Mattawa, Washington Weather Forecast Discussion

204
FXUS66 KOTX 152149
AFDOTX
Area Forecast Discussion
National Weather Service Spokane WA
249 PM PDT Mon Sep 15 2025
.KEY MESSAGES...
- Breezy easterly winds tonight into Tuesday across the
  Cascades.
- Warm and dry Tuesday through the end of the week.
&&
.SYNOPSIS...
Breezy easterly winds across the Cascades Monday night into
Tuesday. High pressure over the region with a warm and dry
conditions through the work week.
&&
.DISCUSSION...
Monday afternoon through Tuesday: As an upper-level ridge of high
pressure continues to build over the Inland Northwest, clouds will
clear from west to east and lingering showers over North ID will
subside. Meanwhile at the surface, breezy easterly winds (sustained
speeds 10-15 mph, gusts 20-30 mph) will pick up across the Cascades
Monday night into Tuesday as a thermally-induced surface trough
develops over western WA. Outside of Central WA/the Cascades, winds
will remain light. For locations including northeastern WA and North
ID that received several tenths of rain on Sunday, light winds
combined with clearing skies Monday night will likely mean fog
development in sheltered valleys overnight into Tuesday morning.
Tuesday afternoon will be notably warmer than Monday particularly
for far eastern WA and the ID panhandle with the ridge axis centered
over the Inland Northwest and no cloud cover to moderate
temperatures. Locations in the Columbia Basin can expect
temperatures to warm by around 10 degrees, while places along and
east of the ID border will see temperatures 15 to 20 degrees warmer
than on Monday.
Wednesday through Sunday: Temperatures will stay relatively
consistent in the mid to upper 80s through the end of the workweek
until our next trough moves in heading into next weekend cooling
temperatures closer to climatologically normal values in the low to
mid 70s. In addition to cooler temperatures, the trough is also
likely to bring breezy winds and returning chances for precip.
/Fewkes
&&
.AVIATION...
18Z TAFS: IFR/MVFR conditions will continue to improve gradually
over the next couple of hours as the surface heats up and dew
point depressions increase. VFR conditions with light winds are
expected this afternoon onward. Lingering shower activity this
morning in eastern Washington and north Idaho will start to
dwindle around 19-22z.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence
in improving conditions for KGEG-KSFF-KCOE through the morning
and into the early afternoon. Low confidence for shower activity
impacting a TAF site.
-----------------------
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:/weather.gov/otx/avndashboard
&&
.Preliminary Point Temps/PoPs...
Spokane        49  82  54  87  54  87 /   0   0   0   0   0   0
Coeur d`Alene  50  84  55  86  55  88 /   0   0   0   0   0   0
Pullman        45  79  51  84  51  85 /   0   0   0   0   0   0
Lewiston       52  84  58  88  59  89 /   0   0   0   0   0   0
Colville       40  82  44  86  44  87 /   0   0   0   0   0   0
Sandpoint      46  81  50  84  49  85 /  10   0   0   0   0   0
Kellogg        51  80  56  84  58  86 /   0   0   0   0   0   0
Moses Lake     51  84  51  87  53  88 /   0   0   0   0   0   0
Wenatchee      56  81  58  86  61  87 /   0   0   0   0   0   0
Omak           53  85  56  88  57  88 /   0   0   0   0   0   0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
WA...None.
ID...None.
&&
$$

NWS OTX Office Area Forecast Discussion