Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 212134
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
134 PM AKDT Mon May 21 2018

.DISCUSSION...

Synopsis...More seasonal weather with showers developing across
the Interior during the afternoon and evening hours. Thunderstorm
activity will be limited the next couple days, but expect as least
a few to pop up during the day. Another weather front will swing
northwest into the interior tonight spreading showers to the area
mainly south and east of Ruby. The Arctic remains quiet with low
stratus ceilings. Trough over the West Coast will continue to
produce some isolated showers. Breakup has moved to the Lower
Yukon, see below for details.

Models...Not a lot of change from yesterday, the surface
solutions initialized well against the 21/18Z analysis. Stability
indicies once again are not great, but there is still some Lifted
Indicies around zero in the Upper Kuskokwim Valley, and along the
AlCan Border, along with some none zero CAPE. Going with a similar
approach as yesterday and going to use use an equal blend for
most elements with a strong lean toward continuity since there are
no significant changes expected.

Aloft...At 500 hpa...Broad trough over the state with a 522 dam
center 250 nm southeast of Kodiak Island. A 537 dam center will
develop over Huslia this evening. the primary center will weaken
to 532 dam by Tuesday afternoon while a 540 dam center will
develop over Eagle, and a 535 dam center will move out of Siberia
over the Chukotsk Peninsula. A weak ridge will stick its nose up
over the Eastern Bering Sea tonight, and over the southwest
mainland Tuesday afternoon, pushing northeast over the Alaska
Range Tuesday night with a 544 dam center over Denali. A 548 dam
center over the Eastern Arctic/Beaufort Sea will persist merging
with a 549 dam center over the Siberian Arctic. As the centers
merge the center over the Eastern Arctic moves to 200 nm north of
Point Barrow. By Wednesday morning the 544 dam center over Denali
will merge with ridging over the Yukon Territory, and the Ridging
over the Arctic. At 850 hpa...Zero Isotherm has pushed north and
west over all but the Northwest Arctic Coast. Expect it to push
back northwest over the coast by Thursday morning. The Zero
isotherm will be push south to the Brooks Range this weekend.

Surface...High pressure persisting over the Arctic with a 1025 mb
center and the axis along 78N. Broad area of low pressure over
the state with a 986 mb low 100 nm southeast of Kodiak Island and
a trough that extends north to a 993 mb low near McGrath, a 993 mb
low near Nenana, and 991 mb low near Delta Junction, and 993 mb
low Beaver Creek YT. A bubble high has pushed northwest over the
Copper River Basin, and a 999 mb low has developed in Kotzebue
Sound. By Tuesday afternoon the low southeast of Kodiak will
weaken to 1002 mb and troughing will lie from a 1003 mb low near
Dillingham to a 998 mb low near Stevens Village to 996 mb low east
of Chalkyitsik. High pressure over the Copper River Basin will
push northwest over the Alaska Range. Not much change by Wednesday
morning as the low near Kodiak continues to weaken before
eventually merging with a low that will be moving through across
the southern Bering Sea. The high pressure over Southcentral and
the Alaska Range will persist, and thermal trough will be over the
Upper Yukon Flats.

Arctic Coast and Brooks Range...The stratus story continues as
spring in the Arctic continues. The 21/2000Z GOES MVFR/IFR/LIFR
Probability products indicate MVFR conditions over the Coastal
areas and Plains, and the SPoRT LEO 24hr Microphysics RGB at
21/1820Z confirms it. Observations showing 400 to 1000 foot
ceilings for most areas. Expect some light snow developing over
the Eastern Arctic as weak upper level wave moves through the area
tonight. Northeast to east winds will continue at 15 to 30 mph.
Temperatures steady, then cooling Friday.

West Coast and Western Interior...Troughing over the area will
bring periods of clouds and sun to the area. A low developing in
Kotzebue Sound will bring cloudy conditions to that area with
showers. Isolated to scattered showers for the remainder of the
area as the front spins into the area and stalls in the Upper
Kuskokwim and Middle Yukon Valleys. Isolated Thunderstorms this
evening south of Kaltag. Patchy Dense Fog will return to the Lower
Yukon Delta Tuesday morning, mainly west of Anvik, with improving
conditions after 10 am AKDT. Winds northeast to northwest at 5 to
20 mph except near the Bering Strait winds to 40 mph this evening
diminishing to 25 mph overnight. No significant change in
temperatures expected. See below for river information.

Central and Eastern Interior...Partly sunny from Fairbanks south
and east this evening, then increasing clouds with showers
developing east of Fairbanks overnight. Mostly cloudy to the north
and west with showers through the evening. As another front moves
northwest it will spread the showers to the north and west
Tuesday. Some heavier showers possible in the Fortymile Country,
Middle Tanana Valley around Delta Junction, and Eastern Alaska
Range with up to one inch of rain from Tuesday morning to
Wednesday morning. As the front spins through the area expect
isolated thunderstorms to pop up in the afternoon hours. Winds
generally less than 15 mph will be swinging around from west to
south by Wednesday morning, then back from the West by Thursday
morning. Some of the rivers are running a bit high, but not expect
to leave their banks, however with the heavier rain possible the
next couple days we will need to monitor them closely, and
residents should do the same if they are near them. No significant
change in high temperatures through midweek, but overnight lows
will be cooler overnight with the cloudy conditions and showers.

&&

Coastal Hazard Potential Days 3 and 4...None.

&&

.Fire Weather...Thermal lies from McGrath to Fairbanks to Beaver
Creek YT and will move to lie from McGrath to Stevens Village to
Central to Eagle by Tuesday afternoon. Around 40 lightning strikes
detected yesterday, expect fewer today with most likely areas
around McGrath, and along the AlCan Border. Showers primarily
developing over the Eastern Interior, and the Middle Yukon and
Upper Kuskokwim Valleys this evening, but expect isolated showers
in most areas. Most shower activity on Tuesday will be south and
east of Ruby, with just some isolated showers in the Central and
Eastern Brooks Range. Thunderstorm activity Tuesday will primarily
be along a line from McGrath to Fairbanks to Eagle. Lowest
Relative Humidity values will be around 30 percent Tuesday, will
some values around 25 percent Wednesday in the Upper Yukon Flats
and Middle Koyukuk Valley. Winds generally less than 15 mph
through Wednesday. For the latest Fire Weather information go to
www.weather.gov/arh/fire.

&&

.Hydrology...Yukon River in the Lower Delta is slowly clearing.
NPP-VIIRS APRFC River Flood Areal Extent product at 20/2345Z shows
some potential overflow flooding from the Sag River near Dalton
Highway milepost 386. Have not received any information concerning
flooding, so will continue to monitor the area and seek more
informations. Interior rivers have slowly risen this weekend, and
the precipitation from last night will be making its way into the
mainstem rivers over the next 24 hours, so expect they will rise a
bit more. Some low lying sloughs adjacent to the rivers may rise
as well, but do not anticipate any flooding at this time. For the
latest breakup information go to www.weather.gov/aprfc.

&&

Extended Forecast for days 4 to 7...Models are not helping out
much with the extended periods, so expect temperatures near
seasonal normals with highs around 50 on the West Coast, around 30
on the Arctic Coast, and in the 60s in the Interior. Thermal
trough will be on the move shifting north and south from the
Tanana Valley to the Upper Yukon Flats through the extended
period. A weather front will move to lie southwest to northeast
across the Interior Friday and slowly move to the west.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...

Heavy Freezing Spray Warning for PKZ230.

Small Craft Advisory for PKZ210-PKZ215-PKZ220-PKZ225-PKZ230.

Brisk Wind Advisory for PKZ235-PKZ240-PKZ245.

&&

$$

SDB MAY 18



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