SPC AC 191249
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0749 AM CDT SAT JUN 19 2010
VALID 191300Z - 201200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE CNTRL PLNS...
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE LWR GRT
LKS...
...SYNOPSIS...
FLAT RIDGE WILL PERSIST OVER TX AND THE LWR MS VLY THROUGH
SUN...WHILE HEIGHTS REBOUND OVER THE UPR MS VLY IN WAKE OF TROUGH
NOW CROSSING THE UPR GRT LKS. THE GRT LKS TROUGH SHOULD CONTINUE E
TO THE LWR GRT LKS BY EARLY SUN AS ORE UPR LOW/TROUGH EDGES SLOWLY E
TOWARD THE NRN GRT BASIN.
AT THE SFC...MAIN FEATURE OF NOTE WILL BE DIFFUSE FRONTAL ZONE
EXTENDING SW FROM THE GRT LKS TO THE CNTRL PLNS. THE ERN PORTION OF
THIS FRONT...PRECEDING BY CONVECTIVE OUTFLOW IN THE OH VLY...SHOULD
CONTINUE STEADILY E/SE ACROSS THE NRN/CNTRL APPALACHIANS BY THE END
OF THE PERIOD...WHILE THE WRN PART REMAINS NEARLY STNRY OR MOVES
SLIGHTLY N TO THE KS/NEB BORDER.
...CNTRL PLNS THROUGH EARLY SUN...
STALLING W/E FRONT NEAR THE KS/NEB BORDER SHOULD BE THE FOCUS FOR
REPEATED ROUNDS OF STRONG TO SVR STORMS THROUGH THE FCST PERIOD AS
BOUNDARY LINGERS BENEATH EML ON SRN FRINGE OF THE WLYS.
SMALL...SLIGHTLY ELEVATED OVERNIGHT MCS NOW OVER N CNTRL KS SHOULD
TRACK MAINLY ESE FOR THE NEXT FEW HOURS...BEFORE PERHAPS TURNING A
BIT MORE SE ACROSS ERN KS. VWP DATA....EXPECTED SFC HEATING...AND
ACCAS CLOUDS SUGGEST THAT OTHER SLIGHTLY ELEVATED STORMS MAY FORM
AHEAD OF MCS OVER NE KS/WRN MO. GIVEN EXPECTED DEGREE OF SBCAPE BY
AFTN /AOA 3500 J PER KG/ AND 30-35 KT DEEP WLY SHEAR...SVR WIND AND
HAIL APPEAR LIKELY.
STRONG EML MAY PROHIBIT STORM DEVELOPMENT S OF FRONT THROUGH THE
DAY. BUT MOIST ESELY LOW-LVL FLOW ALONG AND N OF BOUNDARY WNW INTO
THE WY/NRN CO RCKYS SHOULD CONTRIBUTE TO MODERATE TO STRONG
DESTABILIZATION BY LATE AFTN. STEEP MID-LVL LAPSE RATES AND SBCAPE
OF 2500-3500 J/KG SHOULD BE FAVORABLE FOR A FEW INTENSE
STORMS/SUPERCELLS WITH LARGE HAIL AND DMGG WINDS GIVEN 40+ KT DEEP
WSWLY SHEAR. ALTHOUGH UPR LVL FORCING FOR ASCENT WILL BE
WEAK...SUSTAINED LOW LVL WAA/PRONOUNCED VEERING WITH HEIGHT N OF
FRONT WILL YIELD MODERATE TO STRONG LOW LVL SHEAR. THUS...THREAT
WILL ALSO EXIST FOR A FEW TORNADOES BEFORE THE ACTIVITY ORGANIZES
INTO ONE OR MORE FORWARD-PROPAGATING MCSS THIS EVE. THESE SYSTEMS
SHOULD MOVE GENERALLY E...WITH A CONTINUED THREAT FOR HIGH WIND/HAIL
INTO EARLY SUN.
...LWR GRT LKS/NRN APPALACHIANS THIS AFTN/EVE...
EXPECTED REJUVENATION OF OVERNIGHT MCS IN ERN KY LIKELY WILL
SOMEWHAT DIMINISH LOW LVL MOISTURE RETURN/INFLOW AHEAD OF COLD FRONT
APPROACHING THE LWR GRT LKS. BUT WITH LARGELY UNIMPEDED SFC
HEATING...SUFFICIENT DESTABILIZATION /SBCAPE OF 1500-2000 J PER KG/
SHOULD OCCUR TO SUPPORT SCTD STRONG STORMS ALONG AND AHEAD OF FRONT
FROM WV/WRN PA NEWD INTO UPSTATE NY. COUPLED WITH 30-40 KT DEEP WLY
FLOW AHEAD OF UPR TROUGH...SETUP MAY FOSTER A FEW SUSTAINED
MULTICELL BANDS/CLUSTERS. BOWING SEGMENTS AND ANY MORE ROBUST
STORMS WITHIN THIS ACTIVITY COULD YIELD DMGG WIND AND MARGINALLY SVR
HAIL. THE SVR THREAT COULD MOVE/DEVELOP AS FAR NE AS NRN NEW
ENGLAND BY EARLY EVE.
...LWR OH/TN VLYS AND NRN GULF STATES THIS AFTN...
CNTRL PART OF OUTFLOW BOUNDARY FROM OVERNIGHT MCS IN THE MID MS/LWR
OH VLYS SHOULD DECELERATE AS IT CONTINUES S INTO THE TN VLY LATER
THIS MORNING...WHILE THE ERN PORTION ADVANCES SOMEWHAT MORE RAPIDLY
E TO THE CNTRL APPALACHIANS. SFC HEATING MAY SUPPORT SOME
REDEVELOPMENT/INTENSIFICATION OF STORMS OVER ERN KY AND MIDDLE TN BY
MIDDAY. WIND PROFILES AND THERMODYNAMIC CONSIDERATIONS SUGGEST THAT
ANY STORM CLUSTER EVOLVING IN TN WILL MOVE S INTO NRN AL/MS...WHILE
THE KY STORMS CONTINUE E OR ESE. ALTHOUGH LOCALLY DMGG WINDS MAY
OCCUR...ESPECIALLY IN THE TN VLY... OVERALL SETUP DOES NOT APPEAR
FAVORABLE FOR AN ORGANIZED SVR THREAT.
..CORFIDI/GARNER.. 06/19/2010
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