073
FXUS02 KWBC 031848
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
248 PM EDT SAT OCT 03 2009
VALID 12Z TUE OCT 06 2009 - 12Z SAT OCT 10 2009
THE MODELS AND ENSEMBLES OFFER SOMEWHAT BETTER LARGER SCALE MEDIUM
RANGE AGREEMENT OVERALL IN SHOWING AN AMPLIFYING RIDGE EXTENDING
ALOFT FROM THE NERN PAC TO ERN AK AND WRN CANADA DAYS 4-7. THIS
SUPPORTS CARVING OF A COOLING MEAN MID-UPPER LEVEL NRN STREAM
TROUGH DOWNSTREAM OVER W-CENTRAL NOAM. THIS AMPLIFYING NRN STREAM
INCREASINGLY DOMINATES LOWER 48 FLOW AS EMBEDDED SYSTEMS DIG INTO
THE W-CENTRAL US AND INTERACT WITH A LEAD MIDWEEK SW US CLOSED
LOW...WITH THE BULK OF FLOW ENERGIES SUBSEQUENTLY EJECTING OUT
WITH TIME IN VARIED WAYS FROM THE N-CENTRAL TO NERN US OVER SERN
US RIDGING.
EMBEDDED SYSTEM PROBLEMS START FROM THE GET-GO ACROSS THE NORTHERN
PLAINS/GREAT LAKES...WITH THE 00Z GFS OUTPACING THE REMAINDER OF
THE GUIDANCE WITH THE CYCLONE CROSSING THAT REGION. 00 UTC
MULTI-MODEL ENSEMBLE SUPPORT AND CONTINUITY SEEM TO BEST FAVOR THE
DETAILS OF THE 00Z ECMWF SOLUTION INTO WED/THU...BUT PREFER TO
SMOOTH-IN ABOUT 30% ENSEMBLE GUIDANCE FOR THE ROUGH EDGES.
THEREAFTER INTO NEXT WEEKEND...MODELS SHOW MORE DISAGREEMENT
CONCERNING THE EXTENT OF THE TROUGHING ACROSS THE SOUTHWEST AND
HOW STRONG ENERGY WILL BE CROSSING THROUGH SOUTHERN CANADA. TO
ACCOUNT FOR THE UNCERTAINTY...SWITCHED THE MODEL PREFERENCE
INCREASINGLY TOWARD THE 00 UTC ECMWF ENSEMBLE MEAN AS THE 00Z
ECMWF DEPARTS FROM THE CONSENSUS. THIS SOLUTION KEEPS GOOD HPC
CONTINUITY AND BRINGS MORE ROBUST HEIGHT FALLS AND COOLING
SOUTHWARD INTO THE W-CENTRAL US THAN THE 00 UTC ECMWF...BUT NOT AS
MUCH AS THE 12 UTC GFS. THE NEW 12 UTC ECMWF HAS TRENDED TOWARD
THIS TYPE OF SOLUTION.
ROTH/SCHICHTEL
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