Prognostic Meteorological Discussion
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FXAK02 KWNH 301916
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
316 PM EDT SUN AUG 30 2015

VALID 12Z THU SEP 03 2015 - 12Z MON SEP 07 2015

CONTINUED WITH A NORTHERN STREAM DOMINANT FLOW PATTERN FOR ALASKA
IN THE MEDIUM RANGE FORECAST PERIOD. THIS WAS BEST REPRESENTED BY
THE 30/00Z ECENS/ECMWF THROUGH THE DAY 6 TIME FRAME. AFTER DAY
6...WENT WITH A ECENS MEAN APPROACH ACROSS THE ENTIRE NORTH
PACIFIC BASIN.

THE UPPER-LEVEL TROUGH MIGRATION FROM ITS CURRENT
POSITION/LOCATION NEAR 170E LONGITUDE WILL GRADUALLY SHIFT
EASTWARD...ACROSS THE DATELINE AND FLATTEN THE UPPER-LEVEL RIDGE
IN THE CENTRAL PACIFIC AND EAST CENTRAL PACIFIC. THOUGHTS ARE THAT
THE GEFS IS A BIT QUICKER WITH THE ENTIRE PROCESS...AND BETWEEN
DAY 4-6...APPEARS TO USE SOME ENERGY EMBEDDED IN THE SUBTROPICS TO
ACCOMPLISH THIS TASK. WITH THE `BLOCKY` PATTERN ALONG THE DATELINE
LIKELY TO REMAIN IN PLACE UNTIL DAY 5-6...AND MORE OF A NORTHERN
STREAM INFLUENCE ASSISTING IN THE `FLATTENING` PROCESS...THERE IS
LESS LIKELIHOOD THAT THE GEFS APPROACH WILL VERIFY BY DAY
8---USING SUBTROPICAL ENERGY TRANSFER.

THE GRID FILES---FOR 12-HR PCPN ONLY--- WERE CORRUPT TODAY (ALL
TIMES PRIOR TO 6/12Z). ALL OTHER BLENDED GRID FILES WERE FINE.
POPULATED WITH ECMWF MODEL DATA---BUT BEWARE---NOT SURE OF THEIR
RELIABILITY.

VOJTESAK






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