508
FXUS02 KWBC 251818
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
218 PM EDT SUN OCT 25 2009
VALID 12Z WED OCT 28 2009 - 12Z SUN NOV 01 2009
MODEL AND ENSEMBLE MEMBER SOLUTION SPREAD AND RUN TO RUN
CONTINUITY CONCERNS OVER MUCH OF THE PAC AND NOAM FOR SHORT AND
MEDIUM RANGE TIME SCALES SUGGEST HIGH FORECAST UNCERTAINTY.
ACCORDINGLY PREFER TO MAINTAIN CLOSE HPC CONTINUITY FROM HPC
UPDATED PRELIM TO FINAL PROGS INSTEAD OF CHASING NEWER BUT STILL
QUITE VARIED 12 UTC GUIDANCE.
SHORT TERM DIFFERENCES TUE/WED LEADING INTO THE MEDIUM RANGE
FORECAST SEEM MOST EVIDENT WITH LIFTING SYSTEM ENERGY TOWARD THE
NERN US WHERE INCREASINGLY COMMON SOLUTIONS FROM THE MOST RECENT
ECMWF GFS RUNS MAY BEST BE TEMPERED SOMEWHAT BY AMBIENT SURFACE
HIGH PRESSURE...BUT NOT TO THE SOUTHWARD SUPPRESSED EXTENT SAY OF
THE 00 UTC CANADIAN CONSIDERING SUPPORTING FLOW ALOFT. GUIDANCE
IS MEANWHILE IN MUCH BETTER AGREEMENT INTO MIDWEEK WITH WRN US
MID-UPPER LEVEL TROF DEVELOPMENT...WITH THE 06 UTC GFS TRENDING
MORE IN LINE WITH THE BULK OF MORE AMPLIFIED/WWD DUG SYSTEM
SOLUTIONS VERSUS THE 00 UTC GFS. HOWEVER...FASTLY GROWING
DIFFERENCES BY THU WITH LEAD SURFACE CYCLOGENESIS ACROSS THE
PLAINS AND ESPECIALLY IN ERNEST WITH ALL SYSTEMS AND KICKER
POTENTIAL FURTHER UPSTREAM ACROSS THE NERN PAC QUICKLY LEAD TO A
WIDE ENVELOPE OF SUBSEQUENT SOLUTIONS THEREAFTER.
ACCORDINGLY...PREFER TO QUICKLY TRANSITION TO A BLEND OF GFS/ECMWF
ENSEMBLE MEAN SOLUTIONS FRI THROUGH NEXT WEEKEND AMID HIGH
UNCERTAINTY AS A VARIED MESS OF PAC SYSTEM ENERGIES PROGRESS INTO
AND INTERACT WITH THE LEAD AND AMPLIFIED FLOW PATTERN INLAND
ACROSS THE LOWER 48...EVENTUALLY LEADING TO A TRANSITION TO LESS
AMPLIFIED FLOW OVER TIME.
SCHICHTEL
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