DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 010533
SWODY1
SPC AC 010531

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1131 PM CST FRI NOV 30 2012

VALID 011200Z - 021200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
MODELS INDICATE THAT AT LEAST A COUPLE OF DISTINCT BELTS OF
WESTERLIES EMERGING FROM THE NORTHEAST PACIFIC WILL REMAIN LARGELY
ZONAL ACROSS SOUTHERN CANADA AND THE NORTHERN/CENTRAL TIER OF THE
U.S. DURING THIS FORECAST PERIOD. WITHIN THIS REGIME...ONE
SIGNIFICANT SHORT WAVE IMPULSE IS FORECAST TO ADVANCE INLAND ACROSS
THE PACIFIC NORTHWEST BY 01/12Z...BEFORE CONTINUING EAST
NORTHEASTWARD INTO SOUTHERN SASKATCHEWAN AND MANITOBA LATER IN THE
DAY. SHORT WAVE RIDGING IS EXPECTED TO DEVELOP IN THE WAKE OF THIS
FEATURE...BEFORE A LINGERING MID-LEVEL CIRCULATION AND ANOTHER
SIGNIFICANT SHORT WAVE TROUGH APPROACH BRITISH COLUMBIA AND PACIFIC
NORTHWEST COASTAL AREAS TOWARD 02/12Z. DOWNSTREAM...A NUMBER OF
ADDITIONAL SHORT WAVE IMPULSES WILL PROGRESS EAST OF THE ROCKIES
THROUGH THE EASTERN CANADIAN PROVINCES AND NORTHEASTERN
U.S...GENERALLY OUT OF PHASE AND WITH NO SIGNIFICANT SURFACE
CYCLOGENESIS ANTICIPATED.

...PACIFIC NORTHWEST COAST...
GUIDANCE SUGGESTS THAT WARMING OF THE MID-LEVEL ENVIRONMENT...IN THE
WAKE OF THE LEAD SHORT WAVE TROUGH...WILL BECOME SUFFICIENT TO
INHIBIT VERTICAL DEVELOPMENT OF CONVECTION INTO/THROUGH THE MIXED
PHASE LAYER FAVORABLE FOR CHARGE SEPARATION AND LIGHTNING...TO THE
SOUTH OF THE COLUMBIA RIVER EARLY IN THE PERIOD. OCCASIONAL...
ISOLATED WEAK THUNDERSTORM ACTIVITY MAY PERSIST TO THE NORTH...BUT
RELATIVELY WARM MID-LEVELS MAY CONTINUE TO PRECLUDE THUNDERSTORM
DEVELOPMENT ALONG SOUTHERN OREGON AND NORTHERN CALIFORNIA COASTAL
AREAS EVEN AS THE NEXT FRONTAL BAND MOVES ONSHORE LATE IN THE
PERIOD.

...UPPER MIDWEST...
MODELS CONTINUE TO SUGGEST THAT MID-LEVEL LAPSE RATES WILL NOT BE
STEEP ENOUGH TO SUPPORT SUBSTANTIVE CAPE IN ASSOCIATION WITH THE
WEAK TO MODEST RETURN FLOW OF MOISTURE NOW UNDERWAY OFF THE WESTERN
GULF OF MEXICO. HOWEVER...IT DOES APPEAR POSSIBLE THAT THERE WILL
BE SUFFICIENT DESTABILIZATION...WHEN COUPLED WITH LARGE-SCALE
FORCING FOR UPWARD VERTICAL MOTION WITH A PASSING SHORT WAVE
IMPULSE...TO SUPPORT WEAK THUNDERSTORM ACTIVITY LATE THIS AFTERNOON
AND EVENING...MAINLY ACROSS PARTS OF NORTHERN ILLINOIS INTO SOUTHERN
LAKE MICHIGAN...AND ADJACENT SOUTHERN WISCONSIN/LOWER MICHIGAN.

..KERR/ROGERS.. 12/01/2012

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