| 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 171600 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1000 AM CST SAT DEC 17 2011 VALID 171630Z - 181200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... THE PRIMARY BELT OF WESTERLIES WILL BE MAINTAINED FROM WRN CANADA THROUGH THE MID MS VALLEY TO OFF THE MID ATLANTIC COAST WITH SOME AMPLIFICATION OF ERN CONUS LARGE-SCALE TROUGH FORECAST THIS PERIOD. ELSEWHERE...A CUT-OFF LOW OFF THE BAJA COAST WILL BEGIN TO EDGE EWD TONIGHT IN RESPONSE TO A SHORT WAVE TROUGH PROGRESSING SEWD TOWARD THE PACIFIC NW COAST. IN THE LOW LEVELS...A SURFACE ANTICYCLONE WILL DEVELOP FROM THE SRN PLAINS EWD INTO THE LOWER MS VALLEY...MAINTAINING OFFSHORE FLOW ACROSS THE GULF COAST. ...LOWER CO VALLEY... 12Z MODEL GUIDANCE IS CONSISTENT IN INDICATING THAT A VORTICITY MAXIMUM WILL ROTATE AROUND THE DEEP-LAYER CYCLONE...ENHANCING FORCING FOR ASCENT ACROSS THE REGION AFTER 18/00Z. FORECAST SOUNDINGS SUGGEST THAT THIS FORCING FOR ASCENT WILL ALIGN WITH STEEP MIDLEVEL LAPSE RATES AND A MOISTENING AIR MASS WITH MUCAPE OF 100-200 J/KG AND EL HEIGHTS EXTENDING ABOVE THE -20 DEGREE C ISOTHERM. AS SUCH...A GENERAL TSTM AREA HAS BEEN INCLUDED FOR ISOLATED TO WIDELY SCATTERED...ELEVATED TSTM POTENTIAL TONIGHT. ..MEAD.. 12/17/2011 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z