Blizzard in Alaska, December 18, 2015

NORTHERN ALASKA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FAIRBANKS AK
419 AM AKST FRI DEC 18 2015

.SYNOPSIS...
ALOFT...
THE LONG WAVE PATTERN NOW CONSISTS OF RIDGE OVER WESTERN CANADA
AND EASTERN ALASKA WITH A DEEP LONG WAVE TROUGH OVER THE WESTERN
BERING SEA AND NW PACIFIC. THE PATTERN IS PROGRESSIVE WITH THE
TROUGH MOVING EAST OVER MAINLAND ALASKA OVER THE WEEKEND AND THEN
DEEPENING NEXT WEEK. THIS MEANS THAT CONDITIONS WILL REMAIN
WARMER AND WETTER THAN OVER NORTHERN ALASKA THROUGH THE
WEEKEND...FOLLOWED BY THEN A COOLING AND DRYING TREND NEXT WEEK
WITH TEMPERATURES FALLING BELOW NORMAL.

THE SOUTHWEST FLOW PATTERN WILL ALLOW SEVERAL SHORT WAVES TO MOVE
NORTHEAST ACROSS NORTHERN ALASKA THROUGH THE WEEKEND.

THE FIRST SHORT WAVE LIES FROM POINT LAY TO MINCHUMINA WILL MOVE
TO ANAKTUVUK PASS TO NORTHWAY BY 3PM FRI AND TO NORTH OF BARTER
ISLAND EAST BY 3AM SAT. MID-LEVEL CLOUDS OVER THE EASTERN INTERIOR
AND EASTERN NORTH SLOPE NORTH OF A NENANA TO NORTHWAY LINE WILL
PROVIDE THE MOISTURE FOR THIS SHORT WAVE TO LIFT AND CAUSE LIGHT
SNOW. COULD SEE ANOTHER INCH OF SNOW OVER ZONE 220 TODAY. WILL SEE
SNOW ENDING AND CLOUDS DECREASING SW OF THE TROUGH.

A SECOND SHORT WAVE IS PART OF THE VERY STRONG VERTICALLY STACKED SYSTEM
NOW IN THE WESTERN BERING SEA THAT WILL MOVE INTO SW ALASKA SAT
AND INTO THE WESTERN INTERIOR SUN. THIS WILL BE ADDRESSED IN THE
SURFACE SECTION BELOW.

850 MB TEMPERATURES RANGE FROM -10C TO -16C. TEMPERATURES WARM 2C
SOUTHERN INTERIOR AND SW ALASKA TODAY AND WARM ANOTHER FEW DEGREES
C OVER THE SOUTHERN INTERIOR TONIGHT AND SAT WHILE THE NORTH SLOPE
COOLS SEVERAL DEGREES TONIGHT AND SAT. THIS MEANS SURFACE TEMPS
WILL RISE SOME SOUTH OF THE ARCTIC CIRCLE THROUGH SAT...WHILE
NORTH OF CIRCLE WILL SEE LITTLE CHANGE TODAY AND THEN COOLING SAT.

SURFACE...
A 940 MB LOW IN THE WESTERN BERING WITH A VERY STRONG OCCLUDED
FRONT STRETCHING EAST TO A TRIPLE POINT IN THE SOUTHEAST BERING
SEA WILL MOVE BY 3PM FRI TO THE CENTRAL BERING AS A 942 MB LOW
WITH ITS FRONT STRETCHING FROM THE NORTHERN BERING SEA TO CAPE
ROMANZOF TO KING SALMON. BY 3AM SAT THERE WILL BE A 950 MB LOW
JUST SOUTH OF ST MATTHEW ISLAND WITH A FRONT FROM THE LOW TO
GAMBELL TO ST MICHAEL TO ILIAMNA. BY 3PM SAT IT WILL BE A 962 MB
LOW NEAR NUNIVAK ISLAND WITH A FRONT STRETCHING FROM THE LOW TO
THE BERING STRAIT TO MCGRATH. BY 3AM IT WILL BE A 972 MB LOW NEAR
BETHEL WITH A FRONT FROM THE LOW TO THE BERING STRAIT TO
TALKEETNA. THE LOW WILL MOVE EAST SUN WITH THE FRONT WEAKENING
OVER THE WESTERN AND CENTRAL INTERIOR.

THERE ARE EAST WINDS 50KT JUST NORTH OF THE FRONT OVER THE BERING
SEA NOW THAT WILL SPREAD NE WITH THE FRONT. EXPECT WINDS OF 40 MPH
WITH THE FRONT ALONG THE WEST COAST SOUTH OF THE BERING STRAIT BUT
WILL STILL HAVE UP TO 50 KT OVER ST LAWRENCE ISLAND. WINDS ALONG
THE FRONT WILL DECREASE TO 25KT NORTH OF THE BERING STRAIT AND
INLAND EXCEPT FOR GUSTS 35 KT ALONG CHANNELED AREAS. THERE WILL
BE SUBSTANTIAL BLOWING SNOW WITH THE FRONT WITH BLIZZARD OR NEAR
BLIZZARD CONDITIONS ALONG THE COAST WITH THE FRONT. WILL ADD
WINTER WEATHER ADVISORY FOR ZONE 211 FOR THIS AFTERNOON AND
TONIGHT.

EXPECT 2-4 INCHES OF SNOW ALONG THE FRONT...BUT COULD SEE 4-6
INCHES ZONES 215 AND WILL ADD AN ADVISORY THERE.

.DISCUSSION...
LOW IN WESTERN BERING SEA INITIALIZED AT 940 MB AT 06Z WHICH IS
DEEPER THAN ANY MODEL INITIALIZATIONS SHOWED AT 06Z. SINCE GFS
AND MAINTAINS THE LOWEST DEPTH ON THAT FEATURE PREFER THE GFS
SOLUTION THROUGH SUN.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FOR AKZ213.

WINTER WEATHER ADVISORY FOR AKZ211-AKZ214-AKZ215.

HEAVY FREEZING SPRAY WARNING FOR PKZ210.

GALE WARNING FOR PKZ200.

STORM WARNING FOR PKZ210.

BRISK WIND ADVISORY FOR PKZ220-PKZ225.
&&

JB DEC 15