DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 210601
SWODY2
SPC AC 210600

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT SUN OCT 21 2012

VALID 221200Z - 231200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
A STRONG POLAR JET WILL SPREAD INLAND OVER THE WESTERN STATES AS
LARGE SCALE TROUGH AMPLIFICATION CONTINUES TO OCCUR THROUGH
MONDAY...WITH BROAD SOUTHWESTERLY FLOW ALOFT ENCOMPASSING MUCH OF
THE WESTERN/CENTRAL CONUS. THE UPPER LOW CURRENTLY OFF THE BAJA
MEXICO COAST IS EXPECTED TO SPREAD NORTHEASTWARD OVER THE SOUTHERN
PLAINS TO THE OZARKS/MIDDLE MS VALLEY ON MONDAY AND MONDAY NIGHT.

...SOUTHERN PLAINS/OZARKS...
SOME SPATIOTEMPORAL DIFFERENCES REMAIN AMONG GUIDANCE REGARDING THE
AFOREMENTIONED UPPER LOW/SHORTWAVE TROUGH THAT IS EXPECTED TO
STEADILY SPREAD NORTHEASTWARD OVER THE REGION ON MONDAY...WITH
DESTABILIZATION /THE DEGREE THEREOF/ ALSO POTENTIALLY IMPACTED BY
LINGERING EARLY DAY CLOUD COVER/PRECIPITATION. WHILE A PARTICULARLY
ORGANIZED SEVERE RISK IS NOT CURRENTLY ANTICIPATED...FORCING FOR
ASCENT/VERTICAL SHEAR IN ASSOCIATION WITH THE SHORTWAVE
TROUGH...ALONG WITH 60S F SURFACE DEWPOINTS AND MODEST WARM SECTOR
DESTABILIZATION /1000-1500 J PER KG MLCAPE/...MAY ACCOUNT FOR
SPORADIC WIND/HAIL POTENTIAL MONDAY AFTERNOON/EVENING ACROSS
PORTIONS OF OK/NORTH TX TO THE OZARKS.

...MIDDLE/UPPER MS RIVER VALLEY AND WESTERN GREAT LAKES...
NEAR THE TERMINUS OF A SOUTHWESTERLY LOW LEVEL JET...SCATTERED
ELEVATED CONVECTION WILL LIKELY BE ONGOING MONDAY MORNING ACROSS THE
UPPER MS RIVER VALLEY AND ADJACENT MIDWEST. THIS ACTIVITY MAY
EXPAND/SPREAD NORTHEASTWARD DURING THE DAY ACROSS THE WESTERN GREAT
LAKES REGION...WITH SOME HAIL POSSIBLE.

FARTHER WEST...THE POTENTIAL FOR SUBSEQUENT CONVECTIVE DEVELOPMENT
INTO THE AFTERNOON ACROSS AREAS SUCH AS IA/NORTHERN MO AND THE
ADJACENT MS VALLEY IS UNCERTAIN...ESPECIALLY GIVEN THAT LARGE SCALE
FORCING FOR ASCENT/MASS CONVERGENCE MAY REMAIN RELATIVELY WEAK
THROUGH PEAK HEATING. NONETHELESS...GIVEN A RELATIVELY
UNSTABLE/WEAKLY CAPPED BOUNDARY LAYER NEAR THE SURFACE LOW/WARM
FRONT...SOME SEVERE THREAT WOULD BE POSSIBLE PROVIDED SURFACE BASED
CONVECTIVE DEVELOPMENT MONDAY AFTERNOON/EARLY EVENING.

...COASTAL NORTHERN CA/ORE...
AS AN UPPER TROUGH CONTINUES TO AMPLIFY OVER THE WESTERN
CONUS...LOW-TOPPED CONVECTION INCLUDING SOME EMBEDDED TSTMS IS
EXPECTED FOR THE COASTAL AREAS OF ORE/NORTHERN CA...AND PERHAPS INTO
THE SACRAMENTO VALLEY MONDAY AFTERNOON/EVENING. RELATIVELY STEEP
LAPSE RATES ALOFT MAY ACCOUNT FOR SOME SMALL HAIL POTENTIAL...BUT
ORGANIZED SEVERE TSTMS ARE NOT EXPECTED.

...NORTHERN GREAT DIVIDE TO NORTHERN HIGH PLAINS...
A FEW LIGHTNING STRIKES MAY BE POSSIBLE DURING THE
AFTERNOON/EVENING...BUT MARGINAL BUOYANCY AND LIMITED POTENTIAL FOR
CHARGE SEPARATION IMPLIES A PROBABILITY/COVERAGE OF LESS THAN 10
PERCENT.

..GUYER.. 10/21/2012

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