Tuesday, February 19, 2008

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 190559
SWODY2
SPC AC 190558

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1158 PM CST MON FEB 18 2008

VALID 201200Z - 211200Z

..NO SVR TSTM AREAS FORECAST...

..SYNOPSIS...

SPLIT FLOW UPPER PATTERN WILL CONTINUE TO EVOLVE INTO WEDNESDAY WITH
A LARGE UPPER TROUGH OVER THE NERN U.S. AND A SIGNIFICANT SHORTWAVE
TROUGH THAT IS FORECAST TO UNDERCUT BLOCKY UPPER RIDGE THAT WILL
PERSIST FROM THE NRN ROCKIES INTO SWRN CANADA. THE SHORTWAVE TROUGH
WILL CONTINUE EWD THROUGH THE GREAT BASIN AND SWRN STATES. AT THE
SURFACE ARCTIC HIGH PRESSURE WILL ADVANCE SEWD THROUGH MUCH OF ERN
TWO THIRDS OF THE NATION. COLD FRONT DEMARCATING THE LEADING EDGE OF
THE COLDER AIR SHOULD EXTEND FROM THE SERN STATES WWD THROUGH TX BY
THE END OF THIS PERIOD.


..SRN PLAINS THROUGH LOWER MS VALLEY...

COLD FRONT WILL SETTLE SWD THROUGH OK...TX AND THE LOWER MS VALLEY.
SOUTH OF THE FRONT...PARTIALLY MODIFIED CP AIR WILL BEGIN RETURNING
NWWD THROUGH WARM SECTOR BENEATH STEEPENING MID LEVEL LAPSE RATES
ASSOCIATED WITH EWD ADVECTING EML. THIS WILL CONTRIBUTE TO SOME
DESTABILIZATION WEDNESDAY...MAINLY OVER S AND SERN TX. MUCH OF THIS
REGION WILL BE UNDER THE INFLUENCE OF WEAK SHORTWAVE RIDGING AND
WILL PROBABLY REMAIN CAPPED TO DEEP CONVECTION DURING THE
DAY...THOUGH A FEW SHOWERS WILL BE POSSIBLE. THE CHANCE FOR
THUNDERSTORMS IS EXPECTED TO INCREASE WEDNESDAY EVENING AND
OVERNIGHT AS THE LOW LEVEL JET STRENGTHENS AND CONTRIBUTES TO NWD
DESTABILIZATION AND ISENTROPIC ASCENT...WITH THE STRONGEST LIFT
EXPECTED NORTH OF THE SWD ADVANCING FRONT. STORMS WILL BE ELEVATED.
HOWEVER...INSTABILITY MIGHT BECOME SUFFICIENT FOR A MARGINAL THREAT
FOR HAIL OVER CNTRL AND NRN TX AS STEEPER MID LEVEL LAPSE RATES
ADVECT EWD...ESPECIALLY GIVEN EFFECTIVE SHEAR SUFFICIENT FOR MID
LEVEL UPDRAFT ROTATION. OVERALL THREAT DOES NOT APPEAR TO WARRANT
MORE THAN LOW HAIL PROBABILITIES AT THIS TIME.

..SWRN STATES...

ASCENT AND STEEP MID LEVEL LAPSE RATES ACCOMPANYING EWD ADVANCING
SHORTWAVE TROUGH WILL CONTRIBUTE TO SCATTERED CONVECTION FROM PARTS
OF THE GREAT BASIN INTO THE SWRN STATES. HOWEVER...LIMITED
INSTABILITY SUGGEST ANY LIGHTNING STRIKES WILL PROBABLY REMAIN
ISOLATED.

.DIAL.. 02/19/2008

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