SPC AC 210522
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1222 AM CDT Tue Mar 21 2023
Valid 221200Z - 231200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM FAR
NORTHEAST KANSAS ACROSS NORTHERN MISSOURI AND INTO FAR SOUTHEAST
IOWA AND WEST-CENTRAL ILLINOIS...
Strong to severe thunderstorms capable of large hail are possible
from far northeast Kansas across northern Missouri and into far
southeast Iowa and west-central Illinois late Wednesday evening.
...Synopsis and Discussion...
Upper troughing is forecast to extend across the western CONUS
early Wednesday morning, with more zonal flow across central and
eastern CONUS. A belt of strong southwesterly flow aloft will extend
from the base of the upper trough over southern CA northeastward
through the central Plains. A low-amplitude shortwave trough will
move quickly northeastward within this belt of southwesterly flow
from southern CA through the Four Corners, central Rockies and
central Plains. A strong jet streak, characterized by 100 kt flow at
500 mb, will accompany this shortwave.
At the surface, robust low-level moisture advection will already be
underway early Wednesday morning. This moisture advection is
expected to continue throughout the day amid lowering pressure
across the central Plains and persistent southerly low-level flow.
By Wednesday evening, the surface pattern will likely feature a low
near the central CO/KS border, with a stationary front extending
eastward from this low to another weaker low over northern MO. Low
60s dewpoints may reach as far north as the Kansas City vicinity,
with mid 60s dewpoints remaining farther south across in the
Southerly low-level flow will strengthen across OK, KS, and MO
Wednesday evening, in response to the shortwave moving through NE.
This will increase warm-air advection across the frontal zone, which
is expected to result in elevated thunderstorm development from
northern MO into central IL late Wednesday evening. Steep mid-level
lapse rates and strong mid-level flow will support robust updrafts
capable of hail. The severe threat is greatest with the initial
development during the late evening, but thunderstorms will likely
persist into Thursday morning eastward/northeastward into more of
IN, OH, and southern Lower MI.
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NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z