SWODY1
SPC AC 252000
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0300 PM CDT FRI MAY 25 2007
VALID 252000Z - 261200Z
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE NRN AND
CNTRL PLAINS...
..NRN AND CNTRL PLAINS...
AN UPPER-LEVEL TROUGH OVER THE NRN HIGH PLAINS WILL MOVE EWD TOWARD
THE DAKOTAS LATE THIS AFTERNOON. LARGE-SCALE ASCENT WILL CONTINUE TO
INCREASE AS THE SYSTEM APPROACHES. LATEST SFC ANALYSIS SHOWS A SFC
LOW NEAR THE BLACK HILLS AND SFC DEWPOINTS EAST OF THE LOW ARE IN
THE UPPER 40S TO LOWER 50S F. A POCKET OF MODERATE INSTABILITY
EXISTS IN WCNTRL SD AND INSTABILITY SHOULD CONTINUE TO INCREASE LATE
THIS AFTERNOON. THIS SHOULD SUPPORT SCATTERED THUNDERSTORM
DEVELOPMENT LATE THIS AFTERNOON WITH STORMS MOVING EWD INTO THE
INSTABILITY AXIS THROUGH EARLY EVENING.
CONCERNING THE SEVERE THREAT...RUC MODEL FORECASTS MOVE A 60 KT
MID-LEVEL JET CENTERED OVER NW WY INTO SWRN SD EARLY THIS EVENING.
THIS WILL INCREASE VERTICAL SHEAR PROFILES AND SUPERCELLS WILL
BECOME INCREASINGLY LIKELY. LARGE TEMP-DEWPOINT SPREADS SHOULD KEEP
STORM BASES RELATIVELY HIGH. IN ADDITION...MID-LEVEL LAPSE RATES ARE
VERY STEEP AND 500 MB TEMPS ARE AROUND -18C IN WRN AND CNTRL SD
ACCORDING TO OBJECTIVE ANALYSIS. THIS SUGGESTS ISOLATED LARGE HAIL
WILL BE LIKELY WITH SUPERCELLS THAT DEVELOP. ALTHOUGH THE POTENTIAL
FOR WIND DAMAGE IS MORE UNCERTAIN...0-3 KM LAPSE RATES IN WRN SD ARE
ALSO VERY STEEP EXCEEDING 8.5 C/KM. THIS MAY RESULT IN A POTENTIAL
FOR ISOLATED WIND DAMAGE ESPECIALLY EARLY THIS EVENING WHEN STORMS
WILL LIKELY BE ROOTED CLOSER TO THE SFC AND LOW-LEVEL FLOW WILL BE
STRONGER. AN ISOLATED SEVERE THREAT MAY ALSO DEVELOP SWD INTO SW NEB
AND POSSIBLY INTO FAR WRN KS. HOWEVER...MODEL FORECASTS SUGGEST THAT
THIS ACTIVITY WILL DEVELOP LATER AND WEAKENING INSTABILITY THIS
EVENING MAY LIMIT THE SEVERE POTENTIAL SOMEWHAT.
..SRN ROCKIES/SRN PLAINS...
A WEAK UPPER-LEVEL TROUGH IS EVIDENT ON WATER VAPOR IMAGERY OVER THE
CNTRL ROCKIES AND A SUBTLE INFLUENCE OF THE TROUGH LIKELY EXTENDS
INTO PARTS OF THE SRN ROCKIES. AN AXIS OF DRYER AIR IS PRESENT FROM
CNTRL NM EXTENDING NEWD TO NORTH OF TUCUMCARI NM. ALONG THIS
AXIS...INSTABILITY IS MAXIMIZED AND CONVECTION ACROSS NERN NM WILL
MOVE SEWD INTO INCREASING INSTABILITY LATE THIS AFTERNOON. RUC
ANALYSIS SUGGESTS NRN NM AND FAR SRN CO IS IN A SLIGHTLY STRONGER
SHEAR ENVIRONMENT THAN AREAS FURTHER SOUTH. FOR THIS REASON...A
MARGINAL SUPERCELL THREAT APPEARS TO BE MOST LIKELY IN THIS AREA.
FURTHER SOUTH ACROSS CNTRL AND SRN NM...RUC ANALYSIS INDICATES A
WEAKER SHEAR ENVIRONMENT EXISTS AND SUPERCELLS WILL NOT BE AS
LIKELY. HOWEVER...STEEP LAPSE RATES AND MODERATE INSTABILITY
SUGGESTS MULTICELLS MAY BE CAPABLE OF MARGINALLY SEVERE HAIL AND
STRONG WIND GUSTS.
..OH VALLEY...
WEAK SOUTHWESTLY FLOW IS CURRENTLY IN PLACE ACROSS THE MID MS VALLEY
EXTENDING NEWD ACROSS THE OH VALLEY. AT THE SFC...A COLD FRONT IS
LOCATED FROM NEAR ST LOUIS MO EXTENDING ENEWD TO NEAR CLEVELAND OH.
LOW-LEVEL CONVERGENCE ALONG THE BOUNDARY AND A WEAKENING CAPPING
INVERSION ALONG THE FRONT HAS ALLOWED NUMEROUS STORMS TO INITIATE.
REGIONAL WSR-88D VWPS IN THE VICINITY OF THE BOUNDARY SHOW 0-6 KM
SHEAR VALUES MOSTLY IN THE 20 TO 25 KT RANGE SUGGESTING THE THREAT
WILL REMAIN MULTICELLULAR. INSTABILITY WILL CONTINUE TO INCREASE
OVER THE NEXT FEW HOURS AND THE STRONGEST OF MULTICELLS MAY HAVE A
BRIEF POTENTIAL FOR HAIL AND STRONG GUSTY WINDS MAINLY NEAR PEAK
HEATING.
.BROYLES.. 05/25/2007
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