496
FXUS66 KOTX 160949
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
249 AM PDT Thu May 16 2024

.SYNOPSIS...
Today will be the last day of well above average temperatures for
the next week or two. The arrival of a vigorous cold front this
afternoon will produce widespread windy conditions, with gusts as
high as 40 to 50 mph in parts of central and eastern Washington.
Gusty west winds will continue into Friday, with significantly
cooler temperatures. Seasonably cool and showery weather is
expected this weekend into next week.

&&

.DISCUSSION...

...GUSTY WEST WINDS TODAY AND FRIDAY WITH A TRANSITION TO COOLER
AND SHOWERY WEATHER BY THE WEEKEND...

Today and Tonight: The first half of May has had its fair share
of breezy days across the Inland Northwest, but today and tomorrow
will feature the most widespread windy weather so far this month.
The Polar Jet will descend from B.C. and the Gulf of Alaska today
and push a vigorous cold front across Washington and Idaho this
afternoon. By late in the day, low pressure deepening east of the
Continental Divide will lead to an increasingly tight westerly
pressure gradient across the region. West winds will peak late in
the afternoon and early this evening as cool maritime air spills
through the Cascade gaps. Along and behind the cold front, the NAM
and GFS advertise 850mb winds around 40kts suggesting gust
potential of 40 to 50 mph from Vantage and Wenatchee across the
Waterville Plateau and along the Highway 2 corridor from Coulee
City to the West Plains. A Wind Advisory is in effect from 2 PM to
10 PM emphasizing isolated power outages, patchy blowing dust
near recently worked fields, and treacherous driving conditions
for high profile vehicles. Afternoon highs in the 70s will tumble
into the 40s tonight as west winds continue to gust in the 20 to
35 mph range across the Columbia Basin, West Plains, and Palouse.
Exposed ridge tops in north Idaho and in the Cascades have the
potential of 40 to 50 mph gusts through the night and into Friday
morning as the upper level jet sets up overhead.

Friday: Additional Wind Advisories may be necessary Friday for the
Palouse, Lewiston-Clarkston area, and the Winchester/Craigmont
areas. The tight surface pressure gradient will continue to
support windy conditions well into Friday afternoon. As the wind
direction becomes more northwesterly, southeast Washington and
portions of the southern Idaho Panhandle will experience the brunt
of the winds with gusts of 35 to 45 mph. Cooling aloft under the
500mb trough (-25 to -28C) will generate showers over the Idaho
Panhandle and eastern third of Washington. The National Blend of
Models (NBM) advertises a 30 to 50 percent chance of measurable
precipitation across the eastern third of Washington and a 60 to
80 percent chance for the mountainous terrain of the northern and
central Idaho Panhandle. Some of the strongest cells Friday
afternoon will be capable of producing lightning, small hail, and
wind gusts up to 50 mph. High temperatures on Friday will be a
solid 10 to 15 degrees cooler than Thursday with readings mainly
in the 60s. As winds diminish Friday night, temperatures will
tumble into the 30s and 40s by sunrise on Saturday. Our typical
cold spots in our sheltered valleys of north Idaho and northeast
Washington like Deer Park, Springdale, and Republic may flirt with
freezing temperatures. /GKoch

Saturday to Wednesday: The periods with a trough digging into the
West, before weak and short-lived ridge moves in for the start of
the new work week. Then another low moves in toward next Tuesday
or Wednesday, models start to disagree over the precise timing and
track of that low but they do show it having some impact on the
area. First this weekend, a mid-level trough slides down the BC
coast and deepens as it move into the Pacific Northwest. Moisture
starts to move in early, but the atmosphere really moistens going
into late Saturday into Sunday as it wraps into the low. This will
bring increasing clouds and rain chances. The best rain chances
remain near the Cascades and northern mountain Saturday morning,
then expand across throughout more of the Inland NW later Saturday
into Sunday with the deeper Columbia/lower lee of the Cascades
having smallest chances. The best chances for wetting rains
(>=0.10) will be near the Cascade crest and the NE WA and ID
mountains zones. Some embedded thunderstorms are also possible
during the afternoon hours over the weekend, with the best chances
toward the northern mountains. Additionally, look for breezy
conditions especially in the lee of the Cascades and western
basin, with gusts of 25-35 mph possible. The breeziest time
appears to be around late Saturday and Saturday evening.

Heading into Monday the weak ridge builds in, with a west-
northwest flow. The primary shower chances retreat to the
mountains. It will remain a little breezy again especially near
the Cascades. Then Tuesday into Wednesday a deeper and wetter low
drops down the coast and into the Pacific Northwest. Models take
it in slightly different directions and at different speeds, but
generally starts to really impact the area later Tuesday as it
starts to drop down the WA coast and then tries to make its way
inland, wrapping moisture into it. This will bring broader and
higher over precipitation chances across the region. There will be
a broader opportunity for wetting rains.

Temperatures will be below normal much of the period between
Saturday and Wednesday. High will largely be in the upper 50s and
60s, with some areas near 70 in the deeper Columbia Basin and L-C
valley. Overnight lows will be in 30s and 40s, with some potential
for some pockets of frost in a few sheltered valleys across the
northern mountains early Saturday, early Sunday, and maybe early
Monday. Overall the warmest day of the period appear around
Monday, but Tuesday could be similar if the low is slower to move
in. /Solveig

&&

.AVIATION...
06Z TAFS: VFR conditions will continue through the upcoming
period with bands mid to high level clouds streaming in from the
northwest. Winds will generally be 10 kts or less overnight
before an incoming front on Thursday. By 16z, gusty winds will
develop at most TAF sites with gusts to 20-25kts. These will
steadily increase by afternoon with gusts of 30-40kts. Local gusts
to 45kt are possible across the western Columbia Basin Thursday
afternoon. The gustiness will gradually decrease in the evening,
while a 15% to 30% chance of showers develops across northeast WA
and the ID Panhandle. /rfox.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence
in VFR conditions. There is a low chance of blowing dust to reduce
visibilities to under 6SM. There is also a low chance of light
showers leading to MVFR conditions at the TAF sites Thursday
evening. /rfox.

-----------------------

Confidence descriptors:
Low - Less than a 30 percent chance
Moderate - 30 to 70 percent chance
High - Greater than a 70 percent chance

For additional probabilistic information for NWS Spokane airports,
please refer to the Aviation Dashboard on our webpage:
https://www.weather.gov/otx/avndashboard

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        75  44  63  40  62  40 /   0  10  30  10  10  20
Coeur d`Alene  74  44  59  39  61  39 /   0  20  60  10  10  30
Pullman        72  43  58  39  61  39 /   0  40  20   0   0  20
Lewiston       82  52  67  44  71  45 /   0  20  10   0   0  10
Colville       75  37  63  34  61  36 /   0  20  50  10  50  60
Sandpoint      72  43  56  37  58  39 /  10  30  80  20  40  60
Kellogg        70  44  53  40  57  42 /  10  50  80  20  20  40
Moses Lake     80  44  69  40  69  40 /   0  10   0   0   0   0
Wenatchee      74  46  64  45  65  44 /   0  10   0   0   0   0
Omak           77  42  69  39  66  40 /   0  10   0   0  20  20

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Wind Advisory from 2 PM this afternoon to 10 PM PDT this evening
     for Moses Lake Area-Upper Columbia Basin-Waterville Plateau-
     Wenatchee Area.

&&

$$