***THURSDAYS SEVERE WEATHER OUTLOOK*** NWS STORM PREDICTION CENTER NORMAN OK 1216 PM CDT WED OCT 01 2014 VALID 021200Z - 031200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN AND CNTRL PLAINS...ARKLATEX...OZARKS...MID MS VALLEY AND SRN GREAT LAKES... ...SUMMARY... WIDESPREAD THUNDERSTORM ACTIVITY WILL FORM ON THURSDAY ALONG A COLD FRONT MOVING EASTWARD ACROSS THE PLAINS INTO THE MISSISSIPPI VALLEY. A POTENTIAL FOR DAMAGING WIND GUSTS WILL DEVELOP WITH THE STRONGER THUNDERSTORMS. HAIL WILL ALSO BE POSSIBLE IN THE ARKLATEX AND OZARKS. ...SRN AND CNTRL PLAINS/ARKLATEX/OZARKS... AN UPPER-LEVEL TROUGH WILL MOVE EWD FROM THE SRN ROCKIES AND INTO THE SRN HIGH PLAINS ON THURSDAY. AT THE SFC...A COLD FRONT WILL ADVANCE SEWD ACROSS THE CNTRL AND SRN PLAINS. AHEAD OF THE FRONT...A BROAD WARM SECTOR WITH SFC DEWPOINTS IN THE MID 60S F TO THE LOWER 70S F WILL BE IN PLACE FROM THE RED RIVER VALLEY EWD ACROSS THE OZARKS INTO THE MID MS VALLEY. AS SFC TEMPS WARM...MODERATE INSTABILITY SHOULD DEVELOP BY LATE MORNING AHEAD OF THE FRONT FROM NORTH TX NEWD ACROSS MUCH OF OK INTO SE KS. ELEVATED THUNDERSTORMS MAY BE ONGOING THURSDAY MORNING NEAR THE NOSE OF THE LOW-LEVEL JET IN NE KS...SE NEB...NW MO AND SW IA. THIS ACTIVITY IS FORECAST TO MOVE EWD DURING THE DAY WITH CONVECTIVE COVERAGE EXPANDING SSWWD ALONG THE AXIS OF THE LOW-LEVEL JET. AS CONVECTIVE COVERAGE INCREASES THURSDAY AFTERNOON...MCS DEVELOPMENT APPEARS LIKELY ACROSS THE SLIGHT RISK AREA FROM THE ARKLATEX NEWD ACROSS THE OZARKS. MODEL FORECASTS AGREE THAT NUMEROUS THUNDERSTORMS MAY ALREADY BE ONGOING BY EARLY AFTERNOON SUGGESTING THAT SOME AREAS MAY NOT DESTABILIZE THAT MUCH. PARTS OF THE AIRMASS THAT CAN REMAIN UNDISTURBED BY MORNING CONVECTION SHOULD HAVE THE GREATEST POTENTIAL FOR SEVERE STORMS LATE THURSDAY AFTERNOON INTO THE EARLY EVENING. NAM FORECAST SOUNDINGS FOR DALLAS TX AND FORT SMITH AR AT 00Z/FRIDAY SHOW MLCAPE IN THE 1500 TO 2500 J/KG RANGE WITH STEEP LAPSE RATES IN THE MID-LEVELS AND MODERATE DEEP-LAYER SHEAR. 0-6 KM SHEAR IS FORECAST TO BE IN THE 40 TO 45 KT RANGE WITH SLIGHT VEERING WITH HEIGHT BELOW 850 MB. ALTHOUGH THE INSTABILITY MAY BE A SLIGHT OVERFORECAST...THE AMOUNT OF VERTICAL SHEAR SHOULD BE CONDUCIVE FOR SEVERE STORM DEVELOPMENT AS CELLS ORGANIZE ALONG THE FRONT AND OUT ACROSS THE WARM SECTOR. THE BEST TIMING FOR SUPERCELL DEVELOPMENT WOULD BE EARLY IN THE DAY WHEN STORMS ARE MOST LIKELY TO BE DISCRETE. HOWEVER...LINEAR MODE MAY BE DOMINANT DURING MOST OF THE EVENT AS SEVERAL MULTI-SEGMENTED LINES FORM IN THE AFTERNOON. THIS SHOULD FAVOR WIND DAMAGE AS THE GREATEST THREAT. A POTENTIAL FOR HAIL MAY ALSO DEVELOP ACROSS PARTS OF NORTH TX...ERN OK AND WRN AR WHERE INSTABILITY IS FORECAST TO BE LOCALLY MAXIMIZED. AN ISOLATED TORNADO THREAT CAN NOT BE RULED WITH ROTATING CELLS THAT CAN PERSIST IN SPITE OF THE WIDESPREAD STORM COVERAGE. ...UPPER MIDWEST/SRN GREAT LAKES... SOUTHWEST MID-LEVEL FLOW WILL BE IN PLACE ACROSS THE MID MS VALLEY AND SRN GREAT LAKES REGION ON THURSDAY AS AN UPPER-LEVEL TROUGH APPROACHES THE REGION FROM THE WEST. AT THE SFC...A LOW AND AN ASSOCIATED COLD FRONT WILL MOVE NEWD ACROSS IA DURING THE AFTERNOON AS A CORRIDOR OF LOW-LEVEL MOISTURE BECOMES FIRMLY ESTABLISHED IN THE MID MS VALLEY. SFC DEWPOINTS IN THE MID TO UPPER 60S F WITH SFC HEATING SHOULD RESULT IN THE DEVELOPMENT OF MODERATE INSTABILITY BY AFTERNOON FROM ERN KS EWD ACROSS MO AND IL. ELEVATED THUNDERSTORMS SHOULD BE ONGOING ACROSS ERN NEB AND IA THURSDAY MORNING WITH THIS ACTIVITY SPREADING EWD DURING THE DAY. AS SFC TEMPS HEAT AHEAD OF THE STORMS...A LINE IS EXPECTED TO GRADUALLY ORGANIZE. SQUALL-LINE DEVELOPMENT WILL BE POSSIBLE THURSDAY AFTERNOON. NAM FORECAST SOUNDINGS FOR DAVENPORT IA AND SPRINGFIELD IL AT 21Z/THURSDAY SHOW MLCAPE OF 1000 TO 1200 J/KG WITH 35 TO 40 KT OF 0-6 KM SHEAR. WIND PROFILES ARE FORECAST TO BE UNIDIRECTIONAL WITH A VERY MOIST PROFILE. THIS SHOULD SUPPORT A WIND DAMAGE THREAT AS A LINE ORGANIZES AHEAD OF THE COLD FRONT. THE MAGNITUDE OF THE SEVERE THREAT SHOULD BE DETERMINED BY THE AMOUNT OF DESTABILIZATION THAT OCCURS AHEAD OF THE LINE. WEAK INSTABILITY DUE TO MORNING STORMS COULD LIMIT THE SEVERE POTENTIAL IN A FEW AREAS. ..BROYLES.. 10/01/2014
Posted on: Thu, 02 Oct 2014 02:59:11 +0000
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