SWODY2
SPC AC 120603
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0103 AM CDT MON MAY 12 2008
VALID 131200Z - 141200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM TX INTO THE LOWER MO
VALLEY...
...SYNOPSIS...
AN UPPER TROUGH...NOW OVER THE NWRN CONUS...WILL CONTINUE TO DIG SWD
WITH UPPER LOW CENTER PROGGED TO BE OVER AZ TUE AFTERNOON. RAPID
MOISTURE RETURN WILL BE UNDERWAY ACROSS THE PLAINS ALONG AND AHEAD
OF AN ELONGATED LOW PRESSURE TROUGH THAT WILL EXTEND ROUGHLY FROM
THE UPPER MS VALLEY SWD ACROSS CNTRL OK AND INTO NWRN TX AT MIDDAY.
LOW LEVEL MOISTURE WILL CONTINUE TO SURGE NWWD ACROSS TX DURING THE
DAYTIME AND OVERNIGHT IN RESPONSE TO LOWERING PRESSURES ACROSS W TX
OVERNIGHT...OR JUST AHEAD OF THE EJECTING UPPER TROUGH. THE RESULT
WILL BE A WIDESPREAD AREA OF SEVERE...SOME SIGNIFICANT...FROM TX
INTO MO.
FARTHER N...A STRONG NRN STREAM TROUGH WILL SWEEP ACROSS THE UPPER
MS VALLEY DURING THE DAY AND INTO THE GREAT LAKES OVERNIGHT. LOW
PRESSURE IS FORECAST TO DEEPEN RAPIDLY OVERNIGHT WITH A SHARPENING
SURFACE TROUGH. DUE TO LIMITED INSTABILITY...A MORE LIMITED AND
CONDITIONAL SEVERE THREAT WILL EXIST WITH THIS SYSTEM.
...MO...OK...WRN AR...NRN TX...
MODELS ARE IN FAIRLY GOOD AGREEMENT THAT A LEAD LOW-AMPLITUDE
SHORTWAVE TROUGH WILL MOVE ACROSS OK...SERN KS AND WRN MO DURING THE
DAY. THIS FEATURE SHOULD HELP MAINTAIN A 30-40 KT SWLY LOW LEVEL JET
FROM TX INTO MO...RESULTING IN A RAPID RETURN OF MOISTURE AND
SURFACE DEWPOINTS INTO THE MID 60S AS FAR N AS SERN KS AND SWRN MO
BY AFTERNOON. GIVEN THIS MAGNITUDE OF MOISTURE...AS WELL AS
RELATIVELY COOL TEMPERATURE PROFILES ALOFT...LITTLE CAPPING WILL BE
PRESENT IN THE WARM SECTOR. INDEED...MULTIPLE FORECAST MODELS
GENERATE A LARGE AREA OF INTENSE PRECIPITATION BY AFTERNOON...FROM
NERN TX ACROSS OK...WRN AR AND MO. DEEP LAYER SHEAR ON THE ORDER OF
40-50 KT ALONG WITH STRONG INSTABILITY WILL RESULT IN MULTIPLE
CLUSTERS OF THUNDERSTORMS...INCLUDING SUPERCELLS. VERY LARGE HAIL
WILL BE LIKELY GIVEN THE STEEP MID LEVEL LAPSE RATES AND EXPECTED
SUPERCELLULAR STORM MODE. LOW LEVEL SHEAR AHEAD OF THE COLD FRONT
WILL BE SUFFICIENT FOR A FEW TORNADOES GIVEN THE FAVORABLE MOISTURE
AND INSTABILITY PROFILES.
THE LOW LEVEL JET IS FORECAST TO RESPOND TO THE W TX LOW LATE IN THE
DAY...THUS WEAKENING A BIT OVER OK/AR/MO. THIS WILL LIKELY RESULT IN
LESS THAN OPTIMAL HODOGRAPHS FOR A TORNADO OUTBREAK...BUT A STRONG
TORNADO CANNOT BE RULED OUT SOMEWHERE FROM NE TX INTO SW MO DURING
THE AFTERNOON.
BY EVENING...STORMS MAY FORM INTO AN MCS ALONG AND/OR AHEAD OF THE
ADVANCING COLD FRONT...WITH A FEW DAMAGING WIND GUSTS AND LARGE HAIL
POSSIBLE ALONG THE FRONT OVERNIGHT SEWD TOWARD THE MS RIVER.
...WRN AND N CNTRL TX OVERNIGHT...
SLY LOW LEVEL FLOW WILL BE MAINTAINED THROUGHOUT THE DAY OVER
TX...AS LOW PRESSURE DEEPENS TO THE W. THE UPPER TROUGH WILL
GRADUALLY SHIFT EWD INTO W TX OVERNIGHT. AMPLE INSTABILITY WILL BE
IN PLACE...AND THIS UNSTABLE AIR MASS WILL SURGE NWD AFTER DARK WITH
THE LOW LEVEL JET. ONGOING STORMS OVER OK AND NERN TX MAY BUILD SWWD
ALONG THE COLD FRONT...BUT ADDITIONAL DEVELOPMENT IS ALSO LIKELY
WITH THE DEEPER FRONTAL SURGE AS THE TROUGH MOVES OUT. VERY LARGE
HAIL AND DAMAGING WINDS WILL BE LIKELY AND TORNADOES MAY OCCUR AS
WELL WITH ANY CELLULAR ACTIVITY AWAY FROM THE COLD FRONT.
...ERN IA...IL...WRN IN...LOWER MI LATE IN THE DAY AND OVERNIGHT...
ELEVATED INSTABILITY WILL INCREASE THROUGHOUT THE DAY AS PERSISTENT
SWLY LOW LEVEL JET TRANSPORTS MOISTURE NWD AHEAD OF A STRENGTHENING
LOW PRESSURE TROUGH. VERY COOL TEMPERATURES ALOFT WILL EXIST AND
SEVERE HAIL WILL BE A DISTINCT POSSIBILITY ESPECIALLY FROM 00-06Z
OVER ERN IA AND IL WHERE INSTABILITY LEVELS WILL BE GREATEST.
FARTHER N AND CLOSER TO THE DEEPENING LOW...INSTABILITY WILL BE
LESSER BUT GIVEN THE STRONG FORCING...SOME MARGINALLY SEVERE HAIL
CANNOT BE RULED OUT.
..JEWELL.. 05/12/2008
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