SPC 1200Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0100 AM CDT SUN MAY 27 2012 VALID 271200Z - 281200Z ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PORTIONS OF N CENTRAL KS AND INTO PARTS OF S CENTRAL AND ERN NEB... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CENTRAL PLAINS NNEWD INTO THE UPPER MS VALLEY/WRN UPPER GREAT LAKES REGION... ...SYNOPSIS... FAIRLY POTENT UPPER LOW/TROUGH INITIALLY OVER THE INTERMOUNTAIN WEST IS PROGGED TO SHIFT STEADILY EWD WITH TIME THIS PERIOD...MOVING INTO CENTRAL AND NRN PLAINS REGION THROUGH THE AFTERNOON AND EVENING. SOME WEAKENING OF THIS SYSTEM IS EXPECTED WITH TIME...AS IT IMPINGES ON A PERSISTENT ERN U.S. RIDGE. AT THE SURFACE...A COLD FRONT ASSOCIATED WITH THE AFOREMENTIONED UPPER TROUGH -- INITIALLY EXTENDING FROM THE NRN PLAINS SSWWD INTO THE CENTRAL HIGH PLAINS -- IS FORECAST TO SHIFT EWD IN CONJUNCTION WITH THE UPPER SYSTEM...CROSSING THE MID MO VALLEY REGION THROUGH THE LATTER HALF OF THE PERIOD. MEANWHILE...SUBTROPICAL SYSTEM BERYL IS FORECAST TO MOVE ONSHORE OVER N FL DURING THE EVENING HOURS. ...CENTRAL PLAINS NNEWD INTO THE UPPER MS VALLEY... SUBSTANTIAL SEVERE WEATHER POTENTIAL IS FORECAST TO EVOLVE THIS AFTERNOON -- FOCUSED ON THE CENTRAL PLAINS REGION -- AS A SHORT-WAVE TROUGH/VORT MAX ON THE SERN FRINGE OF THE LARGER-SCALE UPPER SYSTEM EJECTS EWD. AS THE PRE-FRONTAL WARM SECTOR DESTABILIZES -- BECOMING MODERATELY UNSTABLE DURING THE AFTERNOON...EXPECT THE APPROACH OF THE UPPER SYSTEM TO AID IN WEAKENING THE CAP -- AND EVENTUALLY SUPPORTING ROBUST STORM DEVELOPMENT. WHILE STORMS SHOULD DEVELOP ALONG THE FRONT FROM THE UPPER MS VALLEY SWD -- ACCOMPANIED BY POTENTIAL FOR LARGE HAIL AND DAMAGING WINDS...THE MOST CONCENTRATED THREAT APPEARS TO EXIST INVOF A WEAK SURFACE LOW PROGGED TO MOVE ACROSS KS/SRN NEB DURING THE AFTERNOON. HERE...50 TO 60 KT SWLY MID-LEVEL FLOW SPREADING ATOP LOW-LEVEL SLYS WILL RESULT IN SHEAR VERY FAVORABLE FOR SUPERCELLS -- AND RESULTING POTENTIAL FOR VERY LARGE HAIL AND DAMAGING WINDS. WHILE A FAIRLY DEEP BOUNDARY LAYER AND 20 C OR MORE SURFACE DEWPOINT DEPRESSIONS EXPECTED...TORNADO THREAT SHOULD REMAIN LIMITED OVER MOST OF THE AREA...THOUGH A COUPLE OF TORNADOES WILL ALSO BE POSSIBLE IN PROXIMITY TO THE AFOREMENTIONED SURFACE LOW -- I.E. ACROSS PARTS OF NEB AND KS. OVERNIGHT...AS THE FRONT SHIFTS EWD...STORMS SHOULD BECOME MORE LINEARLY ORGANIZED...WITH THREATS FOR LARGE HAIL AND DAMAGING WINDS CONTINUING INTO THE OVERNIGHT HOURS. ...COASTAL GA... THE APPROACH OF SUBTROPICAL SYSTEM BERYL WILL RESULT IN STRENGTHENING LOW-LEVEL FLOW ACROSS THE GA COASTAL REGION DURING THE DAY TODAY. AS LOW-LEVEL SHEAR INCREASES...POTENTIAL FOR SOME ROTATION WITH CONVECTIVE CELLS MOVING ONSHORE IS EXPECTED. THIS COMBINED WITH THE MOIST BOUNDARY LAYER AND CORRESPONDINGLY LOW CLOUD BASES SUGGESTS LOW-PROBABILITY POTENTIAL FOR AN ISOLATED WEAK/BRIEF TORNADO -- MAINLY DURING THE AFTERNOON HOURS. ...PA AND VICINITY... MODEST INSTABILITY WILL LIKELY SUPPORT SCATTERED AFTERNOON STORM DEVELOPMENT AS A WEAK VORT MAX CROSSES THE REGION TODAY. WHILE FLOW ALOFT IS FORECAST TO REMAIN WEAK...ISOLATED/PULSE-TYPE THREAT FOR HAIL/LOCALLY GUSTY WINDS WILL BE POSSIBLE WITH A FEW STRONGER CELLS THROUGH EARLY EVENING. ..GOSS.. 05/27/2012
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_1200.html
Be First to Comment