Area Forecast Discussion
Issued by NWS Fairbanks, AK

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
000
FXAK69 PAFG 152105
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
105 PM AKDT Tue Aug 15 2017

.DISCUSSION...
Not much change in the overall forecast as unsettled, wet, showery
weather will persist across northern Alaska as a broad longwave
trough remains overhead. Main forecast concerns revolve around any
hydro impacts from recent heavy rains across the eastern half of
northern Alaska. Most small streams and mainstem rivers in basing
that received rain have been steadily rising with elevated water
levels expected for the next few days. There is no concern for
flooding, except for the where the ongoing flood advisory in the
Upper Tanana Valley. 15/12Z deterministic models are in good
agreement through Thursday in regards to the overall synoptic
patterns with increasing spread in model solutions after Thursday
with the features within and associated with the broad longwave
trough, but handle the synoptic pattern similarly over Northern
Alaska.

Aloft...A broad longwave trough remains situated over the Alaska, the
Arctic Ocean, and western Canada with a upper level ridge upstream over
eastern Siberian Russia. Multiple low centers or shortwaves
currently reside within this longwave trough. A shortwave over the
lower Yukon Valley will quickly scoot east towards the Middle
Tanana Valley through tonight, then will shift north in the
developing southerly flow. Another shortwave stretching from the
central Brooks Range southeast over the Yukon Flats will lift
north this evening and over the Beaufort Sea by Wednesday
morning. The 545 dam low over the southern Bering will weaken and
become an open wave as it enters the western Gulf of Alaska. A 530
dam upper low 300 NM of Wrangel Island will shift south to be 200
NM early Wednesday morning, and then will move over Point Hope by
Wednesday afternoon at 526 dam. This low will help to reinforce
the already existing longwave trough. Meanwhile, as the
aforementioned low moves south, warm, southerly flow will develop
over the eastern half of Alaska. Colder H850 temperatures below 0C
will accompany the low, while in the warm, southerly flow, H850
temperatures will be as warm as +6 to +7C over the eastern North
Slope.

Surface...Broad cyclonic flow will persist across northern Alaska.
A 994 mb low northeast of MacKenzie Bay with a trough extending
west over the Beaufort Sea will move northwest tonight and will be
a 987 mb low 250 NM north of Point Barrow, then will move to be
400 miles north of Wrangel Island by Wednesday afternoon. A 986 mb
low centered 320 NM miles northwest of Wrangel Island and its
associated occluded front stretching south and over Point Hope and
the Chukchi Sea Coast. This low will continue south towards the
Chukchi Sea and Point Hope through Wednesday afternoon while
weakening. Over the southern Interior, a leeside trough will
develop north of the Alaska Range this evening, which will
persist into Thursday.

West Coast and Western Interior...Unsettled, showery pattern to
continue for most of the west coast and western Interior. Over the
next few days, expect 0.5" of new rainfall over most of the area.
Northwest winds 15 to 25 mph with moderate surf over the Chukchi
Sea from Shishmaref to Wales through tonight. Temperatures will
remain in the 50s during the daytime and in the 40s for most
locations at night, expect in the upper 30s in higher elevations.
There is a slight chance for a few thunderstorms to develop this
afternoon and evening from Ruby south to Nikolai.

North Slope and Brooks Range...Snow has been observed at several
locations along the western Arctic Coast today with rain over the
Beaufort Sea Coast. Chances for precipitation will continue with
snow or a snow/rain mix possible for Barrow, the Arctic Coastal
Plains, and in the central and eastern Brooks Range. Areas from
Anaktuvuk Pass east in the Brooks Range could possibly see up to
1.5" of rainfall through Thursday. Will have to monitor small
streams and rivers in this area for potential elevated water
levels and bankfull conditions.

Eastern and Central Interior...There is no end in sight for the
unsettled, wet regime as looks to continue through late this week
as the Interior remains firmly underneath the broad longwave
trough. There is a slight chance that a few thunderstorms will
develop Tuesday afternoon/evening from Tanana to Minchumina east
over Fairbanks, and over Eagle and Chicken; and over far eastern
Interior and over the Middle Tanana Valley Wednesday afternoon and
evening. Gap winds through Alaska Range passes will develop
Wednesday morning through Thursday with the strongest winds
along the Richardson Highway through Isabel Pass and north to
Delta Junction. Temperatures will remain the 60s during the
daytime, and cool into into the 40s with some valleys and
locations at higher elevations see morning lows in the mid to
upper 30s.

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

&&

.FIRE WEATHER...No concerns at this time as conditions remain cool
and moist.


&&

.HYDROLOGY...
Area from Tok east had 1.5-2.5 inches of rain the last several
days. This combined with heavy snow melt in Eastern Alaska Range
and Wrangel Mountains is causing the Tanana River upstream of Tok
to be near bankfull. The river continues to push through its bank
in the Tetlin area with water flowing down to the Alaska Highway
between milepost 1305 to 1306. There is also high water along the
Northway Village Road due to these same conditions. The Flood
Advisory for the area between the Tetlin Village Road and the
Northway Village remains in effect through Thursday. It`s likely
that high water and minor flooding will persist into the weekend.
See the latest statement at www.weather.gov/fairbanks.

In Eastern Interior north and west of Tok, rivers will be rising
over the next several days but should remain below bankfull. This
area received between 0.5 inch to 1.5 inch the past several days.
Since the Chatanika, Chena, and Salcha Rivers were low before
this rain, expect no problems in those basins.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory for PKZ210-PKZ220.
&&

$$

AUG 17


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.