SPC AC 190550

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1250 AM CDT THU JUN 19 2014

   VALID 191200Z - 201200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS TODAY INTO TONIGHT ACROSS PARTS
   OF THE CENTRAL AND NORTHERN PLAINS INTO THE UPPER MISSISSIPPI
   VALLEY...

   ...THERE IS A SLGT RISK OF SVR TSTMS TODAY ACROSS PARTS OF THE MID
   ATLANTIC COAST STATES...

   ...SUMMARY...
   CLUSTERS OF STRONG TO SEVERE STORMS...MAINLY WITH THE RISK FOR
   POTENTIALLY DAMAGING WIND GUSTS AND LARGE HAIL...WILL BE POSSIBLE
   THIS AFTERNOON AND EVENING ACROSS PARTS OF THE NORTHERN AND CENTRAL
   PLAINS INTO THE UPPER MISSISSIPPI VALLEY.  A FEW SEVERE STORMS WILL
   ALSO BE POSSIBLE ACROSS PARTS OF THE MID ATLANTIC COAST STATES.

   ...ROCKIES INTO MISSISSIPPI VALLEY...
   MODELS SUGGEST THAT UPPER TROUGHING...NOW OVER THE INTERMOUNTAIN
   REGION AND ROCKIES...WILL LOSE AMPLITUDE DURING THIS PERIOD...AS A
   SIGNIFICANT IMPULSE ROUNDING ITS BASE PIVOTS NORTHEASTWARD ACROSS
   THE NORTHERN PLAINS AND CENTRAL CANADIAN/U.S. BORDER AREA.  TO THE
   EAST AND SOUTH OF THIS INCREASINGLY NEGATIVE TILTED FEATURE...MODEST
   CYCLONIC MID/UPPER FLOW WILL OVERSPREAD MUCH OF THE LOWER NORTHERN
   AND CENTRAL PLAINS.  BY THIS AFTERNOON...THIS PROBABLY WILL
   CONTRIBUTE TO SUFFICIENT VERTICAL SHEAR FOR ORGANIZED CONVECTIVE
   DEVELOPMENT...PERHAPS INCLUDING ISOLATED SUPERCELLS...ALONG SURFACE
   TROUGHING ACROSS PARTS OF THE EASTERN DAKOTAS...AS WELL AS ACROSS
   PARTS OF THE CENTRAL PLAINS INTO SOUTHERN HIGH PLAINS.

   ACROSS PARTS OF THE MID MISSOURI INTO UPPER MISSISSIPPI VALLEY...
   THE SURFACE TROUGH LIKELY WILL BE PRECEDED BY CONSIDERABLE EARLY
   PERIOD CONVECTION...AND REMNANT OUTFLOW WILL CONTRIBUTE TO
   UNCERTAINTY WITH REGARD TO SUBSEQUENT DESTABILIZATION AND FOCUS FOR
   AFTERNOON EVENING STORM DEVELOPMENT.  FURTHER COMPLICATING SEVERE
   WEATHER POTENTIAL...MODELS SUGGEST THAT STRONGER SOUTHERLY 850 MB
   FLOW /ON THE 30 KT/ AHEAD OF THE SURFACE TROUGH AT THE OUTSET OF THE
   PERIOD WILL GENERALLY WEAKEN DURING THE DAY SOUTH OF THE
   INTERNATIONAL BORDER AREA.  AND MID-LEVEL LAPSE RATES ARE IN THE
   PROCESS OF BECOMING INCREASINGLY MODEST...WITH WARM ELEVATED MIXED
   LAYER AIR EXPECTED TO BECOME CONFINED TO A PLUME EXTENDING ACROSS
   THE SOUTHERN HIGH PLAINS INTO CENTRAL PLAINS BY LATE THIS AFTERNOON.

   STILL MODERATE BOUNDARY LAYER CAPE /1500 TO 3000 J PER KG/ IS
   EXPECTED IN A CORRIDOR FROM THE TEXAS/OKLAHOMA PANHANDLE
   NORTHEASTWARD INTO WESTERN AND CENTRAL IOWA BY EARLY AFTERNOON...AND
   IN A CORRIDOR ACROSS EASTERN NORTH DAKOTA AND ADJACENT SOUTH
   DAKOTA/MINNESOTA BY LATE THIS AFTERNOON OR EARLY EVENING.  THIS
   SHOULD BE SUFFICIENT TO SUPPORT CONSIDERABLE THUNDERSTORM
   ACTIVITY...WHICH COULD INCLUDE SEVERAL GROWING CONVECTIVE CLUSTERS
   BY LATE AFTERNOON...ACCOMPANIED BY THE RISK FOR SEVERE WIND GUSTS
   AND HAIL.

   ...MID ATLANTIC COAST STATES...
   ON THE SOUTHERN PERIPHERY OF A PROMINENT CLOSED LOW DIGGING ACROSS
   QUEBEC INTO NORTHERN ATLANTIC COASTAL AREAS...A WEAKER IMPULSE IS
   FORECAST TO DIG SOUTHEAST OF THE UPPER OHIO VALLEY TODAY.  AS IT
   DOES...MID-LEVEL FLOW WILL BECOME INCREASINGLY CYCLONIC ACROSS THE
   MID ATLANTIC REGION...PROBABLY WITH AN EMBEDDED 30-40 KT SPEED
   MAXIMUM...WHICH COULD ENHANCE CONVECTIVE DEVELOPMENT EXPECTED AHEAD
   OF A SOUTHWARD ADVANCING FRONT TODAY.  CONSIDERABLE HEATING OF A
   MOIST PRE-FRONTAL BOUNDARY LAYER AIR MASS /CHARACTERIZED BY SURFACE
   DEW POINTS NEAR 70F/ ACROSS THE COASTAL PLAIN INTO PIEDMONT MAY
   YIELD MIXED LAYER CAPE OF 2000 TO 3000 J/KG.  THIS WILL CONTRIBUTE
   TO AN ENVIRONMENT SUPPORTIVE OF THE POTENTIAL FOR THE EVOLUTION OF
   AN ORGANIZED STORM CLUSTER CAPABLE OF PRODUCING DAMAGING WIND
   GUSTS...PERHAPS SOME HAIL.

   ..KERR/ROGERS.. 06/19/2014

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