Severe Storm Outlook Narrative (AC)
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ACUS02 KWNS 190701
SPC AC 190700

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CST Mon Feb 19 2018

Valid 201200Z - 211200Z


Thunderstorms are forecast to occur from the southern Plains
northeast to the Great Lakes on Tuesday.

A highly amplified flow field aloft will continue across the U.S.
Tuesday and Tuesday night, with the long-wave pattern remaining
fixed/quasi-stationary.  At smaller scales, short-wave troughing
embedded within southwesterly flow ahead of the main upper trough
will shift northeastward across the Plains, while on the back side
of the main trough, a second short-wave feature will dig south
across the eastern Pacific/West Coast states/Great Basin.

At the surface, cold air will surge southeast across the Plains and
east across the upper Midwest/Upper Great Lakes region.  At the
leading edge of this polar air intrusion, the advancing cold front
should reach a position extending from Ohio southwest to southern
and eastern Texas by 21/12z (Wednesday morning).

Showers and thunderstorms will accompany the cold frontal advance,
with weak instability limiting overall lightning coverage with
northward extent.  Farther south, greater thunderstorm coverage is
expected -- largely elevated in an anafrontal scenario.  While more
appreciable warm-sector instability will exist over Texas, afternoon
capping should hinder appreciable surface-based convective risk.
This -- plus relatively modest elevated instability expected behind
the front -- suggests that any severe risk should remain quite
limited at best.  As such, even a low-probability risk area will not
be included at this time.

..Goss.. 02/19/2018

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