Severe Storm Outlook Narrative (AC)
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ACUS48 KWNS 220959
SPC AC 220957

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0357 AM CST Wed Feb 22 2017

Valid 251200Z - 021200Z

The upper-air pattern during the extended period will initially
feature a strong shortwave trough over the Mid-Atlantic states
northward into the Northeast U.S.  A low CAPE/high shear setup will
likely develop for a portion of the aforementioned area but
predictability of if/where a severe risk may develop is uncertain at
this time.  A large area of surface high pressure centered over the
MS Valley will preclude the development of severe thunderstorms east
of the Rockies for Sunday (Day 5).  A lee trough becomes more
pronounced by Monday (Day 6) but moisture modification over the
northwest Gulf basin will likely still be ongoing and this casts
considerable doubt about potential for organized severe
thunderstorms over the south-central U.S.  Medium-range models show
the development of an upper trough over parts of the western states
with it moving into the central states during the Tuesday-Wednesday
(Days 7-8) period.  Model variability lends predictability-too-low
concerns with any possible risk for severe thunderstorm development
for Tuesday-Wednesday.

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