Sunday, August 29, 2010

DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 290722
SWODY3
SPC AC 290721

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0221 AM CDT SUN AUG 29 2010

VALID 311200Z - 011200Z

...THERE IS A SLGT RISK OF SVR TSTMS TUE AFTN AND EVE ACROSS PARTS
OF THE CNTRL PLAINS INTO THE UPPER MS VALLEY/GREAT LAKES REGION...

...SYNOPSIS...
VARIABILITY INCREASES AMONG THE MODEL DATA CONCERNING THE EVOLVING
LARGE-SCALE PATTERN DURING THIS FORECAST PERIOD...BUT A TREND TOWARD
A MORE ZONAL BELT OF STRONGER WESTERLIES ACROSS SOUTHERN CANADA AND
THE NORTHERN TIER OF THE U.S. APPEARS MOST PROBABLE. A DIGGING
SHORT WAVE TROUGH COULD REINFORCE BROAD TROUGHING FROM BRITISH
COLUMBIA AND THE PACIFIC NORTHWEST INTO THE NORTHERN ROCKIES...WHILE
A SIGNIFICANT DOWNSTREAM IMPULSE CONTINUES LIFTING NORTH AND EAST OF
THE CENTRAL CANADIAN/U.S. BORDER AREA. AS A DEEPENING SURFACE
CYCLONE ASSOCIATED WITH THE LATTER FEATURE MIGRATES ACROSS NORTHERN
ONTARIO AND THE SOUTHERN HUDSON/JAMES BAY REGION...A WEAKENING
TRAILING COLD FRONT OR WIND SHIFT IS PROGGED TO ADVANCE
SOUTHEASTWARD ACROSS THE UPPER GREAT LAKES AND UPPER MISSISSIPPI
VALLEY REGION...WHILE STALLING/RETREATING ACROSS THE CENTRAL
PLAINS...AS ANOTHER FRONT ADVANCES TOWARD THE UPPER MIDWEST BY LATE
TUESDAY NIGHT.

...CENTRAL PLAINS INTO THE UPPER MS VALLEY/GREAT LAKES REGION...
ALTHOUGH DEEP LAYER MEAN FLOW AND SHEAR APPEAR LIKELY TO WEAKEN
CONSIDERABLY ACROSS THE REGION BY EARLY TUESDAY...A CORRIDOR OF
FAIRLY STRONG SURFACE HEATING ALONG/JUST AHEAD OF THE LEAD WIND
SHIFT IS EXPECTED TO CONTRIBUTE TO AN AXIS OF MODERATELY STRONG
DESTABILIZATION BY TUESDAY AFTERNOON. MOISTURE CONTENT IS EXPECTED
TO BE HIGH ALONG THIS AXIS...CHARACTERIZED BY SURFACE DEW POINTS
NEAR 70F...AND A BAND OF PRECIPITABLE WATER AROUND 2 INCHES...WHICH
PROBABLY WILL CONTRIBUTE TO MIXED LAYER CAPE IN EXCESS OF 2000
J/KG...DESPITE WEAK TO MODEST MID-LEVEL LAPSE RATES.

STRONGEST HEATING...AND DEVELOPMENT OF A DEEPLY MIXED BOUNDARY LAYER
FAVORABLE FOR DOWNBURSTS AND SURFACE COLD POOLS WITH STRONG WIND
GUSTS PROBABLY WILL BE CONFINED TO THE CENTRAL PLAINS/MID MISSOURI
VALLEY REGION. BUT SOMEWHAT STRONGER DEEP LAYER MEAN FLOW LINGERING
ACROSS IOWA...SOUTHEASTERN MINNESOTA AND WISCONSIN ...WHEN COUPLED
WITH THE INFLUENCE OF HEAVY PRECIPITATION LOADING ...MAY COMPENSATE
TO CONTRIBUTE TO THE POTENTIAL FOR DAMAGING WIND GUSTS WITH STORMS
EXPECTED TO DEVELOP DURING THE AFTERNOON HOURS. AN EAST
SOUTHEASTWARD ADVANCING NARROW BROKEN SQUALL LINE COULD
EVOLVE...BEFORE CONVECTION WEAKENS DURING THE EVENING.

..KERR.. 08/29/2010

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