Experimental Day 4-8 Severe Thunderstorm Outlook Issued on Aug 20, 2006
Updated: Sun Aug 20 08:50:03 UTC 2006
Comment Period: Oct 3, 2005 - July 28, 2006.
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Increased variability in model forecasts with time and the
inability of the medium range models to resolve mesoscale features
results in greater uncertainty forecasting severe storms in the
Day 4-8 period.
SPC forecasters examine various deterministic and ensemble model
looking for synoptic patterns that favor at least a 25% or higher
probability for severe thunderstorms, before a severe weather area
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0347 AM CDT SUN AUG 20 2006
VALID 231200Z - 281200Z
INCREASING MID-HIGH LEVEL FLOW ACROSS THE NRN U.S. WILL ENHANCE THE
LIKELIHOOD FOR MULTIPLE ORGANIZED CONVECTIVE EVENTS LATER IN THE
WEEK. MODELS ARE SIMILAR DAY4 EJECTING A SIGNIFICANT SHORTWAVE
ACROSS THE NRN/CNTRL PLAINS TOWARD THE GREAT LAKES DAYS 5-6...WITH
YET ANOTHER PROBABLE TROUGH INTO THE PLAINS DAY6. SUFFICIENT
MOISTURE/INSTABILITY SHOULD EXIST AHEAD OF THESE NOTABLE FEATURES
FOR CONFIDENCE IN THE POTENTIAL FOR SEVERE THUNDERSTORMS.
HOWEVER...MODEL DIVERGENCE BEYOND DAY6 WILL PREVENT A SEVERE OUTLOOK
IN LATER PERIODS.