Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 022238
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
138 PM AKST MON MAR 2 2015

.DISCUSSION...
ALOFT AT 500 MB...RIDGE OF HIGH PRESSURE OVER THE MAJORITY OF
MAINLAND ALASKA WITH AXIS OVER WEST COAST THIS AFTERNOON. THE
RIDGE AXIS WILL MOVE OVER EASTERN INTERIOR AND EASTERN BEAUFORT
COAST ON TUESDAY MORNING. A SHORTWAVE TROUGH WILL APPROACH THE
BERING STRAIT AND WEST COAST ON TUESDAY MORNING AND SLOWLY MOVE
EAST THROUGH THE DAY. THE LOW TROUGH WILL EXTEND FROM BARROW
SOUTHWARD THROUGH HUSLIA TOWARDS MCGRATH BY TUESDAY AFTER
MIDNIGHT. ALTHOUGH THE TROUGH MOVES QUICKLY ACROSS THE ARCTIC
COAST ON WEDNESDAY THE SHORTWAVE LAGS SOUTHWARD ACROSS THE EASTERN
INTERIOR ON WEDENSDAY. BRIEF RIDGING ON THRUSDAY ACROSS MUCH OF
CENTRAL AND EASTERN ALASKA...WITH ANOTHER STRONG TROUGH MOVING
ONTO THE WEST COAST AND WESTERN ALASKA BY THURSDAY NIGHT. THIS
SAME TROUGH WILL MOVE QUICKLY ACROSS THE EASTERN INTERIOR BY
FRIDAY. BOTH THE GFS AND ECMWF ARE IN FAIRLY GOOD AGREEMENT
THROUGH FRIDAY WITH ONLY SOME SLIGHT DIFFERENCES AS HEAD INTO THE
NEXT WEEKEND. HOWEVER EACH OF THE DETERMINISTIC MODELS IN RELATIVE
AGREEMENT. EVEN DISCUSSION BY HPC SHOW THE ECMWF ENSEMBLE MEANS
VERY CONSISTENT WITH THE NAEFS FOR THE NEXT WEEKEND POTENTIAL
STORM MOVING INTO WEST COAST AND INTERIOR.

SURFACE...THE NORTHERN MOST 1000 MB LOW PRESSURE WILL BRANCH OFF
AND CONTINUE TO DEVELOP BY TUESDAY MORNING AND LOCATED NORTHWEST
OF POINT LAY. THIS LOW WILL DEEPEN TUESDAY NIGHT TO 995 MB AND BE
LOCATED ROUGHLY 180NM NORTHEAST OF BARROW...AS IT WILL SLOWLY MOVE
ACROSS THE ARCTIC COAST. THE OTHER 1000 MB LOW CURRENTLY OVER THE
GULF OF ANADYR WILL WEAKEN SLIGHTLY TO BECOME 1006 MB LOW PHASE
INTO THE EXTENSION FROM THE NORTHERN MOST LOW AS A FRONTAL
BOUNDARY MOVING ACROSS THE WESTERN INTERIOR. ANOTHER 996 MB LOW
OVER GULF OF ANADYR WILL DEVELOP AND MOVE ACROSS THE BERING SEA
TOWARDS THE YUKON DELTA ON WEDNESDAY BUT WEAKEN AND DISSIPATE BY
THURSDAY.

NORTH SLOPE...EAST WINDS REMAIN GUSTY WITH 20 TO 25 MPH ACROSS
THE EASTERN BEAUFORT COAST AS THE WIND IS EXPECTED TO DIMINISH
THIS EVENING. THERE WILL BE A BRIEF SHIFT IN WINDS FROM THE
SOUTHWEST FOR AREAS FROM BARROW EAST ON TUESDAY NIGHT AHEAD OF THE
NEXT APPROACHING SYSTEM AND THEN SHIFT FROM THE WEST WITH STRONG
WINDS RAMPING UP ONCE AGAIN OVER THE EASTERN BEAUFORT COAST.
ROUGHLY 2 STANDARD DEVIATIONS ABOVE NORMAL CLIMATOLOGY WITH WINDS
SUGGESTED AT 50 MPH. THE COMBINATION OF SNOW AND STRONG WINDS WILL
AGAIN BRING ANOTHER ROUND OF BLIZZARD CONDITIONS PARTICULARLY FROM
DEADHORSE EAST INCLUDING KAKOTVIK ON TUESDAY NIGHT INTO WEDNESDAY.
HOWEVER DO NOT ANTICIPATE AS STRONG OF SYSTEM LIKE THE PREVIOUS
EVENT OVER THE WEEKEND. FOR AREAS WEST OF BARROW...THE FRONT WITH
SNOW SHOWERS CAN BE EXPECTED ON TUESDAY MORNING WITH THE WIND
SHIFT FROM OFFSHORE TO ONSHORE FLOW BY TUESDAY AFTERNOON AFTER THE
FRONTAL PASSAGE. SNOW FALL AMOUNTS OF 2 TO 4 INCHES CAN BE
EXPECTED WITH THIS SYSTEM WITH MAJORITY OF THE SNOW FALL ON
TUESDAY FOR WESTERN BROOKS RANGE AND WEST OF BARROW AND TUESDAY
NIGHT INTO WEDNESDAY FOR THE EASTERN BROOKS RANGE AND AREAS EAST
OF BARROW.

WEST COAST AND WESTERN INTERIOR...LOW STRATUS AND FOG ALONG THE
BACKSIDE OF THE LOW PRESSURE SYSTEM SOUTH OF ST LAWRENCE ISLAND AS
SEEN IN THE RGB NIGHTTIME MICROPHYSICS THIS MORNING. MOST LIKELY
THIS AREA OF LOW FOG WILL MOVE TO TOWARDS THE YUKON DELTA FOR
TOMORROW. HOWEVER THE APPROACHING SYSTEM CURRENTLY OVER THE BERING
SEA ASSOCIATED THE TROUGH WILL SLOWLY IMPACT YUKON DELTA STARTING
TONIGHT AND THEN EXPAND ACROSS THE ENTIRE WEST COAST ON TUESDAY.
NORTH OF THE NOME AND UNALAKLEET WILL DEFINITELY BE ALL SNOW.
HOWEVER THERE IS A WARM NOSE LAYER THAT IS MORE EVIDENT FURTHER
SOUTH ALONG ZONE 214 AND 215 IN THE YUKON DELTA THAT MAY
POTENTIALLY BE FREEZING RAIN AFTER MIDNIGHT THROUGH EARLY TUESDAY
MORNING. HOWEVER THE KEY WILL BE THE DEPTH OF THAT WARM NOSE LAYER
IN TERMS OF CREATING FREEZING RAIN. WHICH CONFIDENCE IS NOT REALLY
HIGH. THUS HAVE MENTIONED SLIGHT CHANCE PHRASING OF THE FREEZING
RAIN POTENTIAL. AS THIS SYSTEM MOVES INLAND...FOCUS GOES AREAS
SOUTH OF AMBLER AND FROM GALENA NORTH AS DECENT VERTICAL MOTION
WITHIN THE SNOW GROWTH REGION BRINGS ABOUT SOME REASONABLE SNOW
AMOUNTS OF 3 TO 4 INCHES FROM THE GFS AND NAM MODELS. SREF
PROBABILISTIC FORECASTS INDICATES A HINT POTENTIAL FOR 6 INCHES
FOR SMALL AREA WITHIN THE UPPER KOBUK AND NOATAK VALLEYS...BUT
CONFIDENCE NOT NECESSARILY VERY HIGH. THUS WILL HOLD OFF ON THE
WINTER WEATHER ADVISORY FOR SNOW FOR ZONE 217.

CENTRAL AND EASTERN INTERIOR...MOSTLY CLEAR SKIES ONCE AGAIN
MAJORITY FOR EASTERN INTERIOR FOR TONIGHT WITH INCREASE CLOUDS
AFTER MIDNIGHT FOR CENTRAL INTERIOR. THE NEXT SYSTEM TO APPROACH
THE AREA WILL BRING SNOW ON TUESDAY AND WEDNESDAY. A BROAD AREA
OF SNOWFALL AMOUNTS OF 2 TO 3 INCHES CAN BE EXPECTED WITH THIS
SYSTEM. BESIDE THE TYPICAL SNOW ACCUMULATION ON WITH UPSLOPE FLOW
ON SOUTH FACING SLOPES OF ALASKA RANGE...THERE IS ALSO POTENTIAL
FOR 4 TO 5 INCHES NOTED BY BOTH THE GFS AND NAM IN THE WHITE
MOUNTAIN JUST NORTH AND EAST OF FAIRBANKS AND AREAS NORTH OF THE
FORTYMILE COUNTRY IN ZONE 224. SOMETHING TO MAINTAIN CAREFUL WATCH
AS WOULD BE JUST REACHING ADVISORY CRITERIA. HOWEVER...DO NOT
ANTICIPATE THE WINDS TO BE AS STRONG AS WITH THE PREVIOUS SYSTEM OVER
THE WEEKEND. OTHER CONCERN WILL BE THE ICY CONDITIONS ON THE ROADS
EXPECTED AS WE CONTINUE WITH A WARMING TREND TODAY THROUGH
WEDNESDAY BEFORE THE SYSTEM...WITH INCREASED WARMING HOURS THIS
WILL LIKELY CAUSE SOME MELTING OF SNOW AND REFREEZING OVERNIGHT.

EXTENDED FORECAST...
LOOKING AT FRIDAY THROUGH THE UPCOMING WEEKEND. THERE APPEARS TO
BE SOME AGREEMENT AND LEVEL OF CONFIDENCE WITHIN THE MODELS INDICATING
A POTENTIALLY STRONGER SYSTEM BRINGING MOISTURE ADVECTION FOR SNOW
EVENT TO SOUTH FACING SLOPES OF THE ALASKA RANGE AND BROOKS RANGE. AS
MENTIONED IN PREVIOUS DISCUSSIONS THIS SYSTEM WOULD BRING RATHER
SIGNIFICANT COLD ADVECTION AS THE TROUGH EXTENDS FROM NORTH-SOUTH
ACROSS THE MAINLAND ALASKA MONDAY MORNING...BRINGING SHARPLY
COLDER TO NORTHERN ALASKA...ESPECIALLY OVER THE WEST COAST AND
WESTERN INTERIOR WHERE 850 MB TEMPERATURES WILL COOL TO BELOW
-20C. THE COLDEST AIR AT THIS TIME WILL SPREAD EASTWARD TO THE
CENTRAL AND EASTERN INTERIOR BY TUESDAY NIGHT OF NEXT WEEK. THE
TIMING OF THE COLD AIR WILL BE VALUABLE INFORMATION FOR OUTDOOR
ACTIVITIES SUCH AS THE RESTART OF THE IDITAROD IN FAIRBANKS NEXT
MONDAY.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
BRISK WIND ADVISORY FOR PKZ200-PKZ210-PKZ215-PKZ220-PKZ225-
PKZ230-PKZ230-PKZ235-PKZ235-PKZ240-PKZ245.
&&

$$

MAK MAR 15


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