Day 1 Severe Weather Outlook

Valid 270100Z – 271200Z


Showers and isolated thunderstorms may contribute to potential for
locally damaging wind gusts tonight across parts of the Mid Atlantic
coast region. Isolated strong to severe storms also remain possible
across parts of the southern Florida Peninsula.

…01Z Outlook Update…

…Mid Atlantic Coast region…
As a 110 kt 500 mb jet streak noses northeastward to the lee of the
southern Appalachians, 27/00Z surface analysis suggests that a
secondary surface low may be in the process of forming near
Charlotte VA. Spread has been evident within the various model
output concerning this feature, but the latest Rapid Refresh suggest
that it may migrate northeastward toward the Washington D.C. area,
before more rapid deepening takes place after 03-04Z, southeast/east
of Washington D.C., through New Jersey and southeast New York state
by 12Z. The most substantive strengthening of southerly low-level
wind fields will await the more rapid surface deepening. This could
include 40-50 kt at 850 mb, but this may be mostly near/east of
northern Mid Atlantic coastal areas into New England.

Potential for even very weak warm sector boundary-layer
destabilization appears limited (north of the eastern North Carolina
coastal plain), and may be confined to southeastern Virginia into
the Delmarva Peninsula this evening, just ahead of the eastward
surging cold front in the wake of the low. This seems to offer the
best potential for convection which could aid the downward transfer
of higher momentum to the surface and contribute to localized
potentially damaging surface gusts.

To the west and north of the developing surface low, from the lee of
the Blue Ridge into south central and southeastern Pennsylvania,
despite the strong mid/upper-level wind fields, relatively modest
speeds in the lowest 3 km AGL (30-40 kt) and a lingering stable
layer near the surface may mitigate the potential for convectively
enhanced surface gusts.

…Southern Florida…
Forcing to support further intensification of the ongoing
pre-frontal line of thunderstorms (now southeast of Fort Myers and
Vero Beach) remains unclear. However, the boundary layer ahead of
the southeastward advancing line remains weak to modestly unstable
in the presence of strong deep layer shear, and it may remain
conditionally supportive of isolated strong to severe storm
development through 03-06Z.

..Kerr.. 02/27/2020


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