SPC 1200Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1258 AM CDT TUE MAY 01 2012 VALID 011200Z - 021200Z ...THERE IS A SLGT RISK OF SVR TSTMS OVER THE ERN DAKOTAS AND NEB...NERN KS...IA...MOST OF MN AND WRN WI... ...SYNOPSIS... A LOW AMPLITUDE SHORTWAVE TROUGH WILL MOVE FROM THE MO VALLEY ENEWD ACROSS THE OH VALLEY REGION DURING THE DAY...HELPING TO MOVE MOISTURE AND INSTABILITY NEWD WITH A THREAT OF SEVERE HAIL AND WIND. MEANWHILE...A MORE SUBSTANTIAL UPPER TROUGH WILL MOVE INTO THE NRN PLAINS WITH LOW PRESSURE DEEPENING ACROSS THE DAKOTAS INTO WRN MN SWWD ACROSS NEB. BOTH SHEAR AND INSTABILITY WILL BE FAVORABLE FOR SEVERE STORMS ...MID MO INTO THE UPPER MS VALLEY... SCATTERED WARM ADVECTION STORMS MAY EXIST ACROSS MN AND IA EARLY NEAR A WARM FRONT...WITH A MARGINAL HAIL THREAT. THEN...STRONG SLY FLOW WILL BRING MID 60S F BOUNDARY LAYER DEWPOINTS NWD INTO THE REGION...CREATING STRONG INSTABILITY OVER THE WARM SECTOR. CONVERGENCE WILL INCREASE ALONG THE COLD FRONT/SURFACE TROUGH. GIVEN LITTLE IF ANY CONVECTIVE INHIBITION...STORMS SHOULD ERUPT BY 21Z...BEGINNING OVER NRN MN NEAR THE SURFACE LOW...THEN FARTHER SWWD ALONG THE SFC TROUGH. WIND PROFILES WILL FAVOR SUPERCELLS...WITH VERY LARGE HAIL LIKELY. LOW LEVEL SHEAR MAY BE ENHANCED OVER CNTRL/NRN MN DUE TO THE EFFECTS OF EARLY CONVECTION AND WHERE A WARM FRONT WILL HOLD. AS A RESULT...A FEW TORNADOES MAY OCCUR. A STRONG TORNADO CANNOT BE RULED OUT IF LOW LEVEL SHEAR ENDS UP BEING AS STRONG AS SOME OF THE NAM FORECAST SOUNDINGS INDICATE. HOWEVER...THERE ARE VARYING MODEL SOLUTIONS...AND WILL MAINTAIN ISOLATED TORNADO THREAT AT THIS TIME. ...LOWER MO INTO THE OH VALLEY... NUMEROUS STORMS WILL BE ONGOING OVER MUCH OF MO AND NRN AR TUE MORNING SUPPORTED BY AN UPPER SHORTWAVE TROUGH AND WARM ADVECTION WITH A SWLY LOW LEVEL JET. THIS ACTIVITY WILL LIKELY SHIFT NEWD WITH THE UPPER WAVE...WITH AN ISOLATED WIND AND HAIL THREAT OVER A LARGE AREA. STORMS WILL LIKELY REGENERATE ON OLD OUTFLOW AND THE LOCATION OF THE STRONGEST STORMS WILL DEPEND ON WHERE POCKETS OF INSTABILITY CAN DEVELOP...MOST LIKELY ON SWRN FLANKS OF EARLY STORMS. WITH HEATING EXPECTED OVER TN AND SRN KY...THE ZONE OF SEVERE MAY EXTEND ROUGHLY FROM ST. LOUIS TO LOUISVILLE. UNCERTAINTY REGARDING LOCATION OF OUTFLOW BOUNDARIES WILL MARGINAL DEEP SHEAR WILL PRECLUDE A SLIGHT AT THIS TIME. ..JEWELL/GARNER.. 05/01/2012
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_1200.html
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