SWODY1
SPC AC 021959
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0259 PM CDT TUE OCT 02 2007
VALID 022000Z - 031200Z
..THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON AND TONIGHT FROM
PARTS OF THE LOWER MO AND MID MS VALLEYS SWWD INTO OK...
..SYNOPSIS...
EARLY AFTERNOON WATER VAPOR IMAGERY SHOWS POTENT SHORT WAVE TROUGH
TRANSLATING EWD THROUGH THE NRN/CNTRL PLAINS WITH ATTENDANT 50-60 KT
MID-LEVEL JET STREAK AND STRONGEST LARGE-SCALE FORCING FOR ASCENT
SPREADING EWD THROUGH THE MID AND LOWER MO VALLEY. IN THE LOW
LEVELS...PRIMARY SURFACE LOW WAS ANALYZED OVER N-CNTRL MN WITH
TRAILING COLD FRONT EXTENDING SWD THROUGH FAR ERN NEB AND THEN MORE
SWWD THROUGH S-CNTRL KS INTO THE TX PNHDL.
LATEST SHORT TERM MODEL GUIDANCE SUGGESTS THAT SHORT WAVE TROUGH
WILL LIFT MORE NEWD INTO THE UPPER GREAT LAKES TONIGHT WITH
ASSOCIATED SURFACE FRONTAL SYSTEM EXTENDING FROM THE UPPER GREAT
LAKES SWD INTO THE MID MS VALLEY AND TX BY TUESDAY MORNING.
..LOWER MO/MID MS VALLEYS SWWD INTO OK...
CONSIDERABLE CLOUDINESS/PERSISTENT TSTM ACTIVITY HAVE LIMITED AIR
MASS DESTABILIZATION AHEAD OF COLD FRONT FROM N-CNTRL OK NEWD
THROUGH ERN KS AND NWRN MO. TO THE E...NEWD TRANSPORT OF AN
INCREASINGLY MOIST BOUNDARY LAYER COUPLED WITH STRONGER DIABATIC
HEATING ARE CONTRIBUTING TO AN AXIS OF STRONGER INSTABILITY FROM
SRN/CNTRL OK INTO PORTIONS OF SWRN/CNTRL MO...DESPITE THE PRESENCE
OF POOR MID-LEVEL LAPSE RATES /REF. 18Z SGF SOUNDING/. FURTHER
HEATING SHOULD SUPPORT ADDITIONAL DESTABILIZATION THIS AFTERNOON
WITH MLCAPES INCREASING TO 1000-2000 J/KG ACROSS THIS REGION.
LATEST TRENDS IN REGIONAL RADAR DATA SHOW TSTMS SLOWLY INTENSIFYING
ALONG LEADING EDGE OF ABOVEMENTIONED CONVECTIVE BAND FROM WRN MO
INTO N-CNTRL/NERN OK. FORCING FOR ASCENT ALONG SERN PERIPHERY OF
SHORT WAVE TROUGH MOVING THROUGH THE MID MO VALLEY COUPLED WITH
DECREASING STABILITY IN THE SYSTEM WARM SECTOR SHOULD CONTINUE TO
SUPPORT AN INCREASE IN TSTM COVERAGE AND INTENSITY THIS AFTERNOON
AND EVENING ACROSS CNTRL/ERN PORTIONS OF MO SWWD INTO OK.
REGIONAL VWPS/PROFILERS AND RUC OBJECTIVE FIELDS INDICATE THAT THE
STRONGEST LOW AND DEEP LAYER SHEAR RESIDES INVOF WEAK WARM FRONT
LIFTING NWD THROUGH THE LOWER MO VALLEY /I.E. EFFECTIVE SRH OF
300-400 M2 PER S2 AND EFFECTIVE BULK SHEARS OF 50-60 KT/...WITH A
GENERAL DECREASE IN MAGNITUDE OF THESE VALUES SWWD THROUGH
PRE-FRONTAL WARM SECTOR. WHILE PRIMARY CONVECTIVE MODE WILL LIKELY
BE LINEAR...POTENTIAL WILL EXIST FOR EMBEDDED BOWING OR SUPERCELL
STRUCTURES WITH THE THREAT FOR SOME HAIL AND A COUPLE TORNADOES IN
ADDITION TO LOCALLY DAMAGING WINDS.
FOR ADDITIONAL SHORT TERM GUIDANCE...PLEASE SEE MCD/S 2049/2050.
..UPPER MS VALLEY INTO UPPER MIDWEST...
WIDESPREAD CLOUDS AND PRECIPITATION HAVE LIMITED HEATING AHEAD OF
FRONT TODAY WITH AIR MASS EXPECTED TO REMAIN ONLY MARGINALLY
UNSTABLE /MUCAPES AOB 500-800 J PER KG/. NONETHELESS...STRONG DEEP
LAYER FORCING FOR ASCENT AHEAD OF SHORT WAVE TROUGH SHOULD SUPPORT
AN INCREASE IN TSTM COVERAGE AND INTENSITY THIS AFTERNOON AND
EVENING FROM PORTIONS OF MN/IA EWD INTO WI/IL. VERTICAL SHEAR IS
MORE THAN SUFFICIENT FOR ORGANIZED STORMS...HOWEVER THE MARGINAL
INSTABILITY WILL LIKELY PRECLUDE A MORE SUBSTANTIAL SEVERE THREAT.
STILL...SOME POTENTIAL WILL EXIST FOR A FEW SEVERE STORMS WITH HAIL
AND LOCALLY DAMAGING WINDS BEING THE PRIMARY SEVERE WEATHER HAZARDS.
.MEAD.. 10/02/2007
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