Prognostic Meteorological Discussion
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FXAK02 KWNH 261851
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ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
251 PM EDT THU MAY 26 2016

VALID 12Z MON MAY 30 2016 - 12Z FRI JUN 03 2016

WITHIN A COMPLEX/BLOCKY PATTERN FROM THE NRN PACIFIC NWD... THE
LARGEST SCALE AGREEMENT APPEARS TO BE WITH THE IDEA THAT SOME
PROPORTION OF UPR LOW ENERGY NEAR THE WRN ALEUTIANS AND/OR FLOW TO
THE SW OF THE UPR LOW WILL GET PULLED EWD/SEWD AND EVENTUALLY
INTERACT WITH AN INITIAL ERN PAC TROUGH/UPR LOW.  BY THE END OF
THE FCST PERIOD LATE NEXT WEEK THE ENSEMBLE MEANS ARE SIMILAR IN
DEPICTING AN UPR LOW AROUND 155W LONGITUDE AT 45-50N LATITUDE.  OF
COURSE LATEST AND RECENT OPERATIONAL MODEL RUNS VARY SIGNIFICANTLY
WITH SOME OF THE DETAILS.

FROM THE MAINLAND WWD SIGNIFICANT DIFFS EMERGE FAIRLY QUICKLY
REGARDING THE STRENGTH AND WWD PROGRESSION OF THE STRONG UPR HIGH
FCST TO BE NEAR THE NWRN MAINLAND AS OF EARLY MON.  THE 00Z
ECMWF/ECMWF MEAN ARE QUICKEST TO PULL THE RIDGE WWD WHILE IN
VARYING WAYS GFS/GEFS RUNS THROUGH THE 06Z CYCLE HAVE KEPT MUCH
HIGHER HGTS OVER THE MAINLAND.  THE 00Z CMC/CMC MEAN OFFER AN
INTERMEDIATE SCENARIO.  EVOLUTION OF THIS RIDGE WILL LIKELY HAVE
SOME EFFECT ON EXACT LATITUDE OF THE UPR LOW TO THE S OF THE
ALASKA PENINSULA... AS SUGGESTED BY THE 00Z ECMWF MEAN ALLOWING
THE FEATURE TO BE FARTHER NWD AS ALLOWED BY A FARTHER WWD UPR HIGH
POSN.  WHILE OPERATIONAL MODEL RUNS OVER THE PAST 1-2 DAYS HAVE
DIFFERED GREATLY THE MEANS HAVE BEEN MUCH MORE STABLE THOUGH WITH
ECMWF MEANS CONSISTENTLY WEAKER/WWD WITH THE UPR HIGH VERSUS GEFS
MEANS.  LONGER TERM TRENDS SEEM TO FAVOR A SOLN BTWN THE TWO
EXTREMES AND 12Z GFS ADJUSTMENTS ALSO RECOMMEND SUCH AN APPROACH.
AROUND THE NRN/NERN PERIPHERY OF THE UPR HIGH THERE IS A MAJORITY
CLUSTER WITH A SHRTWV THAT WILL HELP TO PUSH A SFC FRONT INTO THE
NRN/ERN MAINLAND MID-LATE WEEK.

BASED ON OPERATIONAL MODEL SPREAD THE 00Z NAEFS/ECMWF MEANS SERVED
AS THE MAJORITY FOUNDATION FOR THE EXTENDED FORECAST.  SOME 00Z
GFS/ECMWF INPUT WAS INCLUDED FOR ADDED DETAIL NEAR THE ALEUTIANS
ON DAY 4 MON.  A LITTLE 00Z GFS COULD BE MAINTAINED INTO DAY 6 WED
BUT THE 00Z ECMWF HAD TO BE EXCLUDED AFTER MON DUE TO A WAVE
TRACKING NEAR KODIAK ISLAND WITH FAIRLY LOW MODEL/ENSEMBLE SUPPORT
FOR SUCH A NWD TRACK.

RAUSCH

$$





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