SPC 0730Z Day 3 Outlook
DAY 3 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0203 AM CDT FRI MAY 04 2012 VALID 061200Z - 071200Z ...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS IL/MO/ERN KS/NERN OK/AR... ...SYNOPSIS... NWRN CONUS TROUGH DESCRIBED IN DAY-2 OUTLOOK IS EXPECTED TO PROCEED ACROSS NRN PLAINS THIS PERIOD...TRAILING SWWD FROM SMALL/CLOSED 500-MB CYCLONE OVER MB. MEANWHILE...BULK OF PROGS INDICATE SEPARATE CLOSED LOW WILL BREAK AWAY FROM NRN-STREAM VORTICITY FIELD DAY-2 AND DRIFT SEWD OVER CA THIS PERIOD. DIFFERENCES IN TIMING/PHASING OF THESE FEATURES RESULTS IN SLOWER EWD PROGRESS OF SFC CYCLONE AND COLD FRONT IN SPECTRAL/ECMWF THAN IN NAM AND MOST SREF MEMBERS. COLD/WARM FRONTAL TRIPLE-POINT LOW SHOULD MOVE EWD FROM CENTRAL PLAINS AT LEAST AS FAR AS INDIANA AND PROBABLY TO NEAR LE BY END OF PERIOD. MEANWHILE COLD FRONT WILL MOVE SEWD OVER MID MS VALLEY...OZARKS AND MUCH OF NRN/WRN TX. LATE-AFTERNOON DRYLINE SHOULD INTERSECT FRONT OVER SRN OK/N-CENTRAL TX REGION AND EXTEND SWWD INTO MOUNTAINS OF NRN COAHUILA. QUASISTATIONARY TROUGHING ALOFT AND ASSOCIATED BROAD AREA OF CYCLONIC FLOW...PERHAPS WITH WEAK/EMBEDDED 500-MB LOW...SHOULD COVER PORTIONS NERN GULF...SRN GA AND FL. ...PORTIONS IL/MO/ERN KS/NERN OK/AR... GIVEN AFOREMENTIONED DISCREPANCIES IN PROGS...AS WELL AS UNCERTAINTIES REGARDING PRIOR MCS ACTIVITY ON MESOSCALE BOUNDARY PLACEMENT THIS PERIOD...OUTLOOK IS NECESSARILY SOMEWHAT BROAD-BRUSHED. HOWEVER...SOME RELATIVELY FOCUSED CORRIDOR OF SVR POTENTIAL SHOULD DEVELOP NEAR SFC LOW...EWD OVER WARM FRONTAL ZONE...AND SWWD ALONG COLD FRONT DURING AFTERNOON. THIS WILL OCCUR AS STG SFC INSOLATION DESTABILIZES RICHLY MOIST BOUNDARY LAYER IN ADJOINING WARM SECTOR...WITH SFC DEW POINTS MID-60S TO LOW-70S F CONTRIBUTING TO MLCAPE 4000-5000 J/KG. DEEP-LAYER SHEAR MAY BE MODEST OVER MOST OF AREA...GIVEN THAT SFC LOW/FRONTAL REGIME IS TOO DISPLACED FROM STRONGER GRADIENT WINDS ALOFT ASSOCIATED WITH NRN STREAM TROUGH. HOWEVER...POTENTIAL FOR EXTREME BUOYANCY AND SPORADIC/LOCALIZED SUPERCELL FORMATION SUGGEST AT LEAST ISOLATED LARGE/DAMAGING HAIL IS POSSIBLE. SVR DOWNDRAFTS ALSO ARE LIKELY GIVEN PROBABILITY OF INTENSE DOWNDRAFTS AND PRECIP LOADING RELATED TO LARGE VALUES OF CAPE AND PW. ANOTHER COMPLEX OF TSTMS MAY DEVELOP FROM AFTERNOON ACTIVITY AND MOVE EWD TO SEWD TOWARD LOWER OH VALLEY REGION AS WELL. ...SRN PLAINS... TSTM DEVELOPMENT IS EXPECTED TO BE MORE ISOLATED TO WIDELY SCATTERED AND DIURNAL ALONG DRYLINE...COMPARED TO FARTHER NE WITH LOW/FRONT. HOWEVER...STEEP MIDLEVEL LAPSE RATES AND FAVORABLE MOIST SECTOR WILL OVERLAP...CONTRIBUTING TO POTENTIAL FOR MLCAPE TO EXCEEDING 5000 J/KG IN SOME PARTS OF CENTRAL/NRN TX AND SRN OK. WHERE SUSTAINED TSTMS CAN DEVELOP...SVR DOWNDRAFTS AND HAIL ARE POSSIBLE. ...SERN CONUS... SCATTERED TSTMS IN CLUSTERS MAY DEVELOP ONCE AGAIN ALONG AND S OF FRONT...IN REGIME OF STG SFC DIABATIC HEATING AND RICH BOUNDARY-LAYER MOISTURE. OUTFLOW AND SEA-BREEZE BOUNDARIES ARE LIKELY TO FOCUS TSTM CLUSTERS AND SVR RISK ON MESOSCALE. WEAK DEEP-LAYER WIND/SHEAR PROFILES SUGGEST PREDOMINANT MULTICELLULAR ORGANIZATION...WITH SPORADIC DAMAGING GUSTS AND SVR HAIL POSSIBLE IN MOST INTENSE DOWNDRAFTS. ..EDWARDS.. 05/04/2012
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day3otlk_0730.html
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