SWODY1
SPC AC 260100
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0800 PM CDT WED APR 25 2007
VALID 260100Z - 261200Z
..THERE IS A SLGT RISK OF SVR TSTMS FROM THE OZARKS/SRN MO ACROSS
THE LOWER MS/TN VALLEYS AND INTO LOWER OH VALLEY...
..SYNOPSIS...
A LARGE DEEP-LAYER CYCLONE WAS CENTERED ACROSS THE SCNTRL CONUS THIS
EVENING. SURFACE LOW WITH THIS SYSTEM IS EXPECTED TO REMAIN STRONG
WITHIN FAVORABLE BAROCLINIC REGIME FROM THE OZARKS ACROSS THE MS
VALLEY THROUGH TONIGHT. A NUMBER OF SMALLER SCALE MID LEVEL
DISTURBANCES/WIND MAXIMA WILL ROTATE THROUGH THE SERN/ERN PERIPHERY
OF THE LARGER SCALE CYCLONE AND ACT TO ENHANCE ASCENT AND TSTM
PROSPECTS ALONG THE ADVANCING COLD FRONT...AS WELL AS ACROSS THE
WARM SECTOR FROM THE LOWER MS VALLEY TO THE TN VALLEY THROUGH
THURSDAY MORNING.
..LOWER MS VALLEY ACROSS TN VALLEY TO LOWER OH VALLEY...
CONVECTIVELY GENERATED LOW LEVEL BAROCLINIC ZONE WAS SUPPORTING A
BROKEN ARC OF STRONG TO OCCASIONALLY SEVERE STORMS FROM MS NNEWD TO
WRN/MIDDLE TN. THIS CONVECTION WAS WELL AHEAD OF SYNOPTIC COLD FRONT
WHICH WAS SITUATED FARTHER WEST. DESPITE DIURNAL DOWNWARD TREND IN
SURFACE TEMPERATURES...MOIST BOUNDARY LAYER AND LOW LFC...AND
INCREASING LARGE SCALE DYNAMICS...SHOULD MAINTAIN A THREAT FOR A FEW
SEVERE STORMS OVERNIGHT. SOMEWHAT WEAK MID LEVEL LAPSE RATES APPEAR
TO BE LIMITING MORE ROBUST UPDRAFTS ATTM WITH MLCAPE TO AOB 1000
J/KG. HOWEVER...AS UPPER IMPULSES AND COLD FRONT APPROACH AND MOVE
ACROSS THE REGION THROUGH LATE TONIGHT...ISOLATED TORNADO AND WIND
DAMAGE POTENTIAL CANNOT BE RULED OUT. THREAT MAY ALSO INCREASE
ACROSS PARTS OF THE LOWER OH VALLEY WHERE WELL-DEFINED
QUASI-STATIONARY/WARM FRONT COULD PROVIDE ADDITIONAL FOCUS FOR STORM
DEVELOPMENT/PERSISTENCE AS UPPER DYNAMICS INCREASE.
..WEST OF THE MS RIVER FROM MO TO SERN TX...
VIGOROUS STORMS ARE PLENTIFUL AND EXIST FROM NEAR THE SURFACE
LOW...IN MO...SWD ALONG THE COLD FRONT ACROSS AR...AND THEN TRAIL
SWWD INTO TX. DESPITE STRONG FORCING AND SUPPORTIVE LOW LEVEL SHEAR
NEAR THE SURFACE LOW AND ALONG THE FRONT...MUCH OF THIS ACTIVITY
APPEARS TO HAVE RECENTLY PEAKED IN INTENSITY. A POSSIBLE EXCEPTION
MAY BE STORMS OVER LA/TX...AND NEAR THE LOW...WHERE INSTABILITY AND
FORCING RESPECTIVELY REMAIN SUFFICIENT FOR POSSIBLE SEVERE. THE BULK
OF THIS CONVECTION MAY BEGIN TO ENCOUNTER A MORE HOSTILE/STABLE
ENVIRONMENT LEFT IN THE WAKE OF THE PREFRONTAL/WARM SECTOR MCS
ACROSS THE LOWER MS VALLEY. THIS SCENARIO IS SUPPORTED BY LATEST
MODEL GUIDANCE DEPICTING A GENERAL DECREASE IN CONVECTIVE QPF ALONG
THE FRONT THOUGH LATE TONIGHT. HOWEVER...GIVEN MAGNITUDE OF LARGE
SCALE FORCING/FLOW...AND POCKETS OF RESIDUAL MOISTURE AND GREATER
INSTABILITY...SEVERE HAIL AND/OR AND ISOLATED TORNADO WILL REMAIN A
POSSIBILITY...AT LEAST FOR A COUPLE MORE HOURS.
.CARBIN.. 04/26/2007
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