Day 1 Severe Weather Outlook

Valid 221200Z – 231200Z


Thunderstorms capable of locally damaging winds and a tornado or two
are possible across parts of central and eastern North Carolina into
the Tidewater region of Virginia this afternoon into the early

…Southeast into the Mid Atlantic…
A deep upper trough covering much of the central/eastern CONUS is
expected to progress slowly eastward today. While the primary
occluding cyclone is expected to move from the Upper Great Lakes
into Ontario, a secondary frontal wave is expected to move from
Upstate SC this morning into the mid Atlantic this evening and
southern New England overnight. As this occurs, relatively rich
low-level moisture is expected to stream northward over portions of
the central/eastern Carolinas into the Tidewater region in advance
of a eastward-moving cold front.

While generally weak midlevel lapse rates will limit buoyancy across
the region, at least modest heating of an increasingly moist
environment may allow MLCAPE to rise into 500-1000 J/kg range from
southern VA into the eastern Carolinas, along and south of the track
of the aforementioned frontal wave. Intensification of ongoing
morning convection and/or renewed development during the afternoon
will result in some damaging wind potential, given relatively strong
low/midlevel flow. Locally enhanced low-level shear near the track
of the surface wave will support the potential for a tornado or two
as well.

…MT into the western Dakotas…
A vigorous shortwave trough over British Columbia this morning is
forecast move southeastward through the period. This feature will
begin approaching MT by late afternoon, moving into portions of the
northern Plains tonight. Despite cool temperatures and limited
low-level moisture, relatively steep low/midlevel lapse rates may
allow very weak surface-based buoyancy to develop over
central/eastern MT late this afternoon, in advance of the shortwave.
Strong unidirectional west-northwesterly flow will favor some
potential for strong wind gusts with any convection that can
develop. At this time, concerns regarding magnitude of available
buoyancy preclude the introduction of any severe wind probabilities.

..Dean/Squitieri.. 10/22/2019


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