SPC 2000Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0233 PM CDT SAT MAY 26 2012 VALID 262000Z - 271200Z ...THERE IS A SLGT RISK OF SVR TSTMS OVER MUCH OF THE NRN PLAINS AS WELL AS THE CNTRL AND SRN HIGH PLAINS... ...THERE IS A SLGT RISK OF SVR TSTMS OVER SRN AND ERN PA...NRN NJ...FAR SERN NY AND WRN CT... ...PA...SRN NY...NJ...WRN CT... VIGOROUS CONVECTION HAS FORMED ALONG A WEAK BOUNDARY AND WITHIN A VERY MOIST AND UNSTABLE AIR MASS. MODIFIED MODEL SOUNDINGS FOR THE AREA INDICATE CONTINUED POTENTIAL FOR TALL MULTICELL STORMS WITH BOTH HAIL AND DOWNBURST POTENTIAL. SOUNDING ANALOGS ARE CURRENTLY MATCHING THIS ENVIRONMENT TO A TYPICAL JUNE PROFILE IN THE SERN STATES. DESPITE WEAK WIND PROFILES...THE HODOGRAPH APPEARS FAVORABLE FOR MINOR STORM TILTING ALOFT AND THE RE-INGESTION OF HAIL EMBRYOS. PRESENCE OF HAIL IN THE DOWNDRAFT MAY RESULT IN FURTHER COOLING/NEGATIVE BUOYANCY AND ENHANCED WET MICROBURSTS. THEREFORE...HAVE UPGRADED TO A SLIGHT RISK. ...SRN HIGH PLAINS... STRONG HEATING WILL CONTINUE TO STEEPEN LAPSE RATES...WITH SCATTERED CONVECTION LIKELY IN THE NEXT FEW HOURS OVER QUITE A LARGE AREA. THIS ACTIVITY WILL BE RATHER UNFOCUSED BUT WILL POSE A MARGINAL WIND AND HAIL THREAT. FOR MORE INFORMATION...SEE MESOSCALE DISCUSSION 0910. ..JEWELL.. 05/26/2012 .PREV DISCUSSION... /ISSUED 1141 AM CDT SAT MAY 26 2012/ ...CORRECTED FOR TYPOS/WORDING... ...CNTRL PLAINS TO MIDWEST... A DIFFICULT AND UNCERTAIN FORECAST SCENARIO TODAY WITH MANY FACTORS POTENTIALLY CONTRIBUTING TO SIGNIFICANT TSTM DEVELOPMENT AND OTHER FACTORS POSSIBLY HINDERING THIS DEVELOPMENT. LARGE SCALE PATTERN FEATURES A DEEP UPPER TROUGH ACROSS THE WEST AND A STRONG RIDGE DOMINATING THE SOUTH AND SOUTHEAST. IN BETWEEN THESE TWO LARGE SCALE FEATURES...DEEP-LAYER SLY FLOW HAS CONTRIBUTED TO COPIOUS LOW LEVEL MOISTURE TRANSPORT ACROSS THE GREAT PLAINS/MIDWEST WHILE AT THE SAME TIME RESULTING IN AN EXPANSIVE ELEVATED MIXED LAYER AIRMASS/CAP THAT WILL INHIBIT MOST CONVECTIVE DEVELOPMENT IN THE ABSENCE OF STRONG FORCED ASCENT AND/OR DIABATIC INFLUENCES. STORM SCALE GUIDANCE FROM 00Z...THE 12Z WRF-NMM...AND THE 12Z NAM-WRF MODELS ALL DEPICT SOME POTENTIAL FOR LATE AFTERNOON STORM INITIATION ALONG OR IMMEDIATELY NORTH OF THE WARM FRONT OVER IA. THIS DEVELOPMENT MAY BE A RESULT OF WEAK DCVA ACCOMPANYING A SERIES OF LOW AMPLITUDE SHORT WAVES TRAVELING WITHIN THE DEEP-LAYER MERIDIONAL FLOW ACROSS THE PLAINS. THESE MAY CREST THE RIDGE AXIS COINCIDENT WITH A MAXIMUM IN DIURNAL HEATING/DESTABILIZATION AND CONTRIBUTE TO TSTM DEVELOPMENT IN A VERY UNSTABLE AIRMASS. RESULTING CONVECTION COULD THEN ORGANIZE INTO A FORWARD PROPAGATING MCS WITH HAIL AND WIND SPREADING EWD ALONG THE INSTABILITY GRADIENT/WARM FRONT FROM IA TO THE UPPER MIDWEST. THUS PARTS OF THESE AREAS HAVE BEEN INCLUDED IN A SLGT RISK WITH THIS UPDATE. EVEN GREATER UNCERTAINTY IN A SCENARIO EXISTS WITH WWD EXTENT ALONG THE WARM FRONT ACROSS NEB. MOST GUIDANCE DEPICTS SOME DEVELOPMENT NEAR THE FRONT...AND ALONG THE DRYLINE/LEE TROUGH FROM NERN CO ACROSS PARTS OF WRN/CNTRL KS BY EVENING. ANY STORMS THAT CAN OVERCOME INHIBITION IN THESE AREAS WILL EXIST IN A KINEMATIC REGIME SUPPORTIVE OF SUPERCELLS. HAIL AND HIGH WINDS WILL BE POSSIBLE AND TORNADO POTENTIAL WILL BE ENHANCED NEAR THE WARM FRONT THAT WILL LIKELY BE SITUATED ACROSS NRN/CNTRL NEB. ADDITIONAL STORMS MAY DEVELOP NORTH OF THE FRONT ACROSS SD THROUGH THE EVENING AND POSE A TREAT OF LARGE HAIL. ...CNTRL HIGH PLAINS SOUTH ALONG LEE TROUGH/DRYLINE TO WEST TX... INFLUENCE FROM THE LARGE WRN TROUGH WILL AID STORM DEVELOPMENT...ESPECIALLY ACROSS WY LATER THIS AFTERNOON. STORMS IN THIS AREA WILL GENERALLY LACK ACCESS TO GREATER INSTABILITY BUT THIS MAY BE COMPENSATED BY MAGNITUDE OF FORCING AND SHEAR. THE RESULT MAY BE A NUMBER OF HIGH BASED CELLS WITH HAIL AND SOME WIND POTENTIAL SPREAD NEWD FROM WY THROUGH THE EVENING. ADDITIONAL HIGH-BASED STORMS...POSSIBLY IN THE FORM OF LP SUPERCELLS APPEAR LIKELY ALONG THE DRYLINE SOUTH TO WEST TX. LARGE SCALE FORCING WILL BE MORE AMBIGUOUS HERE AND MUCH OF THIS ACTIVITY MAY BE DIURNALLY DRIVEN AND SHOULD BEGIN TO DECAY WITHIN AN HOUR OR TWO AFTER SUNSET. HAIL/WIND EVENTS AND POSSIBLY A TORNADO APPEAR POSSIBLE WITH THIS DEVELOPMENT.
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_2000.html
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