Severe Storm Outlook Narrative (AC)
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000
ACUS48 KWNS 260859
SWOD48
SPC AC 260857

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0357 AM CDT Thu Apr 26 2018

Valid 291200Z - 041200Z

...DISCUSSION...
Models have trended toward better agreement regarding evolution of
overall synoptic-scale pattern through day 7. A large-scale trough
over the western states will continue to evolve days 4-5. Return of
more substantial moisture through the Plains should occur later day
5 (Monday) into day 6 as winds over the western Gulf veer to
southerly in wake of a large area of continental-polar high
pressure. Model consensus is that by day 6 (Tuesday) the western
trough will have taken on a positive tilt, while a series of
vorticity maxima eject northeast through the broad fetch of
southwesterly flow established over the plains. Plume of steep
mid-level lapse rates will advect into the central and southern
Plains above the moistening boundary layer contributing to moderate
to potentially strong instability, but also capping issues along the
dryline due to the warm elevated mixed layer. Greatest confidence in
storm initiation day 6 will be from triple point across north
central KS northeast along cold front into the upper MS Valley
region. However, isolated severe storms will be possible farther
south along dryline. By day 7 consensus is that a more substantial
shortwave trough will rotate through base of the synoptic trough and
into the southern and central Plains, suggesting a greater coverage
of severe storms along dryline.

..Dial.. 04/26/2018


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