Winter Storm Warning 24, NWS Fairbanks, AK

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
606 AM AKST TUE NOV 17 2015

.DISCUSSION...
MAIN CONCERNS THIS FORECAST PACKAGE WERE IN THE NEAR-TERM AND IN
THE WED-FRI TIME FRAME. PORTIONS OF NORTHERN AK WILL HAVE TO
CONTEND WITH LOW CEILINGS...FOG...AND LIGHT SNOW SHOWERS OR
FLURRIES IN THE NEAR-TERM. FOR THE LATTER PERIOD...THERE IS THE
POTENTIAL FOR A WINTER STORM AND VARIOUS WEATHER HAZARDS. A
SPECIAL WEATHER STATEMENT WAS ISSUED FOR PORTIONS OF THE WEST
COAST THAT INCLUDES ZONES 212...214...215...216...AND 227 BECAUSE
OF THE POTENTIAL FOR SIGNIFICANT IMPACTS.

00Z DETERMINISTIC MODEL SUITE IS SHOWING BETTER AGREEMENT AND
CONSISTENCY FURTHER OUT IN TIME COMPARED TO YESTERDAY\S GUIDANCE
WITH RESPECT TO THE LARGE SCALE PATTERN. DIFFERENCES IN
PHASE/LOCATION ARE NOT AS LARGE AS SEEN IN PREVIOUS RUNS EARLY ON
ALTHOUGH THERE ARE SOME DIFFERENCES IN AMPLITUDE/STRENGTH WITH
SYNOPTIC FEATURES. 00Z MODELS ARE IN FAIR AGREEMENT THROUGH
AROUND 54-60 HRS BEFORE DIFFERENCES BECOME MORE APPARENT IN
STRENGTH AND LOCATION.

.ALOFT...LONGWAVE TROUGH STILL IN PLACE OVER NORTHERN AK. THE 500
HPA PATTERN WILL BECOME MORE PROGRESSIVE STARTING TONIGHT AS WE
TRANSITION TO A WESTERLY FLOW. NOTABLY...MULTIPLE SHORTWAVE RIDGES
AND TROUGHS WILL MOVE EAST RESULTING IN A RIDGE BUILDING OVER
NORTHERN AK BY EARLY THU WITH A STRONG LOW OVER THE EASTERN BERING
SEA. THE 500 HPA LOW WILL BEGIN TO WEAKEN AND LIFT OVER THE
NORTON PENINSULA BY EARLY FRI AS THE RIDGE SHIFTS OVER SE AK INTO
THE YUKON.

.SURFACE...A WEAK 1008 MB LOW IS LOCATED NEAR NUNIVAK ISLAND EARLY
THIS MORNING AND IT WILL BE ABSORBED THIS AFTERNOON WHILE MOVING
SOUTHEAST BY A LOW IN THE WESTERN HALF OF THE BERING SEA. THIS
AFOREMENTIONED LOW WILL THEN MOVE INTO THE NORTHEAST BERING SEA
EARLY WED AT ABOUT 993 MB. MODELS ARE SHOWING SOME DISCREPANCIES
AT THIS POINT WITH RESPECT TO THE LOW\S LOCATION AND ITS FRONTAL
BOUNDARY WED...HOWEVER...MODELS ARE IN GOOD AGREEMENT IN REGARD
TO ITS OVERALL PROGRESSION. SPECIFICALLY...THE LOW WILL WEAKEN
INTO A TROUGH AS A STRONGER LOW DEVELOPS JUST EAST OF KAMCHATKA
WED. THIS STRONGER LOW WILL MOVE TO THE PRIBILOF ISLANDS AT 974 MB
BY THU MORNING. THERE IS UNCERTAINTY PRESENT IN THE DETAILS WITH
RESPECT TO THE LOCATION AND OVERALL TIMING OF THIS LOW...FRONTAL
BOUNDARY...AND AXIS OF HEAVIEST PRECIP. MODELS ARE IN FAIR
AGREEMENT WITH THE LOW MOVING EASTWARD OVER THE YUKON DELTA BY
EARLY FRI MORNING.

ELSEWHERE...HIGH PRESSURE WILL PERSIST ACROSS THE ARCTIC COAST AND
SPREAD INTO THE WESTERN AND CENTRAL INTERIOR TODAY. HIGH PRESSURE
WILL CONTINUE TO BUILD AND A 1023 MB HIGH WILL BE OVER INTERIOR
AK BY THE END OF TONIGHT. A TROUGH WILL THEN DEVELOP AND DEEPEN
OVERNIGHT FROM THE BERING STRAIT THROUGH THE CHUKCHI SEA FROM THE
PREVIOUSLY MENTIONED 993 MB LOW THAT IS MOVING INTO THE NORTHEAST
BERING SEA EARLY WED. THE TROUGH WILL STRENGTHEN WED THROUGH THU
AS A STRONG CYCLONE MOVES INTO THE NORTHEAST BERING SEA LATE WED.
MEANWHILE...THE SURFACE HIGH WILL PUSH EASTWARD AND BE OVER THE
CENTRAL YUKON BY TOMORROW NIGHT. INTERIOR AK WILL THEN BE IN
POSITION BETWEEN A STRONG LOW NEAR HOOPER BAY AND A 1030 MB HIGH
NEAR THE YUKON/NORTHWEST TERRITORIES BY THURSDAY AFTERNOON.

INTERIOR AK WILL CONTINUE TO SEE FLURRIES TODAY AND OVERNIGHT. THE
MAIN CONCERN THIS FORECAST PACKAGE IS THE POTENTIAL FOR MODERATE
TO HEAVY SNOW AND BLOWING SNOW IN THE SOUTHERN HALF OF THE WEST
COAST DOMAIN. THERE IS GROWING CONFIDENCE IN PERIODS OF MODERATE
TO HEAVY SNOW WEDNESDAY THROUGH LATE THURSDAY. TOTAL SNOWFALL
AMOUNTS EXCEEDING 8 TO 10 INCHES WILL BE POSSIBLE IN THE WED TO
LATE THU TIME PERIOD. SPECIFICALLY...THIS WILL BE FROM THE YUKON
DELTA...TO THE LOWER YUKON VALLEY...TO THE UPPER KUSKOKWIM VALLEY.
ELSEWHERE...GROWING CONFIDENCE IN THE NULATO HILLS AND SOUTH AND
WEST OF GALENA IN THE MIDDLE YUKON VALLEY TO SEE TOTAL SNOWFALL
AMOUNTS OF 4 TO 8 INCHES. THE OTHER HAZARD WILL BE BLOWING
SNOW...AS THE SNOW COMBINES WITH GUSTY WINDS. GUSTS EXCEEDING 25
MPH AT TIMES ARE ANTICIPATED DURING THIS PERIOD. THE WINDOW FOR
THE HEAVIEST SNOWFALL IS EXPECTED TO BE THURSDAY MORNING THROUGH
THURSDAY EVENING.

LASTLY...THU INTO FRI CONFIDENCE IS GROWING IN A MODERATE CHINOOK
EVENT THAT WILL PRODUCE GUSTY WINDS THROUGH THE NORTH SLOPES OF
THE ALASKA RANGE. SPECIFICALLY...ALONG THE RICHARDSON AND PARK
HIGHWAYS. SUPPORT WILL BE SUFFICIENT ALOFT AS 700 MB WINDS WILL BE
45 TO 65 KTS AT THIS TIME AND AT A FAVORABLE DIRECTION COMPARED TO
THE MOUNTAIN BARRIER. THIS TIME FRAME WILL HAVE TO BE WATCH AS WE
GET CLOSER FOR POSSIBLE WIND HAZARD PRODUCTS.

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

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
HEAVY FREEZING SPRAY WARNING FOR PKZ200-PKZ210-PKZ220-PKZ225-
PKZ230.

SMALL CRAFT ADVISORY FOR PKZ210-PKZ220-PKZ225.

GALE WARNING FOR PKZ210.
&&

ET NOV 15