SPC AC 171730

   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1230 PM CDT MON JUN 17 2013

   VALID 181200Z - 191200Z

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

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF NORTHWEST AND
   NORTH CENTRAL MONTANA...

   ...SYNOPSIS...
   BETWEEN GENERALLY FLAT UPPER RIDGING OVER THE SUBTROPICAL PACIFIC
   AND A BLOCKING UPPER HIGH CENTER OVER ALASKA...A BELT OF STRONGER
   WESTERLIES EXTENDS ACROSS THE MID-LATITUDE PACIFIC INTO THE PACIFIC
   COAST REGION.  ON THE LEADING EDGE OF THIS REGIME...MODELS INDICATE
   THAT A BROAD...DEEP MID-LEVEL CLOSED LOW...AND TROUGHING TO THE
   SOUTH...WILL ELONGATE AND PIVOT INLAND IN NEGATIVELY TILTED FASHION
   ACROSS THE PACIFIC NORTHWEST INTO THE NORTHERN GREAT BASIN AND
   NORTHERN INTERMOUNTAIN REGION BY 12Z WEDNESDAY.

   DOWNSTREAM...ANOTHER BELT OF STRONGER WESTERLIES CURVE IN BROADLY
   CYCLONIC FASHION ACROSS THE GREAT LAKES REGION AND NORTHEAST.  AS
   ONE SIGNIFICANT EMBEDDED IMPULSE...NOW DIGGING TO THE SOUTHEAST OF
   HUDSON BAY...CONTINUES EASTWARD THROUGH THE CANADIAN MARITIMES AND
   NORTHERN NEW ENGLAND...AHEAD OF ANOTHER MORE SIGNIFICANT CLOSED LOW
   DIGGING TO THE NORTH OF HUDSON BAY...THIS BELT OF FLOW IS FORECAST
   TO WEAKEN DURING THIS PERIOD.  HOWEVER...AN IMPULSE WITHIN A WEAKER
   BELT OF CYCLONIC FLOW TO THE SOUTH...LIKELY WILL DIG FROM THE UPPER
   MISSISSIPPI VALLEY THROUGH THE OHIO VALLEY.

   ELSEWHERE...IN BETWEEN THE CYCLONIC REGIMES OVER THE WEST AND
   EAST...UPPER RIDGING WITH WEAK FLOW IS EXPECTED PREVAIL ACROSS THE
   PLAINS.  MEANWHILE...GENERALLY WEAK ZONAL FLOW IS EXPECTED ACROSS
   MUCH OF THE SOUTHERN TIER STATES.

   ASSOCIATED WITH THIS PATTERN...STEEP MID-LEVEL LAPSE RATES WILL
   MOSTLY BE CONFINED TO THE INTERMOUNTAIN WEST...ROCKIES AND HIGH
   PLAINS REGION...WHILE HIGHER MOISTURE CONTENT AIR /CHARACTERIZED BY
   PRECIPITABLE WATER AOA 1.75 INCHES/ BECOMES CONFINED TO THE SOUTHERN
   HIGH PLAINS...GULF STATES AND SOUTHERN/MID ATLANTIC COAST STATES.

   ...NORTHWESTERN AND NORTH CENTRAL MONTANA...
   BENEATH DIFLUENT AND INCREASINGLY DIVERGENT UPPER FLOW...AT LEAST
   SCATTERED STORM DEVELOPMENT IS EXPECTED TUESDAY AFTERNOON AND
   EVENING ACROSS THE MOUNTAINS...ON THE LEADING EDGE OF STRONGER
   MID-LEVEL COOLING ASSOCIATED WITH THE APPROACHING UPPER TROUGH. 
   WITH STEEP LAPSE RATES SUPPORTING AT LEAST WEAK TO MODERATE
   CAPE...STRENGTHENING SOUTHERLY MID/UPPER FLOW MAY BECOME SUPPORTIVE
   OF SUPERCELLS CAPABLE OF PRODUCING SEVERE HAIL AND LOCALLY STRONG
   SURFACE GUSTS.

   ADDITIONAL DEVELOPMENT...INCLUDING THE RISK FOR SUPERCELLS...EAST OF
   THE HIGHER TERRAIN INTO PARTS OF NORTH CENTRAL MONTANA IS POSSIBLE
   DURING THE EVENING HOURS...ON THE SOUTHERN FRINGE OF A STRENGTHENING
   LOWER/MID TROPOSPHERIC WARM ADVECTION REGIME FOCUSED GENERALLY
   ACROSS PARTS OF SOUTHERN ALBERTA/SASKATCHEWAN.

   ...HIGH PLAINS...
   MID/UPPER FORCING FOR CONVECTIVE DEVELOPMENT REMAINS UNCLEAR.  BUT
   THERMODYNAMIC PROFILES ARE EXPECTED TO BE CHARACTERIZED BY STEEP
   MID-LEVEL LAPSE RATES AND SIZABLE CAPE...IN THE PRESENCE OF STRONG
   DEEP LAYER SHEAR /MOSTLY DUE TO PRONOUNCED VEERING OF WEAK TO MODEST
   SOUTHEASTERLY LOW-LEVEL FLOW TO MODEST WESTERLY FLOW ALOFT/.  THIS
   ENVIRONMENT APPEARS CONDUCIVE TO VIGOROUS CONVECTIVE DEVELOPMENT OFF
   THE HIGHER TERRAIN...WITH ISOLATED  SUPERCELLS AND THE POTENTIAL FOR
   THE EVOLUTION OF ORGANIZED STORM CLUSTERS...WITH GREATEST
   CONCENTRATION/PROBABILITIES PERHAPS ACROSS PARTS OF SOUTHEAST
   COLORADO AND EASTERN NEW MEXICO INTO WESTERN TEXAS.

   ...OHIO VALLEY INTO SRN NEW ENGLAND AND NRN MID ATLANTIC...
   GIVEN AT LEAST MODERATE DESTABILIZATION WITH DAYTIME HEATING AHEAD
   OF A SOUTHWARD ADVANCING COLD FRONT...THE REMNANT BELT OF MODEST
   WESTERLY MID-LEVEL FLOW COULD ENHANCE ASSOCIATED CONVECTIVE
   DEVELOPMENT TUESDAY AFTERNOON...SUPPORTING AT LEAST LOW
   PROBABILITIES FOR SEVERE WIND AND HAIL.

   ..KERR.. 06/17/2013

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