Small Craft Advisory 229, NWS Fairbanks, AK

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
153 PM AKST THU NOV 19 2015

.DISCUSSION...

AN ACTIVE AND PROGRESSIVE WEATHER PATTERN WILL HIGHLIGHT THE
FORECAST PERIOD. MAIN FORECAST CONCERNS ARE CENTERED AROUND
ONGOING WINTER WEATHER HAZARDS OVER WESTERN AND CENTRAL
ALASKA THROUGH TOMORROW AND THE STRONG CHINOOK OVER THE ALASKA
RANGE ZONES THROUGH TOMORROW MORNING.

THE 19/12Z SUITE OF DETERMINISTIC MODELS ARE IN GOOD AGREEMENT
THROUGH THE FIRST 48 HOURS REGARDING THE OVERALL SYNOPTIC
PATTERN...WITH INCREASING DIFFERENCE/SPREAD IN THE MODELS
THEREAFTER.

ALOFT...THE MAIN WEATHER FEATURE...A VERTICALLY STACKED UPPER
LEVEL LOW OVER ST MATTHEW ISLAND THIS MORNING WILL CONTINUE ITS
TREK NORTHEAST TOWARDS THE WESTERN ALASKA COAST...REACHING NORTON
SOUND THIS EVENING AND THEN MOVING OVER THE SEWARD PENINSULA
OVERNIGHT AND WEAKEN. OUT AHEAD OF THIS LOW...AN UPPER LEVEL RIDGE
RESIDING OVER THE EASTERN HALF OF ALASKA WILL BE PUSHED EAST AND
INTO WESTERN CANADA OVERNIGHT. AS THE AFOREMENTIONED LOW
WEAKENS...A TROUGH OVER EASTERN SIBERIA WILL MOVE EAST AND OVER
THE NORTHERN BERING SEA/BERING STRAIT FRIDAY NIGHT. AN UPPER LEVEL
RIDGE IS PROGGED TO BUILD EASTWARD FROM THE WESTERN BERING SUNDAY
MORNING...THEN SHIFT EAST OVER MAINLAND ALASKA MONDAY AND TUESDAY.
QUICK ON THE HEALS OF THIS RIDGE...ANOTHER UPPER LEVEL LOW WILL
MOVE OUT FROM THE NORTHERN PACIFIC AND INTO THE WESTERN BERING BY
MONDAY NIGHT.

SURFACE...THE SURFACE REFLECTION OF THE AFOREMENTIONED UPPER
LEVEL LOW...A 970 MB LOW OVER ST MATTHEW ISLAND...WILL CONTINUE TO
PROGRESS NORTHEAST TOWARDS TO THE WESTERN ALASKA COAST...AND OVER
NORTON SOUND AS A 983 MB LOW THIS EVENING/TONIGHT AND THEN
WEAKEN...RESULTING IN A BROAD TROUGH OVER MUCH OF NORTHERN ALASKA
THAT WILL REMAIN OVERHEAD THROUGH THE WEEKEND. A 1032 MB HIGH
PRESSURE OVER FAR EASTERN ALASKA AND WESTERN ALASKA WILL BE PUSHED
EASTWARD TONIGHT. A FAST MOVING SURFACE LOW...CURRENTLY OVER THE
NORTHERN PACIFIC...WILL MOVE OVER NIKOLSKI FRIDAY MORNING AND THEN
TRAVERSE THE ALASKA PENINSULA...REACHING SOUTH CENTRAL ALASKA BY
LATE FRIDAY EVENING. ANOTHER LOW IS PROGGED TO MOVE OUT OF THE
NORTHERN PACIFIC AND INTO THE WESTERN BERING LATE SUNDAY THEN MOVE
EAST TOWARDS THE WESTERN ALASKA COAST MONDAY. THIS LOW WILL HAVE
TO BE CLOSELY MONITORED IN FUTURE MODEL RUNS SINCE IT COULD
POSSIBLY BRING ANOTHER ROUND OF WINTER WEATHER HAZARDS AND
POTENTIALLY COASTAL FLOODING ISSUES EARLY NEXT WEEK.

WESTERN ALASKA...ONGOING WINTER WEATHER HAZARDS ARE THE MAIN
FORECAST CONCERN. WINTER STORM WARNINGS FOR ZONES 214 AND 215 HAVE
ALREADY BEEN VERIFIED WITH SNOWFALL REPORTS OF 5 INCHES AT SAINT
MARYS...6 INCHES AT MOUNTAIN VILLAGE...8 INCHES AT SCAMMON BAY AND
ANVIK...AND FINALLY 12 INCHES ESTIMATED AT RUSSIAN MISSION.
SUCCESSIVE IR SATELLITE IMAGES CLEARLY SHOWS THE BACK EDGE OF THE
SNOW...WHICH IS CURRENTLY OVER SOUTHERN ZONE 214...AND SHOULD BE
SEEING THE END OF THE SNOW THIS EVENING. ELSEWHERE...WINTER
WARNINGS LOOK TO BE IN GOOD SHAPE AS 5 TO 8 MORE INCHES OF SNOW IS
STILL EXPECTED TO FALL ACROSS THE WARNED AREA. THERE HAVE BEE
REPORTS OF REDUCED VISIBILITY BELOW ONE HALF MILE DUE TO BLOWING
SNOW AND WINDS ARE CURRENTLY GUSTING INTO THE 30S AT MOST
LOCATIONS. SREF 12-HOUR PROBABILITIES FOR GREATER THAN 6 INCHES OF
SNOW ARE ABOVE 75 PERCENT THIS EVENING FOR ZONES
209...210...211...215...216 AND 217. BLIZZARD WARNING FOR ZONE 213
IS ALSO IN GOOD SHAPE. WINDS ARE GUSTING INTO THE 50S AND A FEW
SITES SUCH AS SAVOONGA ARE REPORTING VISIBILITIES LOWER THAN ONE
QUARTER MILE.

CENTRAL AND EASTERN ALASKA...THE MAIN STORY WILL BE THE STRONG
CHINOOK EVENT...AS WELL AS THE WINTER WEATHER HAZARDS POSTED FOR
THE SOUTHEASTERN BROOKS RANGE...UPPER KOYUKUK VALLEY...AND THE
CENTRAL INTERIOR.

SOUTHERLY WINDS IN THE ALASKA RANGE HAVE BEEN STEADILY INCREASING
THIS MORNING ALONG THE PARKS HIGHWAY IN THE ALASKA RANGE WITH THE
ANTLER CREEK RAWS RECENTLY REPORTING A GUST OF 62 MPH.
HOWEVER...IN ZONE 226...ISABEL PASS AND THE TOK CUTOFF HAVE BEEN
SLOW TO RAMP UP...WITH THE HIGHEST REPORTED GUST OF 47 MPH AT
WASHINGTON RANGE. SOUTHEAST WINDS HAVE BEEN STEADILY INCREASING
FROM DELTA JUNCTION SOUTH...WITH THE MOST RECENT GUST CLOCKED AT
39 MPH. SOUTH TO SOUTHEAST WINDS ARE EXPECTED TO CONTINUE TO
INCREASE THIS AFTERNOON WITH WINDS PEAKING THIS EVENING ALONG THE
PARKS HIGHWAY AND LATE THIS EVENING/EARLY FRIDAY MORNING FOR
ISABEL PASS. THERE IS GOOD SUPPORT ALOFT AS 19/12Z GFS/NAM ARE
CONTINUE TO ADVERTISE 70 TO 80 KTS AT H700 AND H850 ACROSS THE
ALASKA RANGE. HIGH WIND WARNINGS FOR ZONES 223...225 AND 226 ARE
IN GOOD SHAPE AS THEY ARE WITH THE WARNING FOR ZONE 224 BEING
QUESTIONABLE.

REGARDING THE WINTER WEATHER HAZARDS FOR ZONES 218...219 AND
221...MODELS ARE STILL PAINTING ADVISORY/WARNING LEVEL SNOW
AMOUNTS FOR THESE ZONES. SREF 12-HOUR PROBABILITIES FOR 6 INCHES
OR GREATER SNOWFALL AMOUNTS BETWEEN 50 TO 80 PERCENT NEAR TANANA
IN ZONE 221 THROUGH EARLY FRIDAY MORNING...BETWEEN 60 TO 80
PERCENT FROM BETTLES AND ALLAKAKET WEST...AND AROUND 40 PERCENT
WEST OF THE DALTON HIGHWAY IN ZONE 218. WILL KEEP WINTER WEATHER
HAZARDS AS IS WITH 8 TO 12 INCHES FOR ZONE 219 AND 4 TO 7 INCHES
FOR ZONES 218 AND 221.

LOOKING AHEAD...THERE IS THE POSSIBILITY FOR NEAR ADVISORY SNOW...
3 TO 4 INCHES SATURDAY AND SUNDAY FOR THE MIDDLE TANANA VALLEY AS
A SHORTWAVE EMBEDDED IN THE SOUTHWEST FLOW MOVES OVERHEAD.
CONFIDENCE IN TIMING IS LOW AS THERE ARE SLIGHT DIFFERENCES
BETWEEN THE MODELS.

NORTH SLOPE...CLEAR...COLD AND QUIET. SHOULD SEE SOME WARMING
ACROSS THE NORTH SLOPE AS CLOUD COVERAGE INCREASE OVERNIGHT...BUT
OTHERWISE NOT MUCH GOING ON.

.COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FOR AKZ218-AKZ221.

WINTER STORM WARNING FOR AKZ209-AKZ210-AKZ211-AKZ212-AKZ214-
AKZ215-AKZ216-AKZ217-AKZ219-AKZ227.

BLIZZARD WARNING FOR AKZ213.

HIGH WIND WARNING FOR AKZ223-AKZ224-AKZ225-AKZ226.

SMALL CRAFT ADVISORY FOR PKZ200-PKZ215-PKZ225.

HEAVY FREEZING SPRAY WARNING FOR PKZ210-PKZ220-PKZ225.

BRISK WIND ADVISORY FOR PKZ230.

GALE WARNING FOR PKZ210-PKZ215-PKZ220-PKZ225.
&&

LTH NOV 15