Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1139 PM CST Fri Jan 20 2017 Valid 221200Z - 231200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE SOUTHEASTERN STATES... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE FL PANHANDLE TO EASTERN NC... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM AL TO SOUTHERN VA... ...SUMMARY... Widespread thunderstorms, primarily producing damaging winds and a few tornadoes, are expected across much of the southeastern US Sunday. ...Southeastern US... Latest NAM guidance is more in line with other short-range models in the evolution of a strong upper low as it shifts across the northern Gulf States and matures over the southern Appalachians during the latter half of the period. 110kt+ 500mb speed max is forecast to translate along the Gulf coast into northern FL/southern GA by 23/00z. This feature should encourage a surface low to develop and lift northeast into northern GA with subsequent deepening expected as the low moves into the western Carolinas after dark. This is a potentially significant evolution as a strong LLJ will transport moisture/instability well inland ahead of the strong upper system. Latest guidance suggests 12hr 500mb height falls will increase from 180m-240m late in the period and very strong forcing should assist a well-organized squall line that should develop early then race northeast ahead of the speed max. Very strong environmental shear is expected to contribute to damaging wind potential...especially with fast-moving bow-type structures. While a squall line appears to be the primary severe mode, there is some concern for tornadoes, especially if discrete structures develop ahead of the linear MCS. Farther south across the FL peninsula, while the strongest forcing will lift north of this region, substantial height falls and a secondary mid-level speed max will affect the southern peninsula late. Current thinking is a frontal squall line will easily develop and progress across the central/southern peninsula by daybreak Monday. Damaging winds are certainly possible with this convection, along with a few tornadoes. ..Darrow.. 01/21/2017Read more
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