Small Craft Advisory 146, NWS Fairbanks, AK

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
609 AM AKDT THU SEP 24 2015

.DISCUSSION...

UPPER LEVELS...
A LONG WAVE TROUGH ALONG THE ALCAN BORDER WILL REMAIN STATIONARY
THROUGH THIS EVENING THEN WEAKEN AS IT IS PUSHED EASTWARD INTO
NORTHWESTERN CANADA. A RIDGE EXTENDING FROM NORTON SOUND
NORTHEASTWARD INTO THE EASTERN BEAUFORT SEA WILL RAPIDLY DAMPEN
OUT AS IT MOVES TO THE EASTERN INTERIOR BY LATE TONIGHT. A STRONG
UPPER LOW CENTERED ABOUT 500 MILES WEST OF CAPE LISBURNE WILL MOVE
TO NEAR CAPE LISBURNE BY LATE THIS EVENING...AND TO NEAR OLD CROW
BY MIDNIGHT FRIDAY NIGHT...WITH A SECOND UPPER LOW DEVELOPING
ABOUT 150 MILES NORTH OF DEADHORSE. THE SOUTHERN LOW WILL MOVE
EASTWARD INTO NORTHWEST CANADA FRIDAY NIGHT WHILE THE NORTHERN LOW
OPENS UP INTO A TROUGH. THIS WILL LEAVE A WESTERLY FLOW ALOFT OVER
NORTHERN ALASKA WHICH SHOULD LAST THROUGH SATURDAY NIGHT. A SURGE
OF MOIST WESTERLY FLOW ACROSS THE THE SOUTHERN PARTS OF THE
NORTHERN INTERIOR WILL BRING SIGNIFICANT RAIN AND SNOW LATE
TONIGHT THROUGH FRIDAY. ADDITIONAL DETAILS WILL FOLLOW IN THE
SURFACE SECTION OF THIS DISCUSSION. A SHORT WAVE RIDGE WILL MOVE
EASTWARD ACROSS THE NORTHERN ALASKA SUNDAY INTO SUNDAY
EVENING...WHICH WILL BE FOLLOWED BY A STRONG LONG WAVE TROUGH
WHICH WILL EXTEND FROM THE NORTHWEST COAST TO THE NORTHERN GULF OF
ALASKA BY TUESDAY. CURRENT OPERATIONAL MODEL RUNS ARE SIMILAR ON
THE MAJOR FEATURES THROUGH MONDAY AFTERNOON...WITH THE GFS
AGREEING WELL WITH THE GEFS ENSEMBLE MEAN. BY TUESDAY
AFTERNOON...THE ECMWF MOVES THE SOUTHERN END OF THE DEEP LONG WAVE
TROUGH A LITTLE SLOWER THAN THE GFS.

SURFACE...
A 986 MB LOW CENTERED ABOUT 250 MILES NORTHWEST OF WAINWRIGHT
WILL WEAKEN TO A 998 MB CENTER 400 MILES NORTH OF CAPE LISBURNE
BY THURSDAY EVENING...THEN OPEN UP INTO A TROUGH. A 987 MB LOW
WILL DEVELOP ABOUT 125 MILES WEST OF POINT LAY THIS AFTERNOON...THEN
WEAKEN TO A 989 MB CENTER ABOUT 50 MILES SOUTH OF WAINWRIGHT BY
FRIDAY MORNING. THIS LOW WILL DISSIPATE FRIDAY AFTERNOON AS A NEW
992 MB LOW DEVELOPS OVER THE CENTRAL BEAUFORT SEA JUST NORTH OF
THE ARCTIC COAST. THIS LOW WILL WEAKEN INTO A TROUGH OVER THE
EASTERN BEAUFORT SEA BY SATURDAY MORNING. PRECIPITATION OVER THE
WEST COAST AND NORTHWEST ALASKA THIS MORNING...SPREADING INTO
TO THE WESTERN TWO THIRDS OF THE INTERIOR AND ARCTIC SLOPE
THROUGH TONIGHT...AND THE EASTERN INTERIOR THROUGH FRIDAY.

CURRENT GFS/NAM MODELS INDICATING ABOUT 0.4-0.5 INCH OF LIQUID
EQUIVALENT PRECIPITATION IN ZONE 222 AND EASTERN ZONE 221 LATE
TONIGHT THROUGH FRIDAY. SOMEWHAT HEAVIER AMOUNTS ARE INDICATED
BURST OF SNOW IN ZONES 221-222...WITH MOST OF THE SNOWFALL
EXPECTED TO OCCUR BETWEEN 4 AM AND NOON FRIDAY. WITH TEMPERATURES
NEAR FREEZING...THE SNOW WILL BE WET WITH SNOW RATIOS LESS THAN
10:1.

MAJOR WEATHER...
ZONE 222...2 TO 5 INCHES OF SNOW. SNOW MAY BECOME MIXED WITH RAIN
 AT LOWER LEVELS THIS AFTERNOON. MOST OF THE SNOW WILL
 OCCUR LATE TONIGHT AND FRIDAY MORNING. WEST WINDS 20 TO 30 MPH
 THIS AFTERNOON AND TONIGHT...WITH GUSTS TO 40 MPH OVER HIGHER
 SUMMITS. THERE IS LITTLE OR NO COLD ADVECTION WITH THIS
 EVENT...AND RELATIVELY SMALL PRESSURE RISES...THESE FACTORS
 SHOULD PROVIDE SOME MITIGATION OF MAXIMUM WIND GUSTS. WHILE
 WINDY CONDITIONS ARE EXPECTED...IT IS NOT LIKELY TO BE A MAXIMUM
 WIND EVENT. NEVERTHELESS...GUSTY WINDS MAY DOWN SOME TREES AND
 CAUSE SOME POWER OUTAGES.

SOUTHEASTERN ZONE 221 INCLUDING AREAS ALONG THE PARKS
 HIGHWAY...3 TO 5 INCHES OF SNOW LATE TONIGHT THROUGH
 FRIDAY. MOST OF THE SNOW WILL OCCUR LATE TONIGHT
 FRIDAY MORNING.

ZONE 225...5 TO 10 INCHES OF SNOW EXPECTED ABOVE 3000 FT
 LATE TONIGHT THROUGH FRIDAY.

ZONE 227...5 TO 10 INCHES OF SNOW EXPECTED IN AREAS NEAR
 THE ALASKA RANGE ABOVE 3000 FT LATE TONIGHT THROUGH
 FRIDAY.

ZONE 205...ABOUT 2 INCHES OF SNOW EXPECTED FRIDAY.

ZONE 206...ABOUT 3 INCHES OF SNOW EXPECTED FRIDAY.

ZONE 207...STRONG SOUTH WINDS TODAY. STRONG NORTHWEST WINDS
 FRIDAY.

ZONE 208...STRONG SOUTHEAST WINDS TODAY.

ZONE 209...STRONG WEST WINDS FRIDAY. COASTAL FLOODING THIS
 EVENING THROUGH FRIDAY EVENING.

ZONE 210...STRONG WEST WINDS FRIDAY.

ZONE 216...2 TO 4 INCHES OF SNOW EXPECTED THIS AFTERNOON AND
 TONIGHT.

ZONE 217...2 TO 4 INCHES OF SNOW EXPECTED TONIGHT THROUGH FRIDAY.

COASTAL HAZARD POTENTIAL...

CHUKCHI SEA COAST FROM POINT HOPE TO KIVALINA...HIGH SURF
 CONDITIONS TODAY THROUGH FRIDAY MORNING.

NORTHERN SEWARD PENINSULA COAST IN ZONES 207 AND 210 FROM
 SHISHMAREF TO CAPE ESPENBERG AND FROM DEERING TO
 KIWALIK...HIGH SURF CONDITIONS THIS EVENING THROUGH FRIDAY
 EVENING.

ZONE 209...COASTAL FLOODING WILL BE POSSIBLE THIS EVENING THROUGH
 FRIDAY EVENING...MAXIMUM STORM SURGE OF 2 TO 3 FEET IS EXPECTED
 EARLY FRIDAY MORNING.

ZONE 201...HIGH SURF CONDITIONS EXPECTED TO DEVELOP FRIDAY AND
 CONTINUE INTO FRIDAY EVENING ZONE 202...MODERATE SURF CONDITIONS
 POSSIBLE FRIDAY NIGHT AND SATURDAY.

&&

.HYDROLOGY...
NONE.

&&

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

COASTAL FLOOD WATCH FOR AKZ209.

WINTER WEATHER ADVISORY FOR AKZ221-AKZ222-AKZ225-AKZ227.

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

GALE WARNING FOR PKZ220-PKZ225-PKZ230.
&&

RF SEP 15