ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
248 PM EDT THU JUL 07 2016

VALID 12Z MON JUL 11 2016 - 12Z FRI JUL 15 2016

The 7/00Z ECENS/GEFS MEANS AND THEIR DETERMINISTIC RUNS SEEMED TO
BE IN DECENT AGREEMENT WITH THE 'BLOCKY' PATTERN AND SPLIT-FLOW IN
THE NORTHERN BERING SEA THROUGH THE END OF DAY 5.

DIFFERENCES EMERGE QUICKLY BEYOND DAY 5...MAINLY WITH SECONDARY
ENERGY THAT ATTEMPTS TO 'UNDERCUT' THE RIDGE IN THE SOUTHERN GULF
OF ALASKA AND MIGRATE INTO THE MAINLAND'S PACIFIC NORTHWEST. THE
ECMWF AND UKMET WERE AGGRESSIVE BUT NOT TOTALLY UNBELIEVABLE
HERE...BUT OPTED TO MAINTAIN SOME CONTINUITY WITH ALASKA AND CONUS
MEDIUM RANGE FORECASTS---BY BLENDING THE 7/00Z ECENS/GEFS MEANS.

IN EITHER CASE...A CLOSED 500MB LOW WILL ATTEMPT TO RETROGRADE
WESTWARD FROM ~52N 130W-135W ON DAY 5-6---TO A POSITION CLOSER TO
150W BY DAY 8. THIS RESULTS FROM A RIDGE IN NORTHWEST CANADA THAT
SLOWLY BUILDS WESTWARD ACROSS THE STATE ALONG THE ARCTIC CIRCLE.
THE INTEGRITY OF THE WESTERN PERIPHERY OF THIS RIDGE AXIS WILL BE
TESTED BY ANOTHER SERIES OF HIGH ARCTIC SHORTWAVES THAT BRUSH
ACROSS THE NORTHERN PORTION OF THE STATE (EMBEDDED WITHIN THE
NORTHERN BRANCH OF THIS SPLIT-FLOW PATTERN ALOFT).

IN GENERAL...THE LOW-LEVEL WIND PATTERN WILL BE LIGHT AND
VARIABLE---AND TERRAIN-BASED CONVECTION WILL BE A CONSIDERATION.
WITH THE AIRMASS IN PLACE OCCASIONALLY REACHING ITS
'CONVECTIVE TEMPERATURE'---HIT-N-MISS SHOWERS AND ISOLATED
THUNDERSTORMS SHOULD BE A CONSISTENT FEATURE OF THIS PARTICULAR
MEDIUM RANGE PATTERN.

VOJTESAK