DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 171611
SWODY1
SPC AC 171609

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1109 AM CDT THU OCT 17 2013

VALID 171630Z - 181200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...

A BROAD CYCLONIC FLOW REGIME WILL BE MAINTAINED OVER THE CONUS WITH
A BELT OF STRONG MID AND UPPER-LEVEL FLOW STRETCHING FROM THE
CNTRL/SRN PLAINS THROUGH THE NORTHEAST AND MID ATLANTIC STATES.
EMBEDDED WITHIN THIS HIGHER MOMENTUM AIR STREAM...A SHORT-WAVE
TROUGH OVER THE MIDWEST WILL TRANSLATE NEWD INTO THE ST. LAWRENCE
VALLEY BY 18/12Z. OTHER MORE PROMINENT VORTICITY MAXIMA WILL TRACK
FROM THE NRN PLAINS INTO UPPER GREAT LAKES...AND FROM THE NRN
INTER-MOUNTAIN REGION TO CNTRL/SRN ROCKIES DURING THE D1 PERIOD.

IN THE LOW LEVELS...A SURFACE CYCLONE ASSOCIATED WITH THE MIDWEST
SHORT-WAVE TROUGH WILL DEEPEN WHILE DEVELOPING NEWD FROM THE CNTRL
APPALACHIANS THROUGH CNTRL PA LATE THIS AFTERNOON BEFORE REACHING
MAINE EARLY FRI. MEANWHILE...A TRAILING COLD FRONT WILL ADVANCE
EWD/SEWD TO OFF THE MID ATLANTIC COAST.

...CNTRL APPALACHIANS TO NEW ENGLAND THIS AFTERNOON INTO TONIGHT...

BOTH FORCING FOR ASCENT AND VERTICAL SHEAR WILL INCREASE WITH THE
APPROACH OF THE MIDWEST/OH VALLEY SHORT-WAVE TROUGH. HOWEVER...
MORNING VISIBLE SATELLITE IMAGERY INDICATES AN EXPANSIVE CLOUD
SHIELD ATTENDING THIS SYSTEM WHICH WILL PROGRESSIVELY OVERSPREAD THE
REGION TODAY...LIMITING THE DEGREE OF AIR MASS DESTABILIZATION AHEAD
OF THE COLD FRONT.

LATEST CONVECTION-ALLOWING MODEL GUIDANCE SUGGESTS THAT A LOW-TOPPED
CONVECTIVE BAND --WITH A FEW EMBEDDED TSTMS-- WILL BECOME
INCREASINGLY POSSIBLE BY LATE AFTERNOON OR EARLY EVENING FROM
CNTRL/ERN PA INTO NRN VA AS THE STRONGER FORCING FOR ASCENT/DCVA
ASSOCIATED WITH THE SHORT-WAVE TROUGH LINKS WITH THE FRONTAL UPLIFT.
SHOULD SUFFICIENT DESTABILIZATION OCCUR TO SUPPORT SURFACE-BASED
STORM DEVELOPMENT...THE DOWNWARD MOMENTUM TRANSFER OF AN
INCREASINGLY STRONG TROPOSPHERIC WIND FIELD MAY PROMOTE LOCALLY
STRONG WIND GUSTS WITH THE CONVECTIVE BAND.

...CNTRL/ERN GULF COAST THIS AFTERNOON...

ISOLATED TO WIDELY SCATTERED TSTMS WILL BE POSSIBLE THIS AFTERNOON
ALONG AND AHEAD OF THE COLD FRONT WHERE SEASONABLY MOIST CONDITIONS
WILL YIELD MLCAPE OF 500-1000 J/KG. WHILE A STRONG STORM OR TWO IS
POSSIBLE...MARGINAL AMOUNTS OF INSTABILITY AND VERTICAL SHEAR WILL
PRECLUDE SEVERE WEATHER POTENTIAL.

...CNTRL/SRN PLAINS TONIGHT...

THE SEWD PROGRESSION OF A SHORT-WAVE TROUGH THROUGH THE CNTRL PLAINS
WILL CONTRIBUTE TO THE ENHANCEMENT OF A NOCTURNAL LLJ AND THE
POLEWARD RETURN OF A PARTIALLY MODIFIED AIR MASS THROUGH THE SRN
HIGH PLAINS. THIS MOISTURE RETURN WILL OCCUR BENEATH A PLUME OF
STEEP MIDLEVEL LAPSE RATES...BOOSTING MUCAPE TO 500-1000 J/KG.
ISOLATED TO WIDELY SCATTERED ELEVATED TSTMS WILL BECOME INCREASINGLY
POSSIBLE WITHIN THIS REGIME IN THE 18/09-12Z TIME FRAME AS FORCING
FOR ASCENT IS ENHANCED BY WAA/ISENTROPIC AT THE TERMINUS OF THE LLJ.
NO SEVERE WEATHER IS EXPECTED.

..MEAD/LEITMAN.. 10/17/2013

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