High Wind in Alaska, September 4 to 7, 2020

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
354 PM AKDT Fri Sep 4 2020

.SYNOPSIS...

Cloudy and cooler conditions over the Interior will last into
Saturday before clearing and warming back into the 60s on Sunday.
A seasonably strong warm front will move into Southwest region on
Sunday afternoon and quickly spread into the Interior on Sunday
night and Monday. This front will also bring very strong chinook
winds through and across the Alaska Range during this same time
frame.

&&

.DISCUSSION...
Upper Levels and Analysis...
The upper level flow over the state is rather nondescript with
weak flow dominating aloft. The large scale pattern features a
digging longwave trough extending over the western Bering into the
NPAC. There is a weak low over the North Gulf Coast, and this low
is responsible for a "easterly wave" which has stalled over the
Interior. This is responsible for the cloud and showers over the
Interior. There is also a weakening upper level trough over the
West Coast which is promoting a weak onshore westerly wind
gradient.

Central and Eastern Interior...
Showers will continue this evening and then gradually fall apart
tomorrow. Overnight fog will be an issue tonight, but especially
tomorrow night as clouds clear out with the potential for
localized dense fog lasting through the morning on Sunday. Sunday
itself is shaping up to be a beautiful and warmer day as skies
clear and a front approaches from the Pacific. This will result in
increasing flow over the Alaska Range with chinook winds ramping
up dramatically overnight and Monday morning. Right now, it is
possible for wind gusts to get to 60+ MPH in favored locations
such as the exit of Isabel Pass and through parts of Denali.
Expect these Chinook wind to eventually move through the Alaska
Range into Delta Junction with potential for hazardous winds for
flying, as well. Rain will move inland north of the Alaska Range
Sun night and Monday as the warm front lifts north, favoring the
Central Interior and Southern Brooks Range. Areas directly north
of the Alaska Range will experience stronger downslope drying and
will see very light preciptiation amounts. The front will quickly
shift north so most of the area will be dry by Monday afternoon.

West Coast and Western Interior...
Skies gradually clear out as western onshore flow weakens, and an
upper level trough shifts east. Expect areas of fog, some dense in
valleys, to be an issue tonight and again Saturday night.
Otherwise, mostly dry and clear weather as ridging aloft and low
level easterly winds increase Sunday morning and afternoon.
Attention turns to a strong warm front moving in from the Pacific,
which will bring widespread rain Sunday evening through Monday as
it moves northward. This will also be coincident with peak east to
northeast winds in the gale force range as gusts push as high as
50 MPH over the coastal locations, including Norton Sound and
Kotzebue Sound.

North Slope and Brooks Range...
Fog and stratus will continue to be an issue over the next few
days as weak ridging aloft dominates along with weak pressure
gradients. The pattern slowly shifts on Sunday night as a front
moving in from the south will result in increasing easterly winds
along the coast. Extensive rain will move over the Brooks Range
Sunday night and Monday.

Coastal Hazard Potential Days 3 and 4...
NE winds 20-30 kt across West Coast Sunday and Monday will cause
slightly elevated surf along north and west facing shores.

&&

.HYDROLOGY...
Rain which has fallen and will continue to lightly fall over the
Eastern Interior will result in sharp rises along the Chena and
Little Chena Rivers, as well as smaller streams draining the White
Mountains. However, no flooding is anticipated with rivers peaking
Saturday night and Sunday.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
High Wind Watch AKZ225-AKZ226-AKZ227

&&

AHSENMACHER SEP 20

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FAIRBANKS AK
413 PM AKDT FRI SEP 4 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0412 PM     HEAVY RAIN       2 W TWO RIVERS          64.87N 147.17W
09/04/2020  M0.62 INCH       FAIRBANKS NORTH STAAK   TRAINED SPOTTER

            RAINFALL SINCE 10PM YESTERDAY .62 INCHES LOW
            THIS MORNING 45 HIGH TODAY 48.

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