Prognostic Meteorological Discussion
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000
FXAK02 KWNH 171950
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
248 PM EST FRI NOV 17 2017

VALID 12Z TUE NOV 21 2017 - 12Z SAT NOV 25 2017

...GUIDANCE/UNCERTAINTY ASSESSMENT AND WEATHER/THREAT HIGHLIGHTS...

THE MEDIUM-RANGE PERIOD WILL BEGIN WITH AN ARCTIC UPPER-LEVEL
VORTEX CENTERED NEAR THE NORTHEAST CORNER OF ALASKA WHILE A
CUT-OFF LOW SOUTH OF THE GULF OF ALASKA SWINGS BACK TOWARD THE
ALASKA PANHANDLE.  MODEL GUIDANCE THIS MORNING AGREES THAT THE
ARCTIC VORTEX WILL BE NEARLY STATIONARY OVER NORTHEAST ALASKA
BEFORE DRIFTING NORTHWARD INTO THE ARCTIC OCEAN BY THANKSGIVING
DAY.  MEANWHILE...THE CUT-OFF LOW OVER THE NORTHEAST PACIFIC IS
FORECAST TO HEAD TOWARD THE ALASKA PANHANDLE WHERE IT SHOULD
DISSIPATE ON THANKSGIVING DAY.  FARTHER TO THE WEST...THE NEXT
CYCLONE SHOULD BE MOVING RAPIDLY INTO THE PICTURE ACROSS THE
BERING SEA.  MODEL SOLUTIONS SHOW PRETTY GOOD AGREEMENT ON THE
TRACK OF THIS LOW...WITH THE 00Z ECMWF TRACK RIGHT IN BETWEEN THE
06Z AND 12Z GFS.  THE CYCLONE CENTER IS FORECAST TO TRACK ACROSS
THE ALASKA PENINSULA ON THANKSGIVING BEFORE SLIDING INTO THE GULF
OF ALASKA AND GRADUALLY WEAKENS NEXT FRIDAY.  BY NEXT
SATURDAY...MODELS ARE INDICATING THE POSSIBILITY OF A STRONG COLD
FRONT ASSOCIATED WITH THE NEXT LARGE-SCALE CYCLONE MOVING EASTWARD
ACROSS THE BERING SEA AND THE ALEUTIANS.

IN TERMS OF SENSIBLE WEATHER...MUCH OF ALASKA...ESPECIALLY
NORTHEASTERN ALASKA...WILL REMAIN UNDER THE GRIP OF FRIGID AIR
THROUGH THE MEDIUM-RANGE PERIOD UNDER THE INFLUENCE OF THE ARCTIC
UPPER-LEVEL VORTEX...WITH TEMPERATURES FALLING BELOW -30 DEGREES
AND HIGH TEMPERATURES WELL BELOW ZERO IN THE INTERIOR.  THE NEXT
CYCLONE MOVING ACROSS THE BERING SEA ON THANKSGIVING DAY COULD
PRODUCE HURRICANE-FORCE WIND GUSTS FROM THE ALEUTIANS EASTWARD
INTO THE ALASKA PENINSULA BEFORE SUBSIDING NEXT FRIDAY.  BY NEXT
SATURDAY...VERY STRONG WINDS WILL AGAIN BE POSSIBLE ACROSS THE
ALEUTIANS WITH THE ARRIVAL OF THE NEXT STRONG COLD FRONT.
MEANWHILE...OCCASIONAL STORMINESS TYPICAL FOR THIS TIME OF THE
YEAR WILL CONTINUE TO IMPACT THE ALASKA PANHANDLE INTO THE
THANKSGIVING WEEKEND.

KONG

$$





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