DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 130730
SWODY3
SPC AC 130729

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0229 AM CDT SUN MAY 13 2012

VALID 151200Z - 161200Z

...SYNOPSIS...
BROAD/WEAK UPPER-LEVEL TROUGH WILL SHIFT EWD AND ENCOMPASS THE ERN
HALF OF THE CONUS. EMBEDDED WITHIN THIS TROUGH...A SHORT WAVE
IMPULSE SHOULD AMPLIFY SEWD ACROSS ONTARIO INTO PERHAPS THE GREAT
LAKES...IN THE EXIT REGION OF AN UPPER-LEVEL JET STREAK. AN
ATTENDANT SURFACE COLD FRONT SHOULD PUSH SEWD ACROSS THE GREAT LAKES
AND UPPER MS VALLEY. AN UPPER-LEVEL RIDGE SHOULD SHIFT FROM THE
ROCKIES TO THE HIGH PLAINS...WHILE A COMPACT MID-LEVEL LOW DAMPENS
AS IT PROGRESSES OVER THE GREAT BASIN.

...UPPER MIDWEST...
DIFFERENCES EXIST WITH THE 00Z ECMWF/15Z SREF COMPARED TO THE 00Z
GFS/NAM WITH THE FORMER DEPICTING A SOMEWHAT MORE AMPLIFIED/SRN
TRACK OF THE SHORT WAVE IMPULSE EXPECTED TO EVOLVE FROM THE CANADIAN
PRAIRIES. THIS WOULD RESULT IN FASTER TIMING OF THE COLD FRONT
MOVING SEWD ACROSS THE REGION DURING THE DAY ON TUE. MOISTURE RETURN
AHEAD OF THE FRONT WILL BE LIMITED...WITH SURFACE DEW POINTS LARGELY
PROGGED TO BE IN THE MIDDLE 40S TO LOWER 50S DURING THE AFTERNOON
PRIOR TO CONVECTIVE SCHEME ACTIVATION IN MODEL FORECAST SOUNDINGS.
SUBSTANTIAL HEATING AHEAD OF THE FRONT SHOULD RESULT IN STEEP
LOW/MID-LEVEL LAPSE RATES SUFFICIENT FOR AT LEAST ISOLATED TSTM
DEVELOPMENT ALONG THE FRONT AT PEAK HEATING. WITH 30-40 KT EFFECTIVE
SHEAR LARGELY CONCENTRATED IN THE MID/UPPER-LEVELS...THIS
ENVIRONMENT WOULD TEND TO FAVOR HAIL PRODUCTION. BUT GIVEN THE
AFOREMENTIONED CONCERNS WITH TIMING AND BUOYANCY...WILL ONLY ADD
MARGINAL SEVERE PROBABILITIES ATTM.

..GRAMS.. 05/13/2012

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