DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 070505
SWODY1
SPC AC 070502

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1202 AM CDT MON OCT 07 2013

VALID 071200Z - 081200Z

...THERE IS A SLGT RISK OF SVR TSTMS FOR PARTS OF THE UPPER
CHESAPEAKE BAY NORTHWARD INTO ERN NY AND WRN NEW ENGLAND...

...SYNOPSIS...
A VIGOROUS NEGATIVELY TILTED MID-LEVEL TROUGH IS FORECAST TO PIVOT
ACROSS THE LOWER GREAT LAKES THROUGH THE NORTHEAST U.S. THROUGH
DAYBREAK TUESDAY. SHOWERS AND ISOLATED THUNDERSTORMS ONGOING AT THE
START OF THE PERIOD INVOF A COLD FRONT WILL SPREAD EWD ACROSS THE
APPALACHIANS AND A LARGE PORTION OF THE NORTHEAST BY MONDAY EVENING.
A FRONTAL LINE OF LOWER-TOPPED CONVECTION IS EXPECTED TO INTENSIFY
AND BECOME THE PRIMARY FOCUS FOR STRONG TO SEVERE THUNDERSTORMS AS
IT SWEEPS EWD ACROSS THE MID-ATLANTIC STATES NORTHWARD INTO PORTIONS
OF NEW ENGLAND DURING THE DAY.

...MID-ATLANTIC STATES NORTHWARD INTO NEW ENGLAND...
AS THE UPPER TROUGH ACCELERATES EASTWARD...TROPOSPHERIC WIND FIELDS
WILL MARKEDLY STRENGTHEN OVER THE AREA AS LOW LEVEL MOISTURE --DUE
IN PART TO A SLY 50-65 KT H85 JET-- INCREASES FROM SOUTH TO NORTH
ACROSS THE AREA. SURFACE DEWPOINTS RANGING FROM NEAR 70 DEG AROUND
THE MASON-DIXON LINE TO THE MID 60S IN THE ADIRONDACKS WILL
CONTRIBUTE TO MARGINAL BUOYANCY DESPITE EXPECTED WIDESPREAD CLOUD
COVER AHEAD OF THE FRONT. THE TRANSITION FROM A WEAK CONVECTIVE
LINE ALONG THE FRONT TO A SURFACE-BASED SQUALL LINE IS EXPECTED BY
MID-LATE MORNING AS STRONG FORCING FOR ASCENT AIDS IN ORGANIZING AN
EXTENSIVE FRONTAL BAND OF SHOWERS/STORMS. FORECAST SOUNDINGS SHOW
0-1 KM SHEAR AROUND 40 KT WHICH WILL SUPPORT BOTH A WIND DAMAGE
THREAT AND PERHAPS AN ISOLATED TORNADO THREAT WITH ANY LONGER-LIVED
MESOVORTEX CIRCULATIONS THAT MAY DEVELOP. THE ACTIVITY IS FORECAST
TO GRADUALLY WEAKEN BY EVENING OWING IN PART TO LOSS OF DAYTIME
HEATING AND INCREASINGLY MARGINAL THERMODYNAMIC PROFILES TOWARDS THE
NEW ENGLAND COAST.

...CAROLINAS AND VA TIDEWATER...
LOW LEVEL SHEAR IS FORECAST TO WEAKEN DURING THE MORNING AS THE
UPPER TROUGH MOVES AWAY FROM THE REGION THROUGH MIDDAY...CONCURRENT
WITH WANING LARGE-SCALE ASCENT/WEAKENING DEEP SHEAR. DESPITE THESE
LIMITING FACTORS...RICH LOW LEVEL MOISTURE MAY COMPENSATE FOR MODEST
LAPSE RATE PROFILES FORECAST OVER THE REGION AND LEND THE
POSSIBILITY FOR AN ISOLATED WIND DAMAGE THREAT WITH THE STRONGER
STORMS.

..SMITH/BROYLES.. 10/07/2013

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