DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1130 AM CDT THU JUL 25 2013 VALID 251630Z - 261200Z ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON THROUGH TONIGHT FROM THE UPPER MS VALLEY TO THE CENTRAL PLAINS... ...UPPER MS VALLEY TO THE CENTRAL PLAINS THROUGH TONIGHT... THE LARGE-SCALE PATTERN CONSISTS OF A RIDGE OVER THE GREAT BASIN AND A DOWNSTREAM TROUGH OVER THE APPALACHIANS. A PRIMARY EMBEDDED SHORTWAVE TROUGH WILL DIG SEWD FROM MB TO MN/WI BY EARLY FRIDAY...WHILE AN ASSOCIATED SURFACE COLD FRONT PROGRESSES SEWD/SWD INTO THE UPPER MS VALLEY AND CENTRAL PLAINS. OTHERWISE...THE SCENARIO IS COMPLICATED BY REMNANT MCV/S MOVING SEWD OVER CENTRAL SD AND NE CO...AS WELL AS RELATED CLOUD COVER AND WEAKENING CONVECTION ACROSS SD AND FROM SRN NEB TO MUCH OF CENTRAL KS. FARTHER S...THUNDERSTORM CLUSTERS ARE ONGOING OVER THE ERN TX PANHANDLE AND NW TX...WHILE ASSOCIATED CONVECTIVE OUTFLOW MOVES SLOWLY SWD ACROSS THE SOUTH PLAINS AND BIG COUNTRY IN TX. THE OVERALL SEVERE STORM THREAT IS A BIT UNCERTAIN GIVEN ALL OF THE MESOSCALE INFLUENCES OF RESIDUAL CLOUDS/CONVECTION...AND THE IMPACTS OF RELATIVELY WIDESPREAD CONVECTION IN PREVIOUS DAYS ACROSS THE SRN ROCKIES WHICH HAS DISRUPTED THE FEED OF STEEP LAPSE RATES TO THE PLAINS. AT THIS TIME...TWO SCENARIOS SEEM MOST PROBABLE THIS AFTERNOON INTO TONIGHT. THE FIRST INVOLVES THE DEVELOPMENT OF STORMS IN THE ZONE OF STRONGER SURFACE HEATING ALONG THE COLD FRONT FROM NE NEB TO IA/SRN MN THIS AFTERNOON. HERE...MLCAPE WILL INCREASE TO 1500-2000 J/KG WITH DAYTIME HEATING AND BOUNDARY LAYER DEWPOINTS UP TO THE MID 60S...WHILE DEEP-LAYER WNWLY SHEAR WILL BE SUFFICIENT FOR ORGANIZED/SUPERCELL STORMS. OCCASIONAL LARGE HAIL AND DAMAGING OUTFLOW GUSTS WILL BE THE MAIN THREATS. THE SECOND SCENARIO CONSISTS OF CONVECTION FORMING THIS AFTERNOON/EVENING ACROSS EXTREME ERN CO/WRN KS IN ADVANCE OF THE NE CO MCV AND A WEAK COLD FRONTAL SEGMENT. LOW-LEVEL MOISTURE HAS BEEN IMPACTED BY PRIOR CONVECTION...WHILE LAPSE RATES ALOFT ARE RATHER MODEST. CONSIDERING THESE FACTORS AND THE AREA MOST LIKELY TO EXPERIENCE STRONGER SURFACE HEATING IN CLOUD BREAKS /E AND SE CO INTO SW KS/...AFTERNOON BUOYANCY WILL NOT BE PARTICULARLY LARGE BY HIGH PLAINS STANDARDS. STILL...THE POSSIBILITY REMAINS FOR AFTERNOON STORMS TO EVOLVE INTO SOME FORM OF MCS WHILE MOVING SEWD OVERNIGHT TOWARD OK. AT LEAST ISOLATED DAMAGING GUSTS AND LARGE HAIL WILL BE POSSIBLE WITH THE STRONGEST EMBEDDED STORMS. ...NRN MN THIS AFTERNOON... THOUGH THE INITIAL WIND SHIFT AND PRIMARY SURFACE CYCLONE HAVE ALREADY MOVED E/SE OF THIS AREA...A SECONDARY FRONTAL SURGE ACCOMPANIES THE AMPLIFYING MIDLEVEL TROUGH MOVING SEWD FROM SRN MB. A FEW LOW-TOPPED THUNDERSTORMS SHOULD FORM THIS AFTERNOON IN THE ZONE OF ASCENT WITH THE SEWD-MOVING MIDLEVEL TROUGH...WHERE DEEP-LAYER WNWLY SHEAR AND WEAK BUOYANCY WILL SUPPORT SOME RISK FOR ORGANIZED STORMS CAPABLE OF PRODUCING MARGINALLY SEVERE HAIL/WINDS. ..THOMPSON/LEITMAN.. 07/25/2013
Posted on: Thu, 25 Jul 2013 16:37:41 +0000
Trending Topics
Recently Viewed Topics
© 2015