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FXAK69 PAFG 162346
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
246 PM AKST Fri Nov 16 2018

.SYNOPSIS...
Aloft...
The long wave pattern consists of a trough over the Bering and NW
Pacific and a ridge over the Eastern Pacific and Eastern Alaska.
This pattern has several strong short waves moving NE across the
Bering Sea and mainland Alaska, causing the pattern to become
progressive today through Tue with the trough moving over mainland
AK by Mon night and Tue. The generally south flow aloft through
Sun will cause warm air to spread over most of northern AK this
weekend, and bring mixed precip to most the West Coast and SW
Interior south of the Bering Strait and Shageluk, with a slight
chance of mixed precip in the rest of the southern Interior.

Moderate chinook winds over the Alaska Range today will taper off
tonight. The chinook winds will redevelop Sat night and Sun, then
weaken again Sun night and Mon. This will prevent precip other
than very light amounts over the Central and Eastern Interior
north of the Alaska Range until Mon when the Chinook Drops off.
Temperatures will cool with snow becoming more likely south of
the Brooks Range Mon and Tue.



Surface...
A ridge north of the Arctic Coast of Alaska will slowly weaken
Sat and Sun. This is causing east winds along Arctic Coast along
with stratus, fog and flurries which will persist through the
weekend with the winds increasing tonight.

An arctic front that lies from Yakutat to Illiamna to Hooper Bay
to Gambell will move to Mentasta to Denali to Aniak to Nome- to
the Bering Strait by 3am Mon, persist int place through 3am Sun,
and then move to Chisana to Denali to McGrath to Hooper Bay by 3pm
Sun, then move back south of the Alaska Range Mon. Precip that
occurs along the front will be a mix of freezing rain and snow,
while precip north of the front will be a mix of sleet, snow, and
a chance of freezing rain. Where precip is likely we will issue a
winter weather advisory for mix precip and freezing rain now
through Sat night including zones 211, 212, 214, 215, 225 and 226.

A 999 mb low 150 nm southwest of Gambell will move to 200 nm south
of Gambell by 3am Sat then slowly weaken. An occluded front
stretching from the low to the southern Chukchi Sea to Nome to
Bethel will move by 3am Sat to just west of Point Hope to White
Mountain to Bethel, and then remain quasi-stationary through Sun
as several waves moves north along the front. The precip will
increase with each frontal wave and then decrease following the
waves. This will bring snow to zones 201,207, 208 209 210, a mix
of rain and snow to zone 213, a mix of snow rain and freezing
rain to zones 211 214, and a mix of snow, freezing rain, and
sleet to zones 212 and 214, with a chance of sleet, snow and
freezing rain in the remainder of the southwest Interior.
Could see several inches of snow over NW AK from this front, and
will likely see only 1-2 inches of snow over southwest AK with
less than 0.10 ice accumulation in the areas that get freezing
rain. Have issued

A 993 mb low south of Kodiak will move to near Denali as a 1000 mb
low by 3am Sun, and to near Fairbanks as a 996 mb low by 3pm Sun.
An occluded front stretching east from this low will over ride the
arctic front Sat and move to Denali to Eagle by 3pm Sat, to Denali
to Circle by 3am Sun and then dissipating in place. This will
bring freezing rain and snow to the Alaska Range Sat/Sun with a
slight chance north of the Alaska Range Sat and Sun.

A strong low in the Western Aleutians will move to south of Cold
Bay on Sat, to near Kodiak Sun, and to near Denali Mon. This will
bring snow to the Eastern Interior and a chance of freezing rain
to the southeast Interior Sun night and Mon. Could see several
inched of snow with this.


&&

.DISCUSSION...
Models initialize ok aloft and show similar solution through Sun.
By Sun night the GFS is faster moving short waves and the long
wave trough northeast across Mainland AK. Favor the faster GFS
solution as the progressive pattern with numerous strong short
waves pushing east that is now developing favors this faster
solution.

At the surface, at 15z all models initialize 8 mb too weak with
the high pressure located over the Yukon Territory, and about 4 mb
too weak with the high pressure located over the Chukotsk
Peninsula. This is leading to much stronger easterly drainage
winds across the Tanana and Yukon Rivers, and Nenana River Near
Denali Park, than models indicate, and across easterly drainage
areas across all of the area south of the Brooks Range such as the
Kobuk Valley and the Unalakleet River. Winds are 5-10 kt stronger
than models indicate in these areas, and will likely remain much
stronger in these easterly drainage areas through tonight and
possibly into Sat.


Coastal Hazard Potential Days 3 and 4...Mainly off shore flow
along the West Coast and Arctic Coast through Tue. North winds
over Zone 213 Sun through Tue will cause slightly elevated surf
for zone 213 Sun through Tue, but nothing extreme.


&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Wind Advisory for AKZ225.

Winter Weather Advisory for AKZ211-AKZ212-AKZ214-AKZ215-AKZ225-
AKZ226.

Heavy Freezing Spray Warning for PKZ215-PKZ220-PKZ230-PKZ235.

Small Craft Advisory for PKZ200-PKZ215-PKZ220-PKZ225-PKZ230.

Brisk Wind Advisory for PKZ235-PKZ240-PKZ245.
&&

$$

JB NOV 18
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