635
FXUS02 KWBC 201843
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
142 PM EST FRI NOV 20 2009
VALID 12Z MON NOV 23 2009 - 12Z FRI NOV 27 2009
USED THE 12Z/19 ECMWF AND EC ENSEMBLE MEAN TO CONSTRUCT THE
PRELIMINARY FRONTS AND PRESSURES FOR DAYS 3 THROUGH 7. THE ECWMF
LEAD THE WAY AMONG THE GLOBAL MODELS LAST WEEK PREDICTING THE
PATTERN CURRENTLY IN PLACE OVER THE NATION. THE MODEL HAS BEEN
FAIRLY CONSISTENT OVER THE PAST THREE CYCLES FOR THE UPCOMING
MEDIUM RANGE PERIOD...WITH THE 12Z/19 DETERMINISTIC RUN MORE
SQUARELY IN THE MIDDLE OF THE MOST RECENT MEAN THAN THE 00Z/20
VERSION. THE GFS...GEM GLOBAL...AND UKMET ARE DISPARATE ENOUGH ON
DAY 3 TO CAST DOUBT ON THEIR SOLUTIONS THEREAFTER.
UPDATED MORNING PRELIMS INCORPORATE MORE OF THE 00Z ECMWF ENS MEAN
INCREASING DAILY AFTER DAY 4 THRU THE PERIOD.
12Z GUIDANCE OF GFS REMAINS REASONABLY SIMILAR WITH THE BASIC
PATTERN OF THE PLAINS CLOSED LOW LIFTING NEWD INTO THE GREAT LAKES
REGION DAY 4 TUES WITH ANOTHER SHORTWAVE DROPPING SEWD INTO THE
MEAN PLAINS/MS VALLEY TROF TUES INTO WED WHILE UPSTREAM RIDGING
BUILDS OVER THE ROCKIES. 12Z GFS OFFRS A PHASING SOLUTION
DEVELOPING A STRONG NEG TILT CLOSED LOW OVER THE ERN GREAT
LAKES/NEW ENG REGION DAY 7 FRI AND WHILE PHASING SOLUTIONS ARE
SUSPECT AT THIS TIME RANGE THE OVERALL PATTERN REMAINS VERY
SIMILAR TO THE PRIOR ENS MEANS OF BOTH GFS AND ECMWF BY LATE NEXT
WEEK. 12Z CMC/ECMWF AND UKMET EARLY ON DIG THE LEE OF THE ROCKIES
SHORTWAVE FARTHER WEST THAN ANY SOLUTION RESULTING IN A FRONT
RANGE/CO PLAINS SNOWSTORM ON DAY 3. THIS IS A PREFERED TREND BY
HPC MEDIUM RANGE AND MODEL DIAG AND REMAINS A MATCH TO EARLIER
PROGS FROM HPC THAN UTILIZED THE 00Z ECMWF FOR DAY 3.
CISCO/ROSENSTEIN
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