| Sep 4, 2012 0600 UTC Day 1 Convective Outlook | |
| Updated: Tue Sep 4 06:11:31 UTC 2012 | |
| Probabilistic to Categorical Outlook Conversion Table | |
| Categorical Graphic |
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| Probabilistic Tornado Graphic |
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| Probability of a tornado within 25 miles of a point. Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point. |
| Probabilistic Damaging Wind Graphic |
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| Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point. |
| Probabilistic Large Hail Graphic |
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| Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point. |
SPC AC 040607 DAY 1 CONVECTIVE OUTLOOK RESENT 1 NWS STORM PREDICTION CENTER NORMAN OK 0107 AM CDT TUE SEP 04 2012 VALID 041200Z - 051200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE MID MO VALLEY AND UPPER MS VALLEY... ...MID MO VALLEY/UPPER MS VALLEY... WESTERLY FLOW WILL BE IN PLACE ACROSS THE NCNTRL STATES TODAY AS AN UPPER-LEVEL TROUGH MOVES INTO THE NRN PLAINS. AHEAD OF THE UPPER-LEVEL TROUGH...MODEL FORECASTS INDICATE THAT SEVERAL DISTURBANCES WILL BE PRESENT IN THE FLOW MOVING ACROSS THE REGION FROM WEST TO EAST. AT THE SFC...A COLD FRONT IS FORECAST TO ADVANCE SEWD ACROSS THE NRN AND CNTRL PLAINS WITH A CORRIDOR OF LOW-LEVEL MOISTURE IN PLACE FROM THE MID MO VALLEY NEWD INTO THE UPPER MS VALLEY. AS SFC TEMPS WARM DURING THE DAY...SCATTERED THUNDERSTORMS SHOULD INITIATE ALONG THE WRN EDGE OF THE MOIST CORRIDOR FROM WRN UPPER MI SWWD ACROSS WI...IA INTO ERN NEB. SEVERAL CONVECTIVE CLUSTERS ARE EXPECTED TO PERSIST ACROSS THE REGION FROM THE LATE AFTERNOON INTO THE EVENING. FORECAST SOUNDINGS ALONG THE CORRIDOR OF MODERATE INSTABILITY FROM WI SWWD INTO IA AT 00Z/WED GENERALLY SHOW AROUND 40 KT OF DEEP LAYER SHEAR. THIS SHEAR ENVIRONMENT SHOULD SUPPORT SEVERE STORM DEVELOPMENT AS CELLS INITIATE DURING THE LATE AFTERNOON. LARGE-SCALE ASCENT IS FORECAST TO REMAIN RELATIVELY WEAK AND SHOULD ENABLE STORMS TO REMAIN DISCRETE. THIS FACTOR ALONG WITH STEEP LAPSE RATES MAY BE FAVORABLE FOR ISOLATED LARGE HAIL ESPECIALLY WITH STORMS THAT ROTATE. LARGE TEMP-DEWPOINT SPREADS MAY ALSO ENHANCE DOWNDRAFT ACCELERATION AND DAMAGING WIND GUSTS WILL CERTAINLY BE POSSIBLE WITH THE BETTER ORGANIZED STORM CLUSTERS. THE GREATEST SEVERE THREAT COULD EXIST ACROSS THE NERN PART OF THE SLIGHT RISK AREA DURING THE EARLY EVENING WHERE LOW-LEVEL FLOW IS FORECAST TO BE STRONGER. ...CNTRL GULF COAST STATES... AN UPPER-LEVEL TROUGH WILL MOVE SLOWLY EWD ACROSS THE ERN GULF COAST STATES TODAY. ON THE WRN EDGE OF THE UPPER-LEVEL TROUGH...A CORRIDOR OF MODERATE INSTABILITY IS FORECAST TO DEVELOP THIS AFTERNOON ACROSS MS AND WRN AL. AS SFC TEMPS WARM...SCATTERED TO NUMEROUS THUNDERSTORMS SHOULD AGAIN INITIATE ALONG THE INSTABILITY CORRIDOR THIS AFTERNOON. FORECAST SOUNDINGS ACROSS SE MS AND SRN AL AT 21Z GENERALLY SHOW DEEP LAYER SHEAR IN THE 30 TO 35 KT SUGGESTING SEVERE STORM DEVELOPMENT WILL BE POSSIBLE. LINE SEGMENTS THAT HAVE ACCESS TO THE STRONGEST INSTABILITY MAY BE CAPABLE OF PRODUCING ISOLATED DAMAGING WIND GUSTS ESPECIALLY AS LOW-LEVEL LAPSE RATES STEEPEN DURING THE LATE AFTERNOON. AT THIS POINT...UNCERTAINTY REGARDING WHERE THE STRONGEST INSTABILITY DEVELOPS PRECLUDES A SLIGHT RISK ATTM. ..BROYLES/MOSIER.. 09/04/2012 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z