SPC AC 230544
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1244 AM CDT Fri Mar 23 2018
Valid 231200Z - 241200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE CENTRAL U.S....
Strong thunderstorms may impact portions of the Central Plains
vicinity this evening/overnight. A few of these could be
accompanied by a risk for hail this evening.
Very slow progression of the upper pattern across the U.S. is
expected this period, with troughs affecting the west and east
coasts and a ridge over the center of the country. The main feature
with respect to stronger thunderstorm activity will be a
smaller-scale wave shifting quickly northeast across the Four
Corners area/southern Rockies and into the Plains during the second
half of the period.
At the surface, a lee low over Colorado early is forecast to advance
east across Kansas as the upper wave approaches the Plains, with a
warm front extending east-southeast across the Ozarks through the
period. Elsewhere, a cold front is forecast to cross the Great
Basin ahead of the main western upper trough, while high pressure
prevails over most of the eastern states through Saturday morning.
...Portions of the Central Plains/mid Missouri Valley...
Showers and a few thunderstorms are forecast to evolve during the
afternoon across northeast Colorado and the Nebraska Panhandle
vicinity, with convection increasing/expanding eastward with time,
within a zone of warm advection north of the surface low/warm front
across Kansas. With the warm-sector boundary layer expected to
remain capped, convection will be confined to the zone of elevated
instability north of the baroclinic zone.
While rather modest CAPE is generally expected, moderate mid-level
westerlies will provide sufficient shear in the cloud-bearing layer
to support a few stronger storms. With marginally severe hail
possible, will maintain a 5% hail area straddling the
Nebraska/Kansas border and extending into southwest Iowa/northwest
Missouri into the overnight hours.
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z