775
FXUS02 KWBC 311806
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
205 PM EDT FRI JUL 31 2009
VALID 12Z MON AUG 03 2009 - 12Z FRI AUG 07 2009
LIMITED CONSENSUS AMONG THE 00Z/31 MODELS FOR THE MEDIUM RANGE
PERIOD. EARLY PRELIMS USED AN EVEN BLEND OF THE 00Z/31 GFS AND
THE 00Z/30 EC ENSEMBLE MEAN DAYS 3 THROUGH 7. THIS GUIDANCE KEEPS
THE VORTEX OVER THE EASTERN PACIFIC NOT TOO FAR OFF THE NORTHWEST
COAST...WITH A TROUGH OF MODERATE AMPLITUDE OVER THE EASTERN TWO
THIRDS OF NORTH AMERICA. THE 00Z/31 ECMWF HAS POOR CONTINUITY
WITH ITS 12Z/30 RUN...AND IS AN OUTLIER WITH HOW FAR OFF THE WEST
COAST IT RETROGRADES THE BIG VORTEX. THE GEM GLOBAL AND UKMET
BEAR LITTLE RESEMBLANCE TO ANY OF THE OTHER GUIDANCE.
UPDATED MORNING PRELIMS HAVE USE OF 06Z GFS/LAGGED AVERAGE
FORECASTS AND 00Z ECMWF ENS MEANS.
A COMBINATION OF LAGGED AVERAGE FORECAST OF THE LAST 4 CYCLES OF
GFS AND ECMWF AND AN 8 MEMBER COMBINED GFS/ECMWF LAGGED AVERAGE
GIVES A PREFERED SOLUTION SETTLING DOWN INCONSISTENT INDIVIDUAL
RUNS. THIS IS CLOSEST TO THE 00Z ECMWF ENS MEAN AND WAS USED TO A
LARGE DEGREE FOR THE MORNING PRELIM UPDATE.
NO CHANGES TO AFTN FINALS FROM PRIOR MORNING PRELIMS.
CISCO/ROSENSTEIN
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