AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 830 PM EST Tue Jan 10 2012 ...There is a slight Risk of Severe Storms Tonight THRU Wed morning for SE Ala and for the FL Panhandle... .SYNOPSIS... Around 7-730 pm, some small MESO-scale feature moved thru southern Georgia generating brief but strong WIND gusts with multiple trees down across Decatur County. AT UPPER LEVELS... The large scale split FLOW pattern this Tues evening is highlighted in NRN stream by troughing over WRN states and broad ridging EWD to ERN seaboard. Conversely, SRN stream more amplified with ridging Wrn and Ern states and deep TROUGH in between with 553DM closed LOW over NE TX. Potent SHORTWAVE approaching LWR MS Valley. Over the next 12-18 HRS, this low will progress EWD to MS/AL in response to Nrn stream trough amplifying over Nrn Rockies/Plains. Assocd speed MAX approaching 80KT and ahead of H5 low PROGGED to eject NEWD across SRN AL/FL Panhandle and gradually weaken AS upper low opens up. Shortwave moves from Lwr Ms Valley thru TN Valley and strong cooling and HEIGHT falls over LA/MS this evening that will push EWD into the Wrn CWA overnight. AT LOWER LEVELS... Analysis shows an occluding 1006 MB low centered over SE AR with a QUASI-STATIONARY boundary located from this low ESE to across S/CNTRL Al/SRN GA ewd to Atlc. The warm sector continues to be marked by weak INSTABILITY (MU Capes 250-500 j/kg) but strong SHEAR (06km 60-70kt). Another quasi-stationary coastal FRONT had SET up about 50 NM or so south of the FL Panhandle/AL Coast. The result is that the true surface-based instability continues to be well offshore and will prove difficult to go NWD toward the Gulf Coast rest of tonight. In fact,UPSTREAM radars earlier indicated that thunderstorms struggled to develop in the warm sector of Ern LA/MS due primarily to weak lapse rates, extensive CLOUD cover and limited instability. In fact, this extensive cloud cover emanating from ongoing upstream convective clusters kept local conditions mostly CLOUDY and cooler on Tuesday. && .REST OF TONIGHT INTO EARLY WEDNESDAY. Elevated thunderstorms will be possible towards midnight over interior sections with best forcing occurs as the upper low approaches the area. The primary forecast question will be the potential for severe weather but this looking less and less LIKELY. With CURRENT OVERRUNNING over cold front producing extensive cloudiness and warm MID layers, chances of generating enough instability to produce WIDESPREAD surface based land thunderstorms not HIGH. Regional meso-analysis seems to confirm that the area for best surface-based instability will remain along the coast and especially offshore and will likely only gradually pivot northward toward the Gulf Coast States as the surface low continues to occlude, deepen and lift northward into Nrn AL by 12Z Wed dragging cold front to Lwr Ms Valley later tonight and across our CWA on Wed. Still looks like a low CAPE/high shear generally linear event. The kinematic fields and 500 mb height falls remain reasonably impressive locally as the upper low drives ENE through SRN AL with cooling aloft helping to raise DEW points to near 60F...before lifting into N GA on Wednesday allowing for some destabilization. However,lapse rates meager restricting MU Cape to below 500 j/kg and this will focus along a very narrow axis directly ahead of the cold front. However, somewhat veered but still strong LLJ near 50kts crosses Ern Gulf states with strong warm sector moving progressively NWD. Overall, all this kinematic and dynamical forcing will likely be unable to overcome the prohibitive thermodynamic environment at the surface for more than ISOLATED severe weather. Based on upstream events, even the CHANCE of non-severe storms is diminishing with time. If any strong and especially any severe weather occur, it looks to be confined to coastal areas of the FL Panhandle/WRN Big Bend and especially over the adjacent coastal waters where where shear is greatest and where some storms may contain ROTATION producing brief damaging winds. Cannot completely discount an isolated TORNADO. Thunderstorms look to begin around 3AM EST Wrn counties and ending around SUNRISE Ern most counties. SPC still has area in a 15% chance of severe wind gusts and a 5% chance of tornadoes. One thing that is clear is that it will RAIN, so POPS remain at 100 percent across much of the area. Significant rains are not anticipated, but it should be a good soaking rain with most areas receiving between 0.75 and 1 inch by Wednesday, the bulk of which should FALL prior to sunrise. Temperatures overnight will be quite warm given the thick cloud cover. Increasing boundary layer winds will keep FOG from becoming the problem experienced in recent nights. The rain will end from west to east Wednesday morning, followed by clearing skies and slightly drier AIR behind the cold front. Temperatures will return to near average on Wednesday. && .MARINE...Winds and SEAS will be on the increase rest of tonight with a period of ADVISORY level conditions starting west to east. These conditions should continue through Wednesday Afternoon before diminishing. && .AVIATION... Cold front will approach and begin to cross the area through the NIGHT. Large expanse of light to moderate rain has been impacting KECP...KTLH...and KVLD the past FEW hours with generally periods of MVFR cigs/VIS. Appears this main area of rain will be pushing east by the early morning hours, however anticipate another round of showers and a few thunderstorms to move through associated with the actual cold front. Therefore rain will be in the forecast through the majority of the night for all terminals. Expect a gradual lowering of the cigs through the overnight with widespread MVFR and tempo IFR conditions after midnight. Cold front will cross KDHN and KECP during the late night hours, and the remaining eastern terminals during the first few daylight hours of Wednesday. Anticipate a few hours of MVFR cigs post-frontal, followed by conditions improving to VFR for the afternoon hours.