12AM 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.
Discussion
A strong shortwave trough and attendant speed max over the Ohio Valley at the start of the period will quickly dig east/southeast during the day on Sunday, before pivoting north toward southern New England overnight. At the surface, a low, initially over the coastal waters of North Carolina, will deepen through the day as strong large-scale ascent increases with the approaching shortwave trough. The rate of deepening of the surface low will only increase overnight as the shortwave trough takes on a neutral to negative tilt and large-scale ascent increases further.
As the surface low deepens along the coast, the intensifying warm conveyor belt to the north and west of the low, drawing warm, moist Gulf Stream air inland. The combination of strong large-scale ascent, strong low-level warm-air advection, and cooling mid-level temperatures may result in enough elevated instability to support a few lightning strikes within the warm conveyor belt as the low lifts northward along the coast.
Farther south and west, the deepening surface low will drive a cold front south across the Florida Peninsula. Surface temperatures in the 70Fs and dewpoints in the low-to-mid 60Fs may support a narrow ribbon of most-unstable CAPE between 500 and 1000 J/kg ahead of the southward advancing front. As a result, showers and a few thunderstorms may develop along and ahead of the front. Forecast soundings show pronounced mid-and-upper-level warming, which will limit the overall instability and a more robust lightning threat.
Across the West, strong ascent and some moisture advection associated with the next upper-trough may lead to very isolated lightning strikes along and off the Pacific Northwest coast. However, coverage should remain sparse enough to preclude the need for delineation.