SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1029 AM CST Sun Nov 15 2020 Valid 151630Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF OH AND THE NORTHEAST/MID-ATLANTIC STATES... ...SUMMARY... Strong to severe wind gusts will remain possible with low-topped showers and thunderstorms from the Lower Great Lakes to the Northeast and Mid-Atlantic States through early tonight. ...Lower Great Lakes to Mid-Atlantic/Northeast... Scattered thunderstorms are ongoing across southeast Lower MI into western OH with a history of widespread strong to isolated severe wind gusts. This initial activity may struggle to further intensify owing to boundary-layer dew points in the lower 50s within a narrow spatial corridor ahead of this convection. It should eventually outpace this narrow wedge of surface-based instability as it spreads east/north of Lake Erie later this afternoon. A more pronounced squall line is expected to develop around 21-23Z from central NY to central VA and sweep east-northeast across the Northeast and New England coast through early tonight within an intense shear/minimally buoyant environment. This squall should develop as the robust cold front impinges on low-level moisture advecting north from the Carolinas/South Atlantic Coast. Between 00-03Z, mid 50s boundary-layer dew points should reach as far north as eastern PA into southern New England along the track of secondary cyclogenesis. While low-level lapse rates will probably remain weaker relative to the Lower Great Lakes region, the comparatively richer low-level moisture should compensate. It is plausible that lightning generation may be confined to areas farther north amid scant elevated buoyancy and greater large-scale ascent. Nevertheless, the presence of a low-topped squall line amid 50-60 kt 925-mb winds suggest strong to severe wind gusts are possible even in the absence of lightning. As such, this region has been upgraded to Slight Risk. ..Grams/Dean.. 11/15/2020
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