SWODY2
SPC AC 290559
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1259 AM CDT THU APR 29 2010
VALID 301200Z - 011200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PORTIONS OF THE SRN PLAINS
THROUGH THE MS VALLEY AND GREAT LAKES...
...SYNOPSIS...
A BROAD UPPER TROUGH WILL CHARACTERIZE THE UPPER PATTERN OVER THE
WRN TWO THIRDS OF THE COUNTRY FRIDAY WITH AN UPPER RIDGE OVER THE
ERN STATES. SHORTWAVE TROUGH AND ATTENDANT STRONG UPPER JET WILL
EJECT NEWD ALONG ERN PERIPHERY OF THE UPPER TROUGH THROUGH THE CNTRL
PLAINS INTO THE MID-UPPER MS VALLEYS. MAIN SURFACE LOW WILL
CONSOLIDATE AND DEEPEN OVER THE UPPER MS VALLEY...WHILE TRAILING
COLD FRONT ADVANCES THROUGH THE UPPER MS VALLEY AND GREAT LAKES.
SWRN EXTENSION OF THE FRONT WILL STALL OVER THE SRN PLAINS. WARM
FRONT WILL LIFT NWD THROUGH THE LOWER MS VALLEY REGION.
...SRN PLAINS THROUGH LOWER MS VALLEY...
RICH GULF MOISTURE WILL SURGE NWD ALONG STRONG SLY LOW-LEVEL JET
THROUGH ERN PORTIONS OF SRN PLAINS AND LOWER MS VALLEY BENEATH A
MODEST EML PLUME. THIS WILL RESULT IN THE POTENTIAL FOR MODERATE
INSTABILITY. FORECAST SOUNDINGS IN THIS REGION VALID 12Z FRIDAY
INDICATE THE ATMOSPHERE WILL INITIALLY BE CAPPED WITH RESPECT TO
SURFACE BASED PARCELS DUE TO THE PRESENCE OF THE EML.
HOWEVER...MODELS CONTINUE TO SUGGEST EARLY CONVECTION MAY DEVELOP
WITHIN THE PRE-FRONTAL THETA-E ADVECTION REGIME...AND THIS ALONG
WITH LIKELIHOOD OF LOW CLOUDS MAY LIMIT DIABATIC HEATING IN PORTIONS
OF WARM SECTOR. DETAILS REGARDING THE EVOLUTION OF EARLY CONVECTION
REMAIN UNCERTAIN...BUT INFLUX OF RICH LOW-LEVEL MOISTURE AND
POTENTIAL FOR DEEPER ASCENT WITHIN EXIT REGION OF SUBTROPICAL JET
ROUNDING BASE OF UPPER TROUGH MAY EVENTUALLY SUPPORT THE DEVELOPMENT
OF SURFACE BASED STORMS. LARGE HODOGRAPHS ALONG THE LOW LEVEL JET
AXIS AND 40-50 KT DEEP LAYER SHEAR WILL SUPPORT A THREAT OF
SUPERCELLS AND TORNADOES AS WELL AS LARGE HAIL AND DAMAGING WIND.
OTHER STORMS WILL LIKELY DEVELOP OVERNIGHT ACROSS CNTRL/ERN TX AND
OK ALONG SEWD ADVANCING COLD FRONT WITH A THREAT FOR MAINLY ISOLATED
DAMAGING WIND AND HAIL.
...MID-UPPER MS VALLEY AND GREAT LAKES...
PARTIALLY MODIFIED GULF AIR WITH LOW 60S DEWPOINTS WILL ADVECT NWD
THROUGH PRE-FRONTAL WARM SECTOR...BUT WIDESPREAD CLOUDS WILL LIKELY
LIMIT DESTABILIZATION POTENTIAL WITH MLCAPE GENERALLY AOB 1000 J/KG.
A 90 KT MID LEVEL JET ATTENDING THE EJECTING SHORTWAVE TROUGH WILL
CONTRIBUTE TO STRONG DEEP LAYER SHEAR...AND LARGE HODOGRAPHS WILL
EXIST ALONG THE LOW LEVEL JET AXIS. STORMS WILL LIKELY DEVELOP IN
WARM SECTOR AND ALONG SEWD ADVANCING COLD FRONT DURING THE
AFTERNOON. ORGANIZED STORMS INCLUDING SUPERCELLS AND BOWING SEGMENTS
WILL BE POSSIBLE WITH A THREAT FOR DAMAGING WIND...LARGE HAIL AND
ISOLATED TORNADOES.
..DIAL.. 04/29/2010
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