Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
SPC AC 270557
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.
..KERR/SMITH.. 07/27/2014
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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