Small Craft Advisory 178, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
240 PM AKDT Sun Oct 29 2017

.SYNOPSIS...
Aloft...
A long wave trough over the eastern Bering Sea will move over
mainland Alaska Mon, and over NW Canada Tue. A long wave ridge
over the western Bering Sea will build over mainland Alaska Tue
and then persist into next weekend. Northern Alaska will remain
much warmer than normal through the weekend as a result. Stormy
conditions with mixed rain, snow and freezing rain will continue
through Mon night with the long wave trough, followed by mainly
dry conditions from Tuesday through Wed. After Wed several strong
short waves troughs will make their way east across northern
Alaska flattening the long wave trough, turning flow westerly,
and bringing periods of mixed rain and snow through the weekend,
with heavy snow possible next weekend.

A short wave trough stretching from Point Hope to Denali will move
east of the Alcan Border this evening. Periods of rain, snow and
freezing rain east of the trough will diminish along the trough
with brief clearing west of the trough. Precipitation will be
generally light east of this feature this afternoon/evening.

Freezing Levels range from the Surface along the souther Brooks
Range and West Coast up to 4000 feet along the Alaska Range and
will remain near those levels into Mon, then fall Mon Night.

Surface...
A 1008 mb low 300 nm northwest of Barrow will move to 200 nm north
of Barrow as a 1014 mb low by 4am Mon, to 300 nm north of
Demarcation Point as a 1016 mb low by 4pm Mon, to Fort McPherson
as a 1015 mb low by 4am Tue, and then continue moving southeast.
An Arctic front stretching from this low to the Bering Strait will
move east to Prudhoe Bay to Point Lay by 4am Mon, to Barter Island
to Point Lay by 4pm Mon, then by 4am Tue to Old Crow to Nuiqsut
to a 1011 mb low 400 nm northwest of Barrow, and by 4pm Tue to
Eagle to Barter Island to a 1015 mb low 300 nm North of Barter
Island with a trailing cold front from Barter Island to Barrow and
west. Expect light snow showers or flurries along the Arctic
front changing to snow along the Cold front on Tue along the
Arctic Coast. Could see several inches of snow Tue along the
Arctic Coast. Will see south to west winds 15 kt with the front
through Mon night, then expect west winds 20-30 kt with the cold
front along the Arctic Coast Tue. Expect Blowing snow and possible
blizzard conditions at Barter Island Tue Pm and Tue night.

A strong low south of Dutch Harbor will move to near Bethel as a
1003 mb low by 4pm Mon, to near Illiamna as a 1020 mb low by 4am
Tue, and to near Cordova as a 1019 mb low by 4pm Tue. This low
will cause downslope winds combined with gap flow winds through
Alaska Range passes to continue tonight. Winds advisory through
Alaska Range passes will continue through early Mon.

An occluded front stretching from this low into Bristol Bay will
move to Emmonak to McGrath by 4am Mon, to Bethel to Tanana to
Denali by 4pm Mon with a warm front from Tanana to Eagle. By 4am
Tue the front will stretch from Illiamna to Denali to Chicken, and
then move to Gulkana to Beaver Creek by 4pm Tue. Expect mixed
rain and snow on the leading edge of the precipitation ahead of
the front, changing to mainly rain south of the front on Mon.
Since the eastern Interior will clear out tonight ahead of the
front and have cooling at the surface to below freezing, expect
freezing rain mixed in early Mon as the precipitation begins.
Will see less than one tenth of an inch of ice on the roads, but
little if any on trees or power lines. In the southwest Interior
could see .50 inch of rain from tonight into Mon. Precipitation
will change back to snow Mon Night most areas as cool advection
works back in from the north and could see 1-2 inches of snow
then.

Roads in the Interior will remain slippery into Tue.

&&

.DISCUSSION...

Models appear to initialize well and show similar solutions most
fields though 4am Tue. By 4pm Tue the GFS and NAM have a much deep
low north of the easter Arctic Coast, and maintain that deeper
center as it moves south over the Mackenzie River on Tue night and
Wed. Favor the GFS after 4am Tue with its deeper surface center.

By the weekend the remains of typhoon Saola have made their way
across Siberia and then will make their way east across northern
Alaska. Since these systems are generally wetter than models
indicate, this could be a big precip maker for next weekend and
will need to be watched.

Coastal Hazard Potential Days 3 and 4...
High Surf possible zone 204 Tue PM into early Wed.
High surf Possible zones 201 202 Thu.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Wind Advisory for AKZ226-AKZ227.

Winter Weather Advisory for AKZ217-AKZ218-AKZ219-AKZ220-AKZ221-AKZ222.

Heavy Freezing Spray Warning for PKZ230-PKZ235.

Small Craft Advisory for PKZ210-PKZ235.
&&

JB OCT 17