Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 290021
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
421 PM AKDT FRI AUG 28 2015

.DISCUSSION...
MAIN CONCERNS WERE STILL DIRECTED TOWARDS THE COASTAL FLOOD EVENT
IN BARROW. ALSO...FOR HEAVY SNOW IN THE NORTHEASTERN BROOKS RANGE
AND SNOW IN DENALI...ABOVE 2000 AND 3000 FEET...RESPECTIVELY.
DETERMINISTIC MODELS WERE IN FAIR AGREEMENT WITH THE LARGE SCALE
PATTERN. HOWEVER...DIFFERENCES IN THE EVOLUTION OF THE LONG WAVE
TROUGH BECOME MORE APPRECIABLE AROUND 54-60 HRS OUT. THOUGH
MODELS ARE AGREEING ON NORTH PACIFIC RIDGE BUILDING MON AND MOVING
OVER SOUTHWEST AK BY TUE...AND OVER SOUTH CENTRAL ALASKA WED.

.ALOFT...
AN AMPLIFIED LONGWAVE TROUGH IS CURRENTLY POSITIONED OVER
MAINLAND ALASKA WITH A 520 DAM CENTER 200 NM NORTH OF BARROW AND
536 DAM LOW IN THE EASTERN GULF OF ALASKA. THE LATTER LOW WILL
WEAKEN INTO A OPEN WAVE BY SAT AFTERNOON...MEANWHILE THE LOW
OFFSHORE FROM THE CENTRAL ARCTIC COAST WILL MOVE INTO THE ARCTIC
PLAIN. A SHORTWAVE TROUGH AND ASSOCIATED VORT LOBE WILL ROTATE
THROUGH THE EASTERN CHUKCHI SEA TO THE NORTHWESTERN ALASKA COAST
LATE TONIGHT AND TOMORROW. THE MID-LEVEL LOW WILL THEN CONTINUE
TO DRIFT SOUTH SUN AND WILL SPAN ROUGHLY FROM CENTRAL MAINLAND AK
TO SOUTHEAST AK. THE NORTH PACIFIC RIDGE THAT SPANS INTO THE
CENTRAL BERING SEA WILL CONTINUE TO RECEDE OVERNIGHT AND SAT AS
THE AFOREMENTIONED SHORTWAVE ROTATES SOUTHWARD. THE RIDGE WILL
EVENTUALLY START BUILDING AGAIN OVER THE SOUTHEASTERN BERING SEA
INTO THE WEST COAST MON AS THE LONGWAVE TROUGH SHIFTS SOUTH AND
EAST.

THE FOCUS OF STRONGEST WINDS ALOFT...700 AND 850 HPA...WILL SHIFT
MORE WESTWARD FROM THE WESTERN ARCTIC COAST TO THE SOUTHERN
CHUKCHI SEA-BERING STRAIT OVER THE NEXT 12-HRS. THIS IS IN
RESPONSE TO THE SYSTEM OFF THE CENTRAL ARCTIC COAST MOVING TO THE
NORTHWESTERN BROOKS RANGE. AS SUCH...WILL CONTINUE TO SEE
MODERATE WINDS ACROSS THE BERING STRAIT AND FROM POINT LAY WEST
TONIGHT.

.SURFACE...
A 986 MB LOW 150 NM NORTHWEST OF POINT BARROW WILL MOVE OVER
WAINWRIGHT BY 10 AM TOMORROW MORNING. MEANWHILE...A WEAK RIDGE
OVER THE LOWER AND MIDDLE YUKON VALLEY WILL GIVE WAY TO A TROUGH
EXTENDING FROM A 992 MB LOW SOUTHWEST OF ATTU AND LOW PRESSURE IN
THE GULF OF ALASKA TONIGHT. THE LOW OVER WAINWRIGHT WILL WEAKEN
INTO A TROUGH EXTENDING FROM BROAD LOW PRESSURE IN THE GULF OF
ALASKA SAT AND WILL PERSIST INTO SUN. AT THE SAME TIME...WEAK
HIGH PRESSURE OVER THE CHUKOTSK PENINSULA WILL MOVE SOUTH LATE SAT
AND SUN INTO THE CENTRAL BERING SEA.

A DISTURBANCE ALOFT WILL SET THE STAGE FOR ANOTHER WINTER SNOW
WARNING IN THE NORTHEASTERN BROOKS RANGE THIS EVENING AND
OVERNIGHT. SIMILAR TO THE LAST WINTER STORM WARNING...SNOW
ACCUMULATIONS WILL BE LIMITED TO 2000 FEET AND ABOVE. A STORM
TOTAL OF 6-7 INCHES IS EXPECTED. ELSEWHERE...IT HAS BEEN SNOWING
IN DENALI ABOVE 3000 FEET...ZONE 225. A REPORTED 5.4 INCHES FELL
FROM OVERNIGHT AND THIS MORNING AT THE EIELSON VISITOR CENTER IN
DENALI PARK. AS SUCH...A WINTER WEATHER ADVISORY FOR SNOW WAS
ISSUED TODAY AND GOES UNTIL NOON SAT AS SNOW IS NOT EXPECTED TO
LET UP AND WILL CONTINUE OVERNIGHT. AN ADDITIONAL 3 TO 5 INCHES
EXPECTED ABOVE 3000 FEET.

.COASTAL HAZARD POTENTIAL DAYS 3 AND 4...
COASTAL FLOOD WARNING REMAINS IN EFFECT FOR ZONE 202...FOR
BARROW...UNTIL THIS EVENING. MINOR COASTAL FLOODING HAS BEEN
REPORTED. MOST ROADS NEAR THE SHORE ARE CLOSED...INCLUDING
SECTIONS OF STEVENSON STREET...AND EBEN HOPSON. THE BERM IS STILL
BEING REBUILT ALONG STEVENSON STREET WITH STEVENSON STREET CLOSED
IN MOST PLACES. WATER CONTINUES TO PUSH UP TO THE TOP OF THE BEACH
CAUSING BEACH EROSION. WINDS WERE NOT DIMINISHING AS FAST TODAY
AND...AS SUCH...THE WARNING WAS EXTENDED IN TIME. GUSTS UP TO 30
MPH ARE STILL BEING REPORTED EARLY THIS AFTERNOON BUT THEY WILL
START DIMINISHING THIS EVENING.

HIGH SURF ADVISORY REMAINS IN EFFECT FOR ZONE 201 UNTIL 7 PM
TONIGHT. ANOTHER HIGH SURF ADVISORY REMAINS IN EFFECT FOR ZONE
207...SPECIFICALLY FROM SHISHMAREF WEST...FROM 6 AM SAT UNTIL NOON
SUN. FAVORABLE WIND DIRECTION AND OVER 250 NM OF FETCH WILL BRING
WAVES UP TO 9 FOOT...BREAKING OFFSHORE. A SURGE OF ABOUT 1 FOOT IS
EXPECTED.

&&

.FIRE WEATHER...
NO CONCERNS. MINIMUM RH VALUES WILL REMAIN ABOVE CRITICAL
VALUES...40 PERCENT...SAT-MON EXCEPT FOR PORTIONS OF THE EASTERN
INTERIOR TOMORROW.

&&

.HYDROLOGY...
RIVERS IN THE CHENA BASIN CONTINUE TO RESPOND. CHENA RIVER NEAR
TWO RIVERS CRESTED AND IS NOW STARTING TO DROP...CRESTING AT 20.47
FEET...HIGHER THAN PREVIOUSLY EXPECTED. THE FLOOD ADVISORY FOR
THE CHENA RIVER UPSTREAM OF THE MOOSE CREEK DAM CONTINUES UNTIL 2
PM SAT. THE FLOOD ADVISORY FOR THE SOUTH FORK OF THE KUSKOKWIM
RIVER AND NEARBY SMALL STREAMS/CREEKS IN THE AREA WAS ALLOWED TO
EXPIRE. SPS WAS ISSUED FOR HIGH WATER MOVING DOWN THE KUSKOKWIM
RIVER...WITH MCGRATH SEEING A RISE OF ABOUT 2 FEET AT MCGRATH
TODAY.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
COASTAL FLOOD WARNING FOR AKZ202.

HIGH SURF ADVISORY FOR AKZ201-AKZ207.

WINTER STORM WARNING FOR AKZ206.

WINTER WEATHER ADVISORY FOR AKZ225.

SMALL CRAFT ADVISORY FOR PKZ210-PKZ215-PKZ220-PKZ225-PKZ230-
PKZ235-PKZ245.
&&

$$

ET AUG 15


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