11AM Day 2 Convective Outlook for Sunday, February 22. NO SEVERE THUNDERSTORM AREAS FORECAST
SUMMARY
Thunderstorms will be possible across portions of the Florida Peninsula during the day on Sunday. Lightning may also occur across coastal areas from North Carolina north toward Massachusetts and over western Washington State. Severe weather potential is low.
Discussion
A mid-level trough over the lower Great Lakes is expected to rapidly intensify as several smaller perturbations merge with the main trough and western US ridging develops Sunday. A 100+ kt jet streak will round the base of the trough and move over the Atlantic coast through midday Sunday. Increasing large-scale ascent will aid in rapid cyclogenesis off the NC Coast. The resulting mass response will surge a cold front southward over portions of the FL Peninsula.
Ahead of the front, a narrow ribbon of most-unstable CAPE between 500 and 1000 J/kg should develop with daytime heating ahead of the southward advancing front. This may support convective showers and a few thunderstorms Sunday afternoon across portions of central and southern FL. However, warming/drying mid-levels and the departure of stronger mid-level forcing for ascent should tend to limit lightning coverage with southward extent into later Sunday
Across the Carolinas, mid Atlantic and southern New England coasts, intense surface cyclogenesis will support very strong low-level warm advection. The strong ascent may result in enough elevated instability (100-200 J/kg) and intense precipitation rates to support a few lightning strikes within the warm conveyor belt of the Nor'easter as the low lifts northward along the coast Sunday night into early Monday.
Across the West, strong ascent and some moisture advection associated with another upper-trough may support shallow convection along and off the coast of the Olympic Peninsula. While coverage should remain relatively low, cold mid-level temperatures and the strong ascent could support a few lightning flashes through Sunday evening.