DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0100 AM CDT MON JUL 08 2013 VALID 091200Z - 101200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CNTRL AND NRN PLAINS INTO THE MID-UPPER MS VALLEY AND GREAT LAKES... ...SYNOPSIS... EXPANSIVE UPPER RIDGE WILL PERSIST OVER THE SRN TWO THIRDS OF THE U.S. TUESDAY WITH BELT OF STRONGER WLYS OVER THE NRN TIER STATES. A LOW AMPLITUDE SHORTWAVE TROUGH EMBEDDED WITHIN THIS BELT OF STRONGER FLOW WILL MOVE FROM ERN MT EARLY TUE TO THE WRN GREAT LAKES BY 12Z WED. A VORT MAX NOW OVER THE GREAT BASIN AREA WILL CONTINUE THROUGH THE NRN PERIPHERY OF THE UPPER RIDGE...LIKELY REACHING THE UPPER MS VALLEY AREA EARLY TUESDAY AND SUBSEQUENTLY CONTINUING THROUGH THE GREAT LAKES DURING THE DAY. AT THE SFC A QUASI-STATIONARY FRONT /PORTIONS OF WHICH MAY BE CONVECTIVELY REINFORCED/ WILL LINGER FROM THE GREAT LAKES WWD THROUGH IA AND NEB. THE NRN STREAM SHORTWAVE TROUGH WILL PROVIDE THE IMPETUS FOR A COLD FRONT TO ACCELERATE SEWD THROUGH THE NRN/CNTRL PLAINS AND UPPER MS VALLEY. BY THE END OF THE PERIOD THIS FRONT IS FORECAST TO EXTEND FROM THE WRN GREAT LAKES SWWD THROUGH KS. ...CNTRL/NRN PLAINS THROUGH UPPER MS VALLEY AND GREAT LAKES... GREAT LAKES AREA...AT LEAST A COUPLE OF MCSS WILL LIKELY BE ONGOING EARLY TUESDAY INCLUDING PORTIONS OF ND INTO NRN MN AND ANOTHER FARTHER SOUTH ACROSS PORTIONS OF IA AND SRN MN. THE IA MCS WILL EXIST IN ASSOCIATION WITH THE LEAD /PARTIALLY CONVECTIVELY ENHANCED/ VORT MAX AND ITS ATTENDANT STRONGER WIND FIELDS. CURRENT OBSERVATIONS SHOW RICH LOW-LEVEL MOISTURE ALREADY IN PLACE OVER THE MID MS VALLEY AND GREAT LAKES REGION WITH UPPER 60S TO AROUND 70 DEWPOINTS. SOME UNCERTAINTY EXISTS REGARDING THE DEGREE OF DOWNSTREAM DESTABILIZATION OVER THE GREAT LAKES GIVEN POTENTIAL FOR AREAS OF WIDESPREAD CLOUDS. HOWEVER WITH RICH MOISTURE IN PLACE...EVEN MODEST DIABATIC WARMING OF THE BOUNDARY LAYER WILL SUPPORT MODERATE INSTABILITY WITH 1500-2000 J/KG MLCAPE POSSIBLE FROM WI INTO MI. POTENTIAL WILL EXIST FOR STORMS TO INTENSIFY AS THE MCV AND ONGOING MCS INTERACT WITH THE DESTABILIZING ATMOSPHERE. STRONGER VERTICAL SHEAR ACCOMPANYING THE MCV WILL SUPPORT ORGANIZED STORMS INCLUDING BOWING SEGMENTS AND EMBEDDED SUPERCELLS WITH DAMAGING WIND...LARGE HAIL AND PERHAPS A COUPLE TORNADOES. A CONDITIONAL RISK ALSO EXISTS FOR A MORE WIDESPREAD DAMAGING WIND EVENT. MID MS VALLEY AND CNTRL PLAINS AREA...THE MORNING STORMS SHOULD CONTINUE EAST WITH CLEARING FROM THE WEST ALLOWING THE UPSTREAM ATMOSPHERE TO BECOME STRONGLY UNSTABLE...ESPECIALLY FROM ERN NEB...NERN KS INTO IA WHERE PLUME OF STEEP LAPSE RATES SHOULD OVERLAP THE WRN EDGE OF RICHER LOW-LEVEL MOISTURE. SHORTWAVE RIDGING IN WAKE OF THE LEAD VORT MAX AND WARM ADVECTION ALOFT MAY CAP THE BOUNDARY LAYER AND DELAY INITIATION UNTIL LATE AFTERNOON WHEN CONVECTIVE TEMPERATURES WILL LIKELY BE REACHED AND STORMS WILL PROBABLY DEVELOP ALONG THE FRONT FROM ERN NEB INTO KS AND ALSO FARTHER EAST INTO IA ALONG THE CONVECTIVELY ENHANCED STALLED BOUNDARY. VERTICAL SHEAR FROM 30-40 KT WILL SUPPORT SUPERCELLS FROM NEB INTO IA AND EXTREME NRN MO...BUT WITH MULTICELLS MORE LIKELY IN THE WEAKER SHEAR ENVIRONMENT FARTHER SOUTH ACROSS KS. LARGE HAIL AND DAMAGING WIND WILL BE THE MAIN THREATS. MN INTO NRN WI...POTENTIAL EXISTS FOR THE ATMOSPHERE TO DESTABILIZE WITH MODERATE INSTABILITY EAST AND SOUTH OF ONGOING MCS FROM CNTRL AND SRN MN INTO NRN WI. THE MCS WILL LIKELY CONTINUE EWD DURING THE DAY...EVENTUALLY MOVING INTO THE GREAT LAKES AREA...AND SOME INTENSIFICATION OF THIS ACTIVITY IS POSSIBLE WITH DAMAGING WIND THE MAIN THREAT. IF SUFFICIENT DESTABILIZATION OCCURS...OTHER STRONG-SEVERE STORMS MAY DEVELOP OVER CNTRL/SRN MN ALONG SEWD ADVANCING FRONT DURING THE AFTERNOON.
Posted on: Mon, 08 Jul 2013 16:06:50 +0000