Tornado in Washington, April 18, 2024

Area Forecast Discussion
National Weather Service Spokane WA
1103 AM PDT Thu Apr 18 2024

.SYNOPSIS...
Cool and showery conditions continue today, before drying out and
becoming breezy Friday. Showers return for Saturday evening
through Sunday. Mild and dry weather returns for the start of
work week while showers arrive by mid week.

&&

.DISCUSSION...

Today through Saturday afternoon: Winds are light across the region
tonight with cool temperatures. The likelihood of frost this morning
remains over the Western Columbia Basin and Wenatchee area as clouds
have eroded. A weak shortwave will move through the area, ushering
in another bout of showers to northeast WA (perhaps even thunder - a
15% chance) and the ID Panhandle. Meanwhile, Eastern and Central
Washington can expect partly to mostly sunny and dry conditions,
though temperatures will remain cool in the 50s. Showers and winds
will taper off in the evening.

Moving into Friday, an upper-level low will traverse the region,
tightening the pressure gradient and resulting in gusty winds across
the Columbia Basin. Northeast winds will gust up to 35 mph in the
afternoon before easing off overnight. Despite the windy conditions,
temperatures will slightly warm up and the region will experience
sunny weather. Dry and gusty conditions will lead to an elevated
fire weather risk in dead grasses in the Columbia Basin.

Looking ahead to Saturday, a ridge of high pressure will bring more
sunny skies in the morning and temperatures in the 60s. An overcast
cloud deck will move in Saturday afternoon bringing a 15% chance of
showers to Stevens Pass Saturday afternoon. Winds will be breezy,
gusting up to 30 mph across the region. /Butler

Saturday night through Sunday night: There is good agreement of a
negatively tilted upper level trough pivoting across the Pacific
NW this weekend. Moisture spread east of the Cascades Saturday
evening as a cold front marches across eastern WA into north ID
during the overnight hours with chance of showers. Snow levels
start high but lower to 3-4K ft by Sunday morning with light
mountain snow accumulations. Breezy winds accompany the front
Saturday night with wind gusts of 20-30 mph especially across the
Columbia Basin and Palouse. In the wake of the front, surface
based instability will promote afternoon convection especially
across northeast WA and the ID Panhandle with a small chance of a
thunderstorm near the BC border. Sunday will be a cool and brisk
day. The westerly winds remain gusty across the Palouse into north
ID Sunday afternoon. The showers and winds gradually dissipate
Sunday evening.

Monday through Tuesday: An upper ridge builds into WA on Monday
while the upper level trough shifts east, although it still
brushes the ID Panhandle. It will start off cool Monday morning
with areas of frost across the lowlands of eastern WA.
Temperatures on Monday warm to near seasonal levels by afternoon.
Lingering moisture and surface based instability lead to the
redevelopment of mountain showers over north ID. Winds will be
lighter and shift from the east and temperatures rebound to more
seasonal levels. The upper ridge shifts inland Monday night into
Tuesday with light easterly winds and drier conditions. Daytime
temperatures should mild on Tuesday with widespread 60s to lower
70s region-wide.

Tuesday night through Thursday: Model guidance has lower
confidence with the mid week forecast, especially dealing with how
long the upper ridge remains and the timing of the next Pacific
low pushing inland and at what trajectory. At least through
Thursday, the position of the approaching trough remain near the
coast to offshore which should keep a mild southwest flow into the
region. The NBM begins to spread moisture and a chance of showers
across the Inland NW by Tuesday night and continues a low chance
of showers through Wednesday into Thursday. Temperatures look to
remain on the mild side and just above seasonal normals with
little in the way threat of freezing. /rfox.

&&

.AVIATION...
18z TAFS: Showers will redevelop again Thursday afternoon, but
confidence of them going over any particular TAF location is low.
The greatest potential is KGEG-KSFF-KCOE (20-40% chance late this
morning through the afteroon). VFR conditions will prevail.

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        54  31  56  33  62  39 /  20   0   0   0   0  30
Coeur d'Alene  52  30  54  31  61  38 /  30  10   0   0   0  40
Pullman        53  31  56  33  62  38 /  10   0   0   0   0  40
Lewiston       61  34  64  36  69  44 /  10   0   0   0   0  40
Colville       54  27  57  27  63  35 /  30  10   0   0   0  40
Sandpoint      50  30  52  30  60  38 /  30  10   0   0   0  50
Kellogg        49  30  51  32  61  40 /  50  20   0   0   0  50
Moses Lake     62  36  64  38  67  41 /   0   0   0   0   0  10
Wenatchee      61  37  61  37  63  41 /   0   0   0   0   0  10
Omak           59  34  62  34  64  39 /  10   0   0   0   0  30

&&

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