Apr 11, 2013 0600 UTC Day 1 Convective Outlook
Updated: Thu Apr 11 05:51:35 UTC 2013
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20130411 1200 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20130411 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
20130411 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
20130411 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 342,623 48,042,333 Columbus, OH...Charlotte, NC...Nashville, TN...Louisville, KY...Atlanta, GA...
   SPC AC 110547
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1247 AM CDT THU APR 11 2013
   
   VALID 111200Z - 121200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FOR PARTS OF THE OH/TN VALLEYS
   AND CNTRL/ERN GULF COAST STATES INTO THE CAROLINAS...
   
   ...SYNOPSIS...
   A CLOSED UPPER LOW WILL SLOWLY MOVE FROM NEB INTO MN AS A SHORTWAVE
   TROUGH MOVES THROUGH THE BASE OF THE LARGER SCALE TROUGH AND INTO
   THE SRN APPALACHIANS BY FRIDAY MORNING.  A NWD ADVANCE OF RICHER LOW
   LEVEL MOISTURE WILL OCCUR ON THE WRN PERIPHERY OF A STUBBORN
   ANTICYCLONE OVER THE WRN ATLANTIC AND AHEAD OF AN EWD MOVING COLD
   FRONT.  THE FRONT WILL MOVE FROM THE MS VALLEY TO E OF THE SPINE OF
   THE CNTRL-SRN APPALACHIANS BY THE END OF THE PERIOD AS THE PRIMARY
   LOW DEVELOPS EWD ALONG A STATIONARY FRONTAL ZONE LOCATED FROM THE OH
   VALLEY EWD TO THE MID ATLANTIC STATES.  
   
   ...OH/TN VALLEYS AND CNTRL/ERN GULF STATES INTO CAROLINAS...
   A BROKEN BAND OF SHOWERS/TSTMS IS EXPECTED TO BE ONGOING NEAR THE
   COLD FRONT OVER THE LOWER MS VALLEY NWD INTO THE LOWER OH VALLEY AT
   THE START OF THE PERIOD.  IT IS PROBABLE SOME OF THESE WILL
   REGENERATE DURING THE DAY...ALONG WITH NEW TSTMS DEVELOPING AS THE
   AIRMASS DESTABILIZES AHEAD OF THE ENCROACHING FRONT OVER THE OH/TN
   VALLEYS SWD TOWARDS THE MOUTH OF THE MS RIVER.  
   
   A SECONDARY FRONTAL WAVE IS FORECAST IN RESPONSE TO THE SHORTWAVE
   TROUGH AND WILL DEVELOP NEWD FROM THE LOWER MS VALLEY INTO THE SRN
   APPALACHIANS.  DMGG WINDS IN THE FORM OF STRONG TO SEVERE WIND GUSTS
   AND THE POSSIBILITY FOR A TORNADO OR TWO WILL BE THE PRIMARY THREATS
   WITH STORMS ALONG THE FRONT.  MORE APPRECIABLE SURFACE HEATING IS
   LIKELY WITH FARTHER S EXTENT...ESPECIALLY OVER AL/GA/FL PANHANDLE
   WHERE MLCAPE IS FORECAST 750-1500 J/KG DURING PEAK HEATING.  A
   PERSISTENT SLY FETCH OF RICHER MARITIME AIR WILL LEAD TO AN
   INCREASINGLY MOIST/DEEPER BOUNDARY LAYER OVER PARTS OF THE DEEP
   SOUTH...WHERE DIURNALLY AUGMENTED LOW LEVEL CONFLUENCE BANDS MAY
   FOSTER SCTD PRE-FRONTAL STORMS.  
   
   STRONG DEEP SWLY FLOW INCREASING IN HEIGHT WOULD FAVOR STORM
   ORGANIZATION/ROTATION WITH THE MORE INTENSE/PERSISTENT UPDRAFTS.  IT
   APPEARS MID LEVEL LAPSE RATES WILL BECOME INCREASINGLY MARGINALIZED
   WITH EWD EXTENT ACROSS THE NRN GULF STATES...THEREBY TENDING TO
   LIMIT GREATER HAIL POTENTIAL BUT REMAINING HIGHEST WITH
   QUASI-DISCRETE STORMS AHEAD OF THE FRONT.  ALTHOUGH FORECAST
   HODOGRAPH SIZE WILL REMAIN SOMEWHAT TEMPERED...A FEW TORNADOES MAY
   BE POSSIBLE WITH ANY STRONGER UPDRAFTS THAT MANAGE TO DEVELOP AHEAD
   OR EVENTUALLY MERGE AND BECOME EMBEDDED WITHIN A LINE.  DESPITE
   LESSENING INSTABILITY DURING THE EVENING HOURS INTO THE OVERNIGHT
   OVER GA NEWD INTO THE CAROLINAS...A STRONG-SEVERE STORM THREAT
   SHOULD PERSIST AS STORMS LIKELY MAINTAIN A FEED OF SURFACE-BASED
   INFLOW PARCELS WITHIN A STRENGTHENING LOW LEVEL SHEAR ENVIRONMENT.
   
   ..SMITH/EDWARDS.. 04/11/2013
   
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