May 18, 2014 0600 UTC Day 1 Convective Outlook

DAY 1 CONVECTIVE OUTLOOK  

   NWS STORM PREDICTION CENTER NORMAN OK
   1255 AM CDT SUN MAY 18 2014

   VALID 181200Z - 191200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS OVER SOUTH CENTRAL/ERN MT INTO
   NERN WY AND WRN DAKOTAS...

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM CENTRAL GA INTO SRN SC...

   ...SUMMARY...
   ISOLATED TO SCATTERED SEVERE THUNDERSTORMS CAPABLE OF PRODUCING
   STRONG WIND GUSTS AND LARGE HAIL ARE EXPECTED TO DEVELOP DURING THE
   AFTERNOON OVER SOUTH-CENTRAL AND EASTERN MONTANA...THEN SPREAD INTO
   NORTHEAST WYOMING AND THE WESTERN DAKOTAS BY THE EVENING HOURS. 
   ISOLATED SEVERE THUNDERSTORMS ARE ALSO POSSIBLE DURING THE AFTERNOON
   OVER PARTS OF CENTRAL GEORGIA INTO SOUTHERN SOUTH CAROLINA.

   ...SYNOPSIS...
   PROGRESSIVE UPPER FLOW PATTERN IS DEVELOPING TODAY AS A SHORTWAVE
   TROUGH TRANSLATES ENEWD FROM THE PACIFIC NW TOWARD NERN MT/NWRN ND
   BY THEN END OF THE PERIOD...AND THE DOWNSTREAM UPPER TROUGH MOVES
   FROM THE LOWER GREAT LAKES TO NEW ENGLAND.  A WEAK SHORTWAVE TROUGH
   EMBEDDED IN THE NW FLOW OVER THE LOWER MO VALLEY IS EXPECTED TO MOVE
   ESEWD ACROSS THE SRN APPALACHIANS TODAY AND OFF THE SRN ATLANTIC
   COAST TONIGHT. 

   AT THE SURFACE...A LOW IS FORECAST TO DEEPEN OVER NERN WY THIS
   AFTERNOON AND OCCLUDE NNEWD INTO FAR NERN MT/NWRN ND BY LATE
   TONIGHT.  A COLD FRONT IS EXPECTED TO SURGE EWD ACROSS THE NRN HIGH
   PLAINS REACHING A WRN ND/CENTRAL SD/NEB PANHANDLE LINE BY THE END OF
   THE PERIOD.  IN THE SOUTHEAST...A QUASI-STATIONARY FRONT WILL REMAIN
   ACROSS CENTRAL PARTS OF AL AND GA INTO SRN SC.

   ...SOUTH CENTRAL/ERN MT INTO NERN WY AND WRN DAKOTAS...
   SOUTHERLY LOW LEVEL WINDS ARE EXPECTED TO STRENGTHEN INTO THE NRN
   PLAINS THROUGH TONIGHT RESULTING IN MODEST MOISTURE RETURN WITH
   SURFACE DEW POINTS IN THE 40S AND LOW 50S SPREADING INTO THE AREA
   THIS AFTERNOON AND EVENING.  STEEP MID-LEVEL LAPSE RATES WILL
   OVERSPREAD THE RETURNING MOISTURE AND...WHEN COMBINED WITH STRONG
   DIABATIC HEATING...WILL RESULT IN AN UNSTABLE ENVIRONMENT WITH
   MLCAPE OF 1000-1500 J/KG.  

   ONGOING STORMS OVER CENTRAL MT ARE EXPECTED TO PROGRESS EWD AND
   GRADUALLY WEAKEN BY LATER THIS MORNING.  NEW CONVECTIVE DEVELOPMENT
   IS ANTICIPATED THIS AFTERNOON AS INCREASING DIVERGENCE ALOFT WITHIN
   THE LEFT EXIT REGION OF A MODERATELY STRONG WSWLY MID-UPPER LEVEL
   JET COUPLES WITH LOW LEVEL CONVERGENCE ASSOCIATED WITH THE SURFACE
   LOW AND COLD FRONT.  EFFECTIVE SHEAR OF 40-50 KT WILL ENHANCE STORM
   INTENSITY AND ORGANIZATION WITH POTENTIAL FOR A FEW SUPERCELLS TO
   DEVELOP.  STRONGER STORMS WILL BE CAPABLE OF PRODUCING PRIMARILY
   SEVERE WIND GUSTS AND LARGE HAIL. A BRIEF TORNADO OR TWO MAY ALSO BE
   POSSIBLE ALTHOUGH RELATIVELY HIGH LCL HEIGHTS ASSOCIATED WITH A
   DEEPER PBL ARE EXPECTED TO LIMIT THE OVERALL TORNADO THREAT.  

   THE ACTIVITY IS EXPECTED TO DEVELOP EWD AND POSSIBLY SWD ALONG A DRY
   LINE DURING THE LATE AFTERNOON/EVENING...WITH STORMS MOST LIKELY TO
   PROGRESS EWD ACROSS PARTS OF THE DAKOTAS DURING THE OVERNIGHT HOURS.
   THE SEVERE POTENTIAL IS EXPECTED TO GRADUALLY DIMINISH WITH EWD
   EXTENT AFTER 03-06Z AS STORMS MOVE INTO A MARGINALLY UNSTABLE
   ENVIRONMENT.

   ...CENTRAL GA INTO SRN SC...
   STRONGER HEATING IS EXPECTED TO OCCUR SOUTH OF THE AFOREMENTIONED
   QUASI-STATIONARY FRONT TODAY WITH STEEP LOW LEVEL LAPSE RATES
   DEVELOPING WITHIN A WELL-MIXED BOUNDARY LAYER.  GUIDANCE FROM
   NAM/GFS AND MULTIPLE CONVECTION-ALLOWING MODELS ARE GENERALLY
   CONSISTENT INDICATING STORM DEVELOPMENT DURING THE AFTERNOON NEAR
   THE FRONT...WITH ACTIVITY SPREADING ESEWD WITHIN A BAND OF 40-45 KT
   MID-LEVEL FLOW.  ALTHOUGH LOW-LEVEL MOISTURE WILL BE MODEST WITH
   SURFACE DEW POINTS IN THE LOW-MID 50S...THE FAVORABLE LOW-LEVEL
   THERMODYNAMIC STRUCTURE MAY ENHANCE THE VERTICAL TRANSFER OF STRONG
   MID-LEVEL MOMENTUM TOWARD THE SURFACE WITH POTENTIAL FOR OCCASIONAL
   DAMAGING WIND GUSTS...AND ISOLATED HAIL.