Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 271100 AAA
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FAIRBANKS AK
300 AM AKDT WED AUG 27 2014

.DISCUSSION...

UPPER AIR...
A WEAK SHORT WAVE TROUGH ALOFT EMBEDDED IN A LIGHT WESTERLY
FLOW PATTERN IS NOW OVER THE CENTRAL INTERIOR...AND WILL MOVE
EAST TO THE ALCAN BORDER BY EARLY THIS EVENING. A BAND OF SHOWERS
IS ASSOCIATED WITH THIS FEATURE...PRODUCING RAINFALL AMOUNTS OF
AROUND 0.1 TO 0.3 INCHES.

A DEEP UPPER LOW WITH AN EXPANSIVE CIRCULATION CENTERED NEAR
81N/173W...ABOUT 900 NM NORTH OF THE BERING STRAIT...IS PROJECTED
TO MOVE ON A WOBBLY TRACK SOUTHEASTWARD TO ABOUT 50 NM NORTHWEST
OF BARROW BY SUN MORNING. SEVERAL SHORT WAVE TROUGHS ROTATING
AROUND THE LOW CENTER WILL SWEEP EASTWARD ACROSS NORTHERN ALASKA
DURING THE NEXT 7 DAYS.

THE FIRST SHORT WAVE TROUGH IS EXPECTED TO BE A RELATIVELY
STRONG FEATURE...ARRIVING ON THE ALASKA WEST COAST THU MORNING
AND MOVING TO THE ALCAN BORDER AND NORTHWESTWARD BY SAT MORNING.
ALL OF NORTHERN ALASKA WILL EXPERIENCE PRECIPITATION WITH THIS
FEATURE AS IT TRAVELS EASTWARD. OVER THE BROOKS RANGE THE
PRECIPITATION WILL START AS RAIN AND CHANGE TO SNOW AS THE
COLDER AIR MASS MOVES IN. CURRENT GFS/ECMWF INDICATING LIQUID
QPF OF MAINLY 0.25 TO 0.5 INCH OVER THE WESTERN ARCTIC SLOPE AND
WESTERN BROOKS RANGE...AND 0.25 TO AROUND 1 INCH OVER THE EASTERN
ARCTIC SLOPE AND BROOKS RANGE. EVENT SNOW TOTALS IN THE EASTERN
BROOKS RANGE COULD BE AS MUCH AS AROUND 4 INCHES. OVER COASTAL
AREAS...PRECIPITATION WILL LIKELY BE RAIN...POSSIBLY MIXED WITH
SNOW WEST OF BARROW. AREAS SOUTH OF THE BROOKS RANGE WILL
EXPERIENCE RAIN OR SHOWERS WITH THE SHORT WAVE. HEAVIEST EVENT
TOTALS ARE EXPECTED TO BE OVER THE WESTERN INTERIOR AND WEST
COAST...MAINLY 0.25 TO 0.5 INCHES WITH LOCALLY LARGER AMOUNTS.
OVER THE EASTERN INTERIOR...EVENT TOTALS ARE EXPECTED TO BE MAINLY
0.10 TO 0.25 INCH.

THE NEXT SHORT WAVE IS EXPECTED TO ARRIVE ON THE WEST AND
NORTHWEST COASTS SAT EVENING...MOVING TO THE ALCAN BORDER
AND NORTHWESTWARD BY MON MORNING. THIS FEATURE WILL PRODUCE
ANOTHER EPISODE OF PRECIPITATION...RAIN SOUTH OF THE BROOKS
RANGE AND SNOW FROM THE BROOKS RANGE NORTH.

THIS WILL BE FOLLOWED BY A LOWER AMPLITUDE RIPPLE MOVING RAPIDLY
EASTWARD IN A FAST WESTERLY FLOW MON AFTERNOON AND MON NIGHT.
CURRENT GFS AND ECMWF INDICATE A POTENTIAL FOR WIDESPREAD
PRECIPITATION OVER THE NORTHERN WEST COAST...NORTHERN
INTERIOR...BROOKS RANGE...AND ARCTIC SLOPE WITH THIS PATTERN.
ANOTHER SHORT WAVE COULD TRANSIT NORTHERN ALASKA AROUND THE
MIDDLE OF NEXT WEEK.

SURFACE...
A COLD FRONT CURRENTLY EXTENDS FROM AROUND 300 MILES NORTH NORTHWEST
OF BARROW TO NEAR CAPE SCHMIDT ON THE NORTHEAST SIBERIA COAST. THE
FRONT WILL MOVE TO THE CENTRAL BEAUFORT SEA AND CENTRAL ARCTIC COAST
BY EARLY THU MORNING...WEAKENING OVER THE EASTERN BEAUFORT SEA BY
EARLY FRI MORNING. SOUTH TO SOUTHWEST WINDS 20-25 KT EXPECTED
ALONG THE ARCTIC COAST AND IN ARCTIC MARINE AREAS WITH THE
APPROACH OF THE FRONT...SHIFTING TO WEST OR NORTHWEST AND
DECREASING AFTER THE FRONTAL PASSAGE.

A 995 MB LOW IS PROGGED TO MOVE SOUTHWARD OUT OF THE HIGH ARCTIC
TO ABOUT 100 MILES NORTHWEST OF BARROW BY SAT EVENING. A 998 MB
LOW IS EXPECTED TO DEVELOP IN THE NORTHEAST ALASKA INTERIOR LATE
THU AFTERNOON...MOVING TO THE NORTHERN YUKON TERRITORY COAST BY
FRI MORNING.

IN THE FAST WESTERLY FLOW PATTERN EXPECTED EARLY NEXT WEEK...A
SIGNIFICANT SURFACE LOW LOW IS EXPECTED TO SHOOT RAPIDLY EASTWARD
OUT OF SIBERIA ACROSS THE ARCTIC SLOPE. TIMING AND TRACK OF THIS
FEATURE IS UNCERTAIN AT THIS TIME...CURRENT GFS MOVING IT MUCH
FASTER THAN THE ECMWF...BUT IT COULD PRODUCE SIGNIFICANT WINDS AND
PRECIPITATION.

ISOLATED THUNDERSTORMS IN THE NORTHEAST INTERIOR THIS AFTERNOON.
ISOLATED THUNDERSTORMS THU AFTERNOON AND MAYBE EARLY THU EVENING
IN ADVANCE OF THE INCOMING SHORT WAVE TROUGH.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.FIRE WEATHER...
NONE. MIN RH WILL REMAIN ABOVE 40 PERCENT. COOLER TEMPERATURES
OVER THE INTERIOR BEGINNING FRI.

&&

.HYDROLOGY...
SIGNIFICANT PRECIPITATION EXPECTED OVER THE BROOKS RANGE WITH THE
FIRST SHORT WAVE TROUGH. NO RIVER ISSUES EXPECTED SINCE THE
PRECIPITATION IS EXPECTED BE MOSTLY OR ALL SNOW.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY FOR PKZ225-PKZ230-PKZ235.
&&

$$

AUG 14


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