Prognostic Meteorological Discussion
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FXAK02 KWNH 252028
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
327 PM EST SAT FEB 25 2017

VALID 12Z WED MAR 01 2017 - 12Z SUN MAR 05 2017

THE MAIN FEATURE OF INTEREST REMAINS THE STOUT UPPER RIDGE WHICH
IS FORECAST TO INHABIT THE BERING SEA THROUGHOUT MUCH OF THE
PERIOD. MODELS CONTINUE TO INDICATE RATHER IMPRESSIVE MID-LEVEL
HEIGHT ANOMALIES WITH THIS FEATURE...GENERALLY IN THE 3 TO 4 SIGMA
ABOVE AVERAGE RANGE. IN RESPONSE TO THIS SET UP...MOST SYSTEMS
WILL SWING SOUTHWARD THROUGH MAINLAND AK AND EVENTUALLY END UP IN
THE NORTHEASTERN PACIFIC. THIS WILL ULTIMATELY KEEP MUCH OF THE
STATE DRY AND COOL WHILE ALLOWING FOR WETTER CONDITIONS ACROSS
SOUTHEASTERN SECTIONS OF AK.

WHILE MODELS HAVE COME INTO BETTER AGREEMENT ACROSS THE
AREA...THERE ARE STILL VARIATIONS IN HOW MUCH THE UPPER RIDGE WILL
ERODE AND ITS EVENTUAL POSITION TOWARD THE END OF THE PERIOD.
YESTERDAY WAS A SPLIT IN THE GUIDANCE WITH TWO DEFINED CAMPS
EVIDENT. HOWEVER...NOW IT APPEARS THE GFS IS ON ITS OWN IN
BREAKING DOWN THE NORTHERN EXTENT OF THIS UPPER RIDGE. THIS
RESULTS IN A SIGNIFICANTLY DIFFERENT ORIENTATION OF THE SYNOPTIC
FLOW WHICH LEADS TO LARGE-SCALE DIFFERENCES COMPARED TO THE REST
OF THE GUIDANCE AS SUCH...DID NOT UTILIZE ANY OF THE DETERMINISTIC
GFS AND LEANED MORE HEAVILY ON THE 00Z ECMWF/ECMWF ENSEMBLE MEAN
AS WELL AS THE 00Z CMC THROUGH DAY 5/MARCH 2. THEREAFTER...WENT
WITH A 00Z GEFS/ECMWF ENSEMBLE MEANS WITH THE FORMER INCLUDED AS A
MINORITY SOLUTION IN THE BLEND TO ACCOUNT FOR GENERAL
UNCERTAINTIES.


RUBIN-OSTER


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