Lewiston, Idaho 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

332
FXUS66 KOTX 220553
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
953 PM PST Fri Feb 21 2025

.SYNOPSIS...
Warmer temperatures and rain will arrive this weekend as high
temperatures warm into the 40s and low 50s. Runoff from rain and
melting snow will lead to increased flow and minor flooding across
southeast Washington and the central and southern Idaho
Panhandle. Another weather system Monday into Tuesday will bring
more rain and stronger winds.

&&

.DISCUSSION...
Tonight thru Saturday:
As a disturbance moves into and across Inland Northwest, snow
levels will be low enough for light snow to mix in with developing
rain across populated areas this evening into overnight. Snow
levels will rise through Saturday morning so that most
precipitation will be rain outside of the mountains. Areas of fog
will again be a concern overnight in favored areas, though it`s
not anticipated to be as wide-spread as last night. The highest
precipitation totals with this first round of precipitation
through Saturday will be across the Cascades, far eastern
Washington, and north Idaho. /KD

Saturday Night to Wednesday: Three systems will pass through the
PacNW between Saturday Night and Tuesday, with warmer temperatures,
wind, and precipitation. The first will arrive late Saturday, with a
warm front lifting north across the Inland Northwest. Precipitation
will mainly fall as rain at lower elevations and snow at higher
altitudes, with the Cascades, eastern WA, and northern ID expecting
the highest totals. Snow levels will rise throughout the night, with
a wintery mix developing over the Methow Valley that could contain
some pockets of freezing rain.

A second wave will pass through Sunday, driven by a compact low-
pressure system move through the region. Models show varying
forecasts, but we have gone slightly on the higher side. Current
forecast have 0.5 to 1.0 inches of rain for the lowlands and 1.5 to
2.5 inches for the higher mountain peaks. Winds will also increase
as well, mainly over the Columbia Basin and Palouse, with gusts up
to 30 mph.

The combination of rain, rising temperatures and breezy winds will
lead to rapid snowmelt across the lowlands where snow is present.
This could cause localized flooding, particularly in urban areas
with poor drainage and fields. Several creeks and river are expected
to rise, reaching near action stage for areas from Palouse up to the
Spokane area.

A deeper low is expected to bring more preciptiation and possibly
stronger winds to the region on Monday night into Tuesday. Winds
this time will be strongest in the early morning, with gusts of 35
to 40 mph expected near the Columbia Basin and the Palouse. /KK

Tuesday Night through Friday: Models are in good agreement of an
upper level ridge building Wednesday. Thursday and Friday models
start to diverge on a trough moving toward the west coast. 60% of
the ensembles cut off the low off the southern CA coast. 40% show
a faster weaker wave moving through the southwest US. Either way,
it looks like the Pac NW will be under the influence of higher
heights and drier conditions.

Temperatures will remain above average for the end of February.
The NBM is forecasting high temperatures above the 90th
percentile. Have lowered our temps down several degrees closer to
what the ensemble mean has. The tricky part is if fog or stratus
forms after these wet weather systems move through with abundant
low level moisture. If so, our daytime temps will be quite a bit
cooler. If we clear out and see sunny skies, our temperatures will
be warmer. For now, have highs in the mid 40s to mid 50s, and
lows in the upper 20s to mid 30s. /Nisbet

&&

.AVIATION...
06Z TAFS: As a storm system moves into the area with
precipitation beginning around 08Z for many of the TAF sites,
ceilings will lower into MVFR through the night. Every TAF site
but KMWH will stay mostly at VFR/MVFR with lowered ceilings due to
precipitation. KMWH looks to get down to IFR at some point
through the evening due to localized rainfall and low stratus.
KEAT is the only TAF site that has low enough temperatures to
support a possible rain/snow mix. A second round of rain will move
in close to the end of the TAF forecast period. There is the
potential for KGEG-KSFF-KLWS to see wind shear values of 30 knots
or more at 2000 feet Saturday evening.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Moderate
confidence in timing and location of upcoming precipitation,
particularly with the second wave later in the TAF period.
Moderate to high confidence of MVFR ceilings for all but KEAT
through the night. Moderate to low confidence of wind shear values
being greater than 30 knots difference at KGEG-KSFF-KLWS for
Saturday evening. /AS

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

Confidence descriptors:
Low - Less than a 30 percent chance
Moderate - 30 to 70 percent chance
High - Greater than a 70 percent chance

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        35  43  40  49  40  50 /  50  50 100  90  80  50
Coeur d`Alene  35  43  39  47  38  48 /  60  60 100 100  90  50
Pullman        34  42  38  45  39  48 /  40  40 100 100  90  50
Lewiston       37  47  41  52  42  54 /  20  20  90 100  90  40
Colville       33  41  38  46  34  47 /  70  40 100  80  80  40
Sandpoint      35  41  39  44  38  46 /  80  80 100 100  90  60
Kellogg        35  42  41  45  40  46 /  50  70 100 100  90  60
Moses Lake     32  47  39  55  38  52 /  30  20  70  70  40  40
Wenatchee      33  41  39  48  38  47 /  40  30  70  70  50  50
Omak           34  41  36  46  35  47 /  50  40  90  70  60  40

&&

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

$$