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000
FXUS66 KOTX 191106
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
406 AM PDT Fri Apr 19 2024

.SYNOPSIS...
Dry weather conditions will be in place through Saturday. Winds
will be breezy from the northeast. A strong cold front arrives
early Sunday morning ushering gusty westerly winds and chance for
showers. Mild and dry weather returns for the start of work week.

&&

.DISCUSSION...
Today through Saturday: The remnants of an expansive low pressure
system that stretches from Ontario to the Pacific NW will begin
to moderate today as high pressure inches closer to the WA Coast.
500mb temperatures warm nearly 10C today basically eliminating any
threat for afternoon showers. The main weather impact for the
next 24 hours will be breezy northeasterly winds. Offshore
pressure gradients between Kalispell, MT and Portland, OR are
already near 11 mb and expected to range between 11-15 mb through
tonight. This is in response to cooler Canadian air sliding down
the Continental Divide creating surface high pressure and warmer
air nosing along the CA/OR coastline creating thermally induced
lower pressure. Strongest winds will be found through the Purcell
Trench and across the Columbia Basin with speeds up to 20 mph and
gusts to 35 mph. Exposed ridgetops of Northeastern WA and North
Idaho can expect similar speeds. Winds will weaken going into
Saturday with a slow shift back to the southeast and then south as
the next cold front approaches. Saturday will deliver another day
of dry conditions with plenty of sunshine as the ridge axis
passes through the Inland Northwest promoting stable weather
conditions. Temperatures today (FRI) will be several degrees
warmer, especially for NE WA and N ID which experienced quite a
bit of shower activity on Thursday. Afternoon highs will be in the
upper 50s to mid 60s. On Saturday, widespread 60s return with
areas along the Snake River Valley creeping into the lower 70s.

Saturday night - Sunday: A robust shortwave and associated cold
front will swing through the region ushering windy conditions and
chance for showers. This is well agreed upon amongst the forecast
models with subtle differences with the speed/timing of the front.
General timing brings the cold front toward the Cascades around
midnight and to the ID/WA border around 3AM. This is likely to
bring a sharp increase in winds overnight with sustained speeds of
20-30 mph and gusts 30-40 mph. I am more confident with the
sustained winds given the strength of the front and strong cold
air advection. Would not rule out gusts 40-50 mph for some wind
prone areas and exposed benches and ridgetops but right now, a
bulk of the winds aloft are closer to 30-35kts which good news and
a limiting factor for gusts over 40 mph. In the past, these type
of fronts can be impactful due to the sharp increase in winds.
Typically, the strongest speeds only last 1-2 hours with these
nocturnal events but this is not to say it will not remain windy
through the day Sunday as wind speeds persist in the 15-25 mph
range with gusts around 30 mph. Added patchy blowing dust to the
Western Basin for early Sunday morning yet this comes with low
confidence. Would not rule out minor tree damage (small branches)
and a few power outages. Potentially the biggest impact will be
light weight objects blowing around like garbage cans, lawn
furniture, and trampolines. Be sure to secure those patio
umbrellas before heading to bed on Saturday!

The front will not bring much in the way of precipitation with amounts
ranging between a trace and tenth from the lee of the Cascades to
the Palouse and Camas Prairie. The Bitteroots and Selkirks carry
a greater chance for a tenth or more with probabilities around 40%
for at least 0.10". Numerous showers will also be intercepted
along the immediate Cascade Crest where amounts could vary from
0.25-0.60". Snow levels will come crashing down as well falling to
3000 feet before sunrise Sunday morning with slushy accumulations
possible over Stevens Pass. The best chance for precipitation
over the Basin-Palouse will come with the frontal passage early
Sunday morning. Showers will continue for the Cascades Crest,
Northeastern WA, and North Idaho into Sunday afternoon.

Monday through Thursday: High pressure returns to the region early in
the work-week bringing another period of warming and drying.
Temperatures for Monday morning will likely start off cool with
temperatures in the lower 30s and potential for freezing
temperatures. Temperatures rebound into the 60s by the afternoon
and continue to warm into Tuesday with many more locations across
the lower Columbia Basin showing increasing odds for 70s. Winds
will be lighter. The next Pacific trough arrives middle to late
week with yet another change in the weather pattern toward cooler
and unsettled. There are considerable differences with the
evolution of the next trough. Leaning toward an arrival closer to
Thursday-Friday but this will fine tuned over the coming days. As
we transition air masses, winds are likely to become breezy
conditions and precipitation chances will return. /sb

&&

.AVIATION...
12z TAFS: A tight northeast pressure gradient will result in
gusty northeast winds down the Purcell Trench and over the
Columbia Basin. Expect gusts of 20-30 kts for KSZT-KDEW-KCOE-KGEG-
KMWH on Friday. Shortwave ridging into region for Friday will
result in less cloud cover and VFR conditions.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: There is high
confidence in VFR conditions through the TAF period.

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

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        56  34  64  39  57  33 /   0   0   0  30  10   0
Coeur d`Alene  54  33  63  38  54  32 /   0   0   0  50  20   0
Pullman        56  33  64  37  52  33 /   0   0   0  30  10   0
Lewiston       64  36  71  43  60  38 /   0   0   0  20   0   0
Colville       56  26  63  35  57  30 /   0   0   0  50  20   0
Sandpoint      51  34  59  38  52  32 /   0   0   0  70  40  10
Kellogg        51  32  62  39  50  34 /   0   0   0  60  30  10
Moses Lake     63  37  69  40  62  34 /   0   0   0  20   0   0
Wenatchee      60  37  63  41  59  37 /   0   0   0  20   0   0
Omak           61  34  65  40  62  35 /   0   0   0  30  10   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&

$$