Saturday, December 17, 2011

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 170532
SWODY2
SPC AC 170530

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 PM CST FRI DEC 16 2011

VALID 181200Z - 191200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...

SYNOPTIC PATTERN WILL REMAIN DOMINATED BY SPLIT FLOW SUNDAY...BUT
WILL TRANSITION TO QUASI-ZONAL OVER THE ERN STATES AS UPPER TROUGH
MOVES OFFSHORE. SWRN U.S. CUTOFF LOW WILL FINALLY BEGIN TO EJECT EWD
IN RESPONSE TO UPSTREAM IMPULSE FORECAST TO MOVE THROUGH THE PACIFIC
NW AND NRN ROCKIES. A PACIFIC FRONT WILL ACCOMPANY THE UPPER LOW
THROUGH SRN NM...REACHING FAR WRN TX LATE SUNDAY NIGHT.

...SRN ROCKIES THROUGH SRN HIGH PLAINS...

SLY BOUNDARY LAYER WINDS WILL STRENGTHEN OVER THE SRN HIGH PLAINS AS
A LEE TROUGH DEVELOPS WITHIN ZONE OF INCREASING DIVERGENCE AHEAD OF
PROGRESSIVE SRN BRANCH UPPER TROUGH. MODEST LOW LEVEL MOISTURE WILL
BEGIN ADVECTING NWWD INTO TX BENEATH STEEPENING MID-LEVEL LAPSE
RATES. SFC DEWPOINTS SHOULD REMAIN BELOW 50F ACROSS WRN TX DUE TO
LIMITED DURATION OF MOIST ADVECTION AND ONLY PARTIAL MODIFICATION OF
THE GULF BOUNDARY LAYER. NEVERTHELESS THIS PROCESS WILL RESULT IN AT
LEAST MARGINAL INSTABILITY OVER THE SRN HIGH PLAINS. A FEW
THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS WRN TX SUNDAY NIGHT AS
FORCING FOR ASCENT INCREASES ALONG WARM CONVEYOR BELT. COLD AIR
ALOFT AND STEEP LAPSE RATES WITHIN THE CONVECTIVE LAYER MIGHT
SUPPORT A RISK FOR SMALL HAIL...BUT LIMITED INSTABILITY SHOULD
PRECLUDE A MORE SUBSTANTIAL HAIL THREAT.

OTHER MORE ISOLATED THUNDERSTORMS MAY DEVELOP FROM AZ THROUGH NM
WHERE WEAK INSTABILITY WILL EXIST NEAR TRACK OF THE UPPER LOW
CENTER.

..DIAL.. 12/17/2011

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