SWODY1
SPC AC 171252
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0752 AM CDT FRI SEP 17 2010
VALID 171300Z - 181200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE CNTRL
PLNS/LWR MO VLY...
...SYNOPSIS...
ELONGATED RIDGE WILL PERSIST FROM THE SWRN DESERTS ACROSS THE SRN
HALF OF THE PLNS INTO THE NERN GULF OF MEXICO THIS PERIOD...WHILE
SEASONABLY STRONG UPR LOW TRACKS FROM NRN MB TO SWRN HUDSON BAY
...AND A BROADER BUT WEAKER LOW LINGERS OVER THE NE PACIFIC.
AT THE SFC...LEAD COLD FRONT NOW EXTENDING FROM NRN MN TO SW NEB
SHOULD CONTINUE S/SE ACROSS THE CNTRL PLNS/UPR MS VLY TODAY. THE
BOUNDARY SHOULD SLOW OVER SRN NEB OR FAR NRN KS THIS EVE...BEFORE
RESUMING ITS SWD ADVANCE EARLY SAT AS SECONDARY FRONTAL SURGE NOW
OVER NW ND OVERTAKES IT. PERSISTENT SSWLY LOW LVL FLOW OVER WRN
PORTIONS OF THE SRN/CNTRL PLNS AHEAD OF THE FRONT SHOULD TAP
MOISTURE NOW PRESENT OVER THE TX/OK PANHANDLE REGION. THIS WILL
ALLOW PW TO REBOUND OVER CNTRL/ERN NEB AND IA...WITH VALUES AOA 1.25
INCHES EXPECTED BY TONIGHT/EARLY SAT.
...CNTRL PLNS/LWR MO VLY...
LARGE SCALE FORCING FOR ASCENT WILL BE MINIMAL TODAY OVER SLIGHT
RISK REGION...WITH HEIGHTS EXPECTED TO SLIGHTLY REBOUND IN WAKE OF
SHORTWAVE IMPULSE NOW CROSSING THE UPR MS VLY. WEAK HEIGHT FALLS
WILL...HOWEVER...OVERSPREAD PARTS OF THE CNTRL PLNS/LWR MO VLY THIS
EVE/EARLY SAT...AS WEAK DISTURBANCES TRACK ESE TOWARD THE REGION
FROM ID/WY ALONG NRN FRINGE OF UPR HIGH. APPROACH OF THESE
DISTURBANCES...AND NIGHTFALL...SHOULD FOSTER A CONCOMITANT
STRENGTHENING OF EXISTING SSWLY LLJ.
MODERATE WLY MID LVL FLOW WILL MAINTAIN EML PLUME AND ASSOCIATED CAP
OVER THE CNTRL PLNS TODAY. BUT SFC HEATING AND FRONTAL UPLIFT MAY
SUPPORT ISOLD STORM DEVELOPMENT ALONG STALLING COLD FRONT OVER SRN
NEB OR FAR NRN KS LATE THIS AFTN OR EARLY THIS EVE. GIVEN DEGREE OF
INSTABILITY /SBCAPE TO 2500 J PER KG/ AND 30+ KT WNWLY DEEP
SHEAR...ANY SUSTAINED STORMS THAT DO FORM WILL BE
SUPERCELLULAR...WITH THE POTENTIAL FOR LARGE HAIL/LOCALLY DMGG WIND
AND POSSIBLY A TORNADO.
MORE WIDESPREAD STORM DEVELOPMENT APPEARS LIKELY LATER TONIGHT
THROUGH EARLY SAT ALONG AND N OF ACCELERATING COLD FRONT AS
WAA/LARGE SCALE ASCENT STRENGTHEN AMIDST PERSISTENT LOW LVL MOISTURE
RETURN. WHILE SETUP SUGGESTS THAT MUCH OF THIS ACTIVITY SHOULD
BECOME ELEVATED WITH TIME...BOWING SEGMENTS WITH A THREAT FOR DMGG
WIND MAY DEVELOP ALONG THE LEADING/SRN EDGE OF THE EVOLVING COMPLEX
FROM NEB/NRN KS INTO PARTS OF IA AND POSSIBLY NW MO. WIND PROFILES
ALSO MAY SUPPORT AREAS OF REGENERATIVE STORMS WITH MARGINALLY SVR
HAIL/HEAVY RAIN.
...CAROLINAS/SE VA...
UPR IMPULSE SHOWN BY WATER VAPOR IMAGERY OVER KY/TN ATTM SHOULD
CONTINUE E ACROSS THE SRN APPALACHIANS LATER TODAY IN MEAN W TO
WNWLY FLOW. ASSOCIATED FORCING FOR ASCENT/MID LVL COOLING...
COUPLED WITH SFC HEATING...AND LOW LVL UPLIFT OVER THE HIGHER
TERRAIN AND/OR ALONG LEE TROUGH...SHOULD SUPPORT A BAND OR TWO OF
AFTN/EVE STORMS OVER PARTS OF THE CAROLINAS/SE VA. MODEST
INSTABILITY...STEEP LOW LVL LAPSE RATES...AND 20-25 KT WNWLY DEEP
SHEAR MAY YIELD A FEW STORMS WITH STRONG TO POSSIBLY SVR WIND GUSTS.
..CORFIDI/SMITH.. 09/17/2010
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