, but they do not expect to have to issue a watch.
This warm front will move north overnight and Sunday morning, probably making it a line from Jasper to Birmingham to Alex City by late on Sunday.
Rain and thunderstorms will continue to increase overnight and will be numerous tomorrow. North of the front, the storm will be elevated, meaning their bases will be higher off the ground than normal surface based storms. It makes them less likely to produce severe weather, but can make for some great rolling thunder as the lightning can come from higher up in the atmosphere making for a long superheated channel from which the crack of the thunder emanates.
MESOSCALE DISCUSSION 0797
NWS STORM PREDICTION CENTER NORMAN OK
0516 PM CDT SAT MAY 12 2012
AREAS AFFECTED…SRN MS…SRN AL…FL PANHANDLE
CONCERNING…SEVERE POTENTIAL…WATCH UNLIKELY
VALID 122216Z – 122345Z
PROBABILITY OF WATCH ISSUANCE…20 PERCENT
SUMMARY…AN ISOLATED SEVERE THREAT WILL LIKELY CONTINUE FROM SCNTRL
MS EWD ACROSS SRN AL FROM LATE THIS AFTERNOON INTO EARLY THIS
EVENING. HOWEVER…THE THREAT IS EXPECTED TO REMAIN MARGINAL AND WW
ISSUANCE IS NOT ANTICIPATED.
DISCUSSION…THE LATEST SFC ANALYSIS SHOWS A LOW OVER FAR SW MS WITH
A WARM FRONT EXTENDING EWD ACROSS SCNTRL MS INTO SRN AL AND THE FL
PANHANDLE. NUMEROUS THUNDERSTORMS ARE ONGOING ALONG AND TO THE NORTH
OF THE WARM FRONT WHERE THE AIRMASS HAS BEEN WORKED OVER.
MESOANALYSIS SUGGESTS THE STRONGEST INSTABILITY IS LOCATED FROM THE
WARM FRONT SWD WHERE MLCAPE VALUES ARE ESTIMATED FROM 1000 TO 1500
J/KG. IN ADDITION TO THE INSTABILITY…REGIONAL WSR-88D VWPS SHOW 40
TO 50 KT OF DEEP LAYER SHEAR SUGGESTING THE STORMS MAY BE ABLE TO
ROTATE AND APPROACH SEVERE LEVELS. THE SEVERE THREAT MAY BE GREATEST
FROM AROUND HATTIESBURG MS EWD INTO SRN AL ALONG AND JUST NORTH OF
THE FRONT. A WIND DAMAGE AND HAIL THREAT MAY EXIST WITH THE STRONGER
CELLS. HOWEVER…THE STORMS SHOULD BE INCREASINGLY ELEVATED NORTH OF
THE WARM FRONT WITH THE SEVERE THREAT DROPPING OFF QUICKLY WITH NWD
Rain and thunderstorms continue to overspread West Central Alabama at this hour.
The activity is reaching the Tuscaloosa area right now. They are part of a batch of storms that cover parts of Greene, Hale, southwestern Tuscaloosa, much of Pickens and southern Lamar Counties.
Heavy storms are over northern Lamar and western Marion County about to reach Hamilton.
A larger batch of stronger storms extends from Livingston in Sumter County back into eastern Mississippi near Meridian. A flash flood warning was just issued for several counties west of Meridian where 3 to 4 inches of rain has fallen and more rain is on the way.
Still nothing severe and no severe weather is expected. Can’t rule out the need for a warning or two, but so far so good.
There is a slight risk from the SPC over a tiny part of Southwest Alabama that includes Washington County north of Mobile. A tornado warning does continue for Simpson County in SE Mississippi, around Mendenhall.
More storms are forming near the weak surface low which is approaching I-20 west of Vicksburg at this hour.
The rain will arrive in the Birmingham area after 6-7 p.m. It will be the beginning of a wet and sometimes thundery night and Mother’s Day across Central Alabama.
Storms are approaching the western border of Alabama at this hour.
They are less than an hour from Sumter, Pickens, Lamar and western Marion Counties.
There is a severe thunderstorm warning for Neshoba and Kemper Counties in eastern Mississippi. This storm will impact northern Sumter and Pickens Counties.
The NWS Mobile has just issued a severe thunderstorm warning for Washington County.
In Alabama, an isolated storm formed over Walker County and is now moving northnorthwest alongthe WInston/Cullman County line east of Arley. It will cross Smith Lake in the next 15-30 minutes.
The storms in eastern Mississippi will weaken as they move into Alabama since the moisture is not exceptionally high and instabilities are fairly low. But can’t rule out a warning or two through the afternoon. The main threat would be damaging winds.
You should notice the rainfall becoming more widespread as we go through the afternoon over West Central Alabama and into the I-65 corridor this evening. Rain should hold off until after 6-7 p.m. in the Birmingham metro area. It could even be a little later than that.