Lewiston, Idaho 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

122
FXUS66 KOTX 142054
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
154 PM PDT Wed May 14 2025

.KEY MESSAGES...

-Cool and showery at times through at least early next week

-Windy in Central WA this evening

&&

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

&&

.DISCUSSION...
Tonight through Friday Night: An upper low over central British
Columbia today will slide southeast, and sheer apart as it
tracks into NW Montana on Thursday. This will result in the best
lift tracking east of the area bringing a drying trend into
Thursday. Although residual moisture and instability will lead
to continued scattered showers into the early evening over NE
Washington and the ID Panhandle. Isolated thunderstorms are also
expected with uncapped surface based CAPE of 250-500 J/KG.
Storms will be capable of producing pea size hail. Most of the
activity will wind down after sunset with the loss of daytime
heating. On Thursday a short wave ridge moves over the area for
dry conditions except for a chance of showers over the ID
Panhandle and extreme NE Washington.

Thursday Night into Friday the next short wave pushes in from
the west. There are some model differences with the chances and
amount of precipitation, but the GFS and ECMWF ensembles have
trended a little wetter with a tenth to quarter inch of rain
over the ID Panhandle and eastern third of WA, with less than a
tenth in Central WA. POP`s have been increased above the
National Blend of Models (NBM) given the recent trend with the
ensembles. This wave exits Friday evening but the next one is
right on its heels keeping a chance of showers over the area. JW

Saturday morning through Sunday afternoon: Another low pressure
system will move through the area Saturday through Sunday, bringing
precipitation to much of the area, particularly to far eastern
Washington and the Northern Idaho Panhandle. Saturday morning, the
low pressure system will come onshore off the coast of Oregon and
northern California before deepening throughout the day and moving
southeastward further into the Nevada/Utah/Arizona area. Right now,
models are struggling on whether the track of the low will result in
widespread rainfall throughout the forecast area or minimal
rainfall. Half of the WPC clusters have the low moving far enough
south that rain could be minimal, whereas the other half have
lowering heights reaching the area. Additionally, deterministic long-
range models are showing very high mid-level moisture that would
indicate high PoPs, while the NBM has very low overall PoPs outside
of the Northern Idaho Panhandle. Should the higher PoPs end up
coming to fruition, areas in far eastern Washington and the Northern
Idaho Panhandle could see up to a quarter inch of rain on Saturday.
Lower PoPs will lead to roughly a tenth of an inch of rain. Either
way, this low pressure system will bring a wetting rain to at least
the eastern portion of the forecast area. We`ll be watching this
closely, so stay tuned.

Sunday afternoon through Monday evening: After the low pressure
system moves out of the area, higher heights will allow temperatures
to warm by a few degrees. Mostly dry conditions will prevail apart
from some lingering mountain rain due to orographic lift.

Monday evening through Wednesday: The weather continues to stay
overall unsettled as models pick up on another low pressure system
moving through, with rain beginning in the Cascades and Northern
Mountains before becoming more widespread. Temperatures throughout
the extended period hover around normal, with highs mostly in the
low to mid 60s. /AS

&&

.AVIATION...
18Z TAFS: A moist boundary layer combined with low level upslope
flow into NE WA/N ID Panhandle will continue to promote areas of
MVFR stratus this morning, with VFR conditions across Central WA
where downslope northwest winds will persist through this
evening. Heading into the afternoon, showers will again increase
across NE WA/ID Panhandle along with a 15-30% chance of
thunderstorms. The highest potential for thunderstorms will be
north of KGEG/KSFF/KCOE so did not include a mention for any of
the TAF sites. Overnight into Thursday morning showers come to
an end (except the N ID Panhandle) as a short wave ridge moves
over the area.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
High confidence that MVFR conditions will persist through 19-20z
over NE WA/N ID Panhandle, with improvement to VFR after that as
boundary layer mixing helps raise the cloud heights. Although
localized MVFR conditions are possible under any heavier showers
or thunderstorms this afternoon. JW

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

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  63  44  57  44  66 /  20  10  20  60  10  40
Coeur d`Alene  44  61  42  56  42  66 /  40  20  20  60  20  40
Pullman        38  59  42  55  40  63 /  10   0  20  60  10  40
Lewiston       45  66  48  62  45  69 /   0   0  30  40  10  40
Colville       37  66  44  58  41  63 /  60  10  30  70  40  60
Sandpoint      43  60  42  56  41  64 /  70  50  20  70  30  50
Kellogg        43  57  41  54  41  64 /  40  20  20  70  20  40
Moses Lake     41  70  47  68  48  69 /   0  10  40  10  10  40
Wenatchee      45  68  46  68  48  66 /   0  10  30  10  10  40
Omak           41  68  47  65  45  66 /   0  10  30  30  20  60

&&

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

&&

$$