Lewiston, Idaho 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

969
FXUS66 KOTX 260745
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
1245 AM PDT Thu Jun 26 2025

.KEY MESSAGES...

- Breezy winds across Central and Eastern Washington through
  Saturday.

- Occasional rounds of scattered showers over the northern
  mountains Thursday and Friday afternoons.

- Much warmer temperatures Sunday into early next week with
  Moderate and Major HeatRisk on Monday and Tuesday.

&&

.SYNOPSIS...
Weak weather systems will continue to pass over the region
through Saturday. A chance of showers will occur over the
northern mountains and Idaho Panhandle, with a few thunderstorms
possible along the Canadian border. Seasonal normal temperatures
will end the work week with much warmer temperatures expected
through early next week.

&&

.DISCUSSION...
Thursday and Friday: The Pacific Northwest will remain under a broad
upper level trough for Thursday and Friday with temperatures in the
70s to low 80s across the Inland Northwest. Weak waves embedded in
this broad trough will bring another round of afternoon showers
primarily across the northern mountains Thursday afternoon and
evening. Confidence in shower development decreases further south
with a 10-20% chance for showers across southeast Washington and the
southern/central Panhandle in the late afternoon and evening. Weaker
mid-level lapse rates due to thicker cloud cover will limit overall
instability for Thursday afternoon with a 10-20% chance for thunder
confined to far northeast Washington along the Canadian border.
Showers will reemerge Friday afternoon as well, but warming
temperatures aloft will shrink coverage. Cross-Cascade surface
pressure gradients will remain tight through Friday in response to
persistent onshore flow and a deepening marine layer over western
Washington.  Winds will pick up each afternoon and evening across
central Washington as a response with wind gusts up to 35 mph.
Across eastern Washington, sufficient boundary layer mixing up to
750-700mb looks to support wind gusts 25 to 30 mph in the
afternoons.

Saturday through Wednesday: Models are in good agreement for the
trough to exit to the east on Saturday as an upper level ridge
amplifies over the Pacific Northwest. Temperatures will trend warmer
Saturday into early next week with widespread high temperatures in
the 90s to low 100s on Monday and Tuesday. For Monday, the National
Blend of Models is giving the L-C Valley and lower parts of the
Columbia Basin a 60+ percent chance for highs above 100F.
Probabilities remain similar on Tuesday, but increase to 50-60% for
downtown and north Spokane. HeatRisk will be in the Minor to
Moderate category for Sunday, then increasing to Moderate to Major
for Monday and Tuesday. Major HeatRisk will be favored across much
of central Washington and the L-C Valley both days with Major
HeatRisk sneaking into the Spokane-Coeur dAlene metro area on
Tuesday. Temperatures will remain warm into Wednesday, however
confidence in the exact values begins to wane with an increase in
the ensemble spread on the evolution of the upper level ridge. This
can be seen in the spread between the 25th to 75th percentiles for
max temperatures, which increases from 4-5F on Tuesday to 7-11F on
Wednesday to 10-14F on Thursday.

Deterministic models continue to hint at the potential for elevated
convection early Tuesday, but confidence in this occurring remains
low.  Ensembles are in good agreement on the presence of an upper
level low over California, with uncertainty remaining in the exact
placement and overall strength by early to mid next week. If this
low hovers further north, increasing southerly flow into Oregon and
Washington would allow for monsoonal moisture to advect into the
region, which would then increase elevated instability. Combined
with orographics and modest lift from the low, this would introduce
favorable conditions for elevated thunderstorms over the mountains.
While this is not the most likely scenario at this point with the
current forecast keeping PoPs and thunder chances between 10%, this
potential will continue to be monitored over the next couple of
days. /vmt

&&

.AVIATION...
06Z TAFS: VFR conditions will continue for all TAF sites with
mid to high level clouds passing through. Breezy west to
southwest winds will stay breezy for central Washington through
the early morning. Showers and isolated thunderstorms across
far southeast Washington and the southern Idaho Panhandle may
shift far enough north to bring some light sprinkles or virga to
LWS. Large dew point spread may bring some isolated gusty winds
tonight, but confidence is low. Expect afternoon breeziness
again across eastern Washington and central Washington on
Thursday with wind gusts up to 25 knots.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence
of VFR conditions for all TAF sites. Low confidence for
lightning at LWS over the next couple of hours.

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

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        78  54  77  52  80  53 /  10  10   0   0   0   0
Coeur d`Alene  78  55  75  53  78  52 /  10  20  10   0   0   0
Pullman        75  50  74  48  76  49 /  10  10   0   0   0   0
Lewiston       84  60  83  59  86  58 /  10  10   0   0   0   0
Colville       77  45  74  43  79  44 /  20  30  40  10  10   0
Sandpoint      76  54  72  50  76  47 /  20  40  30  10  10   0
Kellogg        74  57  71  56  74  55 /  10  20  10   0   0   0
Moses Lake     81  53  82  52  85  55 /  10  10   0   0   0   0
Wenatchee      80  58  79  58  84  60 /  10  10   0   0   0   0
Omak           80  53  79  51  83  53 /  10  20  10   0   0   0

&&

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

&&

$$