Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0751 AM CDT Wed Sep 06 2017 Valid 061300Z - 071200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE EASTERN CAROLINAS INTO SOUTHEAST VIRGINIA... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE EASTERN STATES... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN CA/NORTHWEST NV AND WESTERN OR... ...SUMMARY... Isolated severe thunderstorms are possible today into this evening across portions of the Mid-Atlantic States and Southeast, parts of southern New England, and also across portions of the northern Sierra Nevada into western Oregon. ...Eastern States... A prevalent longwave trough over the eastern half of the CONUS will continue to shift eastward today with height falls continuing along much of the eastern seaboard coincident with some additional strengthening of deep-layer southwesterly winds. Diurnal destabilization and ascent atop an east/southeastward-moving front, which largely parallels the I-95 corridor, will contribute to increasing thunderstorms into this afternoon, some of which will be strong to locally severe. Initially, a strong storm or two could graze outer portions of Long Island this morning and otherwise develop into southern New England relatively early today. Meanwhile, a somewhat more focused severe risk is expected to materialize farther south this afternoon across Piedmont and coastal portions of the Carolinas into southeast VA near the eastward-advancing front. Modest cloud breaks noted in early morning satellite imagery may allow for somewhat stronger insolation/heating in these areas with thunderstorms gradually increasing in coverage and intensity this afternoon. Aforementioned increasingly strong deep-layer southwesterly winds will support the evolution of prevalent clusters and evolving line segments with wind damage as the most probable severe hazard. Although a few transient supercells could occur before linear transitions, relatively weak mid-level lapse rates, with cooler air aloft tending to lag the front to the west, should limit large hail potential. ...Northern Sierra Nevada/Western Oregon... An upper low off the northern CA coast this morning will continue to gradually spread eastward toward the coast through the afternoon and evening with height falls and strengthening winds aloft overspreading the northern Sierra Nevada vicinity and western OR. In conjunction with a warming and destabilizing boundary layer, a convectively active day is expected in response. Forecast soundings for this region suggest ample instability and steep lapse rates necessary for the production of hail and gusty winds. ..Guyer/Broyles.. 09/06/2017Read more
from SPC Forecast Products http://ift.tt/rATNzD
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