High Surf Advisory 8, NWS Fairbanks, AK

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
153 PM AKDT WED SEP 23 2015

.SYNOPSIS...
ALOFT...
LONG WAVE TROUGH ALONG THE ALCAN BORDER WILL PERSIST THROUGH THU
THEN PROGRESS EAST INTO WESTERN CANADA. THE LONG WAVE RIDGE OVER
THE BERING SEA AND WESTERN ALASKA WILL MOVE EAST OVER THE GULF OF
ALASKA AND MAINLAND ALASKA FRI THROUGH THE WEEKEND. THE RIDGE WILL
BE FLAT TOPPED DUE TO A STRONG SHORT WAVE MOVING THROUGH IT ACROSS
NORTHERN ALASKA FROM THU THROUGH SAT. THIS WILL BRING A STORMY AND
WET PATTERN TO NORTHERN ALASKA OVER THE NEXT SEVERAL DAYS.
THE FLAT TOPED LONG WAVE RIDGE WILL PROGRESS SLOWLY EAST NEXT
WEEK ALLOWING COOL AND WET SOUTHEAST FLOW OVER MOST OF NORTHERN
ALASKA NEXT WEEK...THOUGH THE SE INTERIOR WILL SEE NEAR NORMAL AND
DRY WITH CHINOOK CONDITIONS EARLY NEXT WEEK.

A WEAK SHORT WAVE TROUGH OVER THE EASTERN INTERIOR WILL MOVE EAST
OF THE ALCAN BORDER THU PM. SCATTERED SNOW SHOWERS AND CLOUDS
ACROSS THE EASTERN INTERIOR WITH THIS FEATURE WILL DIMINISH THU.

A VERY STRONG SHORT WAVE TROUGH IN EASTERN RUSSIA WILL MOVE INTO
THE CHUKCHI SEA THU PM...TO WAINWRIGHT TO MCGRATH BY 4AM FRI...AND
TO BARTER ISLAND TO TOK BY 4PM FRI. THERE ARE HIGH MOISTURE LEVELS
ASSOCIATED WITH THIS STORM THAT WERE FED IN FROM A FORMER
TROPICAL STORM THAT WILL CAUSE RAINFALL AMOUNTS OF UP TO AN INCH
WITH UP TO ONE FOOT OF SNOW ABOVE 3000 FEET. STRONG DYNAMICS AND
WINDS ALOFT WITH THE TROUGH WILL MIX DOWN TO THE SURFACE AND CAUSE
STRONG GUSTY WINDS. SURFACE DISCUSSION WILL ADD MORE INFO.

SNOW LEVELS AT SURFACE OVER INTERIOR AND 2000-3000 FT ALONG THE
WEST COAST. RISING TO 2-3000 FT WESTERN ARCTIC SLOPE TONIGHT AND
SW INTERIOR...AND TO 2-3000 FT WESTERN INTERIOR THU...CENTRAL
INTERIOR THU NIGHT. BY FRI SNOW LEVEL RISING TO 2-3000 FT IN THE
EASTERN INTERIOR...WHILE FALLING BACK TO THE SURFACE TO THE NORTH
AND WEST.

SURFACE...
A RIDGE OF HIGH PRESSURE STRETCHING FROM THE BEAUFORT SEA TO
BRISTOL BAY WILL WEAKEN THROUGH THU NIGHT.

A 994 MB LOW JUST WEST OF WRANGEL ISLAND WILL MOVE TO 300 NM
NORTHWEST OF BARROW AS A 986 MB LOW BY 4PM THU AND THEN CONTINUE
NORTHEAST. A WEATHER FRONT ASSOCIATED WITH THAT LOW WILL MOVE TO
POINT LAY TO KOTZEBUE TO BETHEL BY 4AM THU...TO WAINWRIGHT TO
GALENA TO ANVIK BY 4PM THU...TO DEADHORSE TO TANANA TO MCGRATH BY
4AM FRI AND TO DEMARCATION POINT TO EAGLE TO DELTA JUNCTION BY
4PM FRI. BELOW 2000 FEET EXPECT .50-1.00 INCH OF RAIN WITH
FRONT...HEAVIEST AMOUNTS SW FACING SLOPES. EXPECT MIXED RAIN AND
SNOW FROM 2000-3000 FEET WITH SEVERAL INCHES WET SNOW. ABOVE 3000
FT EXPECT 6-12 INCHES OF SNOW IN THE CENTRAL AND EASTERN INTERIOR.
WILL ISSUE SPS ABOUT THIS. NOW HAVE SOUTH WINDS 30-40KT ALONG
FRONT IN NW AK. EXPECT SW WINDS 25KT ALONG FRONT ALONG WEST COAST
SOUTH OF THE BERING STRAIT AND AS IT MOVES EAST ACROSS THE
INTERIOR. COULD SEE GUSTS TO 40 MPH ACROSS THE INTERIOR FRI. THIS
WILL BE THE FIRST SIGNIFICANT WINTER STORM ACROSS THE EASTERN
INTERIOR WITH HEAVY SNOW AND BLOWING SNOW OVER SUMMITS.

A SECOND SURFACE LOW WILL DEVELOP AS A 986 MB LOW IN THE CENTRAL
CHUKCHI SEA BY 4PM THU...MOVING TO BARROW AS A 989 MB LOW BY 4PM
FRI...AND TO 200 NM NORTH OF BARTER ISLAND AS A 992 MB LOW BY 4AM
SAT. A TRAILING ARCTIC COLD FRONT WILL MOVE TO THE CHUKCHI SEA
THU...TO WAINWRIGHT TO THE BERING STRAIT BY 4AM FRI...AND TO
BARROW TO TANANA TO THE YUKON DELTA BY 4PM FRI. EXPECT ALL
PRECIPITATION TO CHANGE TO SNOW SHOWERS WITH THIS COLD FRONT.
COULD SEE SEVERAL INCHES OF SNOW WITH THIS FEATURE ALONG NW FACING
SLOPES. EXPECT NW WINDS 30-40 KT WITH THIS FRONT OVER NW AK THU
NIGHT AND FRI AND 15-25 KT WITH IT IN THE INTERIOR.

&&

.DISCUSSION...
MODELS SIMILAR THROUGH 4PM THU THEN START TO SEE SOME SIGNIFICANT
DIFFERENCES. THE GFS TAKES THE LOW IN THE CHUKCHI SEA ON A FURTHER
NORTH TRACK THAN THE NAM AND ECMF. FAVOR THE GFS ON THIS FEATURE.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...
HIGH SURF ZONE 207 KIVALINA TO POINT HOPE TODAY THROUGH FRI AM.
HIGH SURF ZONES 207 AND 209 SHISHMAREF DEERING THU EVENING
THROUGH FRI EVENING.
MINOR COAST FLOOD POTENTIAL ZONE 209 THU EVENING THROUGH FRI
EVENING.
HIGH SURF POTENTIAL ZONES 201 FRI.
MODERATE SURF POTENTIAL ZONE 202 FRI NIGHT AND SAT.

&&

.HYDROLOGY...
.50-1.00 INCH OF RAIN ACROSS MOST OF FORECAST AREAS NEXT SEVERAL
DAYS SO RIVERS WILL RISE THROUGH WEEKEND.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY FOR AKZ201-AKZ207-AKZ210.

COASTAL FLOOD WATCH FOR AKZ209.

SMALL CRAFT ADVISORY FOR PKZ200-PKZ210-PKZ215-PKZ220-PKZ235.

GALE WARNING FOR PKZ225-PKZ230.

&&

JB SEP 15