Prognostic Meteorological Discussion
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FXAK02 KWNH 271909
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
308 PM EDT FRI MAR 27 2015

VALID 12Z TUE MAR 31 2015 - 12Z SAT APR 04 2015

...GUIDANCE/UNCERTAINTY/CONTINUITY ASSESSMENT...

THE WPC ALASKAN MEDIUM RANGE SURFACE FRONTS/PRESSURES AND 500 MB
PROGS ALONG WITH ASSOCIATED HPCGUIDE HIGH RESOLUTION SENSIBLE
WEATHER GRIDS HAVE BEEN PRIMARILY DERIVED FROM A BLEND OF THE 00
UTC GFS/ECMWF TUESDAY/WEDNESDAY...LEANING MORE ON THE 00 UTC
ECMWF. FORECAST SPREAD AND EMBEDDED SYSTEM UNCERTAINTY GROWS
RAPIDLY THEREAFTER...EVEN MORE THAN YESTERDAY...IN A PATTERN WITH
BELOW NORMAL PREDICTABILITY OVERALL. THIS LEADS TO PREFERENCE FOR
A MAIN EMPHASIS ON THE 00 UTC ECMWF ENSEMBLE MEAN DAYS 6-8
THU-NEXT SAT THAT HAS SLIGHTLY BETTER CONTINUITY THAN OTHER
ENSEMBLE SYSTEMS. EVEN SO...CONTINUITY WAS NOT OPTIMAL THROUGH
THESE LONGER TIME FRAMES...BUT ESPECIALLY ACROSS THE NERN
PACIFIC/GULF OF ALASKA WITH GUIDANCE TRENDED NORTHWARD WITH THE
TRACK OF THE MAIN SURFACE LOW.

...COORDINATION AND SOME SENSIBLE WEATHER HIGHLIGHTS...

THIS OVERALL WPC SOLUTION WAS AGAIN DETERMINED FROM PATTERN
CONSIDERATION AND AS PER COLLABORATION WITH THE LOCAL NATIONAL
WEATHER SERVICE EXPERTS FROM THE FAIRBANKS...ANCHORAGE...AND
JUNEAU WFO OFFICES. FAIRBANKS CONTINUES TO OFFER SUPPORT FOR
MID-UPPER LEVEL TROUGH AMPLITUDE ON THE STRONGER SIDE OF THE FULL
ENVELOPE OF SOLUTIONS OVER NWRN/NRN ALASKA INTO MID-LATE NEXT
WEEK. THIS ALLOWS SOME LOCAL COOLING/SNOW. ANCHORAGE SUGGESTED
PREFERENCE FOR THE 00 UTC ECMWF...EVEN WITH SOME NORTHWARD
CONTINUITY TREND FROM YESTERDAYS GUIDANCE OVER THE GULF OF AK.
CONSIDERING LATEST TRENDS...ORGANIZED LOW DEVELOPMENT OVER THIS
PERIOD NOW OFFERS SOMEHWAT MORE PCPN POTENTIAL OVER THE ALEUTIANS
AND FROM SRN TO ESPECIALLY SERN ALASKA WITH CLOSER OFFSHORE LOW
PROXIMITY POTENTIAL. JUNEAU AGREED NUDGING THE FORECAST TOWARD
THAT THOUGHT PROCESS/SCENARIO FOR THEIR FORECAST AREA OF
RESPONSIBILITY. THE WPC DAY 8 SOLUTION NOW DOES HAVE SUPRISINGLY
CLOSE SUPPORT FROM THE LATEST 12 UTC ECMWF DETERMINISTIC MODEL
RUN.

SCHICHTEL

$$




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