868
ACUS01 KWNS 211553
SWODY1
SPC AC 211551
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1051 AM CDT TUE APR 21 2026
VALID 211630Z - 221200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
OVER THE CA CENTRAL VALLEY...AND OVER PORTIONS OF NORTHERN IL/IN...
..SUMMARY
ISOLATED STRONG THUNDERSTORMS ARE POSSIBLE IN THE CALIFORNIA CENTRAL
VALLEY, CAPABLE OF GUSTY WINDS AND PERHAPS A TORNADO OR TWO. OTHER
STRONG STORMS ARE POSSIBLE IN PARTS OF NORTHERN IN/IL WHERE GUSTY
WINDS MAY OCCUR.
..CENTRAL CA
MORNING WATER VAPOR LOOP SHOWS A WELL-DEFINED SHORTWAVE TROUGH
APPROACHING THE COAST OF CENTRAL CA. AN ASSOCIATED MID/UPPER LEVEL
JET WILL NOSE INTO CA, WITH FORCING FOR ASCENT IN THE LEFT-FRONT
QUADRANT OF THE JET AIDING IN THE DEVELOPMENT OF AFTERNOON/EVENING
THUNDERSTORMS OVER PARTS OF THE CENTRAL VALLEY. FORECAST SOUNDINGS
SHOW STEEP LOW AND MID LEVEL LAPSE RATES AND SUFFICIENT CAPE FOR A
FEW ROBUST UPDRAFTS. VERTICAL SHEAR WILL BE STRONG ENOUGH FOR
SUPERCELL STRUCTURES, INCLUDING A RISK OF A TORNADO OR TWO, SMALL
HAIL, AND GUSTY WINDS.
..NORTHERN IN/IL
A FAST-MOVING SHORTWAVE TROUGH CURRENTLY OVER IA/MN WILL TRACK
QUICKLY SOUTHEASTWARD INTO WI/IL/IN THIS AFTERNOON. VISIBLE
SATELLITE AND RADAR IMAGERY SHOW A LINE OF HIGH-BASED THUNDERSTORMS
DEVELOPING AHEAD OF THE TROUGH OVER SOUTHERN WI. AS THESE STORMS
TRACK INTO NORTHERN IL/IN, CONTINUED HEATING/WEAK DESTABILIZATION
WILL INCREASE THE RISK OF GUSTY/LOCALLY DAMAGING WIND GUSTS AND
SMALL HAIL IN THE STRONGEST CORES THIS AFTERNOON.
..HART/FLOURNOY.. 04/21/2026
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