342
FXUS66 KOTX 172113
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
213 PM PDT Tue Sep 17 2024

.SYNOPSIS...

Some light rain will persist at times over north Idaho and the
eastern third of Washington through early Wednesday. Conditions
will trend drier toward the end of the work week, then
precipitation chances return for the weekend.

&&

.DISCUSSION...

Tonight through Thursday: Upper level longwave trof lingers over a
good portion of the Western US through this interval. At least two
synoptic scale low pressure systems are nested inside it and
rotating around the upper level longwave`s edges. The showery bands
of precipitation extending outward from one such low centered to our
southeast over Southern Idaho/Northeast Nevada is allowing for
considerable cloud cover and narrow bands of precipitation over far
Eastern Washington and North Idaho to linger on into tonight. As
this low, and its associated showers and cloud cover, treks to the
northeast the clouds and showers will be relegated to smaller
portions of North Idaho Wednesday and then eventually a drier
forecast with clearing skies Wednesday night and Thursday.

Friday through Tuesday: The upper level flow pattern is still rather
progressive as a more zonal north/northwest flow drapped atop the
large longwave trof Friday allows for drier air from the northwest
void of significant shortwaves to linger into the weekend, although
sometime late Saturday there is greater likelihood of at least one
frontal feature or more, with increased moisture streaming into
them, dropping through from the northwest. With this in mind a
increase in cloud cover along with some minor pops and light QPF
return to mark late Saturday and beyond coupled with forecast
temperatures generally quite near or slightly below normal. Some
patchy morning frost and fog appear in very small isolated well
sheltered locations of Northeast Washington and the Idaho Panhandle.
/Pelatti

&&

.AVIATION...
18Z TAFS: Scattered showers will continue to rotate north up into
SE Washington, the Idaho Panhandle, and far eastern reaches of NE
Washington through tonight. Showers that form over TAF sites may
result in brief visibility reductions to MVFR. With a moist
boundary layer and middle to high level clouds thinning overnight,
a handful of model soundings are showing a marginal VFR
developing around KGEG, KSFF, KCOE, KDEW around 12Z Wednesday
morning.


FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Moderate
confidence of increasing showers for southeast Washington and
north Idaho through tonight. Some models show some localized
heavier showers, but confidence of these impacting the TAF sites
carries lower confidence. There is low confidence for stratus
development around KGEG, KSFF, KCOE, KDEW early Wednesday morning.
Despite several model soundings showing this development along
with a 40 to 60 percent chance in the High Resolution Ensemble
Forecast (HREF) system, the National Blend of Models is giving
these areas a zero percent chance. Included a FEW015 at KGEG/KSFF
and SCT015 at KCOE to message this potential, but was not
confident enough to reduce conditions to MVFR.

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        73  49  76  49  76  47 /  40  20  10   0   0   0
Coeur d`Alene  71  48  72  48  75  48 /  60  40  20   0   0   0
Pullman        65  45  69  43  73  45 /  60  30  20   0   0   0
Lewiston       74  54  76  53  79  53 /  60  20  10   0   0   0
Colville       77  38  78  39  76  38 /  20  20  10   0   0   0
Sandpoint      70  46  72  45  73  44 /  50  50  20   0   0   0
Kellogg        66  49  67  50  72  49 /  70  60  30  10   0   0
Moses Lake     79  48  79  46  78  46 /   0  10   0   0   0   0
Wenatchee      78  55  80  53  79  53 /   0   0   0   0   0   0
Omak           83  51  82  51  81  48 /  10  10   0   0   0   0

&&

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

$$