SWODY2
SPC AC 051727
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1227 PM CDT WED MAY 05 2010
VALID 061200Z - 071200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF THE CNTRL
PLAINS AND MID MS VALLEY...
...SYNOPSIS...
PROGRESSIVE QUASI-ZONAL UPPER FLOW REGIME WILL PERSIST THIS PERIOD.
UPPER TROUGH OVER THE UPPER MS VALLEY WILL MOVE THROUGH THE GREAT
LAKES AND NERN U.S. THEN OFF THE ATLANTIC SEABOARD THURSDAY NIGHT.
UPPER TROUGH OVER THE PACIFIC NW WILL REACH THE NRN AND CNTRL PLAINS
THURSDAY EVENING AND THE MID-UPPER MS VALLEY LATE THURSDAY NIGHT. A
COLD FRONT WILL ACCOMPANY LEAD UPPER TROUGH EWD THROUGH THE GREAT
LAKES...OH VALLEY AND NERN STATES. TRAILING PORTION OF THIS BOUNDARY
WILL DEVELOP NWD INTO KS AS A WARM FRONT AS LEE CYCLOGENESIS
COMMENCES ACROSS WRN KS THURSDAY AFTERNOON. DRYLINE WILL EXTEND FROM
THE SURFACE LOW IN SWRN KS THROUGH WRN OK AND W-CNTRL TX. SHORTWAVE
TROUGH EJECTING INTO THE CNTRL PLAINS WILL PROVIDE IMPETUS FOR A
POLAR FRONT TO ACCELERATE SEWD THROUGH KS OVERNIGHT.
...CNTRL PLAINS THROUGH MID MS VALLEY AREAS...
LOW-LEVEL JET WILL STRENGTHEN ACROSS TX AND OK THURSDAY IN RESPONSE
TO DEVELOPING LEE CYCLONE OVER THE CNTRL HIGH PLAINS. THIS FEATURE
WILL ADVECT MODIFIED CP AIR NWD THROUGH WARM SECTOR WITH DEWPOINTS
IN THE 50S EXPECTED...EXCEPT POSSIBLY LOW 60S IN VICINITY OF
RETREATING WARM FRONT. STRENGTHENING WSWLY FLOW IN THE 3-6 KM LAYER
ACCOMPANYING THE UPPER TROUGH WILL ADVECT AN EML NEWD ABOVE MOIST
AXIS. THESE PROCESSES AND DIABATIC WARMING WILL RESULT IN A
RESERVOIR OF MODERATE INSTABILITY. THE EML WILL BE WARM ENOUGH TO
CAP THE ATMOSPHERE MOST OF THE DAY. INITIAL STORMS MAY DEVELOP
WITHIN AREA OF FOCUSED MESOSCALE FORCING NEAR TRIPLE POINT EAST OF
THE SURFACE LOW ACROSS S-CNTRL KS DURING THE LATE AFTERNOON OR EARLY
EVENING. EFFECTIVE VERTICAL SHEAR NEAR 50 KT WILL SUPPORT SUPERCELLS
WITH VERY LARGE HAIL THE INITIAL PRIMARY THREAT. HODOGRAPH SIZE IN
THE 0-1 KM LAYER WILL INCREASE SUBSTANTIALLY AS THE LOW LEVEL JET
STRENGTHENS DURING THE EVENING RESULTING IN A SMALL WINDOW FOR
ISOLATED TORNADOES BEFORE THE BOUNDARY LAYER DECOUPLES.
HOWEVER...LARGER THAN OPTIMAL BOUNDARY LAYER TEMPERATURE-DEWPOINTS
SPREADS COULD SERVE AS A LIMITING FACTOR FOR A MORE ROBUST TORNADO
THREAT. STORMS WILL LIKELY EXPAND NEWD TOWARD THE MS VALLEY DURING
THE EVENING WITHIN ZONE OF STRENGTHENING ISENTROPIC LIFT ALONG AND
NORTH OF WARM FRONT AS WELL AS ALONG SEWD ADVANCING COLD FRONT WITH
A CONTINUED THREAT FOR ISOLATED LARGE HAIL AND DAMAGING WIND.
...NERN STATES THROUGH MID ATLANTIC...
AN AXIS OF 50S DEWPOINTS WILL ADVECT NWD THROUGH PRE-FRONTAL WARM
SECTOR ACROSS THE MID-ATLANTIC AND NERN STATES.
HOWEVER...PRE-FRONTAL CLOUDS AND ONGOING CONVECTION MAY LIMIT THE
POTENTIAL FOR MORE ROBUST BOUNDARY LAYER DESTABILIZATION BEFORE
FRONTAL PASSAGE. CONVECTION WILL LIKELY REDEVELOP ALONG AND AHEAD OF
THE COLD FRONT OR OUTFLOW BOUNDARIES DURING THE MORNING. STRONG
UNIDIRECTIONAL SHEAR ACCOMPANYING THE SHORTWAVE TROUGH WILL BE
SUPPORTIVE OF ORGANIZED STORMS WITH A THREAT FOR MAINLY ISOLATED
WIND DAMAGE. AT THIS TIME IT APPEARS A RELATIVELY SMALL WINDOW WILL
EXIST TO DESTABILIZE THE ATMOSPHERE PRIOR TO ARRIVAL OF THE
FRONT...AND THIS COULD SERVE AS A LIMING FACTOR. HOWEVER...A SLIGHT
RISK MIGHT BE NEEDED IN DAY 1 OUTLOOKS IF IT BEGINS TO APPEAR THE
ATMOSPHERE WILL DESTABILIZE MORE THAN CURRENTLY ANTICIPATED.
..DIAL.. 05/05/2010
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