DAY48SVR: Nws Storm Prediction Center Norman Ok

ACUS48 KWNS 100856
SWOD48
SPC AC 100856

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0356 AM CDT WED OCT 10 2012

VALID 131200Z - 181200Z

...DISCUSSION...
UNCERTAINTIES PERSIST DUE TO LINGERING SPREAD AMONG MODELS AND MODEL
ENSEMBLES CONCERNING THE NORTHEASTWARD ACCELERATION OF A SIGNIFICANT
CLOSED LOW OUT OF THE SOUTHWESTERN STATES LATE THIS WEEK THROUGH THE
WEEKEND. HOWEVER...IT STILL APPEARS MOST PROBABLE THAT
INSTABILITY...DEEP LAYER FLOW FIELDS/SHEAR AND FORCING FOR UPWARD
VERTICAL MOTION WILL BECOME MOST SUPPORTIVE OF SEVERE WEATHER
POTENTIAL IN THE WARM SECTOR OF A SUB-1000 MB SURFACE CYCLONE ON
SATURDAY...AS IT MIGRATES ACROSS THE MID MISSOURI VALLEY...TOWARD
THE GREAT LAKES REGION. EVEN WITH ONLY WEAK DESTABILIZATION...THE
ENVIRONMENT NEAR A 70-90 KT SOUTHWESTERLY 500 MB JET STREAK AND
50-70 KT SOUTHERLY 850 MB JET COULD BECOME SUFFICIENT FOR A
SUBSTANTIVE REGIONAL SEVERE CONVECTIVE EVENT WITH DAMAGING WIND AND
PERHAPS TORNADOES.

IT MAY NOT BE COMPLETELY OUT OF THE QUESTION THAT THIS COULD
CONTINUE ACROSS PARTS OF THE OHIO VALLEY AND GREAT LAKES REGION
SATURDAY NIGHT INTO SUNDAY...BEFORE THE UPPER IMPULSE DEAMPLIFIES.
HOWEVER...INCREASING MODEL VARIABILITY CONCERNING THE EVOLUTION OF
THIS SYSTEM...COUPLED WITH PROBABILITY OF DECREASING AVAILABLE
INSTABILITY...RESULTS IN TOO MUCH UNCERTAINTY TO EXTEND THE AREAL
DELINEATION. THEREAFTER...INTO THE MIDDLE OF NEXT WEEK...THE SPREAD
IN MODEL DATA CONCERNING LARGE-SCALE PATTERN DEVELOPMENTS BECOMES
MUCH TOO LARGE TO CONFIDENTLY ASSESS THE POTENTIAL FOR A REGIONAL
SEVERE WEATHER EVENT.

..KERR.. 10/10/2012

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