SPC AC 041953
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0253 PM CDT THU SEP 04 2008
VALID 042000Z - 051200Z
...NO SVR TSTM AREAS FORECAST...
...MID MS/LOWER OH VALLEYS THIS AFTERNOON/EVENING...
EARLY AFTERNOON SURFACE ANALYSIS SHOWED THE LOW ASSOCIATED WITH THE
REMNANTS OF GUSTAV LOCATED IN THE VICINITY OF STL...WITH A WARM
FRONT EXTENDING ENEWD THROUGH CENTRAL IL/IND INTO CENTRAL/NRN OH. A
SURFACE TROUGH EXTENDED SWWD FROM THE LOW THROUGH CENTRAL AR TO E
TX...WITH A ZONE OF CONFLUENCE EXTENDING FROM FAR WRN KY/WRN TN INTO
ERN MS. REGIONAL RADARS INDICATED CONVECTIVE SHOWERS ALONG THIS
LATTER BOUNDARY...WITH TSTMS ALONG THE SRN EXTENT IN ERN MS/SERN LA
AND SW AL WHERE THE AIR MASS WAS MORE UNSTABLE.
GUSTAV WILL CONTINUE TO ACCELERATE NEWD THIS FORECAST PERIOD AHEAD
OF AN UPPER TROUGH APPROACHING THE WRN GREAT LAKES REGION FROM THE
NRN/CENTRAL PLAINS...AND EFFECTIVELY LEAVING WARMER MID LEVEL
TEMPERATURES IN ITS WAKE ACROSS THE LOWER OH TO LOWER MS VALLEYS.
IN ADDITION TO FAIRLY EXTENSIVE CLOUD COVER...THE WARM TEMPERATURES
ALOFT RESULTING IN WEAK MID LEVEL LAPSE RATES ARE LIMITING THE
DEVELOPMENT OF STRONGER INSTABILITY. SATELLITE IMAGERY AND SURFACE
OBSERVATIONS SHOWED A NARROW MOIST AXIS WITH SOME SURFACE HEATING
EXTENDING FROM ERN MS TO SRN IL BENEATH A MID LEVEL DRY SLOT. WIND
PROFILE DATA SHOWING LOW LEVEL DIRECTIONAL SHEAR WILL CONTINUE TO BE
FOUND ALONG AND AHEAD OF THE SURFACE LOW TRACK...WITH THE LOW
EXPECTED TO REACH NWRN IND BY LATE THIS EVENING. ALTHOUGH EFFECTIVE
SHEAR REMAINS SUFFICIENT TO SUPPORT LOW TOPPED SUPERCELLS...THE WEAK
INSTABILITY IS EXPECTED TO LIMIT THE DEVELOPMENT OF ORGANIZED
ACTIVITY THIS AFTERNOON. GIVEN THE PRESENCE OF LOW LEVEL
DIRECTIONAL SHEAR MAXIMIZED FROM IL INTO IND AND SUFFICIENT FOR SOME
STORM ROTATION...THE POTENTIAL FOR A TORNADO CAN NOT BE RULED OUT...
BUT THE THREAT APPEARS TO BE EVEN LESS THAN EXPECTED IN PREVIOUS DAY
1 OUTLOOK. THUS...TORNADO PROBABILITIES ARE BEING REDUCED IN THE
20Z OUTLOOK.
...CENTRAL HIGH PLAINS TONIGHT...
A MID LEVEL SHORTWAVE TROUGH OVER ID WILL DIG ESEWD TOWARD CO
THROUGH TONIGHT. THE APPROACH OF THIS MID LEVEL WAVE WILL INDUCE
WEAK LEE CYCLOGENESIS AND A SLY LLJ OVER THE SRN HIGH PLAINS...
WHICH WILL TRANSPORT RESIDUAL MOISTURE NWD FROM W TX/ERN NM. THIS
MOISTENING WILL OCCUR BENEATH STEEP MID LEVEL LAPSE RATES...
RESULTING IN AN ENVIRONMENT FAVORABLE FOR ELEVATED TSTMS TONIGHT
ACROSS ERN CO/WRN KS. STEEP MID LEVEL LAPSE RATES...MUCAPE
EXCEEDING 1000 J/KG...AND EFFECTIVE BULK SHEAR AOA 40 KT COULD
SUPPORT A FEW STORMS CAPABLE OF PRODUCING MAINLY ISOLATED LARGE HAIL
AND STRONGER WIND GUSTS LATE TONIGHT.
..PETERS.. 09/04/2008
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
|
