SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0213 AM CDT Sun Sep 27 2020 Valid 291200Z - 301200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MID-ATLANTIC STATES... ...SUMMARY... Isolated severe thunderstorms are possible across portions of the Mid-Atlantic States on Monday. ...Synopsis... A deep upper trough is forecast to extend from Quebec into the Lower MS Valley early Tuesday morning. An upper low embedded within this larger trough is expected to gradually move from the middle MS Valley southeastward through the Southeast. Southerly mid-level flow will increase ahead of this low from GA through the Mid-Atlantic. Progression of this upper low will aid in the development of a modest surface low along a front initially extending from the Mid-Atlantic southwestward through the central FL Panhandle. This surface low will likely track northeastward along the front while the front gradually moves eastward. Some deepening of this surface low is possible, resulting in modest moisture advection amid southerly/southeasterly surface wind. This overall pattern evolution will place a modestly moist and unstable air mass across the Mid-Atlantic states ahead of the approaching cold front (and parent upper trough). Previously mentioned strengthening low to mid-level winds ahead of the approaching upper low atop modest southerly/southeasterly surface winds will contribute to at least moderate vertical shear. While some uncertainties remain, including the amount of destabilization as well as the strength of the surface low and frontal position, the environment appears likely to support at least low severe potential. Refinement to this outlook area are likely in subsequent forecasts. ..Mosier.. 09/27/2020
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