Jul 27, 2014 0600 UTC Day 1 Convective Outlook

DAY 1 CONVECTIVE OUTLOOK  

   NWS STORM PREDICTION CENTER NORMAN OK
   1257 AM CDT SUN JUL 27 2014

   VALID 271200Z - 281200Z

   ...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING
   ACROSS PARTS OF SOUTHEASTERN OHIO AND EASTERN KENTUCKY INTO
   WESTERN/CENTRAL WEST VIRGINIA AND ADJACENT SOUTHWEST VIRGINIA...

   ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MODERATE RISK
   AREA ACROSS MUCH OF THE OHIO VALLEY AND MID ATLANTIC COAST REGION
   INTO SOUTHERN NEW ENGLAND...

   ...SUMMARY...
   SEVERE THUNDERSTORMS ARE EXPECTED TODAY INTO TONIGHT ACROSS MUCH OF
   THE OHIO VALLEY AND MID ATLANTIC COAST REGION INTO PORTIONS OF
   SOUTHERN NEW ENGLAND.  SWATHS OF POTENTIALLY DAMAGING WIND GUSTS AND
   LARGE HAIL ARE POSSIBLE...PARTICULARLY ACROSS PORTIONS OF THE MID
   OHIO VALLEY INTO CENTRAL APPALACHIANS...WHERE A COUPLE OF TORNADOES
   MAY ALSO NOT BE OUT OF THE QUESTION.

   ...SYNOPSIS...
   MUCH AS HAS BEEN INDICATE BY THE MODELS...AMPLIFICATION APPEARS
   UNDERWAY WITHIN THE LARGE-SCALE UPPER FLOW PATTERN.  AS SUBTROPICAL
   RIDGING BUILDS NORTHWARD THROUGH THE NORTHERN INTERMOUNTAIN REGION
   AND ROCKIES...A CLOSED LOW...WHICH HAS BEEN UNDERCUTTING THE
   BLOCKING HIGH OVER NORTHERN CANADA...IS CURRENTLY TURNING SOUTHEAST
   OF THE INTERNATIONAL BORDER AREA INTO THE UPPER MIDWEST.  THIS
   FEATURE IS FORECAST TO CONTINUE DIGGING ACROSS SOUTHWESTERN PORTIONS
   OF THE GREAT LAKES REGION TODAY...BEFORE TURNING EASTWARD TOWARD THE
   NORTHERN MID ATLANTIC COAST AND SOUTHERN NEW ENGLAND TONIGHT...TO
   THE SOUTH OF THE PERSISTENT EASTERN CANADIAN VORTEX.  AS THIS
   OCCURS...SEASONABLY STRONG /50-70 KT/ CYCLONIC MID-LEVEL FLOW
   /700-500 MB/ IS EXPECTED TO NOSE SOUTHEASTWARD ACROSS THE OHIO
   VALLEY TOWARD THE MID ATLANTIC COAST REGION.  AND AN INITIAL
   SIGNIFICANT COLD FRONT LIKELY WILL SURGE SOUTHEASTWARD THROUGH MUCH
   OF THE MIDDLE MISSISSIPPI AND OHIO/TENNESSEE VALLEYS BY 12Z MONDAY.

   WITH MOISTURE SEASONABLY HIGH BENEATH THE REMNANTS OF ELEVATED MIXED
   LAYER AIR STILL PRESENT ACROSS THE MIDDLE MISSISSIPPI VALLEY THROUGH
   A LARGE PORTION OF THE OHIO VALLEY...SUFFICIENT POTENTIAL
   INSTABILITY EXISTS TO SUPPORT WIDESPREAD THUNDERSTORM ACTIVITY
   TODAY.  THIS WILL INCLUDE THE RISK FOR SEVERE STORMS...IN THE
   PRESENCE OF ANOMALOUSLY STRONG DEEP LAYER FLOW FIELDS AND SHEAR.  

   OTHERWISE...LINGERING MONSOONAL MOISTURE ACROSS THE SOUTHERN
   PLATEAU/GREAT BASIN INTO THE CENTRAL AND SOUTHERN ROCKIES...AND
   EASTWARD ALONG A FRONTAL ZONE ADVANCING INTO THE SOUTH CENTRAL
   PLAINS...IS EXPECTED TO CONTRIBUTE TO CONSIDERABLE THUNDERSTORM
   ACTIVITY TODAY.  ADDITIONAL SCATTERED THUNDERSTORM ACTIVITY IS
   PROBABLE IN THE CONTINUING PRESENCE OF HIGH MOISTURE CONTENT AIR
   NEAR CENTRAL AND SOUTHERN FLORIDA PENINSULA ATLANTIC COASTAL AREAS.

   ...OHIO VALLEY INTO MID ATLANTIC COAST/SOUTHERN NEW ENGLAND...
   CONVECTIVE DEVELOPMENT NOW SPREADING ACROSS THE CENTRAL APPALACHIANS
   REGION...AS WELL AS ADDITIONAL CONVECTIVE DEVELOPMENT WHICH STILL
   MAY OCCUR UPSTREAM OVER THE MIDDLE MISSISSIPPI VALLEY PRIOR TO
   DAYBREAK...PROVIDE UNCERTAINTY CONCERNING THE EXTENT AND MODE OF THE
   SEVERE WEATHER POTENTIAL FOR TODAY.  THE WEAKENING LEAD CONVECTION
   APPEARS TO BE ASSOCIATED WITH AN IMPULSE THAT EMERGED FROM THE
   SOUTHWESTERN U.S. MONSOONAL REGIME.  THIS FEATURE IS FORECAST TO
   SHIFT EAST OF THE CENTRAL APPALACHIANS INTO MID ATLANTIC COASTAL
   AREAS BY MIDDAY...WHERE ASSOCIATED FORCING MAY SUPPORT RENEWED
   STRONG/SEVERE STORM DEVELOPMENT IN THE PRESENCE OF A DESTABILIZING
   BOUNDARY LAYER.  

   IN ITS WAKE...DEPENDING ON THE EVOLUTION OF UPSTREAM CONVECTION...IT
   APPEARS POSSIBLE THAT A TRAILING LOW-LEVEL BAROCLINIC ZONE ACROSS
   THE CENTRAL APPALACHIANS INTO THE MIDDLE OHIO VALLEY COULD BECOME A
   FOCUS FOR DISCRETE STORM DEVELOPMENT...AS THE MAIN UPSTREAM IMPULSE
   CONTINUES TO DIG ACROSS THE GREAT LAKES.  IF THIS OCCURS...MOST
   GUIDANCE SUGGESTS THAT STRENGTHENING DEEP LAYER FLOW FIELDS AND
   SHEAR...INCLUDING SIZABLE CLOCKWISE CURVED LOW-LEVEL
   HODOGRAPHS...WILL BE SUPPORTIVE OF SUPERCELLS CAPABLE OF PRODUCING
   STRONG TORNADOES.  CONFIDENCE REMAINS RELATIVELY LOW AT THE PRESENT
   TIME...BUT THE BOUNDARY WOULD SEEM TO FOCUS THE HIGHEST TORNADO
   PROBABILITIES ACROSS PARTS OF EASTERN KENTUCKY INTO WEST VIRGINIA.  

   THE EVOLUTION OF A SIGNIFICANT PRE-FRONTAL SQUALL LINE ALSO DOES NOT
   APPEAR OUT OF THE QUESTION...AS STRONGEST MID/UPPER FORCING FOR
   UPWARD VERTICAL MOTION DEVELOPS SOUTHEASTWARD ACROSS THE MIDDLE OHIO
   VALLEY INTO THE CENTRAL APPALACHIANS BY EARLY THIS EVENING...BEFORE
   CONTINUING TOWARD THE MID ATLANTIC COAST OVERNIGHT.  AGAIN THIS
   LARGELY DEPENDS ON THE CONVECTIVE EVOLUTION PRIOR TO MID
   AFTERNOON...WHICH STILL REMAINS UNCLEAR AT THE PRESENT TIME.