Severe Storm Outlook Narrative (AC)
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ACUS48 KWNS 210958
SWOD48
SPC AC 210956

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0356 AM CST Wed Feb 21 2018

Valid 241200Z - 011200Z

...DISCUSSION...
A significant shortwave trough will eject northeast through the
central Plains and middle MS Valley region (Day 4) Saturday and
Saturday night. Some deamplification is expected, but the trough
will take on a more negative tilt as it approaches the middle MS
Valley. GFS is still the stronger solution with deeper cyclogenesis
and suggests potential for a slightly more robust severe threat. In
either case a forced line of potentially strong to severe storms
might evolve in vicinity of cold front initially over northeast TX,
before spreading into the lower MS and TN Valley regions as the
low-level jet strengthens and shifts northeast through moistening
warm sector. While vertical shear and overall character of the wind
profiles should be more than adequate for organized severe storms,
primary limiting factor appears to be a marginal thermodynamic
environment given likelihood of widespread clouds and weak lapse
rates.

Some severe threat might linger into Sunday (day 5) over a portion
of the Middle Atlantic, but confidence is not high enough at this
time to introduce a categorical area. Overall severe potential
should remain low day 6 into day 7 as a cold front settles into the
northern Gulf coastal area.

..Dial.. 02/21/2018



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