Mar 18, 2013 0600 UTC Day 1 Convective Outlook
Updated: Mon Mar 18 05:59:32 UTC 2013
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20130318 1200 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20130318 1200 UTC Day 1 Tornado Probabilities Graphic
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
20130318 1200 UTC Day 1 Damaging Wind Probabilities Graphic
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
20130318 1200 UTC Day 1 Large Hail Probabilities Graphic
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.
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 131,042 17,093,550 Nashville, TN...Atlanta, GA...Lexington, KY...Birmingham, AL...Montgomery, AL...
   SPC AC 180555
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1255 AM CDT MON MAR 18 2013
   
   VALID 181200Z - 191200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF KY AND TN
   SWD INTO THE SOUTHEAST...
   
   ...SYNOPSIS...
   BROAD CYCLONIC FLOW ALOFT WILL CONTINUE TO PREVAIL ACROSS MUCH OF
   THE U.S. THIS PERIOD...AS A TROUGH CENTERED INITIALLY OVER THE
   PLAINS STATES TAKES ON A MORE NEGATIVE TILT AS IT SHIFTS EWD/NEWD
   ACROSS THE GREAT LAKES/MIDWEST REGION.
   
   AT THE SURFACE...A LOW INITIALLY INVOF THE LOWER OH VALLEY IS
   PROGGED TO MOVE NNEWD WITH TIME...EVENTUALLY MERGING WITH A
   SECOND/MORE NRN LOW AND RESULTING IN A DEEP CYCLONE OVER THE UPPER
   GREAT LAKES REGION BY THE END OF THE PERIOD.  AS THIS LOWER OH
   VALLEY LOW DEVELOPS NNEWD...A TRAILING COLD FRONT IS FORECAST TO
   SWEEP ACROSS THE LOWER OH/TN/LOWER MS VALLEYS THROUGH THE DAY. 
   OVERNIGHT...THE FRONT SHOULD CROSS THE APPALACHIANS...AND APPROACH
   THE ATLANTIC COAST BY THE END OF THE PERIOD.  CONVECTION ALONG/AHEAD
   OF THIS FRONT WILL POSE A THREAT FOR SEVERE WEATHER ACROSS THE MID
   SOUTH/SOUTHEAST REGION. 
   
   ...ERN KY/MIDDLE AND ERN TN INTO THE CENTRAL GULF COAST REGION...
   SCATTERED SHOWERS AND THUNDERSTORMS ARE FORECAST TO BE ONGOING
   ACROSS WRN PORTIONS OF THE RISK AREA EARLY IN THE PERIOD...AHEAD OF
   THE DEVELOPING COLD FRONT.  THE CONVECTION IS PROGGED TO SPREAD EWD
   ACROSS THE RISK AREA THROUGH MIDDAY/EARLY AFTERNOON...AFFECTING TO
   SOME DEGREE THE POTENTIAL FOR WARM SECTOR HEATING/DESTABILIZATION. 
   HOWEVER...GIVEN LIKELIHOOD FOR AT LEAST MODEST HEATING AND DEWPOINTS
   INTO THE 60S ADVECTING NWD ACROSS THE AREA...MIXED-LAYER CAPE OF
   1000 TO 2000 J/KG SEEMS LIKELY AT LEAST LOCALLY.  ALONG WITH
   INTENSIFICATION OF THE ONGOING STORMS WITHIN THE DESTABILIZING WARM
   SECTOR...A BROKEN LINE OF CONVECTION SHOULD ALSO DEVELOP FROM THE
   ERN KY VICINITY SWWD ACROSS THE TN VALLEY AREA IN CLOSER PROXIMITY
   TO THE FRONT DURING THE MID TO LATE AFTERNOON.
   
   DESPITE THE UNCERTAINTY REGARDING CONVECTIVE
   EVOLUTION/MODE...DEEP-LAYER WIND FIELD EXHIBITING WEAK
   VEERING/INCREASING MAGNITUDE WITH HEIGHT WILL YIELD SHEAR SUPPORTIVE
   OF ORGANIZED/ROTATING STORMS.  ALONG WITH POTENTIAL FOR LOCALLY
   DAMAGING WINDS -- PARTICULARLY WHERE STORMS CAN ORGANIZE INTO
   SMALL-SCALE LINES/BANDS...A FEW MORE CELLULAR STORMS WILL LIKELY
   BECOME SUPERCELLS -- CAPABLE OF PRODUCING LARGE HAIL.  WHILE TORNADO
   POTENTIAL APPEARS SOMEWHAT LIMITED DUE TO SOMEWHAT MODEST LOW-LEVEL
   SHEAR EXPECTED ATTM...A TORNADO OR TWO MAY BE POSSIBLE WHERE
   LOW-LEVEL BOUNDARIES -- INCLUDING THE RETREATING DAMMING FRONT
   ACROSS THE NRN GA/WRN SC REGION -- COULD LOCALLY ENHANCE THE
   LOW-LEVEL SHEAR.
   
   OVERNIGHT...STORMS SHOULD DIMINISH IN INTENSITY -- PARTICULARLY WITH
   NWD EXTENT WHERE LESS AFTERNOON DESTABILIZATION WILL TAKE PLACE. 
   LIMITED SEVERE THREAT MAY LINGER ACROSS THE SOUTHEAST...AS THE FRONT
   MOVES ACROSS THE SRN APPALACHIANS THROUGH THE END OF THE PERIOD.
   
   ..GOSS.. 03/18/2013
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z