Prognostic Meteorological Discussion
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FXAK02 KWNH 301811
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
210 PM EDT WED JUL 30 2014

VALID 12Z SUN AUG 03 2014 - 12Z THU AUG 07 2014

THE 30/00Z GEFS/ECENS MEANS MAINTAIN A SUBSTANTIAL RIDGE AXIS
ALONG THE WEST COAST OF NORTH AMERICA---AND A DEEP TROUGH AND
CUTOFF 500 MILLIBAR LOW IN THE GULF OF ALASKA THIS MEDIUM RANGE
PERIOD. A QUICK LOOK AT THE 30/12Z GFS DETERMINISTIC RUN INDICATES
A SLIGHTLY FASTER EASTWARD PROGRESSION OF THE MID-LEVEL FEATURE
INTO THE NORTHERN PANHANDLE (DAYS 7-8) THAN IS CURRENTLY DEPICTED
BY THE MOST RECENT WPC 500MB GRAPHICS. HOWEVER...THERE WAS
BASICALLY NO CHANGE NOTED THROUGH DAY 6...AND THE SURFACE PATTERN
DOES NOT DRASTICALLY CHANGE ITS TUNE FROM THE WPC FORECAST EVEN
BEYOND DAY 6.

OF NOTE--THE 30/00Z DETERMINISTIC ECMWF WAS A VERY STRONG SOLUTION
IN THE GULF OF ALASKA AT THE SURFACE AND ITS 996MB LOW WAS
SIGNIFICANTLY DEEPER THAN ITS ENSEMBLE MEAN HEADING INTO DAY 5. AT
TIME OF THIS WRITING...THE 30/12Z ECMWF WAS NOT AVAILABLE FOR
COMPARISON.

WITH MORE DIFFERENCES AT THE SURFACE THAN ALOFT...THOUGHT THE BEST
WAY TO HANDLE THE DAY 6-8 FORECAST WAS TO BLEND THE 30/00Z MEANS
AT A 60/40 CLIP (ECENS/GEFS RESPECTIVELY) TO ALLOW A SLIGHTLY
FASTER PROGRESSION OF THE 500MB PATTERN BUT TEMPER THE SURFACE
REFLECTION EMERGING BENEATH IT.

VOJTESAK




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