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Northern Alaska forecast discussion
National Weather Service Fairbanks Alaska
555 am akdt Tue Jun 19 2018

Discussion...
an unsettled and wet pattern across most of northern Alaska will
persist throughout the forecast period. Moderate to heavy rains
remain a forecast issue, especially over western Alaska and the
southern slopes of the Brooks range where up to 2 inches have
already fallen. Could see another 0.25" to 1.25" over the
northwest and along the southern slopes of the Brooks range
through tomorrow morning with the heaviest amounts in the Selawik
and Kobuk valleys. Strong, gusty winds in the Alaska Range have
weakened significantly over the last couple of hours, but will see
periods of gusty south to southwest winds in Alaska Range passes
through the rest of the week. 22/00z model solutions are similar
in regards to the synoptic pattern through the rest of the week,
but differ in the handling of specific shortwaves that move over
the forecast area. Differences in solutions beyond Friday,
especially with the movement of persistent old upper level low
that currently resides over Bristol Bay.

Aloft...at 500 mb, a quasi-stationary upper level low centered
south of Nunivak Island will persist, but will slowly weaken
through late this week before gradually shifting north and
weakening Friday and Saturday. Meanwhile, an upper level ridge
stretching from western Canada and over eastern Alaska will slowly
breakdown and shift east as several upper level shortwaves moves
north in the south to southwest flow through late this week. An
upper level low west of Banks Island will continue move east over
the Canadian archipelago today, while a weak shortwave moves over
the Arctic coast. A strong shortwave will dive south from the
North Pole Thursday and clip the eastern Arctic coast Thursday
evening while it moving east over the Beaufort Sea. After
Saturday, differences in model solutions develop in regards to the
individual synoptic feature, especially the aforementioned upper
level low.

At the surface, a 1001 mb low 120 miles southwest of Nunivak
Island will move south towards Bristol Bay through Thursday
morning. A 1007 mb low will form over the Chukchi Sea late this
afternoon and then will drift north and weaken through Wednesday
evening. Another 1007 mb low will form over the eastern Brooks
range this afternoon and then remain in place and weaken through
Wednesday afternoon. Surface high pressure will south and east and
extend along and north of the Arctic coast by this evening and
will persist into Thursday.

West Coast and western interior...an unsettled and wet pattern
will persist through the rest of the week as the area remains
under the influence of the aforementioned upper level low.
Moderate to heavy rainfall between 0.50" to 1.25" likely over the
southwestern slopes of the Brooks range, mainly over the Selawik
and Kobuk valleys, and over the northern half of the Seward
Peninsula through late this evening. There will be a brief break
in precipitation in the evening for most of the area tonight,
except for the northwest, before another front moves north into
the southwest tomorrow bringing more showers. Will need to monitor
rivers draining the Brooks range through the rest of the week due
to recent and forecast rainfall.

North Slope and Brooks range...stratus and areas of fog with
visibility below one mile developed overnight from Barrow east
earlier this morning. Low visibilities in fog are expected to
persist along the eastern Arctic coast this morning before
dissipating. May see 0.25" to 0.50" north of the crest of the
Brooks range through Wednesday morning as moisture is spills north
of a stalled front south of the Brooks range. Will have to monitor
rivers draining from the Brooks range north over the next couple
of days as water levels are expected to rise significantly.
Light northeast to east winds under 15 mph will persist along the
Arctic coast, except for west of Icy Cape where winds will be
between 15 to 30 mph. Temperatures will be cool today over the
coastal plains and Brooks range, but will be at least 10 degrees
warmer as warmer air is pushed north along with the moisture
tonight and then along the coast by Thursday.

Central and eastern interior...strong south winds in eastern
Alaska Range passes have weakened overnight. Gusts 40 to 50 mph
are still being observed at a few sites north of Isabel Pass as
well as near Antler creek along the Parks Highway. The downward
trend in winds will continue today. A band of showers developed
this morning between minchumina and Fort Yukon, just west of
Fairbanks with another area of showers over The Flats near Delta
Junction. As the downslope influence has wained from recent strong
southerly flow, could see a few showers move north and isolated
thunderstorms to develop over the eastern interior through the
evening. Upper level ridge will build back over the area tonight
suppressing any shower activity Wednesday afternoon. Temperatures
will be around 5 degrees warmer with temperatures in the 70s
tomorrow and Thursday. Scattered thunderstorms are possible over
the far eastern interior along the alcan border Thursday afternoon
and evening.

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

&&

Fire weather...
an unsettled and wet pattern will persist across the West Coast
and western interior through the rest of the week. Wetting rains
likely over the southwestern Brooks range including the Selawik
and Kobuk valleys as well as the northern half of the Seward
Peninsula expected today. Over the eastern and central interior,
strong southerly flow has weakened significantly overnight and
will continue to do so through the day today. Isolated afternoon
thunderstorms will be possible along a line from Mountain Village
to Huslia and north to Arctic Village, then will shift west to an
area from Shungnak to Huslia and east to the Dalton Highway as
well as the upper Tanana Valley this evening. Scattered
thunderstorms are possible over the far eastern interior along the
alcan border between Northway and the Brooks range Thursday
afternoon and evening. Temperatures will rise into the 70s over
the central and eastern interior tomorrow and continue into
thursday; however, winds will remain under 15 mph and minimum relative humidity
values will be in the 20s and 30s.

&&

Hydrology...
warm temperatures aloft over the Brooks range combined with heavy
rainfall over the last several days and additional rainfall
expected tonight and tomorrow will produce significant rises on
rivers draining the Brooks range and in particular The Sag river.
Current forecasts keep The Sag river below action stage but will
need to monitor closely as additional rain falls over the Brooks
range.

&&

Afg watches/warnings/advisories...
Small Craft Advisory for pkz210-pkz220-pkz225.

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