Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 232148
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
148 PM AKDT Wed May 23 2018

.DISCUSSION...

Synopsis...Active unstable pattern will continue in the interior
with thunderstorms and showers developing this afternoon. Not
quite as active as Tuesday. More showery weather on Thursday, but
less thunderstorm activity. Rainfall amounts will be highest to
the east and south of Fairbanks and high water and potential minor
flooding of low lying areas will remain a concern through the
weekend. Will issue a new Special Weather Statement to address
those concerns. Most active area for Thunderstorms will be the
Middle Yukon River Valley from Galena south, and the Upper
Kuskokwim on Thursday. The Arctic remains quiet, but low ceilings
and some snowfall may create travel issues. Out on the West
Coast they are also dealing with lower ceilings and some areas of
poor visibility in fog.

Models...Short term continuity remains good, and the extended
solutions have somehow come into agreement after being far apart
the last few runs. Surface initialization was good against the
23/18Z analysis. Stability indicies are much better today with
Lifted Indicies of -5 in a few locations, and CAPE values
approaching 200 J/kg. Precipitable water values today range from
0.40 to 0.60 inch. Going with what has worked the last few days as
our approach and that will be an equal blend for most elements to
maintain continuity. Going to blend in a bit of the ARW, and NMM
high resolution solutions to define the area a little better.

Aloft...At 500 hpa...Ridging over central Alaska lies from Eagle
to Teller and will be squeezed out tonight as a strong wave moves
north over the Gulf of Alaska Coast, then over the Southeast
Interior by Thursday afternoon. A 542 dam low develops and moves
over the Upper Yukon Flats, and a 540 dam low develops and moves
near Dawson YT by Thursday afternoon with weak ridging over the
Central Brooks Range and Middle Yukon River Valley north of
Galena, extending west to a 547 dam high near St Lawrence  A 540
dam low over the Upper Noatak Basin will slowly slide to the west
to be over the Chukchi Sea Friday morning at 542 dam. Troughing
will persist over the Southeast Interior as a 535 dam low develops
over the Gulf of Alaska by Friday morning dissipating over the
Kenai Peninsula in the afternoon. The 519 dam low that has been
moving east over the Southern Bering Sea will cross over into the
North Pacific near Nikolski Friday morning and will be 300 nm
south of Kodiak Island Friday night, then moves to 200 nm
southwest of Yakutat by Sunday morning. A 549 dam high over the
Arctic with ridging along 76N will persist, but weaken, then merge
with a 556 dam high near 80N 180 Friday afternoon as ridging
pushes south over the Arctic Coast. At 850 hpa...Zero Isotherm
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 persists over the Arctic with a 1026 mb
center 400 nm north of Prudhoe Bay and high pressure pushing
south over MacKenzie Bay and west to the New Siberian Islands. The
high will move southeast to Banks Island by Thursday morning with
ridging extending west to a 1024 mb center 400 nm north of
Demarcation Point, then northwest. A trough of low pressure
remains over mainland Alaska extending from Dawson YT to Fairbanks
to Anvik to a 989 mb low 200 nm north of Adak. By Thursday
morning the trough strengthens over the Interior with a 1000 mb
low near Dawson YT, a 1000 mb low near Fairbanks, and a 1001 mb
low near McGrath. A weather front will set up over the Southeast
Interior and persist into the evening before weakening. A 1005 mb
low develops near Noatak as will. The low near Adak will move to
100 nm north of Atka, and a developing low will move to 200 nm
southeast of Kodiak Island at 998 mb. By Thursday evening the low
near Fairbanks will be near Fort Yukon at 999 mb, and the low
near McGrath will move to Huslia at 1002 mb. The low near Kodiak
will continue to swing northeast, and the low in the Bering Sea
will be over Dutch Harbor. A bubble high will cutoff from the high
pressure over the Southeast Panhandle and drift over the Western
Alaska Range and dissipate.

Arctic Coast and Brooks Range...Stratus, then more stratus in the
forecast. Add in a little flurries and fog, and spring in the
Arctic. Chance of accumulation snow tonight and Thursday, but less
than one half inch. The 23/2100Z GOES MVFR/IFR/LIFR Probability
products indicate MVFR/IFR conditions over all but the Brooks
Range. Current observations show 400 to 900 foot ceilings with
condition persisting through at least Friday. Ceilings may lift
for short periods. Northeast to east winds at 15 to 30 mph.
Temperatures relatively steady.

West Coast and Western Interior...Stratus continues to be spun
into Kotzebue Sound, and even Norton Sound, so low ceilings will
continue through most of the night. Flurries or sprinkles on the
outer Capes. Dense fog in Kotzebue Sound will continue into
Thursday before clearing significantly. Isolated to scattered
showers in the Middle Yukon and Upper Kuskokwim Valleys tonight with
scattered thunderstorms from Galena south Thursday. Wind
direction remain quite variable at 5 to 20 mph with strongest
winds along the coast. No significant change in temperatures
expected.

Central and Eastern Interior...Showers already popping up and that
will continue into the evening, mainly south of the Yukon River. A
few thunderstorms will also pop up this evening, mainly east of
Fairbanks. Showers developing over most of the area east and south
of Fairbanks tonight with rainfall amounts 0.75 to 1.50 inches.
Rivers remain high, see below for details. Winds generally light.
Temperatures slightly cooler with cloudy conditions the next 36
hours.

&&

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

&&

.Fire Weather...Thunderstorms will be the primary concern the next
couple days, but they will be wet, and isolated. Thunderstorm
activity will diminish in the Central and Eastern Interior
Thursday, but increase a bit in the Middle Yukon River Valley
from Galena south. Wetting rains for most areas south and east of
Fairbanks the next couple days. Thermal trough hanging out in the
Upper Yukon Flats, but will shift a bit south Thursday, then slide
back north to the Flats. Minimum Relative Humidity values above 30
percent, with excellent overnight recovery in most locations. For
the latest Fire Weather information go to
www.weather.gov/arh/fire.

&&

.Hydrology...Upper Chena River continues to run near minor Flood
Stage but is not expected to go above at this time. Special
Weather Statement issued for river basins east and south of
Fairbanks with 0.75 to 1.50 inches of rain expected by Friday
morning. Models are focusing more of the rain over the Fortymile,
Johnson, and Robertson River basins with the latest solutions.
Will continue to monitor this situation along with the River
Forecast Center. Breakup continues in the lower reaches of the
Yukon River with no issues noted the last 24 hours. For the
latest breakup and flooding information go to
www.weather.gov/aprfc.

&&

Extended Forecast for days 4 to 7...Models all of a sudden have
come into much better agreement. Seasonal afternoon showers to
start the week for most areas with a weather front bringing some
rain to most locations Thursday. Temperatures pretty steady
through Tuesday, then slightly warmer Wednesday and Thursday.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...

Brisk Wind Advisory for PKZ240-PKZ245.

&&

$$

SDB MAY 18



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