Gale Warning 105, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
207 PM AKDT Wed Oct 11 2017

.SYNOPSIS...
A long wave ridge is building tonight over mainland Alaska as a
high amplitude trough over the Western Bering Sea and northwest
Pacific moves slowly east. The trough will expand to cover the
Bering Sea Thu and then expand over mainland AK Fri and Sat as a
short wave moves over mainland AK from the west and another drops
over mainland AK from the NE. This long wave will then deepen from
the weekend into next week causing winter to finally descend over
northern Alaska.

A short wave trough from Deadhorse to Northway will move east of
the Alcan Border about midnight. Snow showers along and east of
the trough will taper off along the trough with break in the
clouds to the west. Expect less than 1 inch of snow with this.

Surface...
A 1025 mb high north of the Arctic Coast will persist through
Fri. This is causing stratus and fog along the arctic coast that
will persist through Fri. This will also cause east winds to
increase Thu and Fri as low pressure approaches from the south.

An Arctic Front that stretches from Northway to Arctic Village to
Point Lay will move to Northway to Denali to Point Lay by 4am Thu,
to Northway to Anaktuvuk pass to POint Lay by 4pm Thu, then to
Eagle to Arctic Village to Wainwright by 4am Fri. Precip will be
mostly snow along and north of this front, and mostly rain south
of this front (below 2000 feet).

A 952 mb low in the western Bering Sea will has an occluded front
from the low to south of Cape Navarin to Adak. By 4am Thu it will
be a 949 mb low 200 nm south of Cape Navarin with the front from
the low to the Bering Strait to Cape Romanzof. By 4pm Thu it will
be a 957 mb low near Cape Navarin with a from the low to just
south of Wrangel Island to Point Hope to Anvik. By 4am Fri it will
be a 968 mb low near Anadyr with the front from the low to north
of Wrangel Island to POint Lay to Denali. By 4pm Fri it will be a
975 mb low 80 nm north of Anadyr with the front from North of
Wrangel Is to Umiat to Arctic Village to Northway. After that the
low will weaken in place while the front will stretch east and
weaken.

This is a wet and warm system that will spread rain inland 100-200
miles ahead of of the front and change to showers west of the
front. Expect 0.75 to 1.5 inches of liquid with this front over
the west coast and western Interior tonight through Thu night. In
the Central Interior could see .25 to .50 inch liquid with lesser
amounts tot he east. Could see snow mix with rain at outset of
precipitation, but expect mainly rain in valleys. Above 2000 feet
could see 3-5 inches of snow which will affect the Dalton,
Elliott and Steese Highways Thu night and Fri, as well as the
Parks and Richardson highways in the Alaska Range. Will issue SPS
for that.

Main concern with this low is the wind. Southeast gales of 40-50kt
will occur over the Bering Sea, southern Chukchi Sea and West
Coast tonight just ahead of the front. Winds will turn south 30-40
kt Thu, then will see south-southwest winds 40g60 kt in the
poison tail portion of the front which will lie in the SE quadrant
of the low Thu just south of St Lawrence Is, by Thu night from
the Bering Strait to the Yukon Delta, and by Fri from Point Hope
to Kotzebue. Winds gusting to 60kt occurred today in the poison
tail portion as it moved over Shemya. These strong south to
southwest winds Thu night and Fri are what will cause the highest
water levels most areas. Have upgraded to Coastal Flood watches
zones 213 211 212 and 214, and issued high surf for zones 207 and
209. Will likely see elevated surf in all these areas from late
tonight into Thu with the strong SE winds accompanying the front.

&&

.DISCUSSION...
Deterministic models initialize about 7 mb too weak on sea level
pressure of the strong low in the western Bering Sea, but models
indicate rapid deepening today which should lead to closer to the
correct pressure by tonight. Otherwise models show similar
solutions through 4pm Fri. Will address sea level pressure
difference by adding 5 kt of wind to the area near the low
through tonight especially in the poison tail section of the low,
then 3 kt after that time as expect models SLP and wind speeds to
be closer to what they should be. After 4pm Fri models start to
see differences on timing and strength of short waves Fri night
and Sat. At this time, will use GFS for Fri night and Sat.

Coastal Hazard Potential Days 3 and 4...Water levels will still be
high with hi surf along the west Coast on Fri. Water levels should
receed Sat as winds decrease. No issues for Sun.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Coastal Flood Warning for AKZ211-AKZ212-AKZ213-AKZ214.

High Surf Advisory for AKZ207-AKZ210.

High Wind Warning for AKZ207-AKZ209-AKZ213.

Small Craft Advisory for PKZ225-PKZ230-PKZ235-PKZ240-PKZ245.

Gale Warning for PKZ200-PKZ210-PKZ215-PKZ220-PKZ225-PKZ230.
&&

JB OCT 17