SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1040 AM CST Sat Jan 02 2021 Valid 031200Z - 041200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for thunderstorms appears negligible across much of the U.S., Sunday through Sunday night. ...Discussion... Within one branch of split westerlies emanating from the mid-latitude eastern Pacific, it appears that general large-scale mid-level troughing will undergo substantive evolution, broadening while shifting east of the southern Great Plains through the Atlantic Seaboard. As it translates eastward, initially prominent mid-level subtropical ridging centered over the Caribbean and Bahamas will become increasingly suppressed through this period. As a couple of short wave perturbations embedded within this regime progress across and dig to the lee of the Rockies, one significant downstream impulse, emerging from the southern Great Plains, is forecast to accelerate across the Ohio Valley through the northern Mid Atlantic/southern New England coast vicinity Sunday through Sunday night. Models indicate that this will support significant surface cyclogenesis along a frontal zone across and northeast of the southern Mid Atlantic coast. While the warm conveyor of this developing system may emanate from the southern Gulf of Mexico, it appears that it will be confined to a narrow plume across the Florida Peninsula into areas near or just east of the southern Mid Atlantic coast by 12Z Sunday, before continuing to spread eastward. In the wake of this cyclone, generally dry and/or stable conditions are expected to prevail across most areas east of the Rockies, and into the Intermountain West. A plume of moist air emanating from the subtropical Pacific does appear likely to overspread the Pacific coast (from central California northward), ahead of a cold front trailing a deep, occluding cyclone migrating toward the British Columbia coast. However, relatively warm mid level air on the western flank of building mid-level ridging shifting inland of the Pacific coast is expected to preclude an appreciable risk for thunderstorms through at least this period. ...Southeast... Showers are possible Sunday within the narrow plume of moisture overspreading the Florida Peninsula. However, it appears that this will be mostly elevated above a stable boundary-layer, with relatively warm layers aloft suppressing potential for thunderstorms, By 12Z Sunday, model output generally suggests that the primary risk for thunderstorm activity will be within the moist unstable boundary layer off the North Carolina coast, However, weak elevated instability may linger ahead of the developing surface low near coastal areas, perhaps providing support for convection capable of producing a flash or two of lightning early Sunday. ..Kerr.. 01/02/2021
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