SPC AC 261643
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1043 AM CST FRI DEC 26 2008
VALID 261630Z - 271200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SRN PLAINS INTO THE
LOWER MO VALLEY...
...SYNOPSIS...
12Z UPPER AIR DATA AND SATELLITE IMAGERY INDICATE SRN PART OF THE
FULL-LATITUDE UPPER TROUGH OVER THE WRN STATES IS CONTINUING TO DIG
SEWD ACROSS THE SRN NV/SWRN UT/NWRN AZ REGION...AS STRONG MID/UPPER
LEVEL JET STREAK PROGRESSES SWD ALONG THE CENTRAL CA COAST. THE
SYSTEM IS EXPECTED TO TURN MORE EWD BY TONIGHT...WITH THE TROUGH
EXTENDING FROM THE NRN PLAINS INTO THE SRN ROCKIES BY THE END OF THE
PERIOD. PRIMARY MID/UPPER LEVEL JET STREAK IS FORECAST TO EXTEND
FROM THE SRN HIGH PLAINS INTO THE CENTRAL PLAINS BY THIS TIME...AS
THE MAIN VORTICITY MAX MOVES EWD ACROSS NM.
AT THE SURFACE...LOW OVER NERN CO IS FORECAST TO MOVE NEWD TOWARD
THE UPPER MS VALLEY BY LATER TONIGHT. THE COLD FRONT EXTENDING SWWD
FROM THE LOW ACROSS NWRN NM/SERN AZ IS EXPECTED TO MOVE EWD INTO THE
CENTRAL AND SRN PLAINS TONIGHT. DEVELOPING DRY LINE ON THE WRN EDGE
OF LOW LEVEL MOISTURE RETURN IS EXPECTED TO PERSIST FROM S CNTRL KS
AND WRN OK SWD INTO TX...BEFORE THE ADVANCING COLD FRONT OVERTAKES
THE DRYLINE FROM NORTH-TO-SOUTH TONIGHT. THIS WILL PROVIDE THE
PRIMARY FOCUS FOR THUNDERSTORM DEVELOPMENT.
...SRN PLAINS INTO LOWER MO VALLEY...
MOISTURE CONTINUES TO RETURN NWD ACROSS THE SRN PLAINS INTO THE
CENTRAL PLAINS...WITH MID 60S DEW POINTS ACROSS CENTRAL/ERN TX AND
NEAR 60 DEGREE DEW POINTS AS FAR NORTH AS THE KS/OK BORDER. THE
MOISTURE RETURN IS EXPECTED TO CONTINUE AHEAD OF THE COLD FRONT/DRY
LINE INTO TONIGHT WITH 55-60 DEGREE DEW POINTS SPREADING INTO ERN KS
AND NRN MO BY 03-06Z. ALTHOUGH COLDER MID LEVEL TEMPERATURES AND
STEEPER LAPSE RATES WILL LAG TO THE WEST OF THE WARM SECTOR AND
WIDESPREAD CLOUD COVER MAY INHIBIT DIURNAL HEATING...INCREASING
MOISTURE WILL CONTRIBUTE TO DESTABILIZATION WITH MUCAPE OF 500-1000
J/KG DEVELOPING THROUGH THE MOIST AXIS THIS AFTERNOON AND TONIGHT.
A FEW THUNDERSTORMS MAY DEVELOP WITHIN THE WARM SECTOR OVER PARTS OF
NERN TX/ERN OK AND WRN AR THIS AFTERNOON AND EVENING. THIS AREA
WILL BE ALONG THE SRN EDGE OF STRONGER SWLY FLOW ALOFT AND ATTENDANT
DEEP LAYER SHEAR...SUGGESTING POTENTIAL FOR ISOLATED SEVERE STORMS.
HOWEVER...PRIMARY THUNDERSTORM DEVELOPMENT IS LIKELY TO BE DELAYED
UNTIL TONIGHT WHEN THE COLD FRONT MOVES INTO THE WRN EDGE OF THE LOW
LEVEL MOISTURE/INSTABILITY AXIS. MORE WIDESPREAD COVERAGE OF
STRONG/SEVERE STORMS IS LIKELY TO OCCUR FROM PARTS OF WRN MO INTO
ERN KS INITIALLY...WITH ACTIVITY DEVELOPING SWD ALONG THE COLD
FRONT/DRY LINE MERGER ACROSS OK INTO NRN TX THROUGH THE OVERNIGHT
HOURS. DISCRETE SUPERCELLS WILL BE POSSIBLE...ESPECIALLY EARLY IN
THE STORMS LIFE CYCLES...AS UPDRAFTS WILL BE EMBEDDED WITHIN
FAVORABLE LOW- AND DEEP-LAYER VERTICAL SHEAR. THESE STORMS WILL
HAVE POTENTIAL TO PRODUCE TORNADOES...DAMAGING WIND GUSTS...AND
OCCASIONAL HAIL. STRONG/SEVERE STORMS ARE EXPECTED TO SPREAD
EWD/NEWD THROUGH THE LATE NIGHT HOURS WITH THE CONVECTIVE MODE
TRANSITIONING TO QUASI-LINEAR STRUCTURES CONTAINING EMBEDDED BOW
ECHOES AND ISOLATED SUPERCELLS.
..WEISS.. 12/26/2008
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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