SPC AC 111742

   DAY 2 CONVECTIVE OUTLOOK CORR 1
   NWS STORM PREDICTION CENTER NORMAN OK
   1242 PM CDT MON AUG 11 2014

   VALID 121200Z - 131200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS TUE AFTN AND EVE ACROSS PARTS
   OF THE UPPER OHIO VALLEY AND NORTHERN MID ATLANTIC COAST REGION...

   ...THERE IS A SLGT RISK OF SVR TSTMS TUE AFT AND EVE ACROSS PARTS OF
   THE NORTHERN INTERMOUNTAIN REGION...

   CORRECTED FOR TYPOS

   ...SUMMARY...
   SCATTERED STRONG TO SEVERE STORMS ARE EXPECTED TUESDAY AFTERNOON
   INTO TUESDAY NIGHT ACROSS PARTS OF THE UPPER OHIO VALLEY INTO
   NORTHERN MID ATLANTIC COAST REGION.  CLUSTERS OF STRONG TO SEVERE
   STORMS ALSO APPEAR POSSIBLE ACROSS PARTS OF NORTHEASTERN
   OREGON...CENTRAL AND EASTERN WASHINGTON...AND ADJACENT NORTHERN
   IDAHO.

   ...SYNOPSIS...
   FURTHER AMPLIFICATION OF LARGE-SCALE UPPER TROUGHING ACROSS THE
   EASTERN U.S. APPEARS LIKELY DURING THIS FORECAST PERIOD.  AT THE
   SAME TIME...SOME WEAKENING OF UPSTREAM RIDGING MAY COMMENCE...AS THE
   REMNANTS OF A CLOSED LOW ACCELERATE INLAND ACROSS THE NORTHERN
   CALIFORNIA COAST THROUGH THE NORTHERN INTERMOUNTAIN REGION.  THIS IS
   EXPECTED TO OCCUR IN RESPONSE TO THE APPROACH OF A DIGGING UPSTREAM
   SHORT WAVE IMPULSE...WHICH IS FORECAST TO CONTRIBUTE TO THE
   EVOLUTION OF A MORE PROMINENT CLOSED LOW AS IT APPROACHES THE
   NORTHERN PACIFIC COAST.

   AHEAD OF THIS LATTER FEATURE...AND AROUND THE WESTERN PERIPHERY OF
   THE UPPER RIDGING...THUNDERSTORM PROBABILITIES WILL INCREASE FURTHER
   ACROSS MUCH OF THE INTERMOUNTAIN REGION INTO THE PACIFIC NORTHWEST. 
   EAST OF THE ROCKIES...THUNDERSTORM POTENTIAL WILL REMAIN RELATIVELY
   LOW ACROSS MUCH OF THE NORTHERN AND CENTRAL PLAINS INTO THE UPPER
   MIDWEST...WHILE DRYING ASSOCIATED WITH THE EASTERN UPPER TROUGHING
   ALSO CONTRIBUTES TO DIMINISHING CONVECTIVE POTENTIAL ACROSS THE
   SOUTHERN PLAINS EAST NORTHEASTWARD TOWARD THE TENNESSEE VALLEY.  THE
   RISK FOR THUNDERSTORM ACTIVITY WILL REMAIN RELATIVELY
   HIGH...HOWEVER...ACROSS MUCH OF THE SOUTHERN AND MIDDLE ATLANTIC
   SEABOARD...AND THE CENTRAL APPALACHIANS NORTHWARD INTO THE LOWER
   GREAT LAKES REGION.

   ...UPPER OHIO VALLEY INTO NORTHERN MID ATLANTIC COAST REGION...
   PRE-COLD FRONTAL BOUNDARY LAYER DEW POINTS APPEAR LIKELY TO REMAIN
   HIGH ENOUGH TO SUPPORT MODEST BOUNDARY LAYER DESTABILIZATION WITH AT
   LEAST SOME INSOLATION ACROSS THE UPPER OHIO VALLEY AND ADJACENT
   LOWER GREAT LAKES REGION BY TUESDAY AFTERNOON.  THIS WILL BE AIDED
   BY MID-LEVEL COOLING ASSOCIATED WITH THE FAIRLY VIGOROUS SHORT WAVE
   IMPULSE FORECAST TO TURN EASTWARD ACROSS THE OHIO VALLEY...TOWARD
   THE MID ATLANTIC COAST REGION.  WITH MIXED LAYER CAPE EXPECTED TO
   APPROACH OR EXCEED 1500 J/KG IN THE PRESENCE OF MODESTLY STRONG
   CYCLONIC MID/UPPER FLOW...THE ENVIRONMENT PROBABLY WILL BECOME
   CONDUCIVE TO THE DEVELOPMENT OF SCATTERED BANDS OR SMALL CLUSTERS OF
   STORMS CAPABLE OF PRODUCING POTENTIALLY DAMAGING WIND GUSTS AND
   PERHAPS MARGINALLY SEVERE HAIL.

   ACTIVITY IS EXPECTED TO SPREAD EASTWARD ACROSS PARTS OF THE UPPER
   OHIO VALLEY AND APPALACHIANS THROUGH THE LATE AFTERNOON AND EVENING
   HOURS...WITH ADDITIONAL STORM DEVELOPMENT BECOMING FOCUSED ALONG A
   WARM FRONTAL ZONE ACROSS PARTS OF THE DELMARVA PENINSULA/NORTHERN
   MID ATLANTIC COAST REGION.  ALTHOUGH THE STRONGER SOUTHERLY 850 MB
   FLOW FIELDS ARE EXPECTED MOSTLY NORTH OF THIS FRONT...ABOVE THE
   COOLER AND MORE STABLE BOUNDARY LAYER AIR...IT DOES NOT APPEAR OUT
   OF THE QUESTION THAT LOW-LEVEL HODOGRAPHS NEAR THE FRONT MAY BE
   SUPPORTIVE OF SUPERCELLS CAPABLE OF PRODUCING DAMAGING WIND GUSTS OR
   AN ISOLATED TORNADO OR TWO.  THIS POTENTIAL MAY BE HIGHEST LATE
   TUESDAY NIGHT...WITH THE APPROACH OF THE UPPER TROUGH.

   ...NORTHERN INTERMOUNTAIN REGION...
   MOST MODEL GUIDANCE DOES SUGGEST THAT AN AREA OF ENHANCED MID-LEVEL
   FORCING FOR ASCENT WILL OVERSPREAD PORTIONS OF NORTHEASTERN OREGON
   AND CENTRAL/EASTERN WASHINGTON DURING THE PEAK LATE AFTERNOON
   HEATING.  DESPITE LINGERING UNCERTAINTIES CONCERNING THE DEGREE OF
   CAPE...EVEN GIVEN THE PRESENCE OF SEASONABLY HIGH MOISTURE
   CONTENT...THIS FORCING SEEMS LIKELY TO BE SUFFICIENT TO SUPPORT ONE
   OR TWO SUBSTANTIVE STORM CLUSTERS.  GIVEN THIS DEVELOPMENT...BASED
   ABOVE A FAIRLY HOT AND DEEPLY MIXED BOUNDARY LAYER...THE RISK FOR
   SEVERE WIND GUSTS APPEARS TO EXIST...PERHAPS AIDED BY THE DOWNWARD
   TRANSPORT OF MOMENTUM ASSOCIATED WITH A 30+ KT LOWER/MID
   TROPOSPHERIC SPEED MAXIMUM.

   ..KERR.. 08/11/2014

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