Saturday, December 1, 2007

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 010555
SWODY1
SPC AC 010552

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1152 PM CST FRI NOV 30 2007

VALID 011200Z - 021200Z

..NO SVR TSTM AREAS FORECAST...

..SYNOPSIS...

SHORTWAVE TROUGH NOW EJECTING INTO THE SWRN U.S. WILL CONTINUE NEWD
THROUGH THE CNTRL PLAINS AND UPPER MS VALLEY AREA SATURDAY...WHILE
UPSTREAM SHORTWAVE DROPPING INTO NRN CA FOLLOWS CLOSE ON ITS HEELS.
AS THE INITIAL WAVE MOVES TOWARD CO...A SURFACE LOW WILL DEEPEN AND
CONSOLIDATE OVER THE CNTRL HIGH PLAINS. THIS LOW WILL SHIFT EWD INTO
THE MS VALLEY SATURDAY NIGHT IN ASSOCIATION WITH EJECTING LEAD
SHORTWAVE TROUGH...ALLOWING A COLD FRONT TO DROP SWD INTO THE CNTRL
PLAINS. DIFFUSE DRYLINE MAY SETUP ACROSS WRN TX DURING THE DAY. THIS
FEATURE WILL LIKELY BE OVERTAKEN BY A SECONDARY COLD FRONT ATTENDING
THE UPSTREAM SHORTWAVE TROUGH THAT WILL MOVE INTO THE SRN HIGH
PLAINS SATURDAY NIGHT.

..CNTRL PLAINS THROUGH MID AND UPPER MS VALLEY REGION...

GRADIENT BETWEEN DEEPENING HIGH PLAINS SURFACE LOW AND HIGH PRESSURE
OVER THE ERN STATES WILL RESULT IN THE DEVELOPMENT OF A 70 KT SSWLY
LOW LEVEL JET EARLY SATURDAY OVER THE SRN AND CNTRL PLAINS. THIS
FEATURE WILL VEER AND SHIFT NEWD INTO THE MS VALLEY DURING THE DAY
AS THE INITIAL SHORTWAVE TROUGH EJECTS NEWD. LIFT AND STRONG WARM
ADVECTION ON THE NOSE OF THE LOW LEVEL JET AND LARGE PLUME OF
MID-HIGH LEVEL SUBTROPICAL MOISTURE WILL RESULT IN WIDESPREAD
PRECIPITATION OVER PORTIONS OF THE CNTRL AND NRN PLAINS THROUGH THE
UPPER MS VALLEY DURING THE DAY. HOWEVER...WEAK LAPSE RATES WILL
INITIALLY LIMIT POTENTIAL FOR LIGHTNING. THREAT FOR THUNDERSTORMS
MAY INCREASE LATER IN THE DAY WITH ELEVATED CONVECTION DEVELOPING ON
THE SRN END OF THIS COMPLEX OR IN POST FRONTAL ZONE AS STEEPER LAPSE
RATES SPREAD EWD THROUGH THE CNTRL PLAINS. HOWEVER...INSTABILITY IS
EXPECTED TO REMAIN TOO LIMITED FOR A HAIL THREAT.

..SRN PLAINS...

CIRCULATION AROUND ERN U.S. HIGH PRESSURE IS MAINTAINING FEED OF CP
AIR INTO MUCH OF THE WRN AND CNTRL GULF. THIS IS SLOWING BOUNDARY
LAYER MODIFICATION AND MAINTAINING ONLY 50S TO LOWER 60S DEWPOINTS
OVER ALL EXCEPT DEEP S TX. LOW LEVEL TRAJECTORIES WILL BECOME MORE
SLY AS THE HIGH CENTER SHIFTS EAST SATURDAY. HOWEVER...MOISTURE
RETURN WILL LIKELY REMAIN SOMEWHAT LIMITED WITH AN AXIS OF LOWER 60S
DEWPOINTS POSSIBLE AS FAR NORTH AS OK WITH MID TO UPPER 60S LIKELY
REMAINING CONFINED TO CNTRL AND S TX. WIDESPREAD SUBTROPICAL
MOISTURE PLUME OVERSPREADING THE MOISTENING WARM SECTOR ALONG WITH
WEAK LAPSE RATES WILL RESULT IN VERY MARGINAL INSTABILITY WITH
MUCAPE BELOW 500 J/KG. MOREOVER...WITH THE STRONGER FORCING SHIFTING
NORTH OF THIS REGION DURING THE DAY ...THE WARM SECTOR WILL LIKELY
REMAIN CAPPED TO SURFACE BASED STORMS. MODELS SUGGEST DEEPER
CONVECTION MAY DEVELOP OVERNIGHT AHEAD OF FRONT WITHIN ZONE OF LOW
LEVEL CONFLUENCE AND INCREASING ASCENT AHEAD OF SECONDARY SHORTWAVE
TROUGH FROM PARTS OF N TX INTO OK. HOWEVER...THIS ACTIVITY IS
EXPECTED TO BE ELEVATED...AND GIVEN THE EXPECTED MARGINAL
THERMODYNAMIC ENVIRONMENT...ANY SEVERE THREAT SHOULD REMAIN LOW.

.DIAL.. 12/01/2007

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