740
FXUS66 KOTX 162258
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
358 PM PDT Fri May 16 2025

.KEY MESSAGES...

- Increasing rain showers on Saturday into Sunday with a 20%
  chance of thunderstorms Saturday afternoon

- Breezy conditions Saturday night and Sunday.

&&

.SYNOPSIS...
A cool and showery weather pattern will continue through at
least early next week. In addition, breezy winds are expected at
times.

&&

.DISCUSSION...
Friday night through Sunday afternoon: On Friday night through
early Saturday morning, the low pressure system that will impact our
area through the weekend will be sitting off the British Columbia
coast. By Saturday afternoon, it will move southward down off the
coast of the Pacific Northwest, and will move on land over
Washington state, bringing unsettled weather back to the area.
This system will bring a host of weather types to the area.
First and foremost, widespread wetting rain will fall Saturday
afternoon into Sunday evening for most of the area, with far
eastern Washington and the Idaho Panhandle seeing higher
amounts. NBM probabilities of seeing a wetting rain (0.1 inches
or more) are 60 to 90 percent or higher, increasing as you go
further east into the Spokane/Coeur d`Alene area and down into
the Lewiston/Pullman area. The only places that do not have a 60
percent chance or higher of seeing wetting rain are the
Waterville Plateau, Wenatchee, and Moses Lake areas. When
increasing the precipitation amounts to a quarter inch,
probabilities of higher than 40 percent start roughly in
Spokane and increase further east. The southern panhandle will
see the most rain, with a broad 30 percent chance or higher of
seeing a half inch of rain. Additionally, snow levels will drop
with this system enough to bring small amounts of snow to a
couple mountain passes. NBM probabilities show Stevens Pass has
a 29 percent chance of seeing an inch of snow, Sherman Pass has
a 34 percent chance of seeing a third of an inch of snow, and
Lookout Pass has a 23 percent chance of a tenth of an inch of
snow. The good thing is the snow shouldn`t stick around for too
long.

Saturday night into Sunday morning specifically, there is also a
chance of thunderstorms and gusty winds. The vorticity max will
move right through the state as the low passes through, and the
generated lift will bring a chance of thunderstorms to the
area. There is a 10- 15 percent chance of thunderstorms through
the entire forecast area, with higher chances (near 30 percent)
seen in north central Washington, and Spokane seeing a 20
percent chance of thunderstorms. As such, the SPC has general
thunderstorm chances throughout the forecast area. However, any
cells that develop will be isolated. SBCAPE values are low
(100-200 J/kg), and cloud cover could inhibit warming enough
that it would lower thunderstorm development chances. With this
low pressure system bringing decent mid to high level flow,
there are chances for wind gusts in the Cascades, Waterville
Plateau, and the Northeast Blue Mountains. Sustained wind speeds
could reach 25 mph for these areas, with gusts up to 40 mph.
Right now, these aren`t enough for any wind headlines, but we
will keep an eye on things.

Models right now are struggling with the track and strength of the
low. Half of the WPC clusters show the low moving further north,
which due to a deformation band would bring rain to north of the
forecast area. The other half shows the low moving further south,
which would allow more rain to fall in our area. The ECMWF and GFS
are similarly disagreeing, with the GFS being the wetter solution of
the two. It will be interesting to see what happens once more short
range models begin picking up on the storm track. /AS

Sunday Night through Friday: Models are in general agreement of
a progressive weather pattern with a series of weak weather
disturbances tracking in from the west. None of these
disturbances are particularly strong, but a combination of the
weak lift and afternoon destabilization is likely to produce
scattered showers at times, with the highest coverage along the
Cascade crest, and mountainous terrain of NE Washington into the
Idaho Panhandle. Temperatures are expected to be around 3-6
degrees below normal Monday through Wednesday with highs mainly
in the 60s. Then temperatures begin a warming trend, reaching
the upper 60s to mid 70s on Friday which is close to seasonal
normals. This pattern will also allow for breezy west winds at
times through the Cascade gaps, including places like Chelan,
Wenatchee, and Vantage. JW

&&

.AVIATION...
18Z TAFS: As the light rain across the forecast area comes to an
end within a few hours, ceilings will have improved to VFR
status for all but GEG. Chances of rain for KGEG/KSFF/KCOE
remain through the next few hours, moving out of the area
by 04/05Z. Winds will shift from southwest to northeast around
01Z, then back to southwest at 18Z for KGEG/KSFF/KCOE
throughout the TAF period, but will stay light. By 16-19Z, rain
will pick up again, with KMWH and KEAT seeing rain start sooner,
around 08Z. Ceilings have the potential to drop to MVFR due to
rain but chances are low enough that only KEAT has them in the
TAFs.


FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence
in VFR conditions throughout the TAF period except for around
14-15Z, when the rain starts up again. Confidence is low that
MVFR conditions will develop anywhere but KEAT. With the cloud
cover overnight there is the potential for fog formation, but
confidence is low so it is not included in the TAFs. /AS

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

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        42  64  43  56  41  61 /  20  50  60  70  10  30
Coeur d`Alene  41  65  42  54  40  59 /  20  40  70  80  20  30
Pullman        40  62  39  53  38  60 /  10  50  80  80  10  30
Lewiston       47  69  48  61  45  67 /   0  50  80  80  10  20
Colville       37  63  39  59  41  60 /  20  70  70  70  20  50
Sandpoint      41  64  44  54  40  57 /  30  50  60  80  40  40
Kellogg        42  64  43  49  42  56 /  20  40  70  90  30  30
Moses Lake     49  67  43  67  39  70 /  30  60  30  10   0  20
Wenatchee      51  66  46  64  43  68 /  30  60  20  10   0  20
Omak           46  66  44  67  41  66 /  20  70  50  30   0  30

&&

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

&&

$$