SWOD48
SPC AC 310916
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0416 AM CDT WED AUG 31 2011
VALID 031200Z - 081200Z
...DISCUSSION...
RELATIVE RUN-TO-RUN CONSISTENCY AND GOOD AGREEMENT AMONGST THE
MODELS AND ENSEMBLES REVIEWED FOR THIS FORECAST SUGGEST SOMEWHAT
HIGHER-END SEVERE POTENTIAL MAY EVOLVE ACROSS THE MIDWEST/OH VALLEY
REGION ON D4/SATURDAY INTO D5/SUNDAY. THIS SHOULD OCCUR AS ANOTHER
STRONG SHORTWAVE TROUGH PROVIDES A REINFORCING SURGE OF COOLER AIR
ACROSS THE UPPER MIDWEST AND RESULTING LIFT ALONG THE ADVANCING COLD
FRONT ENCOUNTERS WARMING AND MOIST AIRMASS. THE AREA DEPICTED FOR D4
IS THE REGION WHERE ENSEMBLE OUTPUT SUGGESTS THE HIGHER PROBABILITY
OF CONVECTIVE QPF WILL COINCIDE WITH A MEAN MUCAPE AROUND 1000 J PER
KG. THIS WILL ALSO BE THE AREA LIKELY TO EXPERIENCE SOMEWHAT
STRONGER DEEP-LAYER FLOW ON THE EDGE OF THE STRONGER WLYS ALOFT.
THE TRAILING PORTION OF THE COLD FRONT...ESPECIALLY THAT SEGMENT
INTO THE HIGHER TERRAIN OF THE FRONT RANGE AND SRN HIGH PLAINS WILL
ALSO SERVE AS A FOCUS FOR SCATTERED TSTMS. HOWEVER...DEEP-LAYER FLOW
ACROSS THESE AREAS IS MORE MARGINAL TO SUPPORT A RISK AREA AT THIS
TIME.
BEYOND D4...A WIDE DISPARITY IN MODEL SCENARIOS BEGINS TO
EVOLVE...ESPECIALLY WITH EVOLUTION OF GULF OF MEXICO LOW PRESSURE.
GIVEN THE WIDE SPREAD IN THE FORECASTS...UNCERTAINTY IN SEVERE STORM
DEVELOPMENT AND COVERAGE IS HIGH. HOWEVER...LARGER SCALE PATTERN
DEPICTED IN THE 00Z NCEP MREF SOLUTIONS SUGGESTS THAT THE EVOLVING
PATTERN WILL GENERALLY ACT TO SUPPRESS SEVERE WEATHER ACTIVITY GOING
INTO NEXT WEEK.
..CARBIN.. 08/31/2011
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