SWODY1
SPC AC 221628
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1128 AM CDT SUN APR 22 2007
VALID 221630Z - 231200Z
..THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE LWR MO AND
MID MS VLYS...
..SYNOPSIS...
NRN KS UPR LOW EXPECTED TO OPEN INTO A SHORTWAVE TROUGH LATER
TODAY/TONIGHT AS IT TURNS ENE AND IS ABSORBED INTO NRN STREAM FLOW.
THE UPR VORT SHOULD BE NEAR SUX BY THIS EVENING...NEARLY VERTICAL
WITH ASSOCIATED SFC CENTER. BY 12Z MONDAY THE SFC WAVE SHOULD REACH
SRN WI...50-60 KT MID LEVEL JET STREAK OVERSPREADING IND/WRN OH.
IN THE W...NEXT IN SERIES OF NEGATIVE TILT UPR SYSTEMS WILL AMPLIFY
SE INTO THE SRN GRT BASIN.
..LWR MO VLY...
WHILE KS/NEB LOW WILL WEAKEN OVER TIME...PRESENT WIND FIELD IS QUITE
STRONG AND WINDS WILL REMAIN MORE THAN ADEQUATE TO SUPPORT SVR TSTMS
THIS PERIOD. TODAY'S INITIAL THREAT LIKELY WILL BE CONFINED TO
SYSTEM DRY SLOT OVER THE LWR MO VLY...WHERE MODERATE HEATING WILL
OCCUR. TSTMS SHOULD FORM IN THE DRY SLOT BY EARLY AFTERNOON OVER SE
NEB AND N CNTRL/NE KS....WITH THE ACTIVITY THEN SPREADING E/NE INTO
NW MO AND SW IA /REF MCD #536/.
WIND PROFILES WILL SHOW RAPID SPATIAL/TEMPORAL VARIATION IN DRY
SLOT...COMPLICATING FORECAST OF PREDOMINANT STORM MODE/SVR THREAT.
THE STRONGEST LOW-LEVEL DIRECTIONAL SHEAR MAY REMAIN CONFINED TO SE
NEB...WHILE MORE FAVORABLE DEEP SHEAR ENVIRONMENT FOR SUSTAINED
SUPERCELLS WILL ACCOMPANY EJECTING MID LEVEL SPEED MAX FARTHER S
ACROSS NRN KS/NW MO. BEST COMBINATION OF THERMODYNAMICS AND
KINEMATICS FOR LOW-TOPPED SUPERCELLS/POSSIBLE TORNADOES THROUGH MID
AFTERNOON APPEARS TO BE AREA FROM BIE S AROUND MHK/TOP...WITH THE
PATTERN SHIFTING INTO NW MO A BIT LATER IN THE DAY. SBCAPE IN THIS
REGION SHOULD REACH 1000 J/KG...WITH 0-1 KM SHEAR AOA 200 M2/S2.
..CNTRL IA/CNTRL MO INTO SRN MN/IL/WI...
FARTHER E AND N...WARM CONVEYOR BELT BAND WILL LIMIT HEATING ACROSS
MUCH OF WRN MO AND WRN/CNTRL IA. COUPLED WITH LIMITED LOW LEVEL
MOISTURE SUPPLY...PROSPECTS FOR SFC-BASED STORM DEVELOPMENT WITHIN
THE BAND APPEAR LIMITED. ELEVATED ACTIVITY WITHIN THE CONVEYOR
MAY...HOWEVER...POSE A THREAT FOR MARGINALLY SVR HAIL IN IA. AHEAD
OF THE WARM CONVEYOR...SKIES SHOULD REMAIN MAINLY CLEAR ACROSS NE
MO/ERN IA AND SRN MN. COUPLED WITH INCREASING FORCING FOR ASCENT
WITH APPROACHING KS/NEB UPR SYSTEM...CANNOT RULE OUT POSSIBILITY
THAT A N/S LINE OF FORWARD-PROPAGATING STORMS MIGHT FORM ON LEADING
EDGE OF CONVEYOR BELT. GIVEN STRENGTHENING WIND FIELDS AND
STEEPENING LOW LEVEL LAPSE RATES...SUCH ACTIVITY COULD POSE A THREAT
FOR DAMAGING WIND/MARGINALLY SVR HAIL EWD INTO PARTS OF WI/IL.
..W CNTRL MO SW INTO ERN OK...
A CONDITIONAL THREAT FOR SVR STORMS WILL EXIST FROM W CNTRL MO AND E
CNTRL/SE KS INTO ERN OK LATER TODAY...WHERE SFC HEATING WILL
DESTABILIZE MOISTURE AXIS ALONG PREFRONTAL CONFLUENCE AXIS.
CONVERGENCE WILL BE WEAK/SHALLOW ALONG CONFLUENCE BAND. BUT 40-50
KT DEEP WLY SHEAR ORIENTED PERPENDICULAR TO BAND...AND EXPECTED
SBCAPE AOA 1000 J/KG...SUGGEST A CONDITIONAL PROBABILITY FOR A FEW
SUSTAINED LATE AFTERNOON/EARLY EVENING STORMS WITH HAIL/HIGH WIND.
.CORFIDI/CROSBIE.. 04/22/2007
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