225
ACUS01 KWNS 281942
SWODY1
SPC AC 281941
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0141 PM CST SAT NOV 28 2009
VALID 282000Z - 291200Z
..NO SVR TSTM AREAS FORECAST
NO CHANGES FOR THE 20Z OUTLOOK.
..BROYLES.. 11/28/2009
PREV DISCUSSION
/ISSUED 1022 AM CST SAT NOV 28 2009/
..SYNOPSIS
DEEP CLOSED UPPER LOW OVER SRN CA IS FORECAST TO CONTINUE SLIDING
SEWD ACROSS THE CO RIVER VALLEY BY THE END OF THE FORECAST PERIOD. A
POCKET OF COLD AIR /AROUND -25 DEG C AT 500 MB/ ACCOMPANYING THE
CLOSED LOW WILL MAINTAIN A STEEP LAPSE RATE ENVIRONMENT ABOVE A
MODESTLY MOIST BOUNDARY LAYER AIRMASS OVER COASTAL AREAS OF SRN
CA...RESULTING IN A CONTINUED CHANCE FOR ISOLATED THUNDERSTORMS
THROUGH THE AFTERNOON AND EVENING. FARTHER EAST...A THICK LAYER OF
MID/UPPER LEVEL CLOUDINESS ASSOCIATED WITH WARM CONVEYOR
BELT/SUBTROPICAL MOISTURE FEED IS STREAMING E-NEWD ACROSS AZ/NM.
HOWEVER...PRONOUNCED DRY SLOT OBSERVED IN WV IMAGERY ACCOMPANIED BY
120+ 250 MB JET STREAK /AS DEPICTED IN SHORT TERM MODEL GUIDANCE/
ARE EXPECTED TO MOVE ACROSS AZ DURING THE AFTERNOON.
FAVORABLE UPPER LEVEL DIVERGENCE/LARGE SCALE ASCENT WITHIN THE LEFT
EXIT REGION OF THE SRN STREAM JET COMBINED WITH BOUNDARY LAYER
HEATING BENEATH THE CLEAR SLOT AND COLD MID LEVEL AIR SPREADING EWD
FROM THE CLOSED LOW WILL ACT TO DESTABILIZE THE ATMOSPHERE AND
RESULT IN INCREASING STORM DEVELOPMENT AND COVERAGE OVER AZ...WHICH
WILL EVENTUALLY SPREAD EAST INTO NM DURING THE EVENING/OVERNIGHT.
MORNING SURFACE OBSERVATIONS INDICATE SLIGHTLY HIGHER DEWPOINTS /30S
TO LOW 40S/ OVER THE SRN HALF OF AZ...WHICH WILL AID IN THE
DEVELOPMENT OF MUCAPE VALUES AS HIGH AS 500 J/KG AS TEMPERATURES
CLIMB THROUGH THE 60S. THIS INSTABILITY COMBINED WITH STEEP MID
LEVEL LAPSE RATES AND STRENGTHENING DEEP LAYER SHEAR VALUES MAY
FAVOR SOME STORM ORGANIZATION AND A MARGINAL HAIL/GUSTY WIND THREAT.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page