Wednesday, March 11, 2009

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 111254
SWODY1
SPC AC 111252

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0752 AM CDT WED MAR 11 2009

VALID 111300Z - 121200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
AS POTENT UPR GRT LKS TROUGH RETREATS ENE INTO QUEBEC AND THE
CANADIAN MARITIMES...THE MAIN FOCUS FOR TSTMS OVER THE CONUS DURING
THE NEXT TWO DAYS WILL SHIFT TO THE SRN STREAM JET. ATTM...THE JET
EXTENDS IN AN ARC FROM OFF THE CNTRL CA CST ACROSS BAJA CA. FROM
THERE IT CURVES EAST AROUND A TROUGH IN NW MEXICO...BEFORE TURNING
NE ACROSS THE RIO GRANDE INTO S TX. THE TROUGH SHOULD DEAMPLIFY AS
IT CONTINUES ENE INTO N TX BY THE END OF THE PERIOD.

AT THE SFC...PRESSURE RISES OVER THE SRN PLNS/LWR MS VLY WILL FORCE
SHALLOW COLD FRONT STEADILY S ACROSS ALL BUT EXTREME S TX BY LATE IN
THE DAY. ABOVE THE FRONTAL SURFACE...SSELY 850 MB WILL NEVERTHELESS
PERSIST AND POSSIBLY STRENGTHEN DOWNSTREAM FROM APPROACHING UPR
TROUGH.

...LWR RIO GRANDE VLY/DEEP S TX...
WAVES OF ELEVATED CONVECTION/STORMS EXPECTED TO INCREASE ACROSS S
CNTRL/CNTRL AND NE TX TODAY THROUGH TONIGHT AS APPROACH OF MEXICAN
UPR IMPULSE ENHANCES UPR DIFLUENCE ATOP DEEPENING POST-FRONTAL COOL
AIR DOME. ELEVATED INSTABILITY SHOULD REMAIN TOO WEAK IN MOST AREAS
TO POSE ANY THREAT FOR SVR HAIL.

A BIT FARTHER S...A LIMITED/CONDITIONAL SVR THREAT WILL EXIST IN THE
LWR RIO GRANDE VLY/DEEP S TX....WHERE RESIDUAL EML PLUME WILL BE
PRESENT AND WHERE A FEW SFC-BASED STORMS MAY DEVELOP PRIOR TO
FRONTAL PASSAGE. IN ADDITION...THIS REGION MAY EXPERIENCE A FEW
STORMS/POSSIBLE CLUSTERS MOVING ENE OFF THE HIGHER TERRAIN W OF THE
RIO GRANDE. PROXIMITY OF SRN STREAM JET WILL MAINTAIN SUFFICIENT
CLOUD-LAYER SHEAR FOR STORM ROTATION/SUSTENANCE. COUPLED WITH
FAIRLY RICH MOISTURE INFLOW...A LOW PROBABILITY...CONDITIONAL RISK
WILL EXIST FOR HAIL/LOCALLY DMGG WIND.

..CORFIDI/GARNER.. 03/11/2009

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