782
FXUS66 KOTX 110457
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
957 PM PDT Sat Aug 10 2024

.SYNOPSIS...
Showers and thunderstorms will expand across the region this
afternoon. Lightning from thunderstorms will be capable of
starting new fires. Thunderstorms will also come with brief heavy
rain and gusty outflow winds. There is a growing threat for
nocturnal thunderstorms over southeast Washington into the Idaho
Panhandle Sunday night into Monday morning. Thunderstorms will
also be possible in the afternoon and again on Tuesday. Most of
them will occur over the northern third of eastern Washington
into the northern half of the Idaho Panhandle. Quieter weather
looks likely for the middle of the week, but thunder chances will
rise once again by the end of the work week. Daytime temperatures
will begin the week slightly warmer than normal but should drop
to average or slightly below by midweek.

&&

.DISCUSSION...
UPDATE: Thunderstorm activity has calmed with the arrival of
night. A band of showers will push through the Spokane-CdA
corridor for the next few hours. Precip accumulation is not
expected to be more than a tenth or two.

This afternoon and tonight: Isolated to scattered
showers and thunderstorms will impact parts of the Inland NW. An
unstable upper trough and smaller scale embedded disturbances will
continue to migrate across the region through about 06Z, before
subtle shortwave ridging develops overnight. With daytime heating
and convective instability and the timing of the features, this
will keep the best chance of showers before midnight. One area of
showers and thunderstorms has been found around the mountains near
the ID/MT border and these will continue to pulse up, while they
shift east. A second area of showers and thunderstorms is also
developing around the Cascades. As the subtle shortwave initiating
this activity shifts east across the Cascades, this latter
activity is expected to propagate eastward too. The best chances
will be near the Cascades and central before 03Z, then expand
eastward between 03Z-06Z. The high-resolution convective models
differ on just how robust these get or just how much a line
develops and some of them weaken the line as it pushes east,
especially away from the mountains. So confidence in how much may
reach the Spokane/C`dA metro area is degraded. So this will not be
a certain shower/t-storm risk for anyone. Additionally, high-
resolution models continue to support this line pushing east with
briefly gusty winds, potentially gusting near 40 mph as it passes.
This can happen even if the line weakens enough to no pass some
areas with much actual precipitation. This tends to wash out as it
is heading toward Idaho. Overall some of thunderstorms this
evening will bring the risk for heavy downpours, gusty winds and
lightning, as well as perhaps some small hail. Heading past 05-06Z
the risk for precipitation wanes and skies clear out.

Sunday into Tuesday: Another potential for showers and
thunderstorms comes to the region. Sunday is expected to start off
dry, then the next shortwave starts to move in. Shower/t-storm
chances expand over the northern mountains Sunday afternoon and
evening. Then Sunday night into Monday morning the shortwave
continues to pivot into the region in and some elevated
instability starts to migrate into the southeastern CWA. A risk
for showers/t-storms expands over the Blue Mountains Sunday
evening, expanding toward the L-C Valley, Camas Prairie, Palouse
and central Panhandle. Chances may also push as far north as
Spokane/C`dA area. This nocturnal/elevated convection will have a
faster storm motion, compared to some of the more recent storms.
That will increase the potential for dry lightning (i.e.
thunderstorms without a wetting rain, i.e. <0.10 inches of
precipitation). They could push through with 20 mph or so winds.
This could be a concern from a fire weather standpoint as any
lightning started wildfires could be fanned, at least initially.

By Monday afternoon the overall unstable upper trough and heating
of the day will lead to overall increased coverage in shower and
thunderstorms chances, with the better risk around the mountain
zones by then. Monday night the threat wanes but we will have to
watch for another wave slipping by the southeast for a continued
risk for nocturnal elevated showers/t-storms. The threat wanes
some into Tuesday morning, then expands a little bit in the
afternoon near the Cascades and central Panhandle mountains.
Overall, however, Tuesday looks like a drier day.

Wednesday to Saturday: The Inland NW will be in an evolving
weather pattern, which starts off relatively quiet then comes with
the potential deeper upper low moving on the region heading into
next week. Wednesday to early Thursday looks dry with a weak col
or ridge in the region. Look for limited cloud cover too. Later
Thursday into the weekend the models starts to deepen a low
pressure trough around the coastline and perhaps start to shift it
inland toward the latter part of next weekend. Overall this will
bring increasing shower chances late Thursday into the weekend,
though right now the best risk sits in the mountains until late
Friday into Saturday.

As for temperatures: expect above normal temperatures through
Monday, then cooler than normal readings Tuesday and Wednesday,
moderation toward the latter part of the work week before trending
back down toward next Saturday. This translates to upper 80s and
90s on the above normal days and upper 70s to mid-80s on below
normal days. /Solveig


&&

.AVIATION...
06Z TAFS: The thunder activity has calmed with the arrival of
night. A band of shower activity will continue to move across
GEG-SFF-COE for the next few hours. While the rest of the
overnight is expected to calm, another round of isolated showers
and thunderstorms across the North Washington and Idaho. The
activity are not expected to impact TAF sites. Smoke and haze
will continue to impact areas near wildfires.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Confidence is high
for VFR conditions. Moderate confidence in shower activity for
the Spokane corridor as precip might have a difficult time
reaching surface and accumulating.


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

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        60  89  62  87  57  80 /  30  10  20  20  10  10
Coeur d`Alene  57  86  61  86  55  78 /  30  20  10  20  10  10
Pullman        55  86  57  83  52  75 /  20  10  20  20  20  20
Lewiston       66  96  68  93  63  84 /  10  10  20  20  20  20
Colville       47  88  49  86  48  83 /  30  20  10  20  10  10
Sandpoint      53  84  57  84  53  78 /  30  20  10  20  10  10
Kellogg        60  83  64  84  58  75 /  20  20  10  20  20  10
Moses Lake     59  91  61  89  56  84 /  10   0   0  10  10   0
Wenatchee      67  91  66  88  62  84 /  10  10  10  10   0   0
Omak           62  93  64  92  62  89 /  20  20  10  30  10  10

&&

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

$$