SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0159 PM CST Sun Nov 01 2020 Valid 012000Z - 021200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS COASTAL NORTH CAROLINA... ...SUMMARY... Severe risk will gradually decrease over the next 1 to 2 hours across far eastern North Carolina and the Outer Banks, as storms move offshore. ...Discussion... As storms continue moving eastward across coastal North Carolina in conjunction with the advancing cold front, organization has been limited -- with storms primarily oriented in quasi-linear manner. Though limited/local risk for a stronger wind gust, or brief tornado/waterspout is still evident, this potential will diminish from west to east over the next couple of hours, as storms move offshore. Elsewhere, showers and a few embedded thunderstorms are ongoing across the Florida Peninsula ahead of the cold front, but any severe risk here would be isolated/minimal this afternoon. Finally, a few lightning flashes persist over portions of south-central Pennsylvania, the adjacent Maryland/West Virginia Panhandles. However, as convection crosses the ridges, downsloping suggests that lingering lightning should further diminish with time. As such, a thunder area will not be introduced for this region. ..Goss.. 11/01/2020 .PREV DISCUSSION... /ISSUED 1032 AM CST Sun Nov 01 2020/ ...Eastern North Carolina/coastal southeast Virginia... Large-scale trough amplification will continue to occur today into tonight over the Great Lakes/Ohio Valley toward the Eastern Seaboard. Low-level moisture characterized by low/mid 60s F surface dewpoints continues to increase/stream northward across coastal North Carolina ahead of increasingly organized convection near/ahead of a wind shift and sharpening front. Short-term anticipations are that a low-topped quasi-linear convective line (much of it with little or no lightning flashes) will continue to evolve early this afternoon across east-central/northeast North Carolina into coastal southeast Virginia, with the possibility that semi-discrete thunderstorms will precede this band across the immediate coast of North Carolina (within 50-70 miles of the Atlantic). MLCAPE may briefly reach 500-1000 J/kg before convection spreads offshore by early evening. Low-level hodographs will become increasingly enlarged as a swath of 40-45 kt 850-mb winds shift east and overlap the confined warm sector ahead of the leading cold front. Locally damaging convectively enhanced winds will be a concern with the linearly organized convection or the convection preceding it. Given that 0-1 km SRH appears likely to reach 150-250 m2/s2, a supercell or two capable of producing a tornado will also be possible mainly across far eastern North Carolina including the Outer Banks. ...Central Florida... Slow-moving thunderstorms are occurring late this morning about 50 miles west of the west-central Florida coast, with other showers/few thunderstorms also occurring near the east-central Florida coast. Modest destabilization will support development across/into other parts of the interior. While gusty thunderstorm winds may occur, poor mid-level lapse rates and minimal deep-layer/low-level shear will likely preclude an organized severe risk.
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