346
FXUS66 KOTX 171105
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
405 AM PDT Sat May 17 2025

.KEY MESSAGES...

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

- Breezy conditions Saturday night and Sunday.

- Showery pattern through start of next week.

&&

.SYNOPSIS...
A cool and showery weather pattern will continue through the
weekend with Sunday being breezy to windy. Showers at times
with temperatures gradually warming closer to normal next week.

&&

.DISCUSSION...
Today and Sunday: A Low is currently driving south through
Western WA and Oregon and deepening a trough over the region.
Ensembles are in decent agreement with the path and timing of
the system. It is ushering in PWAT values 120-150% of normal
across the Inland Northwest for today. Main impact will be
widespread rainshowers. While the bulk of the precip will be
South of the region, many locations across the region can expect
decent amounts of rain ranging from 0.2-0.4". The lower Cascade
Valleys can expect up to a tenth. A weaker Low will begin to
press into the Northwest Washington during the afternoon. It
will bring increasing winds and instability for the region for
the late afternoon and early evening hours as it swings a cold
front through the region. An isolated thunderstorms is possible
during this time. The highest winds will stretch from the
Waterville Plateau to Southeast Washington with gusts near 40
mph possible. The Low is expected to exit the the region through
Sunday with a push of drier air and decreasing shower activity
into Sunday night. Winds will continue to be breezy across the
Basin through Sunday morning. Highs will be in the 60s to low
70s on Saturday and dip into the upper 50s and low 60s for
Sunday. Overnight lows will be in the 40s for Saturday and 30s
for Sunday. /JDC

Monday through Saturday: The flow pattern will be fairly zonal with
an active but not particularly strong upper level jet stream. This
will result in a series of storm systems that brings across light
precipitation at times through next week. There`s good agreement
agreement among the model ensembles for a shortwave that brings
showers over the Inland Northwest on Monday. The parent upper level
low will track across the Gulf of Alaska and into the central coast
of BC by Monday afternoon. The frontal occlusion that pushes through
looks rather weak more than likely will fall apart as it pushes east
of the Cascades. Precipitation will likely fall as light showers.
Instability parameters shows weak instability as well. There is
potential for deeper instability Tuesday afternoon, but even this
looks quite week. Potential for convection looks pretty paltry. Best
potential for a wetting rain (greater than a tenth of an inch within
12 hours) will be right at the Cascades crest; otherwise, most areas
across eastern Washington into the Idaho Panhandle will end up with
less than a tenth of an inch early next week, and there`s a good
chance that the Columbia Basin will get skipped completely by
accumulating rainfall. Slightly better potential for some
instability on Tuesday with some energy coming across may result in
scattered showers over the mountains in the afternoon.

Additional shortwave disturbances look to push across the region at
the end of the work week, but the consensus is that these weather
disturbances will also be weak and bring little in the way of
impacts. There`s a clustering of around 20% of the ensemble members
that shows the possibility of spotty wetting rains Thursday into
Friday. It will be breezy at times through next week, but I`m not
seeing anything in the pattern that would signal significant winds.
Gusty westerly winds through the Cascade gaps is expected,
especially during the typical breezier hours in the late afternoon
and evening.

Friday into Saturday may be the last couple of days with
showers heading into the holiday weekend. Seventy percent of the
model ensembles show a rather strong ridge that builds in over the
west coast of the U.S. by next Sunday. This would dry things out and
would pump up temperatures above normal. There is a rather large
spread in the potential for how warm temperatures will become over
Memorial Day Weekend though, but the current trend is that
temperatures will be above normal with the potential for a return
into the 80s. /SVH

&&

.AVIATION...
12Z TAFS: Ceilings will hover around MVFR to IFR conditions for
eastern sites through the morning, before additional rain and
lowing ceilings moves into the region. Light winds will
continue. Afternoon convection could bring isolated
thunderstorms to the region but low confidence on impacting any
TAF sites. A cold front passage starting Saturday afternoon will
bring breezy west winds across the Basin impacting TAF sites
into the Sunday morning.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Moderate
confidence in VFR conditions throughout the TAF period.
Low confidence on thunderstorms impacting TAF sites. Moderate
confidence for wind gusts into the 30s for EAT- MWH- PUW
starting around 03Z.

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

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        65  42  58  39  61  42 /  50  70  50  10  20  30
Coeur d`Alene  65  42  55  39  59  42 /  30  80  70  20  20  50
Pullman        62  39  54  36  59  41 /  50  90  50  10  20  30
Lewiston       67  47  62  42  67  47 /  60  90  50  10  20  20
Colville       64  39  57  34  59  35 /  70  80  70  20  30  40
Sandpoint      64  44  54  40  58  42 /  30  80  90  40  30  60
Kellogg        64  42  51  41  57  44 /  30  90  90  30  20  60
Moses Lake     68  43  66  37  68  42 /  70  30  10   0  10   0
Wenatchee      65  46  62  41  68  44 /  70  20   0   0  20   0
Omak           64  41  65  38  66  40 /  80  60  10   0  20  10

&&

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

&&

$$