488
FXUS02 KWBC 151718
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
117 PM EDT SUN JUN 15 2008
VALID 12Z WED JUN 18 2008 - 12Z SUN JUN 22 2008
THE MEDIUM RANGE WEATHER FORECAST REMAIN HIGHLIGHTED BY AN
UNSEASONABLY AMPLIFIED MID-LATITUDE LONGWAVE FLOW PATTERN FROM THE
ERN PAC THRU NOAM WITH BLOCKY FLOW AT HIGHER LATITUDES FROM NOAM
THRU THE N ATLANTIC. IN THIS PATTERN...A COOL AND UNSETTLING
MID-UPPER LEVEL TROF REMAINS ESTABLISHED ACROSS THE ERN US WHILE
LOWERING HEIGHTS ALOFT LEADS TO PRONOUNCED TROFFING ALONG/OFFSHORE
THE WEST COAST. IN BETWEEN...A BUILDING RIDGE AND MORE SUMMERTIME
TEMPS BUILD FROM THE SOUTHWEST THRU CENTRAL US DURING THE UPCOMING
WEEK.
THE MODELS AND ENSEMBLES ARE IN EXCELLENT AGREEMENT WITH THE
OVERALL SYNOPTIC PATTERN SO FORECAST CONFIDENCE IS ABOVE
NORMAL...ALBEIT EVEN WITH MORE SMALLER SCALE DIFFERENCES.
THERE SEEM TO BE MINIMAL BIG GUIDANCE DIFFERENCE ISSUES WED INTO
FRI...BUT RECENT GFS RUNS OVERALL LOOK SLIGHTLY TOO PROGRESSIVE
WITH THE ENERGY MOVING THROUGH NRN NEW ENGLAND COMPARED TO OTHER
GUIDANCE AND CONSIDERING DOWNSTREAM BLOCKING. HOWEVER...THERE IS
MUCH BETTER AGREEMENT AND CONTINUITY THAN RECENTLY.
MORE NOTICEABLE DIFFERENCES LIE ACROSS THE NORTHEAST PAC INTO THE
PAC NW...WHERE THE 00Z ECMWF BECOMES FLATTER WITH THE FLOW THAN
THE REMAINDER OF THE GUIDANCE HEADING INTO/THRU NEXT
WEEKEND...INCLUDING THE ECMWF AND NCEP ENSEMBLE MEANS. THE 00Z
GFS ON THE OTHER HAND MAY OFFER TOO AMPLIFIED OF AN OFFSHORE LOW
AMID UNCERTAINTY CONSIDERING TRENDS FROM ITS 06 AND 12 UTC
RUNS...BUT THE 00Z RUN IS IT AT LEAST SHOWING DEVELOPMENT IN THE
MEAN MID-UPPER LEVEL TROF POSITION AS PER ENSEMBLE MEANS.
OVERALL...PREFER TO MAINTAIN CONTINUITY AND MAKE MINIMAL CHANGES
TO PRELIM HPC GUIDANCE WITH THE FINAL PROGS. CONSIDERING THE
ABOVE...A SOLUTION CLOSEST TO THE 00Z ECMWF FOR DETAILS THRU FRI
REMAINS SLIGHTLY PREFERRED...BUT THE 00Z GFS GUIDANCE IS FAIRLY
CLOSE TO THAT TOO AND ENSEMBLES ARE PRETTY COMPATIBLE. GUIDANCE
DIFFERENCES CREEP IN MORE BY NEXT WEEKEND THOUGH SO USED A 50-50
BLEND OF NEARLY IDENTICAL 00Z GFS/ECMWF ENSEMBLE MEANS...BUT MADE
A FEW MANUAL ADJUSTEMENTS TO THE HPC PRESSURE PROGS TO MAINTAIN A
BIT MORE DETAIL.
ROTH/SCHICHTEL
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