878
FXUS02 KWBC 011812
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
211 PM EDT SUN JUN 01 2008
VALID 12Z WED JUN 04 2008 - 12Z SUN JUN 08 2008
MODELS AND ENSEMBLES CONTINUE TO FAVOR A MEAN TROUGH OVER THE WRN
STATES THRU THE MEDIUM RANGE PERIOD...ALONG WITH A BUILDING RIDGE
FROM THE LOWER MS VALLEY TO MUCH OF THE EAST. PREFER TO MAINTAIN
CLOSE HPC CONTINUITY FOR OUR FINAL PROGS WITH NO SIGNIFICANT
CHANGES MADE TO PRELIM HPC GUIDANCE.
THE 00/06 UTC RUNS OF THE GFS...THE 00 UTC
ECMWF/CANADIAN/UKMET...AND RESPECTIVE ENSEMBLES WERE LARGELY
SIMILAR WED/THU AND A SOLUTION IN THAT VEIN WAS GENERALLY FOLLOWED
WITH ABOVE NORMAL FORECAST CONFIDENCE OVER NOAM. ONE MAIN FEATURE
IN THIS PATTERN IS A STRONG SENSIBLE WEATHER/FRONTAL SYSTEM
FOCUSING SFC LOW ORGANIZING OVER THE PLAINS THU THAT LIFTS SLOWLY
NNE INTO ONTARIO FRI. PREFER A 50-50 BLEND OF THE 00 UTC GFS AND
ECMWF TO SORT OUT SMALL SCALE DETAILS AND TIMINGS. THE 00/06 UTC
GFS AND THE 00 UTC ECMWF/ECMWF ENSEMBLES ACTUALLY REMAIN IS
REASONABLE AGREEMENT OVERALL INTO FRI AS WELL...BUT FORECAST
CONFIDENCE DROPS A BIT AS MANY LOWER RESOLUTION GFS ENSEMBLE
MEMBERS AND THE UKMET ARE SLOWER TO EJECT PLAINS LOW SUPPORTING
MID-UPPER LEVEL TROF ENERGY.
THEREAFTER WITHIN THE OVERALL ENVELOPE OF SOLUTIONS...PREFER A
SOLUTION DERIVED BY BLENDING THE 00 UTC ECMWF WITH 30% OF
REASONABLY SIMILR 00 UTC ECMWF ENSEMBLE MEAN GUIDANCE TO ACT AS A
SMOOTHER OF LESS PREDICTABLE SMALLER SCALE FORECAST COMPONENTS
OVER THE PAC/NOAM. MODEL AND ENSEMBLE DIFFERENCES BECOME
INCREASINGLY PROFOUND FROM THE PAC/AK INTO THE LOWER 48 FRI-SUN.
THIS EVENTUALLY LEADS TO A MAIN 00/06 UTC GFS MID-UPPER LEVEL TROF
POSITION OVER THE W-CENTRAL US NEXT WEEKEND COMPARED TO AN ECMWF
AND PREDOMINANT ENSEMBLE SOLUTION ALONG THE WEST COAST THAT ALLOWS
POTENTIAL FOR STRONGER RIDGING DOWNSTREAM OVER THE E-CENTRAL US.
FORECAST UNCERTAINTY INCREASES BUT THE HIGHER RESOLUTION ECMWF AND
ECMWF ENSEMBLES ALSO HAVE A SEEMINGLY BETTER/DEEPER DEPICTION OF
CURRENT WRN PACIFIC TYPHOON NAKRI OVER TIME WHOSE WELL DEVELOPED
EXTRATROPICAL TRACK NEWD TO THE N-CENTRAL PACIFIC INTO NEXT
WEEKEND SEEMS TO BE A POSITIVE CONTRIBUTING FACTOR ALONG WITH NRN
STREAM UNCERTAINTIES TOWARD DOWNSTREAM DIFFERNCES OVER THE ERN PAC
AND ACROSS THE LOWER 48 AND VICINITY.
HEDGE/SCHICHTEL
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