Severe Storm Outlook Narrative (AC)
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ACUS48 KWNS 200913
SPC AC 200912

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0312 AM CST Mon Feb 20 2017

Valid 231200Z - 281200Z

Medium-range deterministic models continue to show good run-to-run
consistency in their depiction of a powerful speed max ejecting into
the Great Plains on Thursday (Day 4) and subsequently moving
downstream into the OH Valley and southern Great Lakes on Friday
(Day 5).  A deep surface cyclone will develop northeastward from the
central Great Plains to the southwestern Great Lakes vicinity on
Friday.  Models show the advection of an elevated mixed layer and a
dryline into IL with a cold front eventually overtaking the boundary
and rapidly surging east-northeast.  This outlook has accounted for
possible diurnal warm-sector development near the surface low and
the possibility for a strongly forced squall line posing a risk for
damaging winds.  Models variability increases by Sunday (Day 7) and
Monday (Day 8) on the evolution of a possible disturbance moving
eastward from the southern Great Plains and affecting parts of the
MS Valley during this timeframe.

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