481
FXUS02 KWBC 181804
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
203 PM EDT SUN OCT 18 2009
VALID 12Z WED OCT 21 2009 - 12Z SUN OCT 25 2009
LATEST MODEL AND ENSEMBLE GUIDANCE CONTINUES TO AGREE UPON THE
IDEA OF PROGRESSIVE PACIFIC FLOW BRINGING A SERIES OF SHRTWVS INTO
THE CONTIGUOUS UNITED STATES TO RELOAD AN EAST-CENTRAL UNITED
STATES MEAN TROUGH DURING THE MEDIUM RANGE PERIOD.
TELECONNECTIONS WITH A SLIGHTLY RETROGRESSIVE NEGATIVE ANOMALY
PASSING 45N 165W AGREES WITH THIS SCENARIO AS WELL. THE SYSTEM
EXPECTED TO LEAD THE WAY IN ESTABLISHING THIS LARGE SCALE PATTERN
IS FCST TO TRACK NORTHEAST FROM THE PLAINS INTO THE GREAT LAKES
LATE THIS WEEK. THE 06Z GEFS MEAN AND 00Z ECMWF ENSEMBLE MEAN
BEST SUPPORTS THE 06Z GFS AND 00Z ECMWF. THE 12Z GFS/12Z CANADIAN
OUTPACED THE ENSEMBLE MEAN SOLUTIONS WITH THE TROUGH AND WERE
CONSIDERED QUICK OUTLIERS.
DUE TO HURRICANE RICK AND THE NHC TRACK OF THIS SYSTEM...STARTED
WITH THE 06Z GFS SOLUTION EARLY ON BEFORE COMPROMISE BETWEEN THE
06Z GFS/00Z ECMWF FROM THIS WEEKEND ONWARD...WHICH KEPT GOOD
CONTINUITY AND TAKES CARE OF SOME OF THE DETAIL ISSUES SEEN
BETWEEN THESE PIECES OF GUIDANCE. FOR RICK...THE 12Z CANADIAN
SOLUTION IS A REASONABLE ALTERNATIVE. SOME ADJUSTMENT WAS MADE TO
THIS BLEND PER THE NHC TRACK OF RICK AND THE 00Z MULTI-MODEL
ENSEMBLE LOW POSITIONS. THIS PATTERN SHOULD BE WET FROM THE
PLAINS EASTWARD THROUGH THE MIDWEST AND EASTERN STATES...WITH
LESSER PRECIPITATION ANTICIPATED ACROSS THE PACIFIC NORTHWEST
EASTWARD INTO THE NORTHERN PLAINS NEXT WEEKEND.
ROTH/RAUSCH
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