Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Mon Apr 17 2023 06:02:12

ACUS02 KWNS 170602
SWODY2
SPC AC 170600

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Mon Apr 17 2023

Valid 181200Z - 191200Z

....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE GREAT PLAINS...

....SUMMARY...
Thunderstorms associated with hail, and perhaps a few strong wind
gusts will be possible in parts of the Great Plains Tuesday and
Tuesday night.

....Central and Northern Plains/Mid Missouri Valley...
An upper-level ridge will shift eastward from the central and
northern Plains on Tuesday to the mid to upper Mississippi Valley on
Tuesday night. At the surface, a lee trough in the High Plains will
deepen during the day, with a low consolidating and moving eastward
into the central Plains during the afternoon and evening. In
response to southwesterly mid-level flow, a broad low-level jet will
gradually strengthen in the central and northern Plains. Instability
in the central and northern Plains will increase, especially in the
mid-levels. By early to mid evening, convective initiation will be
possible on the western edge of the low-level jet across western
South Dakota and western Nebraska. This convection is forecast to
move eastward into strengthening low-level flow during the evening
into the overnight. Forecast soundings at 06Z from Sioux Falls to
Omaha have MUCAPE around 2000 J/kg, with effective shear generally
from 40 to 50 knots, and 700-500 mb lapse rates in the 8.5 to 9.5
C/km range. This should be favorable for isolated large hail with
elevated rotating storms. Due to a relatively strong boundary-layer
temperature inversion, the wind-damage threat is expected to be
minimal.

....Southern Plains...
An upper-level ridge in the southern Plains on Tuesday will move
eastward into the lower to mid Mississippi Valley Tuesday night. At
the surface, a dryline will become well-defined during the day, as
low-level moisture increases across much of the southern Plains. A
strong capping inversion (CIN near -200 J/kg) during the morning and
early afternoon will likely prevent convective initiation for most
of the day. The cap may weaken enough to allow a cell or two to
initiate in the 23Z to 01Z time-frame. NAM forecast soundings to the
east of the dryline at 00Z, have MLCAPE mostly in the 1000 to 2000
J/kg range, with 0-6 km shear of 30 to 40 knots, and 700-500 mb
lapse rates in the 8.0 to 8.5 C/km range. This would be favorable
for a severe threat, if deep convection can develop. Isolated large
hail and wind-damage would be the primary threats. The isolated
severe threat would likely diminish quickly in the evening, as the
cap strengthens.

...Broyles.. 04/17/2023

$$

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