Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 012231
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
231 PM AKDT WED APR 1 2015

.DISCUSSION...
ALOFT...WEAK RIDGE OVER EASTERN ALASKA AND TROUGH OVER WESTERN
ALASKA CURRENTLY. IN THE TROUGH THERE IS A WEAK LOW JUST WEST OF
KOTZEBUE WHICH WILL DRIFT EAST TO KOBUK THU AM AND TO JUST EAST OF
BETTLES 4AM FRI. THIS LOW WILL THEN MOVE TO DENALI PARK THROUGH
4AM SAT WHILE THE UPPER TROUGH MOVES EAST TO EXTEND FROM BARROW
TO ANCHORAGE AT THAT TIME. A MODERATE RIDGE OF HIGH PRESSURE WILL
BUILD OVER THE WESTERN COAST OF ALASKA BEHIND THIS TROUGH. THE
RIDGE WILL WEAKEN SOME SAT AS A LOW MOVES EAST ACROSS THE CENTRAL
BERING SEA TO SOUTH OF BETHEL. THE RIDGE NOW OVER EASTERN ALASKA
WILL RETREAT INTO CANADA THROUGH THE REST OF THE WEEK AS THE
TROUGH LIES OVER THE INTERIOR AND NORTH SLOPE OF ALASKA LATE
SAT...BRINGING A COOLING OF THE AIRMASS TO THESE REGIONS.

SURFACE...1044 MB HIGH NEAR 80N LAT 160W LONG WILL DRIFT
SOUTHEAST FRI THROUGH SAT. WEAK LOW PRESSURE OVER THE INTERIOR
WITH A LOW IN THE GULF OF ALASKA WILL SLOWLY FILL AND THE LOW WILL
MOVE SOUTHEAST. 1004 MB LOW FORMING OVER THE WESTERN ALEUTIANS FRI
AM THEM MOVING TO JUST SOUTH OF NUNIVAK ISLAND SAT AM. ASSOCIATED
OCCLUSION WILL STRETCH FROM SAINT MATTHEW ISLAND TO NUNIVAK ISLAND
SAT AM THEN BEGIN TO SLOWLY DRIFT SOUTH.

MODELS...GOOD AGREEMENT BETWEEN THE OPERATIONAL GFS NAM AND ECMWF
IN THE SHORT TERM...EVEN WITH THE SMALL LOW WEST OF KOTZEBUE
TREKKING EAST THEN SOUTH OVER THE INTERIOR. THE NAM WANTS TO PUT
AN ACTUAL BROAD UPPER LOW NEAR FAIRBANKS SAT PM...BUT THE OTHER
MODELS LEAVE IT AS A TROUGH WHICH IS PREFERRED AT THIS TIME. IN
THE MEDIUM TERM AGREEMENT BETWEEN THE GFS AND ECMWF ENSEMBLES IS
FAIRLY GOOD ALONG WITH THE GFS OPERATIONAL RUN IN THAT THEY
REBUILD THE RIDGING OVER EASTERN AK. WHEREAS THE 12Z ECMWF
OPERATIONAL RUN IS RETAINING THE TROUGH OVER EASTERN AK.

NORTH SLOPE...WINDS RELAXING SLOWLY TODAY AND TONIGHT. ON SATURDAY
EXPECT WINDS TO PICK UP SOME OVER THE BEAUFORT SEA COAST WITH THE
HIGH CENTER DRIFTING SOUTH TOWARD THE AREA.

WESTERN ALASKA...SPOTTY PRECIP OVER INTERIOR AREAS WILL SLOWLY
SHIFT EAST WITH MOVEMENT OF THE SMALL LOW AND THE MIGRATION THE
THE UPPER TROUGH EASTWARD THROUGH SAT. VERY LITTLE WX OTHERWISE
THOUGH SOME SLIGHT CHANCE FOR SNOW OVER SOUTHERN YUKON DELTA SAT
WITH THE OCCLUSION NEARING FROM THE SOUTH.

CENTRAL AND EASTERN INTERIOR...AS THE SMALL UPPER LOW TREKS INTO
THE REGION LATER THIS WEEK...EXPECT SPOTTY LIGHT SNOW SHOWERS TO
MOVE EAST ACROSS THE NORTHERN ZONES INTO FRI AM. WEAK SOUTHWEST
FLOW WILL SET UP OVER THE SOUTHERN INTERIOR AND POSSIBLY BRING
LIGHT SNOW TO THE UPPER TANANA...FORTYMILE AREA...EASTERN ALASKA
RANGE...AND DELTANA AREA FRI AND SAT. SUCH SNOW MAY DEVELOP
FARTHER WEST OVER THE MIDDLE TANANA VALLEY AND THE CENTRAL ALASKA
RANGE...FOR NOW WILL KEEP THIS PORTION DRY...BUT IS AN ITEM TO
CONSIDER FOR UPCOMING FORECAST ISSUANCES. WITH OVERALL COOLING AS
THE UPPER TROUGH MOVES IN THE HIGH TEMPERATURES OVER THE FAIRBANKS
AREA WILL SETTLE INTO THE MID 30S...WHICH IS A NORMAL VALUE FOR
THIS TIME OF YEAR.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
BRISK WIND ADVISORY FOR PKZ235-PKZ240-PKZ245.
&&

$$

JL APR 15



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