Prognostic Meteorological Discussion
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462
FXAK02 KWNH 031934
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
234 PM EST SAT DEC 03 2016

VALID 12Z WED DEC 07 2016 - 12Z SUN DEC 11 2016

...BELOW AVERAGE TEMPERATURES TO PERSIST FOR SOUTHERN AREAS AND
THE PANHANDLE NEXT WEEK...


...GUIDANCE/UNCERTAINTY ASSESSMENT...

NO BIG CHANGES TO THE ONGOING FORECAST. UPPER HIGH IS FORECAST TO
MEANDER AROUND WRANGEL ISLAND WHICH SUPPORTS TROUGHING THROUGH THE
INTERIOR BUT ESPECIALLY INTO THE GULF. GFS CONTINUES TO MOSTLY
TAKE AN APPROACHING SYSTEM FROM THE NORTHEAST PACIFIC FARTHER EAST
THAN THE OTHER MODELS AND MOST ENSEMBLES, THOUGH ITS 00Z PARALLEL
RUN WAS FARTHER WEST LIKE THE 00Z ECMWF/CANADIAN/UKMET. USED THAT
LARGER CONSENSUS WITH THE 00Z ECMWF ENSEMBLE MEAN AS A STARTING
POINT TO THE FORECAST. THIS MADE FOR A LITTLE SLOWER SOLUTION THAN
THE FORECAST YESTERDAY. SYSTEM MAY TRY TO EASE NORTHWARD BUT
LATEST ENSEMBLE CONSENSUS TAKES THE SFC LOW EASTWARD NEAR HAIDA
GWAII, PERHAPS RELATED TO MORE RIDGING OVER THE INTERIOR VIA A
CLOSER/STRONGER UPPER HIGH IN THE ARCTIC OCEAN/CHUKCHI SEA. NEXT
SYSTEM SHOULD PASS NEAR THE WESTERN ALEUTIANS AND THEN SLIDE
SOUTHEASTWARD, THOUGH ENSEMBLE SPREAD IS FAIRLY LARGE. LARGE
CYCLONIC FLOW IN THE GULF SHOULD PREVENT MUCH EASTWARD MOVEMENT AS
LONG AS THE UPPER HIGH REMAINS TO THE NORTHWEST.


...HIGHLIGHTS/THREATS...

STRONG HIGH PRESSURE (>1050MB) WILL SLIDE SOUTHEASTWARD THROUGH
THE YUKON AND NW TERRITORIES OF CANADA WHICH WILL SEND COLD
TEMPERATURES VIA STRONG EASTERLY FLOW INTO THE PANHANDLE (WINDS
30-40KTS POSSIBLE) WHILE THE INTERIOR STAYS TYPICALLY COLD (BUT
BELOW AVERAGE) AS WELL (-30S TO -40S F). 2M TEMPERATURES VIA AN
ENSEMBLE BLEND WERE STILL COLDER THAN THE STATISTICAL FORECASTS
(GFSMOS AND ECMWF-BASED MOS) BUT WERE TRENDING CLOSER TOGETHER IN
BETWEEN. KEPT THE INTERIOR QUITE COLD VIA THE STABLE AIRMASS.
OVERRUNNING EVENT FOR THE PANHANDLE REMAINS A STRONG POSSIBILITY
WITH LIGHT TO MODERATE SNOW ATOP A COLD SURFACE AND CONTINUED
BRISK EASTERLY FLOW. TRACK OF THE SFC LOW WILL INFLUENCE HOW FAR
NORTH AND INTENSE THE SNOW MAY BE.


FRACASSO

$$





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