459
FXUS66 KOTX 272301
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
401 PM PDT Mon May 27 2024

.SYNOPSIS...
Tuesday will see a return of showers and thunderstorms to Eastern
Washington and Idaho Panhandle. A few storms could be strong with
gusty outflow winds in southeastern Washington and the Idaho
Panhandle. Cool and showery conditions continue through the end
of the week with drier and warmer conditions at the start of the
upcoming weekend.

&&

.DISCUSSION...
Today and tomorrow: Today is shaping up to be a very nice day in the
Inland Northwest. Temperatures are 8 to 19 degrees warmer than
yesterday in the 70s and low 80s. Cirrus clouds are thickening over
deep southwest flow ahead of a shortwave trough off the coast of
British Columbia.

The main focus tomorrow will be widespread thunderstorms that
may be strong in the afternoon. Storms will be capable of frequent
lightning, large hail, and gusty winds. The main window for strong
storms will be around noon to 10 PM tomorrow with an early focus on
the northern mountains and a later focus on southeast Washington and
the southern ID Panhandle. A complicating factor for tomorrow is
that models show elevated showers come through overnight tonight in
Eastern Washington and North Idaho. The main question is how will
this limit day time heating for stronger storms tomorrow afternoon
via cloud cover. Models suggest it will inhibit activity a little
later than usual but I have witnessed them firing thunderstorms 1 to
3 hours too late around here. Cells will be moving fast but new
storms being initiated on the same mountain peaks may lead to a
flash flood threat as well given a fairly moist atmosphere.

Wednesday through Friday: A trough of low pressure will be
established over the region on Wednesday delivering cooler than
normal temperatures and widely scattered showers around the outer
rims of the Columbia Basin and across the mountain zones. A few
weak thunderstorms will also be possible. Initially, these will be
more of the hit or miss variety forming with the assistance of
afternoon heating however by the late afternoon and evening,
several models continue to forecast a shortwave rounding the base
of the trough. This could create more organized bands of showers
and embedded thunderstorms. Any storms will be capable of
lightning, brief downpours of small hail/rain, and wind gusts up
to 30 mph as the main threats. The air mass will be cool with snow
levels near 4000 feet. The heaviest cells will be capable of a
quick 0.25" of rainfall.

Blustery west to southwest winds will be in place Wednesday.  Sustained
winds across the Columbia Basin and through the Cascade Gaps will
remain in the 15-20 mph range with gusts up to 35 mph. Most other
areas will be closer to 10-15 mph with gusts around 25 mph.

The trough begins to drift eastward on Thursday with shortwave ridging
moving toward the WA Coast. Pops have decreased on Thursday with
the system departing sooner compared to 24 hours ago. The air mass
is also becoming quite dry with PWATS close to 0.35" or 50% of
normal. The combination of the dry air, clearing skies, and light
winds will lead to cool morning lows each Thursday and Friday.
Thursday looks to be the coolest.

Here are the latest probabilities for Thursday morning lows of 34F
or colder at communities most vulnerable:

Winthrop - 10%
Republic  - 60%
Colville - 70%
Priest Lake area - 60%
Davenport - 20%
Deer Park = 25%


Friday will feature mostly dry conditions under shortwave ridging.  By the
weekend and early next week, there remains moderate uncertainty
with the forecast with the latest trends toward a flatter ridge
over the weekend and increasing threat for showers with an axis of
deeper moisture becoming directed inland and weak shortwaves
skirting through. Details are far from certain but blending the
medium range models has led to increasing PoPs in the mountains.
The west to east orientation of the flow pattern suggest little to
no precipitation in the lee of the Cascades which is observing
one of the largest deficits over the last 60 days. Winds will
likely be breezy at times with temperatures running near to warmer
than normal. /sb


&&

.AVIATION...
00Z TAFS: Mid to high clouds will continue to filter through the
region as the ridge begins to slowly be replaced with the next
trough system. VFR conditions will prevail through 0z Wednesday.
Weather changes arrive late tonight into Tuesday for an increasing
chance of showers and thunderstorms over eastern Washington and
north Idaho along with breezy winds. Thunderstorms will be capable
of hail and gusty outflow winds.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
There is high confidence for VFR conditions to continue across the
TAF sites. Low confidence on showers impacting TAF sites after
12z.

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

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        52  74  45  62  39  65 /  10  30  10  20  10   0
Coeur d`Alene  51  73  45  59  38  62 /  20  40  30  30  20   0
Pullman        52  71  44  58  37  61 /  20  40  40  10  20   0
Lewiston       57  80  52  66  45  70 /  10  40  60  10  20   0
Colville       45  73  38  61  31  66 /   0  70  40  60  20  10
Sandpoint      48  71  45  56  38  61 /   0  60  60  60  40  10
Kellogg        53  74  48  55  39  59 /  10  40  70  50  40  10
Moses Lake     53  78  43  67  39  72 /  10  20   0  10   0   0
Wenatchee      56  73  45  63  43  69 /   0  10   0  10   0   0
Omak           51  76  42  66  39  71 /   0  20  10  10   0   0

&&

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

$$