Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0229 AM CDT Sat Apr 01 2017 Valid 031200Z - 041200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS MONDAY ACROSS PARTS OF THE EASTERN GULF COAST STATES INTO SOUTHERN APPALACHIANS... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS SURROUNDING AREAS OF THE SOUTHEAST... ...SUMMARY... Severe thunderstorms are possible across parts of the Southeast on Monday. This is expected to include a risk for severe wind gusts, hail and perhaps a few tornadoes. ...Synopsis... Little change in the general large-scale pattern is expected into and through this forecast period. Another couple in a series of significant short wave perturbations, emanating from a strong mid-latitude Pacific jet before advancing inland, appear likely to remain progressive. The lead impulse is expected to accelerate northeast of the southeastern Plains/Sabine Valley by early Monday, accompanied by a deepening surface cyclone, into and through the Ohio Valley/Great Lakes region by late Monday night. This is expected to occur as an upstream impulse digs across the Four Corners region, and supports the initiation of surface cyclogenesis to the lee of the southern Rockies. In the wake of the lead system, some moisture return may commence across the lower Rio Grande Valley, but a substantive inland return flow of moisture appears unlikely during this period. Within the potentially broad warm sector of the eastern cyclone, guidance remains suggestive that richer inland boundary layer moisture return off the Gulf of Mexico may become cut off at some point, by some combination of considerable convective development across the northeast Gulf of Mexico or eastern Gulf Coast states, and an increasingly westerly component to the low-level flow across much of the Gulf Coast region. ...Southeast... Model output appears to be generally trending a bit farther to the north with the track of the lead impulse and associated surface cyclone, leading to increasing concern that a more substantive influx of moisture may spread farther inland across portions of Alabama and Georgia than previously anticipated. It appears that this could precede at least the remnants of a significant mesoscale convective system which may be ongoing at 12Z Monday, and in the process of advancing east of the lower Mississippi Valley. Guidance is unclear whether the primary severe weather potential will accompany continuation or re-intensification of this activity, or redevelopment in its wake. It appears possible that it could be some combination of the two scenarios, with a continuing risk for severe wind gusts/tornadoes with the initial line as it progresses across parts of eastern Alabama and the Florida Panhandle into parts of western Georgia during the day Monday before weakening. As stronger mid/upper forcing for ascent shifts northeast of the lower Mississippi Valley and Gulf Coast region, renewed strong/severe storm development may not be out of the question on its southern periphery, across the piedmont of Georgia into the Carolinas. Deep layer shear is likely to be sufficient to support organized severe storm development. However, potential for appreciable boundary layer destabilization appears to decrease to the north and northeast of the Georgia piedmont. ..Kerr.. 04/01/2017Read more
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