Valid 262000Z – 271200Z
…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE MID ATLANTIC REGION…AND ACROSS PARTS OF FLORIDA…
A few storms may pose a risk for strong to damaging winds late this
afternoon and into this evening across the Mid-Atlantic States, and
across parts of central Florida this afternoon.
Aside from minor line adjustments, no changes appear necessary to
the ongoing outlook at this time. A weak band of convection is
ongoing over central Florida, with some attempts at storm
development farther south. However, warm temperatures aloft/weak
lapse rates suggest that convective intensity should remain
generally limited — and thus severe risk marginal.
Farther north, a forced convective band is expected to develop
across the Mid-Atlantic region ahead of the front — with initial
indications of this band’s development now indicated over the higher
terrain of the West Virginia vicinity. Despite fairly strong flow
aloft, very weak instability at best suggests only low-end risk for
.PREV DISCUSSION… /ISSUED 1005 AM CST Wed Feb 26 2020/
…Mid Atlantic Region…
Water vapor loop shows a large upper trough over the MS valley, with
a progressive shortwave trough rounding the base of the larger
system. This will lead to an increasingly negatively-tilted trough
and significant large-scale forcing spreading across the central
Appalachians and Mid Atlantic region later today/tonight. A line of
showers currently extends from southern OH into eastern KY/TN. This
line will move slowly eastward through mid-afternoon before
beginning to accelerate as the enhanced winds aloft arrive. By
early evening, a fast-moving narrow line of showers and isolated
thunderstorms is expected to track across portions of VA/MD into
southeast PA. Thermodynamic profiles are quite weak, and low-level
winds are considerably weaker than the case a couple of weeks ago.
Nevertheless, a few instances of gusty/damaging winds are possible
this evening until activity moves into stable surface conditions.
An area of thunderstorms has intensified during the past few hours
over the eastern Gulf of Mexico. These storms are ahead of a weak
upper trough and along a surface cold front. This activity will
move across the FL peninsula this afternoon and evening, with a
consensus of 12z CAM solutions suggesting that a few of the storms
will be organized. A few strong storms may also form ahead of the
line along the east coast. Forecast soundings show strong
deep-layer shear, but weak mid-level lapse rates and modest CAPE.
The primary mitigating factors are the veered and relatively weak
low-level winds, and patches of cloud cover which will limit daytime
heating/destabilization. Considered an upgrade to SLGT risk, but
will defer to later updates if trends warrant.