887
FXUS66 KOTX 102218
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
318 PM PDT Mon Jun 10 2024

.SYNOPSIS...
A dry cold front arrives Tuesday afternoon ushering gusty
westerly winds across the region. Breezy conditions continue into
Wednesday with cooler temperatures. Temperatures rebound on
Thursday then a pattern shift late in the week will lead to cooler
temperatures, another round of gusty winds, and shower chances
for Friday into the weekend.

&&

.DISCUSSION...

Tonight through Wednesday night:  A progressive, spring weather pattern
will continue across the Northwest through this period. During
the next 12 hours, shortwave ridging will be passing through. This
is delivering stable weather conditions, temperatures a handful
degrees of average, and light breezes of 15-20 mph. Quickly on its
heels, the next area of low pressure is swinging to the coast and
will begin crossing 130W by midnight. This wave will swing into
the Northwest on Tuesday delivering our next bout of gusty winds.
The system will largely be moisture deprived with just a 10-20%
chance for showers along the immediate Cascade Crest and immediate
Canadian Border. The more impactful element of the system will be
strong winds arriving with the cold front in the afternoon and
early evening. The Inland Northwest should brace for another round
of sustained winds of 15-30 mph with gusts of 30-45 mph. The
windiest locations will be found in the lee of the Cascades and
into the Western Columbia Basin. Wind advisories have been issued
to address these areas although, some of these stronger winds will
likely expand across the Upper Columbia Basin along Highway 2
into Wilbur and Davenport. The foothills of the Blue Mountains
will be another wind prone area. The sheltered northern valleys
will experience lower sustained speeds of 10 mph or less but
afternoon mixing will likely transport wind gusts up to 30 mph at
times into the valley floors. The winds will be driven by a 16 mb
cross-cwa pressure gradient and enhanced by cold air advection
late in the day into the evening.


Impacts: Use caution around dry grasses with the potential for new
fire starts to become problematic for local resources. Grasses on
south aspects and in the Western Columbia Basin are quickly
curing and will support fire spread. Those venturing on area lakes
in small vessels such as kayaks should be prepared for choppy,
changing conditions throughout the afternoon.


Winds will remain elevated Tuesday night but speeds will be significantly
lighter compared to the early evening. Much drier air will
continue to flood into the region. Locations that decouple from
the winds will cool sharply with overnight temperatures dipping
into the upper 30s to lower 40s; otherwise the winds will keep
temperatures in the 40s and 50s. Zonal or westerly flow will
remain over the region on Wednesday with continued breezy
conditions. Wind gusts in the afternoon will be lower, only
topping out near 25 mph. Temperatures on Wednesday will be nearly
10 degrees cooler than Tuesday topping out in the 70s. /sb


Thursday to Monday: The
Inland NW starts off this period dry and mild, before the next
system moves in with cooler temperatures, breezy conditions and,
for some, a chance of showers and thunderstorms and even be some
high terrain snow. Patchy frost is also possible toward Saturday
night/Sunday morning in some of the sheltered northern valleys.
First Thursday a shortwave ridge migrates across the Pacific
Northwest and pushes toward the northern Continental Divide
Thursday night, while a deep low approach the Pacific Northwest
coast. Highs are forecast to reach the upper 70s to mid-80s. Skies
will be mostly clear to partly cloudy during the day, then clouds
start to increase heading into later Thursday into Thursday
night.

Friday into Saturday a couple shortwave disturbances pivot around
the approaching low and cross the region, thickening clouds and
another increase in winds. Winds actually start increasing
overnight into Friday morning near the Cascades and increase
throughout the region heading through the day, peaking once in the
evening, subsiding some overnight and then increasing again
through Saturday afternoon. Speeds of 15-30 mph, with gusts of 30
to 40 mph will be possible, strongest around the lee of the
Cascades through the Waterville Plateau and Upper Columbia Basin.
In terms of fire weather concerns, afternoon RH values will hover
near critical values, especially Friday so this will be need to be
monitored. Wind gradually decline late Saturday night into Sunday
morning.

Precipitation-wise, the main precipitation chances lay near the
Cascade crest Friday and perhaps skimming near the Canadian
border. By Saturday the atmosphere moistens up some and the
threats of showers expands over most of the Cascades and northern
mountains and central Panhandle mountains, with a risk for snow in
the higher terrain. Some snow may be found near Washington Pass
and a rain/snow mix could even be seen near Stevens and Sherman
Pass. It is borderline for showers outside of those mountain
zones. Places like Spokane and Coeur d`Alene and the Palouse were
held to just a ten percent chance. Thunderstorms are possible
around the northern mountains Saturday afternoon. Some could be
locally stronger and could enhance the synoptic scale winds.

Sunday and Monday the area remains in a troughy pattern, but
models really start to diverge over the details of where the
individual features lay. The overall pattern will favor continued
shower chances around the mountain zones and at least a slight
chance around the eastern third of WA and lower ID. As the models
start to settle on a solution confidence in who will have the
higher risk will start to come into focus. A limited risk for
t-storms will linger over the northern mountains too. Wind will
still remain a bit breezy, but not as much as previous days with
gusts near 10-20 mph strongest near the Cascades to Waterville
Plateau.

As for temperatures they being to drop heading into Friday and
especially the weekend. Highs on Friday are forecast in the 70s
to near 80, then 60s to mid-70s for the weekend, then warming a
couple degrees on Monday. Lows are forecast to be in the 50s
Friday morning, the 40s to near 50 Saturday morning, then the 30s
to mid-40s Sunday morning, moderating slightly Monday morning.
These latter cooler temperatures could bring some frost to the
sheltered valleys near the Cascades and Canadian border counties.
Overnight Saturday into Sunday morning has the highest risk. As
we get closer we will have more confidence, but could impact
anyone with sensitive plants or crops. /Solveig


&&

.AVIATION...
18Z TAFS: Shortwave ridging passing through the region will
deliver VFR skies through the taf period. Fair cumulus clouds will
build up along the higher terrain producing sct-bkn cigs btwn 5-7k
ft in N Idaho and far NE WA. There is a 10% chance an isolated
cell around Bonners Ferry and Sandpoint matures into a shower.
Winds will increase in the afternoon with occasional gusts up to
20 mph.

A dry cold front presses through the region on Tuesday with winds
increasing around 18z then becoming strong from 21-02z. Sustained
winds 20-30 mph with gusts around 40 mph expected for most sites
across the Basin and within the aligned Cascade valleys. This
includes Wenatchee, Chelan, Ritzville, Pullman, and Spokane. The
sheltered northern valleys will experience sustained winds closer
to 10kts or less with infrequent gusts 20-30 mph.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
There is low confidence for maturing showers along the Idaho-
Montana border. Otherwise, confidence is high for VFR skies today
and tomorrow. There is high confidence for windy conditions
Tuesday afternoon and early evening. Confidence is high for wind
gusts to 30 mph and moderate to low for wind gusts in excess of 40
mph. Highest probabilities for gusts in excess of 40 mph is around
Wenatchee, Moses Lake, Douglas, and Ephrata.

We will need to monitor localized blowing dust given these wind
speeds but time of year is not favorable for widespread impacts.
/sb

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

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        55  83  46  74  45  79 /   0   0   0   0   0   0
Coeur d`Alene  53  79  45  71  44  79 /   0   0   0   0   0   0
Pullman        51  78  45  69  44  77 /   0   0   0   0   0   0
Lewiston       58  89  54  79  50  87 /   0   0   0   0   0   0
Colville       48  80  40  74  40  79 /   0  10   0   0   0   0
Sandpoint      51  78  44  70  42  77 /   0  10   0   0   0   0
Kellogg        55  76  48  67  47  77 /   0   0   0   0   0   0
Moses Lake     55  87  47  79  46  83 /   0   0   0   0   0   0
Wenatchee      60  80  50  76  49  82 /   0   0   0   0   0   0
Omak           55  84  46  79  47  83 /   0   0   0   0   0   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Wind Advisory from noon to 8 PM PDT Tuesday for Moses Lake Area-
     Waterville Plateau-Wenatchee Area.

&&

$$