SPC AC 210552
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1252 AM CDT FRI MAY 21 2010
VALID 211200Z - 221200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER THE CNTRL AND SRN HIGH
PLAINS...
...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF THE TN AND OH
VALLEYS...
...SYNOPSIS...
UPPER TROUGH CURRENTLY OVER THE MID MS VALLEY WILL CONTINUE SLOWLY
ENEWD INTO THE OH VALLEY AND GREAT LAKES REGION...WHILE UPSTREAM
TROUGH AMPLIFIES ACROSS THE WRN STATES. AT THE SURFACE AN OCCLUDED
LOW WILL LIFT NEWD THROUGH IL WITH TRAILING FRONT EXTENDING SWWD
INTO THE LOWER MS VALLEY. LEE CYCLOGENESIS WILL COMMENCE OVER THE
CNTRL HIGH PLAINS IN ASSOCIATION WITH INCREASING SWLY FLOW ALOFT AND
HEIGHT FALLS RESULTING FROM AMPLIFYING UPPER TROUGH. A DRYLINE WILL
DEVELOP SWD FROM THE LOW THROUGH THE CNTRL AND SRN HIGH PLAINS.
...CNTRL THROUGH SRN HIGH PLAINS...
RICHER MOISTURE RESIDING OVER TX WILL ADVECT NWWD INTO THE SRN AND
CNTRL HIGH PLAINS AS SLY LOW-LEVEL JET STRENGTHENS IN RESPONSE TO
DEVELOPING LEE CYCLONE. SURFACE DEWPOINTS IN THE 50S F WILL ADVECT
AS FAR NORTH AS WRN NEB AND SERN WY...WITH 60S F FARTHER SOUTH INTO
THE SRN HIGH PLAINS BENEATH STEEP MID-LEVEL LAPSE RATES RESULTING IN
AN AXIS OF 1500-2000 J/KG MLCAPE. THE ATMOSPHERE WILL REMAIN CAPPED
TO SURFACE BASED STORMS UNTIL LATE AFTERNOON WHEN INITIATION WILL
BECOME MORE PROBABLE. STORMS MAY DEVELOP OVER THE HIGHER TERRAIN OF
CO AND WY AND INTENSIFY AS THEY INTERCEPT THE MOIST AXIS. OTHER MORE
ISOLATED ACTIVITY MAY DEVELOP FARTHER SWD ALONG THE DRYLINE. UPPER
FLOW IS FORECAST TO BECOME INCREASINGLY DIFFLUENT OVER THE CNTRL
HIGH PLAINS WHERE STORMS WILL LIKELY BE MORE NUMEROUS. STRONG DEEP
LAYER SHEAR OF 45+ KT WILL SUPPORT SUPERCELLS WITH LARGE HAIL
LIKELY. HODOGRAPH SIZE WILL INCREASE SUBSTANTIALLY DURING THE EARLY
EVENING AS THE LOW-LEVEL JET STRENGTHENS RESULTING IN A WINDOW FOR
ISOLATED TORNADOES. ANY STORMS THAT DEVELOP OVER THE CNTRL HIGH
PLAINS SHOULD CONTINUE EWD...POSSIBLY EVOLVING INTO AN MCS OVERNIGHT
SUPPORTED BY ISENTROPIC LIFT AND THETA-E ADVECTION ALONG THE STRONG
LOW LEVEL JET.
...TN AND OH VALLEYS...
THE ATMOSPHERE SHOULD DESTABILIZE DURING THE DAY IN WAKE OF
CONVECTION CURRENTLY MOVING THROUGH THE TN AND OH VALLEYS WITH AN
AXIS OF 1500-2000 J/KG MLCAPE POSSIBLE AHEAD OF THE FRONT. A BELT OF
40 KT WLY FLOW ALONG THE SRN PERIPHERY OF THE UPPER TROUGH WILL
RESULT IN 35-40 KT UNIDIRECTIONAL DEEP SHEAR. POTENTIAL WILL EXIST
FOR STORMS TO REDEVELOP ALONG AND AHEAD OF THE FRONT DURING THE
AFTERNOON WITH A THREAT FOR MAINLY ISOLATED DAMAGING WIND AND HAIL
THROUGH EARLY EVENING.
..DIAL/GRAMS.. 05/21/2010
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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