DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 100730
SWODY3
SPC AC 100729

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0229 AM CDT WED OCT 10 2012

VALID 121200Z - 131200Z

...THERE IS A SLGT RISK OF SVR TSTMS FRI/FRI NIGHT ACROSS PARTS OF
THE CNTRL AND SRN HIGH PLAINS...

...SYNOPSIS...
MODELS SUGGEST THAT THE MAIN BRANCH OF STRONGER WESTERLIES WILL
EXTEND IN A BROADLY ANTICYCLONIC BELT FROM THE EASTERN PACIFIC
ACROSS CANADA INTO THE WESTERN ATLANTIC DURING THIS FORECAST PERIOD.
BUT A SIGNIFICANT CLOSED LOW WITHIN A REMNANT WEAKER BRANCH TO THE
SOUTH IS STILL FORECAST TO FINALLY ACCELERATE OUT OF THE
SOUTHWESTERN STATES. THIS FEATURE IS EXPECTED TO TAKE A
NORTHEASTWARD TRACK ACROSS THE CENTRAL ROCKIES INTO THE CENTRAL
PLAINS...AROUND THE NORTHWESTERN PERIPHERY OF A PROMINENT
SUBTROPICAL RIDGE CENTERED OVER THE GULF OF MEXICO. AS IT DOES...IT
APPEARS LIKELY TO CONTRIBUTE TO STRONG SURFACE CYCLOGENESIS TO THE
LEE OF THE CENTRAL ROCKIES...WHICH PROBABLY WILL COMMENCE AS EARLY
AS FRIDAY NIGHT.

A RIDGE AXIS EXPECTED TO EXTEND SOUTHWESTWARD FROM A COLD SURFACE
HIGH CENTER...OVER THE UPPER MISSISSIPPI VALLEY...INTO THE CENTRAL
HIGH PLAINS AT THE START OF THE PERIOD MAY INITIALLY LIMIT
CONVECTIVE POTENTIAL...PARTICULARLY NORTH OF THE TEXAS/OKLAHOMA
PANHANDLE REGION. HOWEVER...GUIDANCE INDICATES IT WILL WEAKEN BY
LATE IN THE DAY...AS THE HIGH CENTER REDEVELOPS EASTWARD INTO THE
GREAT LAKES REGION. IT IS POSSIBLE THAT A SHALLOW STABLE SURFACE
BASED LAYER MAY LINGER ACROSS MUCH OF WESTERN KANSAS AND NEBRASKA
UNTIL LATE FRIDAY EVENING...BUT EVENTUALLY 60F+ SURFACE DEW POINTS
ARE EXPECTED TO ADVECT NORTHWARD FROM THE SOUTHERN PLAINS...AS A
SOUTHERLY 850 MB JET STRENGTHENS FROM 30-50+ KT THROUGH MUCH OF THE
PLAINS.

...PARTS OF CNTRL/SRN HIGH PLAINS...
ALTHOUGH JUST TO THE SOUTH OF A CYCLONIC 70-90 KT 500 MB JET STREAK
EXPECTED TO NOSE INTO THE CENTRAL HIGH PLAINS LATE FRIDAY
AFTERNOON...ISOLATED TO SCATTERED STORM DEVELOPMENT DOES APPEAR
POSSIBLE ACROSS THE TEXAS PANHANDLE HANDLE...NEAR THE REMNANT
SURFACE FRONT AND A DEVELOPING LEE SURFACE TROUGH/DRY LINE. THIS
MAY INCLUDE DISCRETE SUPERCELLS...AS MODESTLY STEEP MID-LEVEL LAPSE
RATES AND BOUNDARY LAYER WARMING CONTRIBUTE TO CAPE ON THE ORDER OF
1000 J/KG...IN THE PRESENCE OF STRONG SHEAR.

SOME OF THIS ACTIVITY MAY PERSIST WELL INTO THE EVENING HOURS...
WITH NEW DEVELOPMENT ALSO POSSIBLE...SPREADING NORTHEASTWARD ACROSS
AT LEAST PARTS OF WESTERN KANSAS INTO SOUTH CENTRAL NEBRASKA...IN
RESPONSE TO LOW-LEVEL THERMAL/MOISTURE ADVECTION AND STRENGTHENING
LARGE-SCALE FORCING FOR UPWARD VERTICAL MOTION. LARGE HAIL MAY BE
THE MOST PROMINENT SEVERE THREAT...BUT THE RISK FOR TORNADOES MAY
ACCOMPANY LATE AFTERNOON/EARLY EVENING ACTIVITY.

..KERR.. 10/10/2012

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