DAY48 Day 4 Severe Risk
From
Mike Powell@618:250/1 to
All on Fri Mar 28 09:11:00 2025
ACUS48 KWNS 280910
SWOD48
SPC AC 280909
Day 4-8 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
0409 AM CDT Fri Mar 28 2025
Valid 311200Z - 051200Z
...DISCUSSION...
Widespread storms and at least some attendant severe risk will be
ongoing at the start of the Day 4 period (Monday March 31) -- with
the band of convection likely extending along the west slopes of the Appalachians initially. Diurnal destabilization along and east of
the mountains remains a question, particularly with northward extent
into the Northeast, and thus the northern periphery of the risk area
remains in question -- in what will likely be a very low CAPE/high
shear environment -- suggestive of damaging gusts being the primary
concern over northern portions of the area.
Farther south, greater CAPE is expected, particularly from the
Carolinas into the central Gulf Coast states. Here, an all-hazards
risk is forecast to continue from the Day 3 period into Day 4.
Storms/severe risk will shift eastward with time, crossing the East
Coast states through the afternoon and evening, before clearing the
coast overnight.
Day 5/Tuesday looks to be a relative down day in terms of severe
potential, with moisture beginning to return northward into the
central U.S. ahead of the next system.
Day 6/Wednesday, moisture will continue returning northward across
the central U.S., though substantial differences in timing/evolution
of the upper system exists between the (slower) ECMWF and (faster)
GFS. However, the GEFS ensemble mean is slower than the operational
GFS, not quite as slow as but more in line with the ECMWF -- and the
Euro ensemble mean. Given this, confidence is high enough to
proceed with introduction of a broad -- though areally uncertain --
15% area. This system would appear to have the potential to produce
another fairly widespread/all-hazards severe event, but will likely
require a good bit of adjustment over the next few days.
Beyond Day 6, confidence in evolution of the large-scale features
diminishes further, due to the aforementioned differences between
operations runs of the global models. As such, no areas will be
delineated beyond Day 6.
..Goss.. 03/28/2025
$$
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