May 21, 2014 0600 UTC Day 1 Convective Outlook

 DAY 1 CONVECTIVE OUTLOOK

   NWS STORM PREDICTION CENTER NORMAN OK

   1259 AM CDT WED MAY 21 2014

   VALID 211200Z - 221200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE MID MS

   VALLEY...OH VALLEY...CNTRL APPALACHIAN MTNS AND MID-ATLANTIC...

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL HIGH

   PLAINS...

   ...SUMMARY...

   ISOLATED TO SCATTERED SEVERE STORMS WITH LARGE HAIL AND WIND DAMAGE

   WILL DEVELOP LATE THIS AFTERNOON FROM THE MID-MISSISSIPPI VALLEY

   EASTWARD INTO THE CENTRAL APPALACHIAN MOUNTAINS AND MID-ATLANTIC

   REGION. OTHER SEVERE STORMS WILL DEVELOP ACROSS THE CENTRAL HIGH

   PLAINS WHERE TORNADOES...LARGE HAIL AND WIND DAMAGE WILL BE

   POSSIBLE.

   ...CNTRL HIGH PLAINS...

   AN UPPER-LEVEL LOW WILL MOVE SLOWLY ACROSS THE INTERMOUNTAIN WEST

   TODAY AS DIVERGENT SSWLY MID-LEVEL FLOW REMAINS OVER THE CNTRL

   ROCKIES AND CNTRL HIGH PLAINS. AT THE SFC...A CORRIDOR OF LOW-LEVEL

   MOISTURE SHOULD EXTEND NWWD FROM NCNTRL KS INTO NW CO AND SE WY

   WHERE SFC DEWPOINTS SHOULD BE IN THE 50 TO 55 F RANGE. THIS SHOULD

   ALLOW FOR MODERATE INSTABILITY TO DEVELOP ALONG THIS CORRIDOR BY

   AFTERNOON WITH THUNDERSTORMS INITIATING IN THE FOOTHILLS OF THE

   FRONT RANGE AND MOVING SEWD ONTO THE PLAINS OF NE CO. OTHER STORMS

   SHOULD INITIATE IN SE WY AND MOVE SEWD ALONG THE INSTABILITY AXIS.

   SEVERAL CLUSTERS OF SEVERE STORMS APPEAR LIKELY TO CONGEAL INTO A

   MCS...MOVING SEWD INTO WRN KS BY LATE EVENING AND INTO THE CNTRL

   PLAINS DURING THE OVERNIGHT PERIOD.

   FORECAST SOUNDINGS ALONG THE INSTABILITY AXIS AT 21Z FOR GREELEY AND

   LIMON CO SHOW MLCAPE OF 1500 TO 2000 J/KG RANGE WITH 45 TO 50 KT OF

   0-6 KM SHEAR. IN ADDITION...VEERING OF THE WINDS WITH HEIGHT IS

   FORECAST FROM THE SFC TO 500 MB WITH VERY STEEP LAPSE RATES

   SUGGESTING THE ENVIRONMENT WILL BE FAVORABLE FOR SUPERCELLS AND

   LARGE HAIL. HAILSTONES OF GREATER THAN 2 INCHES IN DIAMETER MAY

   OCCUR WITH CELLS THAT BECOME DOMINANT AND MOVE DOWN THE AXIS OF

   INSTABILITY. A FEW TORNADOES MAY OCCUR WITH THE BETTER ORGANIZED

   SUPERCELLS DURING THE LATE AFTERNOON AND EARLY EVENING. ISOLATED

   WIND DAMAGE WILL ALSO BE POSSIBLE DUE TO THE STEEP LOW-LEVEL LAPSE

   RATES. THE SEVERE THREAT COULD CONTINUE INTO THE OVERNIGHT PERIOD IF

   A MCS CAN ORGANIZE AND MOVE INTO THE CNTRL HIGH PLAINS.

   ...MID-MS VALLEY AND OH VALLEY...

   AN UPPER-LEVEL RIDGE WILL REMAIN IN PLACE ACROSS THE LOWER TO MID-MS

   VALLEY TODAY AS AN UPPER-LEVEL TROUGH MOVES EWD INTO THE GREAT LAKES

   REGION. AT THE SFC...A COLD FRONT WILL ADVANCE SEWD ACROSS THE UPPER

   MS VALLEY INTO THE CNTRL GREAT LAKES REGION THIS AFTERNOON.

   INCREASING LOW-LEVEL CONVERGENCE AND INSTABILITY ALONG AND AHEAD OF

   THE COLD FRONT SHOULD RESULT IN SCATTERED THUNDERSTORM DEVELOPMENT

   LATE THIS AFTERNOON. SEVERAL CLUSTERS OF CONVECTION SHOULD ORGANIZE

   AND MOVE SEWD ACROSS THE OH VALLEY. MCS DEVELOPMENT WILL BE POSSIBLE

   ACROSS THE REGION THIS EVENING.

   NAM FORECAST SOUNDINGS DURING THE LATE AFTERNOON FOR INDIANAPOLIS

   INDIANA AND CINCINNATI OH SHOW IMPRESSIVE THERMODYNAMICS WITH MLCAPE

   IN THE 2000 TO 3000 J/KG RANGE AND STEEP MID-LEVEL LAPSE RATES. THIS

   ALONG WITH 40 TO 45 KT OF 0-6 KM SHEAR SHOULD BE FAVORABLE FOR

   SEVERE STORM DEVELOPMENT. SUPERCELLS WITH LARGE HAIL WILL BE

   POSSIBLE WHERE CELLS REMAIN DISCRETE AND HAVE ACCESS TO THE STRONGER

   INSTABILITY. HAILSTONES OF GREATER THAN 2 INCHES IN DIAMETER MAY

   OCCUR FROM SCNTRL IL EWD ACROSS SCNTRL INDIANA WHERE THE COMBINATION

   OF SHEAR AND INSTABILITY IS FORECAST TO BE MAXIMIZED. LOW-LEVEL

   LAPSE RATES AROUND 8.5 C/KM SHOULD BE FAVORABLE FOR ISOLATED

   DAMAGING WIND GUSTS WITH CELL MERGERS AND SHORT-LINE SEGMENTS.

   ...CNTRL APPALACHIAN MTNS/MID-ATLANTIC...

   NORTHWEST FLOW WILL BE IN PLACE ACROSS THE CNTRL APPALACHIAN MTNS

   AND MID-ATLANTIC REGION TODAY. AT THE SFC..A LOW WILL DEVELOP AND

   MOVES EWD ACROSS VA WITH A SFC TROUGH LOCATED IN THE APPALACHIAN

   FOOTHILLS. AS SFC TEMPS WARM...MODERATE INSTABILITY IS FORECAST TO

   DEVELOP FROM SRN PA SWD INTO NRN NC WHERE SFC DEWPOINTS SHOULD BE IN

   THE 55 TO 60 F RANGE. THIS ALONG WITH INCREASING LOW-LEVEL

   CONVERGENCE ALONG THE SFC TROUGH SHOULD RESULT IN SCATTERED

   THUNDERSTORM DEVELOPMENT. DUE TO MODERATE DEEP-LAYER SHEAR AND STEEP

   LOW-LEVEL LAPSE RATES EVIDENT ON FORECAST SOUNDINGS...A WIND DAMAGE

   THREAT MAY ACCOMPANY THE STRONGER DISCRETE CELLS AND SHORT LINE

   SEGMENTS. HAIL MAY ALSO OCCUR WITH THE MORE INTENSE STORMS.