SWODY2
SPC AC 080611
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1211 AM CST SUN MAR 08 2009
VALID 091200Z - 101200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE SOUTHERN
PLAINS...
...SYNOPSIS...
A MEAN LONGWAVE TROUGH WILL PERSIST OVER THE WESTERN HALF OF THE
CONUS THROUGH MONDAY. WITHIN THIS LONGWAVE TROUGH...THE PRIMARY
FEATURE OF NOTE WILL BE A BROAD UPPER TROUGH TRANSITIONING EASTWARD
OVER THE INTERMOUNTAIN WEST/ROCKIES...WITH A SOUTHERN
SPLIT/SUBTROPICAL STREAM FROM BAJA/NORTHERN MEXICO TO THE MIDWEST.
...SOUTHERN PLAINS...
MASS FIELDS ACROSS THE SOUTHERN PLAINS WILL BEGIN TO RESPOND TO THE
APPROACHING WESTERN STATES TROUGH ON MONDAY...WITH LEE SIDE
CYCLOGENESIS ACROSS THE SOUTH CENTRAL HIGH PLAINS AND A STEADY
NORTH-NORTHWESTWARD RETURN OF A SURFACE WARM/MOIST SECTOR ACROSS
PORTIONS OF NORTH TX/OK INTO KS/MO. WHILE LARGE SCALE HEIGHT FALLS
WILL REMAIN LIMITED ACROSS THE EXPANDING MOIST SECTOR ACROSS
TX/OK/KS DURING THE DAY...A SOUTHERN/SUBTROPICAL STREAM SHORTWAVE
TROUGH/POTENTIAL SPEED MAX SHOULD CONTRIBUTE TO TSTM DEVELOPMENT
DURING THE AFTERNOON...ALTHOUGH CONSIDERABLE SHORT TERM TIMING
VARIABILITY EXISTS IN THE 00Z BASED NUMERICAL GUIDANCE.
REGARDLESS...SUCH DEVELOPMENT WOULD BE MOST LIKELY INITIALLY ACROSS
PORTIONS OF OK/NORTH TX ALONG/AHEAD OF A PROGRESSIVELY ESTABLISHED
SURFACE LOW/DRYLINE.
ASIDE FROM THE AFOREMENTIONED SHORTWAVE TROUGH TIMING...THE SEVERE
SCENARIO IS FURTHER COMPLICATED BY THE POSSIBILITY OF AN EXPANSIVE
CIRRUS CANOPY DURING THE AFTERNOON...AND ACCORDINGLY MID LEVEL LAPSE
RATES WILL NOT BE PARTICULARLY STEEP BENEATH THE SUBTROPICAL PLUME.
AROUND 60F SURFACE DEWPOINTS IN THE PREFRONTAL/DRYLINE WARM SECTOR
MAY SUPPORT MLCAPE VALUES TO AROUND 750-1000 J/KG PROVIDED
SUFFICIENT HEATING...ALTHOUGH MARGINAL MOISTURE QUALITY WILL BE
CONDUCIVE FOR MIXING ESPECIALLY ACROSS TX. GIVEN SUFFICIENT
HEATING/FAVORABLE TIMING OF UPPER FORCING GLANCING THE WARM
SECTOR...RATHER FAVORABLE SHEAR PROFILES BENEATH 50-60 KT MID LEVEL
FLOW WOULD SUPPORT SUPERCELLS WITH AN ASSOCIATED SEVERE RISK MONDAY
AFTERNOON/EVENING.
...LOWER/MIDDLE MISSOURI VALLEY AND MIDWEST MONDAY NIGHT...
AS THE UPSTREAM UPPER TROUGH APPROACHES THE CENTRAL HIGH PLAINS LATE
MONDAY NIGHT...THE PASSING CENTRAL STATES LEAD SHORTWAVE TROUGH AND
A STRENGTHENING SOUTHWESTERLY LOW LEVEL JET /50+ KT/ WILL LIKELY
LEAD TO A NOCTURNAL INCREASE/NORTHEASTWARD EXPANSION OF TSTMS ACROSS
THE REGION ALONG/NORTH OF A RETREATING WARM FRONT. AS A
MOIST/UNSTABLE ELEVATED AIRMASS ADVECTS NORTHEASTWARD TOWARD THE
REGION...AT LEAST AN ISOLATED HAIL THREAT WILL EXIST MONDAY NIGHT.
IF ELEVATED INSTABILITY PROVES STRONGER THAN CURRENT
EXPECTED...PORTIONS OF MO/IL/SOUTHERN IA COULD EVENTUALLY WARRANT AN
UPGRADE TO A CATEGORICAL SLIGHT RISK FOR PRIMARILY A HAIL THREAT.
..GUYER.. 03/08/2009
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