Prognostic Meteorological Discussion
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FXAK02 KWNH 191954
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
353 PM EDT TUE SEP 19 2017

VALID 12Z SAT SEP 23 2017 - 12Z WED SEP 27 2017

THE BULK OF THE UPCOMING FORECAST CENTERS AROUND A LARGE CLOSED
LOW OR DOUBLE BARREL LOW OVER THE STATE, WHICH GRADUALLY BECOMES
ONE AND SHIFTS FROM THE SERN BERING SEA TO THE GULF OF AK. THIS
SHOULD RETURN THE MOIST AND WET ONSHORE FLOW INTO THE SOUTHERN
PORTION OF THE STATE AND PANHANDLE. DESPITE SOME SLIGHT DETAIL
DIFFERENCES EARLY ON, LIKE THE PRESSURE DIFFERENCE ON GULF OF AK
SURFACE LOW, IT APPEARS THE OPERATIONAL GFS AND ECMWF HAVE THE
LARGE SCALE PATTERN INTACT. WPC USED A FAIR PERCENTAGE OF THE
OPERATIONAL GFS/ECMWF ON D4-5/WEEKEND BUT BY D6-8/MON-WED THE
MEANS APPEARED TO BE A BETTER ROUTE TO GO, REDUCE THE SMALL SCALE
FEATURES AND CAPTURE THE LARGE SCALE REGIME. OTHER HIGHLIGHTS
DURING THE PERIOD INCLUDE, A CENTRAL PAC SHORT WAVE WHICH ARRIVES
INTO THE NERN PAC/GULF OF AK LATE IN THE PERIOD AND A SET OF
HEIGHT FALLS THAT CLIP THE NORTHERN PART OF THE STATE WITH A
PROGRESSIVE FRONTAL ZONE LATE IN THE PERIOD.


MUSHER


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