Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 300002
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
402 PM AKDT FRI MAY 29 2015

.DISCUSSION...

ALOFT AT 500M MB...UPPER LEVEL LOW CENTERED OVER EASTERN BROOKS
RANGE THIS MORNING HAS SLOWLY SHIFTED EASTWARD TOWARDS THE AK AND
CANADA BORDER. THIS UPPER LEVEL CLOSED LOW WILL WEAKEN INTO AN
UPPER LEVEL TROUGH BY SATURDAY MORNING OVER CANADA NEAR THE
MCKENZIE BAY. THIS WILL LEAVE RIDGE OF HIGH PRESSURE OVER THE
WESTERN COAST AND INTERIOR WITH LITTLE CHANGE AS ANOTHER CLOSED
UPPER LEVEL LOW MOVES SOUTHWARD FROM THE ARCTIC ON SUNDAY. THIS
SYSTEM WILL SLIDE SOUTHWARD ALONG THE ALASKA AND CANADA BORDER
AND INTO THE EASTERN INTERIOR OF ALASKA ON SUNDAY NIGHT INTO
MONDAY. THIS SYSTEM WILL ALLOW MUCH COLDER AIRMASS TO SLIDE DOWN
INTO THE CENTRAL AND ALASKA INTERIOR STARTING SUNDAY NIGHT INTO
EARLY NEXT WEEK WITH THE COLDEST TEMPERATURES APPEARING ON TUESDAY
MORNING.

SURFACE...THE 1030 MB HIGH OVER BARROW EARLY TODAY HAS MOVED
ONSHORE NEAR DEADHORSE WITH RIDGING EXTENDING NORTHWEST TO A 1034
MB HIGH NEAR OVER THE ARCTIC. THIS HIGH PRESSURE OVER THE ARCTIC
WILL PERSISTS AND STRENGTHEN TO 1040 MB BY SUNDAY MORNING. A
WEATHER FRONT WILL MOVE SOUTH ACROSS THE NORTH SLOPE ON SATURDAY
NIGHT AND PUSH SOUTHWARD INTO THE EASTERN AND CENTRAL INTERIOR.
THIS WILL BRING MUCH COLDER AIRMASS SUNDAY NIGHT INTO TUESDAY. A
RIDGE OF HIGH PRESSURE OVER WESTERN ALASKA WILL MOVE EXPAND
TOWARDS THE WEST COAST AND BERING STRAIT AND PERSIST THROUGH THE
WEEKEND.

ARCTIC COAST AND BROOKS RANGE...A BIT OF A MESS UP ON THE NORTH
SLOPE WITH A NICE SNOW BAND DEVELOPING OVER POINT THOMPSON WITH
REPORTS OF 3 INCHES ACCUMULATED SNOW. INITIALLY THERE WAS
FREEZING RAIN THIS MORNING THAT HAD MOVED EAST PAST DEADHORSE AND
DALTON. ALTHOUGH THERE ARE STILL SOME LOCATIONS OF SNOW OR MIX OF
RAIN AND SNOW ALONG PORTIONS OF THE DALTON HIGHWAY. PRECIPITATION
WILL ALL TURN TO SNOW AS THE SYSTEM CONTINUES TO SHIFT EASTWARD
OUT OF THE AREA. COOLER TEMPERATURES OVER MOST OF THE ARCTIC COAST
WILL ONLY GET COOLER AS THE WEEKEND PROGRESSES. AS THE NEXT FRONT
MOVES SOUTH ON SATURDAY EXPECT SNOW SHOWERS WITH MODELS
SUGGESTING ANOTHER 2 TO 4 INCHES OF SNOW POSSIBLE SATURDAY NIGHT
AND SUNDAY EAST OF BARROW. NO SIGNIFICANT WINDS OVER THE ARCTIC
COAST.

WEST COAST AND WESTERN INTERIOR...POTENTIALLY DEVELOP SOME AREAS
OF FOG IN AREAS OF SCATTERED RAIN SHOWERS MAINLY ALONG COASTAL
AREAS OF THE SEWARD PENINSULA AND YUKON DELTA WILL SHIFT WEST AND
BE ISOLATED BY SATURDAY AS THE FRONT CONTINUES TO DECAY BY SUNDAY
MORNING. WINDS GENERALLY LIGHT AND OFFSHORE NEAR THE COAST. SLIGHT
WARMING WITH RIDGE OVER THE AREA ALONG THE COAST AND WESTERN
INTERIOR FOR THE WEEKEND.

CENTRAL AND EASTERN INTERIOR...MOSTLY CLEAR ACROSS THE INTERIOR AS
THE LOW OVER THE BROOKS RANGE MOVES EAST. BRIEF WARMING FOR THE
WEEKEND BEFORE A SIGNIFICANT COOLING EVENT ON MONDAY THAT COULD
PUSH OVERNIGHT TEMPERATURES TUESDAY AND WEDNESDAY DOWN NEAR
FREEZING FROM THE TANANA RIVER NORTH. LOOKING FOR INCREASING
CLOUDS ON SUNDAY OVER THE NORTHEAST INTERIOR WITH A MIX OF RAIN
AND SNOW SHOWERS OVER THE UPPER YUKON FLATS SUNDAY EVENING AND
OVER THE FORTYMILE COUNTRY EARLY MONDAY. COULD SEE SNOW LEVELS
AROUND 2000 FEET FOR FORTYMILE COUNTRY.

EXTENDED PERIOD...AFTER THE UPPER LEVEL LOW MOVES BRINGS IN MUCH
COLDER AIR ACROSS CENTRAL AND INTERIOR ALASKA ON MONDAY AND
TUESDAY...ANOTHER UPPER LEVEL SYSTEM IS FORECASTED BY BOTH THE
ECMWF AND GFS TO MOVE ACROSS THE NORTH SLOPE MID NEXT WEEK. IT
WILL STALL TO THE NORTH AND SLIDE INTO WESTERN INTERIOR WHILE
THERMAL TROUGH BUILDS BACK INTO INTO THE CENTRAL AND EASTERN
INTERIOR. BASICALLY KEEPING THE COOLER AND WET TREND.

&&

.FIRE WEATHER...
NO SIGNIFICANT METEOROLOGICAL FIRE WEATHER ISSUES
ANTICIPATED OVER THE NEXT 72 HRS. ISOLATED THUNDERSTORMS STILL
EXPECTED SOUTH OF CHICKEN AND EAST OF MENTASTA PASS THIS AFTERNOON
AND EARLY EVENING IN ZONES 224 AND 226.

RELATIVE HUMIDITY WILL RECOVER WELL OVERNIGHT. RH VALUES WILL THEN
BE A BIT DRIER SAT AND SUN FOR MUCH OF THE AK INTERIOR COMPARED TO
TODAY GIVEN DECENT INSOLATION...SUFFICIENT MIXING...AND THE ABSENCE
OF PRECIPITATION FOR MOST AREAS. HOWEVER...SOME PRECIPITATION IS
EXPECTED ON SUNDAY WHERE A TROUGH ALOFT WILL BRING INCREASE CHANCES
OF RAIN OVER THE EASTERN BROOKS RANGE AND PORTIONS OF THE EASTERN
INTERIOR. OTHERWISE...WILL SEE RH VALUES BETWEEN TWENTY AND THIRTY
PERCENT IN AREAS DURING THE DAY HOWEVER...WINDS WILL NOT BE
SIGNIFICANT DURING THIS TIME PERIOD.

BESIDES THE AFOREMENTIONED ISOLATED THUNDERSTORM POTENTIAL THIS
AFTERNOON AND EARLY EVENING...ADEQUATE MOISTURE WILL COMBINE WITH
MARGINAL INSTABILITY ON SUNDAY AFTERNOON AND EVENING OVER THE LOWER
YUKON VALLEY AND INLAND OF THE YUKON DELTA. WARRANTS MONITORING AND
ISOLATED THUNDERSTORMS ARE FORECAST.

&&

.HYDROLOGY...
THE SPECIAL WEATHER STATEMENT FOR SAG RIVER WAS REPLACED WITH A
FLOOD ADVISORY FROM PUMP STATION 3 DOWNSTREAM TOWARDS DEADHORSE
WITH POTENTIAL MINOR FLOODING ALONG THE DALTON HIGHWAY. THE FLOOD
ADVISORY FOR THE SAG RIVER WILL CONTINUE THROUGH SUNDAY. THE CREST
CURRENTLY IS AT 19.5 FEET AND IS APPROACHING THE FLOOD STAGE AT
20 FEET. IT IS EXPECTED TO CREST TONIGHT AT PUMP STATION 3 ON THE
SAG RIVER AND IT WILL TAKE AROUND 24 HOURS FOR THE CREST TO MOVE
DOWNSTREAM. THIS MAY CAUSE MINOR FLOODING IMPACTS TO CURRENT
REPAIRS ALONG THE DALTON HIGHWAY.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY FOR PKZ230.

BRISK WIND ADVISORY FOR PKZ225.
&&

$$

MAK/ET MAY 15


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