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Northern Alaska forecast discussion
National Weather Service Fairbanks Alaska
324 PM akdt sun Aug 18 2019

Discussion...
our main forecast concern in the short term will be high water on
rivers in the interior. While the heavy rainfall ended Friday
night, it will take a few days for all of the water to work its
way through the system.

The operational models are all in relatively good agreement out
through Tuesday. Thereafter, they begin to diverge on the
synoptic scale pattern. The European model (ecmwf) and the NAM both want to drop a
500 mb low south from the Brooks range into the interior on
Wednesday, while the GFS wants to keep it over the Brooks range.
We will lean more with the NAM/European model (ecmwf) solution as it seems to be
more consistent from run to run.

Interior: recent heavy rains have left many rivers across the
interior high. There is ongoing flood products out for parts of
the chena, Salcha, Tanana and Nenana rivers. This will be
described in more detail in the hydrology section below.
Relatively clear skies tonight will allow for temperatures to
drop into the 30s tonight with a few places dropping down into
upper 20s. For Fairbanks, we expect that the temperatures will
remain in the upper 30s in town; however, it is not out of the
question that some of the lower elevation locations on the
outskirts of Fairbanks will see a frost overnight. Shortwaves
around an upper low over the eastern Brooks range will bring
chances for showers to areas along the Canadian border during the
day on Monday. The hrrr actually has the showers as far west as
Fairbanks. We opted to give this a little bit of play by extending
the isolated pops into Fairbanks. Chances for showers for Tuesday
and wednesday; however, the exact placement and amount of
precipitation expected still remains a little bit fuzzy. The fine
scale details with this will depend on the placement of the upper
low. The European model (ecmwf) has the low diving to the European model (ecmwf) has the low diving
to the south Tuesday night, bringing around a quarter of an inch
of rainfall to the interior, mainly along a line from Coldfoot to
Fairbanks to Denali National Park, the NAM doesn't bring the low
as far to the south and keeps bulk heaviest precipitation east of
Fairbanks, mainly over the fortymile country. The GFS doesn't
really move the low that far south and keeps most of the
precipitation along the Canadian border. We kept out pops chance
over the area at the moment until we can get some better agreement
with the models.

North Slope and Brooks range: we will likely see some fog and low
stratus overnight tonight. An upper low will move west to be
situated over the eastern Brooks range by Tuesday afternoon. This
low will bring precipitation to the eastern Arctic coast and the
eastern Brooks range late Tuesday into early Wednesday. Along the
coast this we expect that this precipitation will be in the form
of rain. In the Brooks range, we expect snow for areas above 2,000
feet in elevation. This system has the potential to bring a
couple of inches of snow. The models aren't in the best of
agreement on how this low will progress on Wednesday. The GFS
keeps the low in place over the eastern Brooks range longer than
the European model (ecmwf) or the NAM. The GFS solution would result in higher
snowfall totals over the Brooks range given the more persistent
upslope flow on the north side of the range. We are leaning more
to the NAM/European model (ecmwf) solution that moves the low and the associated
precipitation south into the interior much quicker.

West coast: a shortwave will dive south over the West Coast on
Monday this will bring rainfall to the Seward Peninsula (including
nome) during the morning hours on Monday and to the Yukon Delta
in the afternoon. After this precipitation passes through the
area we aren't expecting any precipitation for the remainder of
the week.

Coastal hazard potential days 3 and 4...none.

&&

Fire weather...
no big concerns for the upcoming week. A cool and mainly dry
pattern will persist into Monday. Minimum relative humidity values are expected
to remain above 35 percent across the entire area for Monday. Relative humidity
values will increase slightly for Tuesday.

&&

Hydrology...
rainfall between Thursday and Saturday was over 1 inch in the
area south of Circle to Tanana (excluding the fortymile basin
which was drier), with 2 inches over most of the area south of
Wonder Lake to Fairbanks to the gerstle river, and 3 to 4 inches
along the Alaska Range between the Delta Junction and Denali, with
the eielson visitor center come in at 4 inches. Most of this rain
fell in a 24 hours period between early Fri morning and Saturday
morning. Most of the water has moved out of streams and into
larger rivers. The Nenana river has a flood advisory, with minor
flooding occuring in the city of Nenana, and that flooding is
expected to continue for several more days. The Tanana river has a
flood advisory from Shaw creek all the way to the city of Tanana
with flooding in low lying areas along the Tanana river, which
will last for several more days.

The little chena and goodpaster rivers crested Sat below bankfull
and the threat of flooding is over on both of those rivers. The
upper chena river crested Saturday at minor flood stage, and the
chena river near hunts creek is expected to crest today near minor
flood stage, with the chena in Fairbanks cresting on Monday
below bankfull. The Salcha river will crest today over a foot
above flood stage, which is the highest water level on the Salcha
river since 2014.

&&

Afg watches/warnings/advisories...
Small Craft Advisory for pkz245.

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