DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 060728
SWODY3
SPC AC 060726

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0226 AM CDT SAT APR 06 2013

VALID 081200Z - 091200Z

...THERE IS A SLGT RISK OF SVR TSTMS FOR PARTS OF THE CNTRL/SRN
PLAINS...

...SYNOPSIS...
AN AMPLIFIED UPPER-LEVEL TROUGH SHOULD GRADUALLY PROGRESS EWD ACROSS
THE WRN CONUS WITH A VIGOROUS MID-LEVEL SPEED MAX POTENTIALLY
EJECTING THROUGH THE BASE OF THE TROUGH BY EARLY TUE. AT THE
SURFACE...PRIMARY CYCLONE SHOULD REMAIN NEARLY STATIONARY IN THE LEE
OF THE SRN ROCKIES. A SHARP DRYLINE WILL MIX INTO FAR WRN OK AND THE
TX BIG COUNTRY. A COLD FRONT SHOULD SWEEP SWD ACROSS THE NRN PLAINS
MERGING WITH A QUASI-STATIONARY FRONT FROM THE CNTRL HIGH PLAINS TO
MID-MO VALLEY BY EARLY TUE.

...CNTRL/SRN PLAINS...
TWO PRIMARY UNCERTAINTIES RENDER LOWER-THAN-AVERAGE CONFIDENCE IN
MAKING ANY SUBSTANTIAL ADJUSTMENTS TO THE INHERITED 30 PERCENT AREA
THAT BEGAN ON D5. FIRST AS ALLUDED TO IN THE CURRENT D2
OUTLOOK...LOW-LEVEL MOISTURE RETURN APPEARS TO BE SOMEWHAT OVERDONE
IN MOST MODELS GIVEN THAT RICHER TROPICAL MOISTURE HAS BEEN
CURRENTLY RELEGATED INTO THE CARIBBEAN. STILL...PRECEDING DAYS OF
SLY RETURN FLOW BENEATH A STOUT EML SHOULD YIELD A MODIFIED GULF AIR
MASS WITH WIDESPREAD SURFACE DEW POINTS IN THE 50S...INCREASING TO
THE LOWER 60S ALONG THE DRYLINE IN OK/TX. THIS SHOULD BE ABLE TO
YIELD AT LEAST A MODERATELY UNSTABLE WARM/MOIST SECTOR GIVEN THE
PRESENCE OF VERY STEEP MID-LEVEL LAPSE RATES.

THE SECOND UNCERTAINTY IS WITH REGARD TO THE EVOLUTION OF THE WRN
CONUS TROUGH AND EJECTION/TIMING OF SHORTWAVE IMPULSES. THE ECMWF
APPEARS MORE REASONABLE AND CONSISTENT WITH A SLOWER PROGRESSION OF
THE TROUGH GIVEN THE ATTENDANT INTENSE MID/UPPER-LEVEL SPEED MAX.
THIS SUGGESTS THAT UPPER-LEVEL FORCING MAY NOT BE PHASED WELL WITH
THE DIURNAL HEATING CYCLE. IN ADDITION...TIMING THE EJECTION OF ANY
SUBTLE LEAD IMPULSES IS PREMATURE AT THIS POINT. THE MORE LIKELY
FORCING MECHANISM FOR SUSTAINING TSTMS WILL BE LOW-LEVEL WAA
OCCURRING ALONG THE FRONTAL ZONE MON EVENING/NIGHT...AS CONTINUED
STRONG CAPPING WILL LIKELY MITIGATE OPEN WARM SECTOR DEVELOPMENT.
HOWEVER...SUFFICIENT LOW-LEVEL CONVERGENCE MAY EXIST FOR INITIATION
IMMEDIATELY ALONG THE DRYLINE FROM WRN OK INTO SWRN KS.
ELONGATED/CURVING HODOGRAPHS WILL BE QUITE FAVORABLE FOR
SUPERCELLS...WITH A PRIMARY RISK OF VERY LARGE HAIL ALONG WITH A FEW
TORNADOES.

..GRAMS.. 04/06/2013

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