Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 252246
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
246 PM AKDT Mon Sep 25 2017

.DISCUSSION...
The models are in good agreement overall through the middle of the
week. The main forecast challenge in the short term is the
precipitation that will fall through tonight along a stalled
front stretching from Eagle to Fairbanks to McGrath.

Aloft, at 500 mb, a 534 dam low over Bristol Bay will move to
south of Unalaska by tomorrow afternoon and will continue south. A
536 dam low will approach Kodiak Island from the south on
Wednesday and will move over Kodiak island on Thursday. An upper
level trough will continue to push eastward across northern Alaska
tonight and will move east of the Canadian border tomorrow. An
upper level ridge will briefly build northward over the west coast
tomorrow but will be knocked back south by a shortwave that will
move eastward across the Chukchi Sea on Wednesday. This shortwave
will move across the Chuckchi Sea Coast of Alaska Wednesday
night. An upper level ridge will build over the central and
eastern Interior Wednesday and Thursday. The GFS and the ECMWF are
both showing a decent upper level low moving across the Arctic
Coast Friday into the weekend. The trough associated with this
low looks to spread colder air across much of the Interior. There
is however, still a differences between the models on the exact
details of this system.

At the surface, a front remains stalled out along a line from
Eagle to Fairbanks to McGrath to the Kuskokwim Delta. This front
will gradually weaken in place through early tomorrow morning.
High pressure will build eastward across the North Slope on
Tuesday. A front associated with this low will move across the
Arctic Coast at some point on Thursday or Thursday night;
however, at this a lot of disagreement between the models on the
details of this in terms of timing and placement. An area of high
pressure will also build into the Bering Sea on Tuesday. This area
of high pressure will be pushed eastward as a low moving through
the Chukchi Sea. This area of high pressure will slide west some
on Thursday and will build back east Friday.

Central and Eastern Interior: Precipitation is expected to
continue tonight along a stalled front stretching from Eagle to
Fairbanks to McGrath. The front will stretch out during the
overnight hours causing the front to weaken. This in turn will
cause the precipitation to gradually end by tomorrow morning. The
precipitation type for most locations along the front tonight
will be rain. Above 2000 feet snow will start to mix with the rain
this evening. Some of the higher points along the Steese Highway
(particularly Eagle Summit) could see around two inches of snow
tonight and early tomorrow morning. There is also at least some
possibility for fog to become rather thick right before sunrise
across the Interior. With the precipitation ending tomorrow
morning cloud cover will gradually decrease during the day
tomorrow. Dry conditions are expected from tomorrow afternoon
through Wednesday evening. The next round of precipitation will
push in on Thursday. On Thursday snow levels look to be high
enough that the precipitation will fall as rain with the exception
of areas above pass level in the Alaska range.

North Slope and Brooks Range: A weather front will a couple of
inches of snow to inland areas north of the Brooks Range and east
of Barrow this evening. Areas closer to the coast will see some
rain mixing with the snow and this will limit the potential for
snowfall somewhat. As high pressure builds eastward just north of
the Brooks Range tomorrow expect winds to have some southerly
component which should help to limit the potential for fog or low
ceilings along the coast. A front will push east along the Chukchi
Sea coast on Thursday. This will bring northerly winds to areas
east of Barrow. At this point there is still some differences in
the placement of the low between the ECMWF and the GFS that will
affect how strong the winds will be along the coast, and thus will
affect any potential impacts in terms of coastal hazards. We will
have to continue to monitor this.

West coast and western Interior: Generally quiet weather is
expected for the next few days. There is some potential for winds
causing coastal impacts for the northern Seward Peninsula Coast
Thursday into Friday; however, this will depend on the placement
of the low and associated front as it moves through the Chukchi
Sea. As mentioned above there are still differences between the
models in the placement of this low. The models are hinting a
system that will bring precipitation and stronger winds to the
west coast this weekend; however, at this the exact details of
this are still up in the air.


Coastal Hazard Potential Days 3 and 4...There is some potential
for coastal impacts along the Chukchi Sea coast and the northern
Seward Peninsula coast with a front associated with a low moving
through the Chukchi Sea Thursday and Friday. At this point there
are a lot of differences in the placement of the low between the
models, thus there it a lot of uncertainty in the placement and
timing of any potential impacts. The models are also hinting at
the potential for coastal impacts along the west coast this
upcoming weekend, but again there is a lot of uncertainty in the
details at the moment.

&&

.HYDROLOGY...
No issues at this time.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...

&&

$$

SEP 17


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