SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1219 PM CDT Sat Oct 31 2020 Valid 011200Z - 021200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN NORTH CAROLINA AND VICINITY... ...SUMMARY... A couple of strong/severe thunderstorms are possible over eastern North Carolina and far southeastern Virginia on Sunday. ...Synopsis... A strong upper trough crossing the Great Lakes/Mississippi Valley area through the beginning of the period/Sunday morning is expected to amplify further with time, while advancing eastward across the eastern half of the country. Meanwhile, west of the trough, ridging will prevail over the West. At the surface, a cold front -- trailing from a low near the Quebec/Ontario border area -- is forecast to be crossing the Great Lakes and Ohio/Tennessee Valleys early Sunday. The front will continue moving quickly eastward, crossing the Appalachians during the afternoon and reaching the coast by early evening, where a weak secondary low/frontal wave may develop along the boundary off the Mid Atlantic Coast, and shift northward along the New England Coast through the end of the period. ...Eastern North Carolina and Coastal Virginia... Some northward advection of low-level moisture off the Atlantic is expected to occur across the Mid Atlantic area and southern New England, ahead of the advancing cold front. As this occurs, minimal afternoon CAPE development is expected from coastal southern New England southward to the Chesapeake Bay area. More substantial CAPE development is expected farther south, from far southeastern Virginia across eastern North Carolina, as well as over parts of Florida. As a result, showers and scattered thunderstorms are expected to develop by late morning/midday across this region, spreading eastward and then shifting offshore in conjunction with frontal advance. Strong deep-layer southwesterly flow on the leading flank of the upper system will also overspread the region from west to east during the day. This increasing shear, across areas with ample CAPE, will support a few more vigorous storms -- particularly across the eastern North Carolina vicinity, where CAPE/shear combination is expected to be maximized during the early afternoon hours. As such, some risk for locally damaging wind gusts -- and possibly a brief tornado -- remains evident with a few of the strongest storms. Therefore, will maintain 5% wind probability/MRGL risk level across this region, until the front -- and associated convection -- move offshore through late afternoon. ..Goss.. 10/31/2020
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