Significant Severe Weather Day looks to be very possible for Monday afternoon into Early Tuesday Morning over the entire area. With the Threats being Large Hail Damaging Winds and Tornadoes. Everyone in these areas should keep an eye on the weather and be ready to take action if storms threaten your areas. DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0100 AM CDT MON JUN 30 2014 VALID 301200Z - 011200Z ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PORTIONS OF IA/MO/IL AND FAR SOUTHERN WI... ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SOUTH-CENTRAL PLAINS TO THE GREAT LAKES REGION... ...SUMMARY... WIDESPREAD SEVERE THUNDERSTORMS CAPABLE OF LARGE HAIL...TORNADOES...AND SWATHS OF WIND DAMAGE ARE EXPECTED ESPECIALLY THIS AFTERNOON INTO TONIGHT ACROSS MUCH OF THE CORN BELT AND MIDWEST. ADDITIONAL SEVERE STORMS WILL BE POSSIBLE ACROSS THE SOUTH-CENTRAL PLAINS. ...SYNOPSIS... THE LONGWAVE PATTERN WILL UNDERGO AMPLIFICATION DURING THE PERIOD TO THE NORTH OF A PERSISTENT UPPER RIDGE ACROSS THE SOUTHERN THIRD OF THE CONUS. IN PARTICULAR...A CLOSED LOW WILL MOVE SLOWLY EASTWARD OVER NORTHERN ONTARIO...WITH A SEASONALLY STRONG UPPER JET/AMPLIFYING SHORTWAVE TROUGH OVER THE NORTH-CENTRAL CONUS. AS A RESULT...HEIGHT FALLS AND INCREASINGLY STRONG CYCLONIC FLOW ALOFT WILL OVERSPREAD MUCH OF THE GREAT LAKES REGION/UPPER MIDWEST AND LOWER MO RIVER VALLEY THROUGH TONIGHT. A SOUTHEASTWARD-MOVING COLD FRONT ACROSS THE MIDDLE/LOWER MO VALLEY...UPPER MIDWEST...AND SOUTH-CENTRAL PLAINS WILL BE A GENERAL FOCUS FOR DEEP CONVECTIVE DEVELOPMENT AND ASSOCIATED SEVERE POTENTIAL. ...LOWER/MIDDLE MO VALLEY TO MIDWEST/UPPER GREAT LAKES... AS COMPARED TO SUNDAY...UPPER-LEVEL FORCING FOR ASCENT WILL BE MUCH MORE CONSEQUENTIAL /ESPECIALLY BY LATE JUNE STANDARDS/ AND MORE OPTIMALLY TIMED RELATIVE TO PEAK HEATING. IN THE PRESENCE OF A VERY MOIST AIR MASS AND ROBUST INSTABILITY...LARGE HAIL...TORNADOES...AND POTENTIALLY WIDESPREAD DAMAGING WINDS ARE EXPECTED ACROSS THE REGION LATER TODAY AND TONIGHT. EARLY DAY CONVECTION AND RELATED OUTFLOWS/CLOUD DEBRIS ONCE AGAIN ACCOUNT FOR SOME UNCERTAINTY RELATED TO SOME OF THE FORECAST DETAILS LATER TODAY. IN PARTICULAR...A REMNANT OVERNIGHT MCS COULD PERSIST EARLY TODAY ACROSS LOWER MI/NORTHERN INDIANA VICINITY...WHILE ADDITIONAL STORMS ARE LIKELY TO HAVE DEVELOPED ACROSS NEB/NORTHERN KS TO WESTERN IA THIS MORNING. ITS POSSIBLE THAT THESE STORMS ACROSS THE MIDDLE MO VALLEY COULD PERSIST/BECOME SURFACE-BASED DURING THE DAY UNDER THE INFLUENCE OF PERSISTENT WARM ADVECTION/DPVA. OF GREATER LIKELIHOOD MAY BE FOR THESE STORMS TO GENERALLY DECAY...WITH SUBSEQUENT SURFACE-BASED DEVELOPMENT DURING THE AFTERNOON AS HEIGHT FALLS OVERSPREAD THE REGION AND THE BOUNDARY LAYER AGGRESSIVELY DESTABILIZES. OF NOTE RELATED TO NUMERICAL GUIDANCE...THE 00Z NAM/GFS APPEAR TO BE OVERLY INFLUENCED BY CONVECTIVE FEEDBACK ACROSS IA INTO THE UPPER MS VALLEY/LAKE MI VICINITY. WHILE REAL-WORLD FEEDBACK IS INDEED POSSIBLE GIVEN STRONG DIABATIC HEATING/RICH MOISTURE...THE EXACT RAMIFICATIONS ARE UNCERTAIN...AND THE EXTREME DETAILS OF THESE PROGGED DOWNSTREAM INFLUENCES /ROBUST MAGNITUDE OF THE PROGGED LOW-LEVEL WIND FIELD ETC./ ARE PROBABLY AT LEAST SOMEWHAT OVERDONE. REGARDLESS...THE MOST PROBABLE SCENARIO IS FOR SURFACE-BASED STORMS TO DEVELOP/INTENSIFY THIS AFTERNOON...ESPECIALLY ACROSS IA/NORTHERN MO TO THE EAST OF AN ADVANCING SURFACE LOW AND NEAR THE SOUTHEASTWARD-MOVING COLD FRONT. GIVEN EARLIER EVENING /00Z/ OBSERVED REGIONAL RAOBS...A VERY MOIST AIR MASS WITH LOWER TO MIDDLE 70S SURFACE DEWPOINTS ARE EXPECTED TO PREVAIL WITHIN THE NEARBY WARM SECTOR. THIS WILL LIKELY CONTRIBUTE TO VERY STRONG DESTABILIZATION...IN THE ABSENCE OF OUTFLOWS AND LINGERING THICK CLOUD COVER...WITH AS MUCH AS 4000-5500 J/KG OF MLCAPE EXPECTED FROM KS INTO IA/NORTHERN MO AND IL. ROBUST INSTABILITY IN THE PRESENCE OF 40+ KT OF EFFECTIVE SHEAR WILL SUPPORT INTENSE SUPERCELLS AS THE INITIAL STORM MODE WITH A RISK OF VERY LARGE HAIL AND SOME TORNADOES. THE TORNADO POTENTIAL WILL BE INFLUENCED BY DIURNALLY STRONG LOW-LEVEL WINDS/SRH...ESPECIALLY NEAR/EAST OF THE DEVELOPING SURFACE LOW. GIVEN RELATIVELY STRONG FORCING FOR EARLY SUMMER...AND THE INFLUENCE OF THE COLD FRONT...UPSCALE QUASI-LINEAR GROWTH IS LIKELY TO OCCUR BY EARLY/MID-EVENING. AS SUCH...A POTENTIALLY WIDESPREAD DAMAGING WIND THREAT COULD EVOLVE ACROSS PORTIONS OF IA AND NORTHERN MO INTO IL/SOUTHERN WI AND POSSIBLE LOWER MI/NORTHERN INDIANA DURING THE EVENING/OVERNIGHT HOURS. ...SOUTH-CENTRAL PLAINS... STRONG WARM SECTOR HEATING/FRONTAL UPLIFT SHOULD OVERCOME WARM MID-LEVEL TEMPERATURES/CAPPING WITH ISOLATED TO WIDELY SCATTERED STRONG TO SEVERE THUNDERSTORM DEVELOPMENT EXPECTED BY LATE AFTERNOON/EARLY EVENING. THE REGION WILL GENERALLY BE SOUTH OF THE STRONGER WESTERLIES ALOFT...BUT AROUND 30 KT OF EFFECTIVE SHEAR AND MODERATE TO STRONG BUOYANCY /NEAR THE FRONT AND DRYLINE/ WILL ALLOW FOR SUSTAINED/ORGANIZED MULTICELLS AND POSSIBLY A FEW SUPERCELLS. LARGE HAIL AND LOCALLY DAMAGING WINDS WILL BE THE PRIMARY HAZARDS. ...SOUTHERN APPALACHIANS/SOUTHEAST STATES... WHILE VERTICAL SHEAR/OVERALL FORCING WILL BE WEAK...SUFFICIENT LOW-LEVEL LAPSE RATES AND BUOYANCY MAY EXIST FOR PULSE-TYPE STORMS CAPABLE OF MICROBURSTS THIS AFTERNOON. ..GUYER/DEAN.. 06/30/2014
Posted on: Mon, 30 Jun 2014 06:14:23 +0000
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