Severe Storm Outlook Narrative (AC)
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000
ACUS48 KWNS 241001
SWOD48
SPC AC 240959

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CST Wed Jan 24 2018

Valid 271200Z - 011200Z

...DISCUSSION...
The last two runs of the ECMWF are in greater agreement with the
last several runs of the GFS with keeping the evolution of the D1-D3
Pacific trough progressive and less amplified as it advances east of
the Great Plains beginning on D4/Saturday.  Each model also
amplifies this trough across the eastern U.S. during D5/Sunday, with
the ECMWF version of this trough not moving off the East coast until
after D6/Monday.  A transition from nearly zonal flow early
D7/Tuesday across the CONUS to a highly amplified pattern is
indicated by the ECMWF/GFS through D8/Wednesday.  This evolution
should occur as the next northeast Pacific cyclone moves inland and
amplifies across the Intermountain West, Rockies, Great Plains to
the upper MS Valley during D8.

...D4/Saturday...
The surface ridge extending westward across the Gulf Coast region on
D3 will persist into the central Gulf Coast states on Saturday,
further limiting the inland return of Gulf moisture.  While
thunderstorms will be possible from the northwest Gulf Coast region
including part of the lower MS Valley, relatively greater
instability is expected to remain offshore, precluding a
severe-weather threat.

...D5/Sunday...
A cold front will move east through the eastern states and into FL
as the aforementioned trough amplifies east of the Great Plains,
with some thunderstorms possible across mainly FL.  Weak lapse rates
and meager instability will preclude a severe-weather threat.

...D6/Monday and D7/Tuesday...
Offshore flow into the Atlantic and Gulf of Mexico as a large
surface anticyclone builds east from the Plains will shunt
substantial moisture and available instability well east and south
of the contiguous United States.  This will preclude any
severe-weather threat.

..Peters.. 01/24/2018



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