SPC AC 051711
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1211 PM CDT WED SEP 05 2012
VALID 061200Z - 071200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CENTRAL AND
SOUTHERN PLAINS...
...CENTRAL/SOUTHERN PLAINS...
WEAK/NEUTRAL HEIGHT FALLS WILL OVERSPREAD THE NRN/CNTRL PLAINS
THURSDAY IN RESPONSE TO STRONGER WLY FLOW THAT SHOULD GRADUALLY SAG
SWD ACROSS THE NRN U.S. BOTH THE NAM/GFS SUGGEST A VERY WEAK LOW
AMPLITUDE SHORT-WAVE TROUGH WILL EJECT ESEWD INTO THE CNTRL HIGH
PLAINS BY 07/00Z...THOUGH THE NAM IS A BIT FASTER WITH THE TROUGH
AXIS INTO SCNTRL NEB/NWRN KS BY EARLY EVENING. IN THE WAKE OF THIS
FEATURE SFC PRESSURES SHOULD BUILD ACROSS THE NRN HIGH PLAINS
FORCING A COLD FRONTAL SURGE SWD ALONG THE LEE OF THE NRN ROCKIES TO
A POSITION FROM SCNTRL SD/NEB PANHANDLE/SERN WY BY 00Z. WHILE MID
LEVEL FLOW IS NOT EXPECTED TO BE THAT STRONG ACROSS THE CNTRL PLAINS
SOUTH OF THE FRONT...PERHAPS ON THE ORDER OF 30-40KT...DEEP LAYER
SHEAR WILL PROVE MORE THAN ADEQUATE FOR THE MAINTENANCE OF ORGANIZED
MULTI-CELL UPDRAFTS AND PERHAPS ISOLATED DEEP ROTATING TSTMS.
THERMODYNAMICALLY...STRONG BOUNDARY LAYER HEATING WILL PROVE
EFFECTIVE AND INSTRUMENTAL IN CONVECTIVE DEVELOPMENT ALONG ADVANCING
COLD FRONT/LEE TROUGH. FORECAST SOUNDINGS SUGGEST SFC TEMPERATURES
IN THE MID 90S ACROSS KS WILL WEAKEN THE CAP SUFFICIENTLY FOR DEEP
THERMALS/TSTM DEVELOPMENT. WHILE THE STRONGEST FORCING WILL
INITIALLY BE FOCUSED WITHIN THE STRONGER ZONE OF LOW LEVEL WARM
ADVECTION ACROSS THE MID MO VALLEY...LLJ IS EXPECTED TO INCREASE
ACROSS THE TX PANHANDLE INTO SWRN KS DURING THE EVENING HOURS AND
THIS MAY ENCOURAGE MULTIPLE THUNDERSTORM CLUSTERS TO EVOLVE ACROSS
THE SLGT RISK REGION. AT THIS TIME IT APPEARS ISOLATED DAMAGING
WINDS AND LARGE HAIL WILL BE THE MAIN CONCERNS WITH CONVECTION THAT
MATURES THROUGH THE AFTERNOON INTO THE EVENING HOURS.
...OH VALLEY...
HIGH LEVEL FLOW WILL BE DECIDEDLY DIFFLUENT FROM THE UPPER OH VALLEY
INTO THE TN VALLEY/NRN GULF STATES DURING THE DAY2 PERIOD. THIS
FLOW REGIME MAY ULTIMATELY ALLOW A FEW OVERNIGHT THUNDERSTORM
CLUSTERS FROM LATE DAY1 TO LINGER INTO THE DAY2 PERIOD AS THEY
PROPAGATE SLOWLY DOWNSTREAM. IT/S NOT ENTIRELY CLEAR HOW THESE
POTENTIAL CONVECTIVE DEBRIS FIELDS WILL INFLUENCE THE BOUNDARY LAYER
FROM WRN NY...SWWD ACROSS WRN PA/OH THROUGH KY/TN INTO NRN MS. AT
THIS TIME IT APPEARS 5 PERCENT SEVERE PROBS SHOULD BE SUFFICIENT TO
ACCOUNT FOR DIURNALLY DRIVEN ISOLATED SEVERE THUNDERSTORMS WHERE
STRONGEST HEATING OCCURS AND PERHAPS WITH RENEWED DEVELOPMENT ALONG
LEADING EDGE OF DAY1 ACTIVITY. FORECAST SHEAR PROFILES ARE
INADEQUATE TO SUPPORT MORE THAN PULSE/MULTI-CELL STORM STRUCTURES
THAT COULD PRODUCE LOCALLY DAMAGING WINDS.
..DARROW.. 09/05/2012
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z
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