Prognostic Meteorological Discussion
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FXAK02 KWNH 051852
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
251 PM EDT THU MAY 05 2016

VALID 12Z MON MAY 09 2016 - 12Z FRI MAY 13 2016

LATEST GUIDANCE SHOWS BETTER THAN AVERAGE AGREEMENT IN ADVERTISING
THE BUILDING AND THEN MAINTENANCE OF A STRONG MEAN RIDGE ORIENTED
CLOSE TO 140W LONGITUDE WHILE A MEAN LOW SFC/ALOFT SETTLES OVER
THE BERING SEA.  THE PRIMARY UNCERTAINTIES IN THIS OVERALL PATTERN
INVOLVE THE TRACK OF THE BERING LOW ALONG WITH DETAILS OF ENERGY
FLOWING AROUND THE PERIPHERY OF THE LOW... AND THEN TOWARD THE END
OF THE PERIOD UPSTREAM ENERGY THAT COULD BEGIN TO DISPLACE THE
BERING LOW.

BASED ON THE LATEST ARRAY OF GUIDANCE AND COORDINATION WITH WFO
AFC... TODAY`S FCST BLEND LEANS MORE IN THE OVERALL DIRECTION OF
THE 12Z GFS/06Z GEFS MEAN/00Z CMC RELATIVE TO THE 00Z ECMWF/ECMWF
MEAN.  THE PRIMARY CONSIDERATION FOR THIS PREFERENCE IS FOR THE
BERING SEA LOW AS THERE IS NOT YET A CONVINCING CASE FROM THE
MAJORITY OF MODELS/ENSEMBLE MEMBERS FOR A TRACK AS FAR NWWD AS THE
00Z ECMWF.  ALSO THE 00Z ECMWF MEAN ADJUSTED SOMEWHAT NWD FROM ITS
PRIOR RUNS AT SOME FCST HRS.

BY MID-LATE PERIOD RECENT OPERATIONAL RUNS HAVE BEEN INCONSISTENT
WITH HOW ENERGY FLOWING AROUND THE WRN-SRN-ERN PERIPHERY OF THE
MEAN UPR LOW WILL AFFECT SYSTEM EVOLUTION... POTENTIALLY PULLING
THE AREA OF MEAN LOW PRES AT LEAST AS FAR S/SE AS THE ALEUTIANS.
AT THE SAME TIME THERE ARE INDICATIONS THAT FLOW EMERGING FROM ERN
ASIA COULD BE PROGRESSIVE ENOUGH TO BEGIN DISLODGING THE BERING
SEA UPR LOW BY LATE NEXT WEEK THOUGH THE DOWNSTREAM MEAN RIDGE
WOULD BE MAINTAINED.  PREFER LEANING MORE TOWARD THE MORE STABLE
ENSEMBLE MEANS LATE NEXT WEEK BUT STILL WITH MODEST OPERATIONAL
INPUT THAT PROVIDES SOME HINT OF A TRAILING WAVE/FRONTAL SYSTEM
NEARING THE ALASKA PENINSULA DAY 8 FRI AFTER THE DISSIPATION OF
THE FRONTAL SYSTEM INITIALLY ASSOC WITH THE PRIMARY BERING LOW.
ALSO OF NOTE THE FAVORED BLEND HOLDS ONTO MORE NERN PAC AND
PANHANDLE/SRN COAST RIDGING SFC-ALOFT... THUS TRIMMING EWD EXTENT
OF MOISTURE... VS THE 00Z GFS LATE IN THE PERIOD.

RAUSCH

$$





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