SWODY1
SPC AC 021252
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0752 AM CDT WED SEP 02 2009
VALID 021300Z - 031200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE CNTRL PLNS...
...SYNOPSIS...
LARGE SCALE PATTERN OVER THE LWR 48 WILL REMAIN LARGELY UNCHANGED
THIS PERIOD...WITH THE MAIN BELT OF THE WLYS REMAINING WELL TO THE N
IN CNTRL CANADA. SD UPR LOW SHOULD CONTINUE SLOWLY SE INTO ERN NEB
BY 12Z THU...BACKED BY WEAK HEIGHT RISES OCCURRING DOWNSTREAM FROM
UPR LOW/TROUGH NOW APPROACHING THE WA/ORE CST. FARTHER S...
HURRICANE JIMENA EXPECTED TO MOVE SLOWLY NW ALONG THE BAJA CA CST.
...PLNS...
SD UPR LOW WILL CONTINUE TO BE THE MAIN FOCUS FOR TSTM DEVELOPMENT
THIS PERIOD. A FEW OF THE STORMS COULD BE STG TO SVR FROM SRN SD
INTO CNTRL/ERN NEB THIS AFTN/EVE AS ENHANCED MID LVL NWLY FLOW ON SW
SIDE OF LOW INTERACTS WITH SOMEWHAT GREATER MOISTURE /PW AOA 1 INCH/
THAN HAS BEEN AVAILABLE TO THE SYSTEM IN RECENT DAYS.
ALTHOUGH BOUNDARY LAYER MOISTURE WILL STILL BE MODEST BY EARLY
SEPTEMBER STANDARDS...COMBINATION OF 50S F SFC DEWPOINTS AND
COOL MID LVL TEMPERATURES /AOB MINUS 10 C AT 500 MB/ WILL SUPPORT A
RISK FOR SVR HAIL/GUSTY WINDS...ESPECIALLY ALONG N-S SFC TROUGH/WEAK
FRONT...WHERE SBCAPE MAY REACH 1000-1500 J/KG .
LOW LVL VEERING WIND PROFILES BENEATH 40 KT WNW MID LVL FLOW SHOULD
SUPPORT SCTD MULTICELLS AND PERHAPS A FEW SUPERCELLS THROUGH EARLY
EVE. WHILE THESE MAY COALESCE INTO A SMALL MCS LATER TONIGHT...
DIURNAL COOLING AND MODEST LLJ SUGGEST THAT SVR THREAT SHOULD
DIMINISH AFTER DARK.
FARTHER SW FROM UPR LOW...EWD ADVECTION OF EML AND MODEST MOISTURE
LIKELY WILL PROHIBIT DEVELOPMENT OF DAYTIME STORMS OVER THE LWR PLNS
ROUGHLY FROM THE NEB/KS BORDER OR I-70 SWD. DIURNAL STORMS
WILL...HOWEVER ...LIKELY FORM OVER THE HIGHER TERRAIN OF SE CO/FAR
NE NM BY LATE THIS AFTN ON WRN FRINGE OF LOW LVL MOISTURE AXIS OVER
THE SRN/CNTRL HI PLNS. AND...DEVELOPMENT ALSO MAY OCCUR A BIT LATER
OVER THE OK/TX PANHANDLES...N AND E OF WEAK THERMAL/LEE LOW AND
ASSOCIATED STNRY FRONT. ISOLD SVR HAIL/WIND MAY OCCUR WITH THESE
STORMS THROUGH EARLY TONIGHT...BUT ACTIVITY SHOULD REMAIN FAIRLY
WEAK/DISORGANIZED GIVEN LIMITED DEEP SHEAR ON ERN FRINGE OF GRT
BASIN RDG.
...SRN AZ...
MOISTURE HAS INCREASED SUBSTANTIALLY OVER SRN AZ SINCE EARLIER IN
THE WEEK...WITH PW NOW ABOUT 1.50 INCHES PER RAOB/GPS AND STLT DATA.
PROXIMITY OF UPR RDG WILL KEEP MEAN FLOW WEAK...AND SOME LARGE SCALE
SUBSIDENCE MAY AFFECT THE REGION ON THE NRN FRINGE OF JIMENA. BUT
COMBINATION OF INCREASED MOISTURE WITH STEEP LOW LVL LAPSE RATES AND
THE LIKELIHOOD FOR AT LEAST SCTD DIURNAL STORMS SUGGESTS THE
POSSIBILITY FOR ISOLD DMGG WIND EVENTS WITH OUTFLOW-INDUCED BLOWING
DUST.
..CORFIDI/SMITH.. 09/02/2009
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