[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 260554
SWODY2
SPC AC 260553

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1253 AM CDT SAT AUG 26 2006

VALID 271200Z - 281200Z

...THERE IS A SLGT RISK OF SVR TSTMS SUN AFTN/EVE ACROSS THE UPPER
OHIO VALLEY....

SHORT WAVE TROUGHS WITHIN SPLIT BELTS OF POLAR WESTERLIES WILL
REMAIN PROGRESSIVE THROUGH THIS FORECAST PERIOD.  MODELS SUGGEST
PHASING OF A SIGNIFICANT NORTHERN STREAM TROUGH AND A WEAKER
SOUTHERN STREAM IMPULSE WILL OCCUR LATE TODAY INTO EARLY SUNDAY
ACROSS THE GREAT LAKES REGION. HOWEVER...THIS APPEARS LIKELY TO BE
SHORT-LIVED...AS THE NORTHERN SYSTEM IS FORECAST TO LIFT THROUGH
QUEBEC LATER SUNDAY INTO EARLY MONDAY. SOUTHERN IMPULSE IS PROGGED
TO TURN SOUTHEAST OF THE LOWER GREAT LAKES AND CONTINUE ACROSS THE
MID ATLANTIC COAST...AS UPSTREAM SHORT WAVE RIDGING BUILDS INTO THE
GREAT LAKES.  THIS WILL OCCUR AHEAD OF A MORE SIGNIFICANT SOUTHERN
STREAM TROUGH SLOWLY ADVANCING EAST OF THE CENTRAL ROCKIES.

MEANWHILE...A SUBTROPICAL RIDGE WILL GENERALLY HOLD FIRM FROM THE
SOUTHEASTERN STATES INTO THE LOWER LATITUDE WESTERN ATLANTIC. 
AND...AN UPPER RIDGE WILL BUILD ACROSS THE INTERMOUNTAIN WEST...
AHEAD OF ANOTHER VIGOROUS NORTHERN BRANCH TROUGH DIGGING ACROSS THE
NORTHEAST PACIFIC.

...UPPER OHIO VALLEY/LOWER GREAT LAKES INTO THE NORTHEAST...
IN THE WAKE OF A SIGNIFICANT UPPER TROUGH ALREADY EAST OF THE NORTH
ATLANTIC COAST BY EARLY SUNDAY...SURFACE RIDGING WILL BE SLOW TO
RETREAT EAST OF NORTHERN/MID ATLANTIC COASTAL AREAS.  THIS WILL
MAINTAIN COOLER SOUTHEASTERLY FLOW ALONG COASTAL AREAS...AND WARM
ADVECTION CLOUDINESS LIKELY WILL MINIMIZE DESTABILIZATION AHEAD OF
APPROACHING SOUTHERN BRANCH IMPULSE.

HOWEVER...AHEAD OF A COLD FRONT ADVANCING INTO THE UPPER OHIO
VALLEY...AT LEAST WEAK SURFACE HEATING OF VERY MOIST BOUNDARY
LAYER...CHARACTERIZED BY SURFACE DEW POINTS NEAR 70F...IS EXPECTED
TO CONTRIBUTE TO CAPE OF 1000 TO 1500. THOUGH ANTICIPATED
INSTABILITY IS NOT PARTICULARLY STRONG...DEEP LAYER SHEAR BENEATH
MODERATE WEST NORTHWESTERLY MID-LEVEL FLOW IS FORECAST TO BE
MARGINALLY SUFFICIENT FOR UPDRAFT ROTATION.  A FEW SEVERE STORMS ARE
POSSIBLE...INCLUDING ISOLATED SUPERCELLS WITH ENHANCED RISK OF
HAIL/DAMAGING WIND GUSTS...PERHAPS A TORNADO OR TWO.  INITIATION OF
STORMS APPEARS LIKELY BY EARLY SUNDAY AFTERNOON ACROSS PARTS OF
NORTHERN OHIO/NORTHWESTERN PENNSYLVANIA...POSSIBLY PARTS OF WESTERN
NEW YORK STATE...BEFORE DEVELOPING SOUTHEASTWARD INTO/ACROSS THE
NORTH CENTRAL APPALACHIANS BY SUNDAY EVENING.

...CENTRAL ROCKIES INTO SOUTHERN PLAINS/OZARKS...
CONSIDERABLE UNCERTAINTY EXISTS CONCERNING SEVERE POTENTIAL SUNDAY. 
WIDESPREAD CONVECTIVE DEVELOPMENT APPEARS POSSIBLE AIDED BY
LARGE-SCALE FORCING ACCOMPANYING SOUTHERN BRANCH TROUGH. 
HOWEVER...STABILIZING INFLUENCE OF EARLY SUNDAY MORNING CONVECTION
ALONG CONVECTIVELY GENERATED/ENHANCED BOUNDARY ADVANCING SOUTHWARD
TOWARD THE RED RIVER VALLEY...AND THROUGH THE OZARKS...IS UNCERTAIN.
 AND...TENDENCY MAY BE FOR BOUNDARY TO ADVANCE SOUTH OF STRONGER
MID/UPPER FLOW...MINIMIZING SHEAR IN AXIS OF STRONGER INSTABILITY.

..KERR.. 08/26/2006