Prognostic Meteorological Discussion
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FXAK02 KWNH 221924
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ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
323 PM EDT FRI AUG 22 2014

VALID 12Z TUE AUG 26 2014 - 12Z SAT AUG 30 2014

THE UPPER PATTERN OVER ALASKA DURING THE MEDIUM RANGE REMAINS HARD
TO SORT OUT AS THE EVOLUTION IS VERY SENSITIVE TO SMALL SCALE
DETAILS IN THE SHORT RANGE WELL WEST/NORTHWEST OF THE REGION...
THUS LEADING TO POOR RUN-TO-RUN MODEL AND EVEN ENSEMBLE
CONTINUITY. ONE PIECE OF THE ATMOSPHERIC PUZZLE LIES OVER
KAMCHATKA SAT AND IT APPEARS THAT THE TREND HAS BEEN TO TAKE THE
BULK OF THIS FORMING UPPER LOW TOWARD THE SOUTHWEST... WHICH OPENS
UP THE FLOODGATES OF THE NORTHERN STREAM AND ALLOWS ENERGY TO DIVE
SOUTHEASTWARD THROUGH THE BERING SEA RATHER THAN GETTING TUGGED
BACK FARTHER WEST BY THE LEAD UPPER LOW. NET RESULT IS FOR A MORE
SUPPRESSED SOUTHERN SYSTEM THAT SHOULD TRAVEL ACROSS THE EASTERN
ALEUTIANS AND INTO THE SOUTHERN GULF RATHER THAN LIFTING
NORTHEASTWARD TOWARD THE BERING STRAIT. THE 12Z GFS CAME AROUND TO
THE 00Z ECMWF/CANADIAN IDEA WHICH FITS NEAR THE 00Z EC ENSEMBLE
MEAN. DESPITE THE CHANGES FROM 24 HRS AGO... HARD TO IGNORE THE
RELATIVELY GOOD BUT BROAD CLUSTERING. 12Z GEFS MEAN SHOWED A LARGE
CHANGE TOWARD THE 12Z GFS IDEA/PROGRESSION AND THE 12Z ECMWF
STAYED WITH THIS THINKING AS WELL.

PRECIPITATION WILL FOCUS OVER THE PANHANDLE INITIALLY AS THE FIRST
SYSTEM PASSES INTO CANADA. ATTENTION WILL THEN SHIFT INTO NW
ALASKA AND ACROSS THE ALEUTIANS AS THE TRAILING SOUTHERN/NORTHERN
STREAM SYSTEMS PUSH EAST/SOUTHEAST. NW AREAS BETWEEN
BETTLES/KOTZEBUE/BROOKS RANGE MAY BE IN A CONFLUENCE ZONE FOR
ENHANCED PRECIP... BUT THIS IS CONTINGENT ON THE CURRENT FRONTAL
TIMING WHICH IS HARDLY SET IN STONE. NEVERTHELESS... THE STRENGTH
OF EACH SYSTEM WILL LIKELY YIELD AT LEAST SOME MODEST RAINS TO
WESTERN ALASKA LATE NEXT WEEK.



FRACASSO

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