SPC AC 021617
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1117 AM CDT MON APR 02 2007
VALID 021630Z - 031200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE MIDWEST AND
UPPER MS VALLEY...
...SYNOPSIS...
STRONG TROUGH PAC NW FORECASTED TO CONTINUE EWD REACHING THE NRN HI
PLAINS BY 12Z TUE. VIGOROUS MID/UPPER JET WILL BE CROSSING NEB
TONIGHT ENHANCING BOTH SHEAR AND UPPER DIVERGENCE. SURFACE LOW
ORGANIZING OVER WY ATTM WITH WARM FRONT EXTENDING ESEWD THEN EWD
ACROSS SRN NEB. BY THIS EVENING SURFACE LOW WILL BE INTO SWRN NEB AS
WARM FRONT SHIFTS NWD INTO CENTRAL NEB AND THEN ACROSS SRN IA.
...IA AND PORTIONS OF ADJACENT STATES...
30-40KT SLY LOW LEVEL JET IS QUICKLY RETURNING GULF MOISTURE NWD
THRU SRN PLAINS WITH DEWPOINTS RISING INTO THE LOW 60S ACROSS OK AND
TO NEAR 60F INTO SRN KS. STEEPENING MID LEVEL LAPSE RATES CONTINUE
TO SPREAD EWD ACROSS CENTRAL/SRN PLAINS ENHANCING THE POTENTIAL AIR
MASS INSTABILITY. BY LATE AFTERNOON WITH THE LOW LEVEL MOISTURE
RETURN MLCAPES WILL RANGE UPWARDS FROM AROUND 1000 J/KG CENTRAL KS
TO IN EXCESS OF 2000 J/KG SRN OK INTO TX.
BY THIS EVENING THREAT OF AT LEAST ELEVATED THUNDERSTORMS ALONG AND
N OF WARM FRONT WILL BE ON THE INCREASE CENTRAL/ERN NEB AHEAD OF
SURFACE LOW AND THE APPROACHING MID LEVEL WIND MAX. PRIMARY SEVERE
THREAT WILL BE LARGE HAIL AS MUCH OF CONVECTION EXPECTED TO REMAIN
ELEVATED N OF FRONTAL ZONE. HOWEVER WITH MOISTURE/INSTABILITY
EXPECTED TO INCREASE THROUGH THE NIGHT...A FEW SUPERCELLS AND AN
INCREASING THREAT OF ISOLATED TORNADOES AND WIND DAMAGE COULD
DEVELOP IN PROXIMITY TO THE WARM FRONT. SEVERE THREAT SHOULD SPREAD
EWD ACROSS IA AND POSSIBLY INTO NRN MO OVERNIGHT AS THE LOW LEVEL
JET VEERS TO MORE SWLY...DIRECTING STRONGEST DESTABILIZATION TOWARD
THIS AREA WITH THE SURFACE LOW BY 12Z TUE LOCATED VICINITY NWRN
MO/SWRN IA.
...SRN PLAINS...
MODELS INDICATE THAT THE AIRMASS BECOMES MDTLY TO STRONGLY UNSTABLE
BY LATE THIS AFTERNOON FROM SRN OK SWD INTO TX WITH MLCAPES IN
EXCESS OF 2000 J/KG COMMON. WHILE THE CAP WEAKENS AS SURFACE
TEMPERATURES WARM THROUGH THE 80S...FOCUS FOR SURFACE INITIATION AND
ONLY MODEST DEEP LAYER SHEAR PRECLUDES AN INTRODUCTION OF A SLIGHT
RISK. THUNDERSTORMS ARE MORE LIKELY TO DEVELOP VICINITY THE TX
COASTAL AREAS WHERE CONVERGENCE ALONG SEA BREEZE FRONT AND DEEPER
MOISTURE AVAILABLE. ALSO STORMS COULD FORM OVER HIGHER TERRAIN OF
MEXICO AND MOVE ACROSS RIO GRANDE INTO SWRN TX WHERE STRONG HEATING
AND VERY STEEP LAPSE RATES ARE EXPECTED.
WITH SFC-6KM SHEAR AROUND 30KT STORMS FOR THE MOST PART WILL BE
MULTICELLULAR WITH PRIMARILY A LARGE HAIL THREAT. HOWEVER ISOLATED
SUPERCELLS ARE POSSIBLE GIVEN THE MODEST SHEAR AND POTENTIALLY VERY
UNSTABLE AIRMASS.
..HALES/GUYER.. 04/02/2007
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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