Asotin, Washington Weather Forecast Discussion

987
FXUS66 KOTX 051147
AFDOTX
Area Forecast Discussion
National Weather Service Spokane WA
447 AM PDT Fri Sep 5 2025
.KEY MESSAGES...
- Temperatures trending cooler heading into this weekend and
  next week.
- Smoke and haze expected to continue through the weekend
- Unsettled weather returning to the region over the weekend and
  into next week with increasing threat for showers and
  thunderstorms.
&&
.SYNOPSIS...
Smoke and haze is expected to continue over the weekend while
temperatures gradually trend cooler. Precipitation chances will
be on the gradual increase next week, along with more significant
cooling across the region as high temperatures drop into the
70s.
&&
.DISCUSSION...
Today-Sunday: The strong upper-level ridge responsible for our latest
heat wave will begin to shift eastward as an area of low
pressure drifts toward the WA Coast. Conditions will remain very
warm with highs in the upper 80s to 90s but on average, 5-10
degrees cooler than those experienced through the week.
Additionally, haze and smoke from area wildfires will contribute
to the cooling, shielding some areas from shortwave radiation.
As the ridge limps eastward, midlevel flow will increase from the
south and southwest. This will open the door to increasing
moisture and shortwaves. Friday looks to be the last region-wide
dry day though there could be enough moisture and instability
in the Cascades for isolated thunderstorms in the afternoon
(5-15% chance). On Saturday, the shower and thunderstorm threat
increases further for the Cascades (20-40%) and starts to expand
into southern WA and additional areas of Central WA (10-20%
chance). The remnants from this activity will drift northward
into E WA and N ID Saturday night into Sunday morning. The trend
continues into Sunday with region-wide chances varying from
20-50%. Given the very dry antecedent low levels, there is
increasing concern for any showers or storms to initially start
off high based with dry lightning and gusty outflow winds. In
the presence of stronger dynamics, ie a shortwave, storms will
also be capable of hail.
Winds will remain light today and Saturday with low probabilities
for much change to smoke, haze, and air quality. On Sunday,
there will be a slight increase in southwest winds across the
basin and westerly winds on the East Slopes. Smoke and haze will
move around some but the increase winds is concerning to the
impacts it could have on the active fires.
Monday-Thursday: There is increasing confidence for a significant
pattern change over the Northwest with the low slowly migrating
through the region. This leads to high confidence for cooler
temperatures and higher humidities which is great news for the
fires. The low will also bring increasing chances for on and off
periods of showers and thunderstorms. Shower and thunderstorm
activity will trend wetter with time with NBM indicated a 30-80%
chance for wetting rains by midweek. Given the convective
nature of the precipitation bands, it conceivable that some
areas miss out, thus the 30% which found across the lower Basin,
but many areas where the fires are burning are closer to 50-80%
chances. Temperatures will be cooling back into the 80s and
then 70s as the low moves inland. At this time, we do not
anticipate a significant wind event with this changing air mass
as this system slowly meanders inland but locally breezy
conditions are not out of the question, especially near any
convection.
Heading into Friday and next weekend, there is a lot more
uncertainty with the forecast. A second low approaches from the
E Pac. This will help kick the first low to the east. Likely
there will be a period of dry and warm conditions between these
features but how long is uncertain. Consensus amongst the
ensembles is for 2-3 days. We will need to closely monitor the
evolution of the offshore low. Some of the ensembles sweep this
wave through swiftly which could be a wind maker while others
develop split flow and would yield far less wind. More to come
on this in the coming days. /sb
&&
.AVIATION...
12Z TAFS: Visibility is expected to be restricted from wildfire
smoke regionwide for the next several days. Visibility is
expected to range from 4-7 miles for most of Central and Eastern
Washington and north Idaho, but areas near fires including
Colville will see restrictions as low as 1 mile.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
Low confidence in precise visibilities at the TAF sites due to
shifting winds out of the northeast into Friday morning for the
Columbia Basin, Palouse, and north Idaho. The wind shift could
shift the surface smoke around with fluctuating visibility.
-----------------------
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        89  61  92  63  86  59 /   0   0   0  10  10  20
Coeur d`Alene  89  61  92  63  87  60 /   0   0   0  10  10  30
Pullman        88  58  90  58  83  55 /   0   0   0  20  20  30
Lewiston       94  67  95  67  90  63 /   0   0   0  20  20  30
Colville       88  52  92  53  86  49 /   0   0   0  10  20  40
Sandpoint      86  56  89  58  84  55 /   0   0   0  10  20  40
Kellogg        87  63  90  65  85  61 /   0   0   0  20  20  40
Moses Lake     93  63  90  62  87  57 /   0   0  10  20  30  20
Wenatchee      92  71  88  69  85  62 /   0  10  20  30  40  30
Omak           93  66  90  66  88  61 /   0   0  10  20  30  40
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
WA...Air Quality Alert until noon PDT Monday for Central Chelan
     County-Lower Garfield and Asotin Counties-Moses Lake Area-
     Northeast Blue Mountains-Northeast Mountains-Okanogan
     Highlands-Okanogan Valley-Spokane Area-Upper Columbia
     Basin-Washington Palouse-Waterville Plateau-Wenatchee
     Area-Western Chelan County-Western Okanogan County.
ID...Air Quality Alert until noon PDT Saturday for Central
     Panhandle Mountains-Coeur d`Alene Area-Idaho Palouse-
     Northern Panhandle.
     Air Quality Alert until 11 AM PDT this morning for Lewis and
     Southern Nez Perce Counties-Lewiston Area.
&&
$$

NWS OTX Office Area Forecast Discussion