SPC Increases Slight Risk For Severe Storms For Today

From the Storm Prediction Center…

The main threat for severe weather today should be with damaging gusts and a few tornadoes, in a band of thunderstorms crossing parts of Alabama, Georgia and the Florida Panhandle.

A prefrontal band of strong-severe thunderstorms is expected to continue to pose a threat for sporadic damaging gusts and a few tornadoes as it moves eastward across the outlook area, this morning into parts of the afternoon.

Recent lightning and radar-reflectivity trends have indicated a general lessening of organization from north to south, with a consolidation of lightning production nearer to the coast. This is consistent with the weak lapse rates evident in the 12Z BMX sounding, and southward increase in theta-e in the warm sector, with surface dew points decreasing eastward. Theta-e advection in the warm sector, and diffused diabatic heating under the anvil canopy over land, will lead to a slight increase in buoyancy in support of slight to marginal severe-wind and tornado potential across the outlook area through the afternoon, amidst large low-level and deep-shear vectors. Late this afternoon into the evening hours, the prefrontal convection should encounter weakening of both low-level lapse rates and convergence over portions of southern GA and the eastern FL Panhandle. Accordingly, the severe probabilities should diminish eastward and with time from mid/late afternoon into evening, though isolated damaging gusts or a tornado cannot be ruled out amidst favorably strong deep shear.

LATER THIS AFTERNOON AND INTO THE EVENING HOURS
A narrow, relatively shallow band of convection also may form this afternoon along the cold front farther northwest and west over portions of OH, central/eastern KY, middle-eastern TN, and AL, where low-level lift will be maximized near and south of the surface low. Strong/isolated damaging gusts cannot be ruled out as this activity moves eastward to northeastward, but severe potential currently appears too conditional and isolated for a categorical outlook. This activity will be embedded within strong deep-layer wind fields ahead of the synoptic trough, but also, very weak surface-based instability, with air-mass recovery very uncertain behind the morning convective/precip band. Forecast soundings suggesting MLCAPE staying under 300 J/kg in most areas north of AL, and weakening/more-shallow lift with southern extent over AL. If mesoscale trends show boundary-layer recovery and/or frontal lift more robust than currently expected, some parts of this corridor may need to be included in a marginal wind area in a later update.

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