678
ACUS11 KWNS 211835
SWOMCD
SPC MCD 211834
CAZ000-212030-
MESOSCALE DISCUSSION 0494
NWS STORM PREDICTION CENTER NORMAN OK
0134 PM CDT TUE APR 21 2026
AREAS AFFECTED...PORTIONS OF THE SACRAMENTO AND SAN JOAQUIN VALLEYS
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 211834Z - 212030Z
PROBABILITY OF WATCH ISSUANCE...20 PERCENT
SUMMARY...A FEW STRONGER STORMS ARE POSSIBLE THIS AFTERNOON ACROSS
PORTIONS OF THE SACRAMENTO AND SAN JOAQUIN VALLEYS. ISOLATED GUSTY
WINDS AND SMALL HAIL WILL BE THE MAIN HAZARDS, ALTHOUGH A TORNADO OR
TWO CANNOT BE RULED OUT.
DISCUSSION...A CLOSED UPPER-LEVEL LOW IS CURRENTLY LOCATED OFF THE
COAST OF NORTHERN CALIFORNIA, WITH A TROUGH AXIS EXTENDING
SOUTHEASTWARD ALONG THE COAST. THIS TROUGH AXIS IS CURRENTLY
PIVOTING NORTHEASTWARD -- PER CURRENT WATER VAPOR IMAGERY -- OVER
THE CENTRAL CALIFORNIA COAST. BROAD SYNOPTIC FORCING HAS YIELDED
EXTENSIVE SHOWERS STREAMING NORTHWARD ACROSS THE REGION, LIMITING
TEMPERATURES TO THE MID-50S. SOME CLEARING IS OCCURRING IN THE WAKE
OF THESE SHOWERS WITH TEMPERATURES INCREASING INTO THE LOW 60S
ACROSS THE WESTERN PORTION OF THE DELINEATED AREA.
AS THE EARLY-DAY SHOWERS AND CLOUDINESS MOVES EASTWARD, CONTINUED
INSOLATION AND ASCENT IN THE LEFT-FRONT QUADRANT OF THE LANDFALLING
JET WILL YIELD CONVECTIVE DEVELOPMENT. CURRENT MLCAPE VALUES ARE
MARGINAL (< 100-200 J/KG) BUT ARE EXPECTED TO INCREASE TO AROUND 500
J/KG THROUGH THE AFTERNOON. UPPER-LEVEL FLOW WILL BACK AND REMAIN
STRONG (AROUND 50 KTS AT CLOUD TOP), YIELDING LONG AND RELATIVELY
STRAIGHT WIND PROFILES. THIS SHOULD SUPPORT CONTINUED THUNDERSTORM
DEVELOPMENT THROUGH THE AFTERNOON AND EVENING. SOME STRONGER STORMS
ARE POSSIBLE, YIELDING AN ATTENDANT THREAT FOR SCATTERED GUSTY
WINDS. A TORNADO OR TWO IS POSSIBLE WITH ANY TRANSIENT SUPERCELL
STRUCTURES, ALTHOUGH THIS THREAT WILL BE LIMITED BY GENERALLY MEAGER
LOW-LEVEL SHEAR.
..FLOURNOY/LYONS/HART.. 04/21/2026
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...HNX...STO...MTR...
LAT...LON 36742057 37372148 38172157 38552105 38292048 37651964
37051917 36601915 36391992 36742057
MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH
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