SWODY1
SPC AC 051258
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0758 AM CDT MON OCT 05 2009
VALID 051300Z - 061200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
NRN PART OF ELONGATED WRN U.S. TROUGH WILL MOVE FROM THE CNTRL RCKYS
INTO THE NRN/CNTRL PLNS THIS PERIOD AS SRN PART EVOLVES INTO A
POSITIVE-TILT CLOSED LOW OVER CNTRL CA. ON SRN FRINGE OF RCKYS
TROUGH...SW TO WSW FLOW WILL INCREASE OVER THE SRN/CNTRL HI PLNS
THIS AFTN...AND OVER THE SRN HALF OF THE PLNS TONIGHT...AS
SUBTROPICAL RDG LINGERS OVER THE NW GULF OF MEXICO.
AT LWR LVLS...LEE CYCLONE NOW FORMING OVER NE CO SHOULD REDEVELOP S
INTO SE CO LATER TODAY...BEFORE TURNING NE ACROSS KS AND IA TONIGHT/
EARLY TUE. IN RESPONSE...EXPECT FRONT NOW STALLED OVER THE CNTRL
RCKYS TO ACCELERATE SE ACROSS THE CNTRL PLNS DURING THE SECOND HALF
OF THE PERIOD. ALTHOUGH SLY FLOW WILL STRENGTHEN AND DEEPEN AHEAD
OF THE CO LOW...STNRY FRONT NOW EXTENDING FROM S CNTRL TX EWD ALONG
THE CNTRL/ERN GULF CST LIKELY WILL EDGE ONLY SLOWLY NEWD TODAY AS
SHALLOW LAYER OF RESIDUAL COOL/MOIST AIR PERSISTS TO ITS N AND E.
...CNTRL/SRN PLNS...
SEASONABLY RICH MOISTURE /WITH PW AT OR WELL ABOVE 1 INCH/ NOW
PRESENT ALONG AND EVEN N OF STALLED FRONT IN S TX WILL SPREAD N
ACROSS MUCH OF THE SRN AND CNTRL PLNS LATER TODAY/TONIGHT AHEAD OF
DEVELOPING COLD FRONT WITH CO LOW. AT THE SAME TIME...MID/UPR LVL
SW TO WSW FLOW WILL INCREASE...WITH 500 MB SPEEDS OF 50-70 KTS FROM
NW TX NWD INTO ERN CO/KS AND NEB.
PERSISTENT MOIST ELY SFC FLOW LIKELY WILL MAINTAIN SOLID TO BKN LOW
CLOUDS OVER MUCH OF W TX TODAY. BUT SOME SUNSHINE MAY OCCUR ALONG
WRN EDGE OF DENSER CLOUDS...WHERE SOME SFC-BASED TSTMS MAY FORM
LATER THIS AFTN INTO EARLY EVE.
DESPITE THE ABUNDANT MOISTURE AND AMPLE DEEP SHEAR FOR SUSTAINED
STORMS IN W TX...LOW LVL CONVERGENCE WILL REMAIN WEAK AS THE
STRONGEST SLY FLOW AND LLJ DEVELOP FARTHER N OVER THE CNTRL HI PLNS.
IN ADDITION...LARGE SCALE ASCENT WILL BE WEAK AND MID LVL
TEMPERATURES WILL REMAIN RELATIVELY WARM /AROUND MINUS 5-6 C AT 500
MB/ ON NW FRINGE OF SUBTROPICAL HIGH. FOR THESE REASONS...A
CATEGORICAL SLGT RISK DOES NOT SEEM WARRANTED ATTM. NEVERTHELESS
...AREA WILL BE CLOSELY MONITORED FOR POSSIBLE UPGRADE SHOULD MORE
SUBSTANTIAL SFC HEATING APPEAR LIKELY TO OCCUR THAN IS NOW EXPECTED.
FARTHER N...COMBINATION OF MORE LIMITED MOISTURE AND A STG EML
SHOULD PROHIBIT SFC-BASED STORM DEVELOPMENT ALONG SHARPENING DRY
LINE/LEE TROUGH FROM THE TX/OK PANHANDLES INTO SW KS. STILL FARTHER
N... HOWEVER...INCREASING FORCING FOR ASCENT...MID LVL COLD
ADVECTION...AND SFC HEATING SHOULD SUPPORT LATE AFTN/EVE LOW-TOPPED
STORMS INVOF LEE TROUGH OVER NE CO/SW NEB AND NW KS. THESE MAY
YIELD MARGINALLY SVR HAIL THROUGH EARLY TONIGHT.
LATER TONIGHT AND EARLY TUE...40-50 KT SWLY LLJ AND ASSOCIATED
MOISTURE TRANSPORT ATOP RESIDUAL COOL LAYER EXPECTED TO SUPPORT
INCREASING COVERAGE OF ELEVATED TSTMS FROM SW/CNTRL OK NEWD INTO
PARTS OF KS/ERN NEB/IA AND WRN MO. SUFFICIENT ELEVATED CAPE/CLOUD
LAYER SHEAR WILL EXIST FOR A FEW CELLS WITH SVR HAIL.
..CORFIDI/SMITH.. 10/05/2009
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