[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 050619
SWODY2
SPC AC 050617

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1217 AM CST FRI JAN 05 2007

VALID 061200Z - 071200Z

...NO SVR TSTM AREAS FORECAST...

A STRONG NORTHERN STREAM JET STREAK OVER THE NORTHERN PACIFIC IS
NOSING TOWARD THE BRITISH COLUMBIA/PACIFIC NORTHWEST COAST... AND
PROGGED TO CONTINUE EASTWARD...INLAND AND ACROSS THE CANADIAN/
NORTHERN AND CENTRAL U.S. ROCKIES LATER TODAY THROUGH SATURDAY/
SATURDAY NIGHT.  AS THIS OCCURS...THE COMPLEX SPLIT UPPER FLOW
PATTERN CURRENTLY IN PLACE ACROSS MUCH OF THE NATION IS FORECAST TO
BEGIN CONSOLIDATING INTO A BROAD LARGE-SCALE TROUGH...WHICH WILL
ENCOMPASS MOST AREAS EAST OF THE ROCKIES BY 12Z SUNDAY.

THE EXCEPTION WILL BE THE SOUTHEAST...WHERE UPPER RIDGING WILL BUILD
ONCE AGAIN SATURDAY IN THE WAKE OF REMNANTS OF A WEAKENING CLOSED
LOW...NOW BEGINNING TO LIFT OUT OF THE SOUTH CENTRAL STATES.  MODELS
INDICATE THAT AN UPSTREAM IMPULSE WILL LIFT OUT OF THE SOUTHERN
ROCKIES IN A POSITIVELY TILTED FASHION BY EARLY SATURDAY...TRAILING
A MORE VIGOROUS NORTHERN BRANCH SHORT WAVE...WHICH IS PROGGED TO
RAPIDLY LIFT FROM THE UPPER MISSISSIPPI VALLEY THROUGH THE ST.
LAWRENCE VALLEY AND NORTHEAST BY EARLY SUNDAY.  SOUTHERN SYSTEM
APPEARS LIKELY TO BECOME INCREASINGLY SHEARED ACROSS THE LOWER
MISSISSIPPI VALLEY AS IT APPROACHES THE UPPER RIDGE AXIS...WHILE
ANOTHER MUCH STRONGER NORTHERN STREAM SHORT WAVE DIGS EAST OF THE
ROCKIES INTO THE NORTH CENTRAL STATES.

IN RESPONSE TO THE EVOLVING UPPER PATTERN...MODELS INDICATE A
SURFACE LOW WILL DEEPEN AS IT LIFTS THROUGH THE ST. LAWRENCE VALLEY.
 THIS WILL FORCE THE PRIMARY SURFACE COLD FRONT EAST OF THE OHIO
VALLEY AND OFF THE NORTH ATLANTIC COAST STATES BY EARLY SUNDAY. 
BUT...THIS BOUNDARY IS EXPECTED TO BE MUCH SLOWER TO PROGRESS EAST
OF THE TENNESSEE VALLEY AND CENTRAL/EASTERN GULF STATES.

...NORTHERN ATLANTIC COAST...
MODELS SUGGEST WEAK INSTABILITY WILL BE PRESENT IN AN AREA OF
FOCUSED LOW-LEVEL WARM ADVECTION TO THE EAST OF THE DEEPENING
SURFACE LOW...MAINLY NEAR SOUTHERN NEW ENGLAND COASTAL AREAS EARLY
SATURDAY.  THIS MAY BE SUFFICIENT TO CONTRIBUTE TO SCATTERED WEAK
THUNDERSTORM ACTIVITY...BEFORE STRONGER FORCING SHIFTS WELL EAST OF
COASTAL AREAS BY SATURDAY AFTERNOON.

...CNTRL/ERN GULF STATES AND TENNESSEE VALLEY...
ANY SUPPRESSION OF MOISTURE LEVELS IN THE WAKE OF LEAD WEAKENING
SOUTHERN BRANCH IMPULSE IS EXPECTED TO BE RELATIVELY MINOR/
SHORT-LIVED.  HOWEVER...LAPSE RATES WILL BE WEAK...AND THIS IS
LIKELY TO MINIMIZE CAPE ALONG/AHEAD...AND IN THE WAKE...OF SURFACE
COLD FRONT AS IT SLOWLY ADVANCES EASTWARD ACROSS REGION.  STRONGER
FORCING FOR UPWARD VERTICAL MOTION WILL PROBABLY BE CONFINED TO A
POST-FRONTAL BAND LATE IN THE PERIOD...FROM NORTHERN MISSISSIPPI
THROUGH THE UPPER TENNESSEE VALLEY...WHERE BEST CHANCE FOR STORMS
MAY EXIST.  GIVEN THERMODYNAMIC ENVIRONMENT...HAIL POTENTIAL SEEMS
REMOTE...AND EVEN IF A FEW STORMS DO DEVELOP IN THE PRE-FRONTAL
REGIME...ISOLATED TORNADO/DAMAGING WIND POTENTIAL SEEMS NEGLIGIBLE
DUE TO ANTICIPATED WEAK LOW-LEVEL FLOW/SMALL LOW-LEVEL HODOGRAPHS.

..KERR.. 01/05/2007