DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 221250
SWODY1
SPC AC 221249

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0749 AM CDT TUE MAY 22 2012

VALID 221300Z - 231200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE NRN
PLAINS FROM ND SOUTH ACROSS NORTHWEST NEB AND INTO WRN/N-CNTRL MN...

...THERE IS A SLGT RISK OF SVR TSTMS OVER THE SOUTHEAST FROM ERN
AL...PARTS OF THE FL PANHANDLE...AND MUCH OF GA/SC TO SWRN NC...

...SYNOPSIS...
IN THE MID/UPPER LEVELS...A STRONG TROUGH WILL MOVE EWD ACROSS THE
PACIFIC NW...NRN ROCKIES...AND OVER THE NRN PLAINS. AS 500-MB HEIGHT
FALLS IN EXCESS OF 90 M OVERSPREAD THE NRN PLAINS...SFC LOW PRESSURE
OVER SERN MT WILL INTENSIFY WHILE DEVELOPING ENEWD ALONG A WARM
FRONT GRADUALLY ADVANCING NWD OVER ND/MN. A COLD FRONT TRAILING SWWD
FROM THE LOW WILL SURGE SEWD ACROSS THE NRN PLAINS THIS AFTERNOON
INTO TONIGHT...WHILE MODEST MOISTURE RETURN LIES EAST OF A
N-S-ORIENTED LEE TROUGH/DRYLINE THAT WILL BECOME OVERTAKEN BY THE
SURGING FRONT. BETWEEN THE STRONG TROUGH AND A BROAD AREA OF
PERSISTENT MID/UPPER-LEVEL CYCLONIC FLOW OVER THE SERN STATES...A
WEAK RIDGE WILL EXTEND FROM PARTS OF THE MID MS VALLEY SWWD INTO THE
SRN PLAINS.

...NRN PLAINS AND PARTS OF THE UPPER MS VALLEY LATE THIS AFTERNOON
INTO TONIGHT...
MODERATE TO STRONG INSTABILITY WILL DEVELOP THIS AFTERNOON WITHIN
THE WARM SECTOR LEADING THE COLD FRONT/LEE TROUGH...AS A FAIRLY
STRONG EML OVERLAYS MODEST LOW-LEVEL MOISTURE -- I.E. SFC DEWPOINTS
MAINLY IN THE 50S. SCATTERED TSTMS WILL LIKELY DEVELOP BY LATE
AFTERNOON/EARLY EVENING ACROSS THE CNTRL DAKOTAS INTO NWRN NEB INVOF
THE SFC LOW AND COLD FRONT...AS LARGE-SCALE ASCENT/DIURNAL HEATING
CONTRIBUTE TO ERODING ANTECEDENT STRONG INHIBITION ASSOCIATED WITH
THE EML. WITH 35-50 KT OF DEEP SHEAR COINCIDING WITH THE
BUOYANCY...ORGANIZED STORM STRUCTURES /POSSIBLE SUPERCELLS/ WILL BE
LIKELY...INCLUDING THE THREAT FOR LARGE HAIL AND SVR WIND. DESPITE
AT LEAST MODEST LOW-LEVEL SHEAR...ESPECIALLY INVOF THE WARM
FRONT...SIZABLE SFC TEMPERATURE-DEWPOINT SPREADS DURING THE
AFTERNOON FOLLOWED BY NOCTURNAL STABILIZATION SHOULD MITIGATE THE
TORNADO THREAT THROUGH THE PERIOD.

THE ACTIVITY MAY ORGANIZE INTO ONE OR TWO FORWARD-PROPAGATING
CONVECTIVE SYSTEMS THAT COULD APPROACH THE ERN DAKOTAS/WRN MN
OVERNIGHT TONIGHT. REMNANT ELEVATED CONVECTION MAY OFFER A HAIL
THREAT AS FAR EAST AS N-CNTRL MN LATE TONIGHT IN ASSOCIATION WITH
INCREASING WAA ACCOMPANYING AN INTENSIFYING LOW-LEVEL JET STREAM.

...SOUTHEAST THIS AFTERNOON INTO THIS EVENING...
A POCKET OF RELATIVELY COOL MID-LEVEL TEMPERATURES ACCOMPANYING THE
BROAD AREA OF CYCLONIC FLOW WILL CONTRIBUTE TO THE DEVELOPMENT OF
1000-2000 J/KG OF MLCAPE THIS AFTERNOON. SCATTERED STORMS WILL
DEVELOP ALONG A NE-SW-ORIENTED SFC FRONT DRAPED ACROSS THE AREA AND
INVOF REMNANT OUTFLOW BOUNDARIES/HIGHER TERRAIN TO THE EAST OF THE
FRONT. WITH 15-30 KT OF MID-LEVEL FLOW OVER THE SRN PERIPHERY OF THE
CYCLONIC FLOW AREA...DEEP SHEAR SHOULD BE SUFFICIENT FOR MULTICELL
STORMS WITH DMGG WIND GUSTS AND SVR HAIL.

...CNTRL AND SRN PLAINS THIS AFTERNOON INTO THIS EVENING...
ISOLATED HIGH-BASED SUPERCELL STORMS ARE FORECAST TO DEVELOP NEAR
THE LEE TROUGH/DRYLINE FROM WRN NEB SOUTH TO TX. PRIMARILY NEUTRAL
MID-LEVEL HEIGHT TENDENCIES WILL BE ASSOCIATED WITH LIMITED
CONVECTIVE COVERAGE. HOWEVER...STEEP LOW/MID-LEVEL LAPSE RATES AND
MODEST DEEP SHEAR SHOULD YIELD AN ISOLATED SVR WIND/HAIL THREAT.

..COHEN/CORFIDI.. 05/22/2012

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