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 Forecast Discussion

  
000
ACUS01 KWNS 290052
SWODY1
SPC AC 290051

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0751 PM CDT Fri Apr 28 2017

Valid 290100Z - 291200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM THE
SOUTHERN PLAINS TO THE OZARK PLATEAU...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF
THE SOUTHERN PLAINS TO THE OH VALLEY...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE EASTERN
TX PANHANDLE TO WESTERN MD...

...SUMMARY...
Scattered severe thunderstorms are expected to concentrate near the
Ohio River from southern Illinois to southern Ohio this evening and
across the southern Great Plains and Ozarks tonight. Large hail, a
few tornadoes, primarily across the southern Plains, and damaging
winds are anticipated.

...Evening Update...

Severe thunderstorms have struggled to organize across the OH Valley
in the presence of significant large-scale mid-level height rises. 
However, a long-lived cluster of mostly weak convection has migrated
across IL into IN/OH where storms have gradually strengthened,
especially along the southern fringe of this precip shield near the
OH River.  00Z soundings across this region exhibit strong veering
wind profiles with height and a modestly unstable air mass primarily
across the lower OH River Valley.  ILN sounding was not particularly
unstable but BNA was quite moist/unstable with MUCAPE on the order
of 3000 J/kg.  Primary negative for significant organized severe
thunderstorms across the OH Valley tonight will be the meager
large-scale forcing for ascent.  Even so, scattered severe storms
remain possible and have focused severe probs near the OH River
along southern fringe of aforementioned MCS where greater buoyancy
will overlap with higher concentration of storms.

Strong forcing for ascent is beginning to spread across the southern
Great Plains from NM into southwest KS.  Mid levels are moistening
significantly across this region and precipitation is
spreading/developing rapidly atop cool boundary layer.  Earlier
thoughts regarding the convective evolution over the southern Plains
remain.  Low-level warm advection should increase over the next few
hours and a marked increase in thunderstorms is expected near the TX
Panhandle/OK border by mid-late evening.  This activity will spread
east along well-defined frontal zone draped along the I-44 corridor
with activity expected into the Ozark Plateau by sunrise Saturday.

..Darrow.. 04/29/2017

$$