DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 080730
SWODY3
SPC AC 080728

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0228 AM CDT MON APR 08 2013

VALID 101200Z - 111200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE MIDWEST TO
THE WRN GULF COAST STATES...

...SYNOPSIS...
AN AMPLIFIED UPPER-LEVEL TROUGH WILL CONTINUE TO GRADUALLY PROGRESS
EWD FROM THE ROCKIES ACROSS THE GREAT PLAINS THROUGH EARLY THU. A
DOWNSTREAM MID-LEVEL RIDGE WILL PERSIST FROM THE SOUTHEAST TO THE
GREAT LAKES. AT THE SURFACE...A CYCLONE SHOULD SLOWLY MOVE EWD IN
PARTS OF THE MIDWEST WITH AN ATTENDANT COLD FRONT FROM THE LOWER MO
VALLEY TO THE SRN PLAINS PROGRESSING AT LEAST ACROSS THE MID/LOWER
MS VALLEY BY 12Z/THU. A QUASI-STATIONARY FRONT SHOULD BE DRAPED E OF
THE MIDWEST CYCLONE TO THE NRN APPALACHIANS.

...MIDWEST TO THE WRN GULF COAST STATES...
A BROAD SWATH OF ORGANIZED SEVERE POTENTIAL IS EXPECTED DURING THE
PERIOD WITH ALL SEVERE HAZARDS PROBABLE.

MODEL PREDICTABILITY LESSENS SUBSTANTIALLY FROM D2 WITH THE
EVOLUTION OF KEY SYNOPTIC FEATURES...RENDERING LOW CONFIDENCE IN
BOTH THE AMPLITUDE OF THE SEVERE THREAT AND IN IDENTIFYING ANY
CORRIDOR OF COVERAGE AOA 45 PERCENT. MODELS DIFFER WITH THE EJECTION
OF A SRN HIGH PLAINS SHORTWAVE IMPULSE...WITH THE MORE CONSISTENT
ECMWF/CMC SUGGESTING A SLOWER AND MORE N/NELY TRACK TOWARDS THE
MID-MO VALLEY. THIS YIELDS A SLOWER EWD PROGRESSION OF THE SURFACE
COLD FRONT AND LOW/MID-LEVEL S/SWLYS NOT AS INTENSE OVER THE WARM
SECTOR COMPARED TO THE GFS/NAM.

REGARDLESS OF THE MODEL DISCREPANCIES...SCATTERED TO WIDESPREAD
CONVECTION IS EXPECTED ALONG THE FRONTAL ZONES. SURFACE DEW POINTS
WILL CONTINUE TO INCREASE WITHIN THE WARM SECTOR...LIKELY THROUGH
THE 60S FROM PARTS OF THE MIDWEST TO THE GULF COAST. WITH A REMNANT
EML PLUME OVER MOST OF THE ERN CONUS CONTRIBUTING TO STEEP MID-LEVEL
LAPSE RATES...STRENGTHENING LOW/DEEP-LAYER SHEAR SHOULD PROVE
FAVORABLE FOR SCATTERED DAMAGING WINDS...A FEW TORNADOES...AND
ISOLATED LARGE HAIL. AS FLOW BECOMES INCREASINGLY PARALLEL TO THE
COLD FRONT...AN EXTENSIVE QLCS MAY ULTIMATELY FORM PRIOR TO THE
FRONT REACHING THE MS VALLEY.

..GRAMS.. 04/08/2013

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