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000
FXUS66 KOTX 120458
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
958 PM PDT Thu Apr 11 2024

.SYNOPSIS...
The upcoming weather moving into the weekend will feature a few
chances of mostly mountain showers along with a warming trend.
There will be a small chance for thunderstorms near the Lewiston-
Clarkston Valley Friday and Saturday afternoons. High
temperatures for much of the area will climb into the upper 60s to
mid 70s over the weekend. A cold front will bring a return of
cooler and showery weather early next week. Cold front passage
will bring breezy to windy conditions Sunday afternoon through
Monday.

&&

.DISCUSSION...
Evening update: Showers are spreading into southeast WA and lower
ID. I increased PoPs further west and north across the region this
evening into the overnight, including further west into the Upper
Columbia Basin and the Spokane and Coeur d`Alene area. The highest
potential still remains over southeast WA through the central
Panhandle.  /Solveig

Tonight through Friday night: A deep and tightly wound up upper
level low pressure system sits out at around 38N 138W. A slow moving
cold front is inching its way toward the west coast. This frontal
band will stall out over western Washington/Oregon as the parent low
digs south off the coast toward northern California. Dynamics will
be lacking over the Inland Northwest as this front stalls out and
will leave only minor potential for showers over the higher terrain
of eastern Washington. Models indicate a strip of mid level
instability that will extend from northeast Oregon into the southern
to central Idaho Panhandle late this evening into the overnight
hours. There will be a narrow strip where measurable precipitation
is expected roughly near to or over the Lewiston-Clarkston Valley,
Camas Prairie, Pullman/Moscow up towards Clarkia, St. Joe, and
Wallace. There`s potential for localized moderate rainfall under
this narrow band that develops. Otherwise, much of the region will
generally remain under thick mid to high level clouds with possibly
a few sprinkles.

Surface heating on Friday will destabilize lower levels of the
atmosphere over northeast Oregon into the southern Idaho Panhandle.
Convective allowing models indicate the potential for stronger
thunderstorms to develop over the higher terrain in these areas.
Steering flow to the northeast will take thunderstorms off of the
higher terrain toward the Lewiston-Clarkston Valley and Camas
Prairie late in the afternoon and evening. Most likely scenario is
for these storms to be weakening as they move into these communities
as storms will be moving into an environment that is less unstable.
Main concern to watch out for will be for gusty outflow winds as
storms decay. There is a 15% chance that thunderstorms will maintain
enough strength to move into the Lewiston/Clarkston areas where
lightning and small hail will be possible.

Temperatures will be a little warmer tomorrow and start a warming
trend with even warmer temperatures for over the weekend. /SVH

Saturday through Thursday: The INW will see a shift in weather
patterns starting early next week. The weekend will start with
warmer temperatures ranging from the upper 60s to upper 70s, but
this will change as a robust cold front sweeps through the region on
Sunday night. Ahead of this front, a deep shortwave trough on Sunday
will intensify the 500 mb height gradient, leading to breezy
conditions Sunday afternoon. Dry weather and recently dry fields
will heighten the risk of grass fires and blowing dust on both
Sunday and Monday, particularly in areas like the Waterville Plateau
and Columbia Basin. In areas from Coeur D’Alene to Wenatchee,
there`s a 40-60% chance of wind gusts exceeding 30 mph during the
day Monday.

By Monday, snow levels will plummet to below 2500 feet in the
Cascades. Although the risk of significant snowfall during the day
is low, there`s a 40% chance of seeing over 3 inches of snow by
Tuesday morning at Stevens Pass (70% at Snoqualmie Pass). While
marginal road temperatures may mitigate impacts, a heavier burst
of snow could lead to minor travel disruptions on Cascade passes.
Monday will usher in much colder temperatures, with highs only
reaching the mid-50s regionwide. Cooler conditions will persist
through the week, accompanied by brisk north winds and occasional
chances (20-40% chance) for non-impactful showers. /Butler

&&

.AVIATION...
06Z TAFS: A slow moving cold front will push in off of the
eastern Pacific and stall out over western Washington/Oregon
tonight. Moisture will increase ahead of this frontal system
across the Inland Northwest with a 20-40% chance for showers over
northeast WA and north ID, and a 60-80% chance for showers along
a strip of elevated instability stretching from northeast Oregon
into the southern to central Idaho Panhandle. This will result in
showers increasing at the KPUW and KLWS terminals after 06Z this
evening into the early morning morning hours on Friday, with
smaller chances near GEG/SFF/COE between 06-12Z. Cloud bases will
lower with the rain, but flight conditions remaining VFR with
ceilings expected to lower between 4-7 kft agl. Expect mountain
obscurations over the Cascades into tonight. Additional shower
chances will move into lower ID/southeast WA later Friday into
Friday evening.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Confidence remains
high for VFR conditions across the region through Friday morning. The
one alternate scenario is if a band of precipitation across KPUW/KLWS
contains moderate rain. If this occurs, visibilities and ceilings
may lower to below VFR with the HREF model indicating up to a 30%
chance for MVFR conditions occurring. Some IFR conditions may
develop in the L-C Valley between 12-17Z but confidence is low.

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

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        44  63  40  71  45  72 /  10  10   0   0   0   0
Coeur d`Alene  43  64  39  70  46  71 /  10  10  10   0   0  10
Pullman        43  62  42  70  46  67 /  70  30  30   0  10  20
Lewiston       48  68  49  78  52  74 /  60  30  40   0  10  20
Colville       40  64  35  73  41  75 /  10  10   0   0   0   0
Sandpoint      42  62  36  68  43  70 /  10  10   0   0   0  10
Kellogg        45  61  44  69  48  69 /  50  30  10   0   0  20
Moses Lake     42  66  39  77  47  77 /  10   0   0   0   0   0
Wenatchee      45  64  45  74  49  74 /  10   0   0   0   0   0
Omak           42  67  38  75  45  77 /  20  10   0   0   0   0

&&

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

$$