785
FXUS66 KOTX 132139
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
239 PM PDT Tue Aug 13 2024

.SYNOPSIS...
Isolated showers and thunderstorms over the northern mountains of
eastern Washington this afternoon. A break in showers and
thunderstorms comes Wednesday before more unsettled conditions
return late Thursday into the weekend. Daytime temperatures will
be near normal through the week.

&&

.DISCUSSION...

Today and tomorrow: Isolated thunderstorms have started to develop
in the Cascades, Okanogan Highlands, and northern mountains. SPC
mesoanalysis shows an uncapped 100-500 J/kg of SBCAPE with very
weak (less than 20 kt) effective bulk shear in the aforementioned
locations. Weak terrain based lift and shear has promoted weaker
single cell convection this afternoon. Thunderstorms will be
capable of small hail, gusty winds, and brief heavy downpours.
Burn scars are being monitored for potential flash flooding.
Breezy Cascade gap winds will develop this evening at Wenatchee
elevating fire weather concerns despite higher relative
humidities.

Tomorrow: Tomorrow will be mild and dry as a shortwave ridge noses
into the Inland Northwest. Temperatures will be in the 80s in the
lowlands. /Butler

Thursday through Monday: A shortwave trough is on track to move up
from Oregon into Washington and Idaho Thursday afternoon into
Friday, prompting a return of overcast skies, showers, and
thunderstorms. The Cascade Crest, Southeast Washington, and the
South and Central Idaho Panhandle will be the first areas impacted
by storms, then coverage will expand over the majority of Eastern
Washington and Idaho by Friday morning. Model guidance is showing a
35 to 50 percent chance of measurable rainfall during the Thursday-
Friday timeframe for most locations.

Heading into Friday evening, a larger trough will develop just
offshore while a ridge simultaneously develops to our east over the
Rockies. As a result, the Inland Northwest will be caught in a
stream of southwesterly flow between the two. Warm, moist air
flowing in out of the southwest will keep us in an active, unstable
pattern with chances for showers and thunderstorms through the
weekend.

Models have not yet reached a consensus on the exact placement of
the offshore trough over the weekend and into next week. How far
offshore the trough develops will determine how warm our
temperatures get. Around 60 percent of models are predicting the
trough will be closer to shore which would keep our temperatures
near to slightly below average. Average daytime highs are in the mid
80s this time of year. The remaining 40 percent of models show the
trough developing further offshore which would allow the ridge to
our east to have a greater influence on our temperatures. This means
temperatures would likely be a few degrees above average in the 90s.
More on that as the weekend gets closer. /Fewkes

&&

.AVIATION...
18Z TAFS: VFR conditions will prevail. Expecting another round of
weak thunderstorms in far north-central and northeast Washington
and north Idaho between 18-03Z today. Breezy northwest winds will
pick up at the Wenatchee Airport (KEAT) this evening after 00Z.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Confidence is high
for VFR conditions.

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

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        53  83  56  88  59  81 /   0   0   0   0  30  40
Coeur d`Alene  54  81  54  86  58  78 /   0   0   0  10  40  50
Pullman        50  80  50  82  52  78 /  10   0   0  10  40  40
Lewiston       60  88  62  90  65  86 /  10   0   0  10  50  30
Colville       48  84  45  88  48  79 /  10   0   0   0  20  50
Sandpoint      54  80  51  84  55  76 /   0   0   0  10  40  60
Kellogg        55  79  58  84  59  75 /  20   0   0  10  50  60
Moses Lake     54  85  55  89  58  85 /   0   0   0   0  20  20
Wenatchee      62  86  63  89  64  84 /   0   0   0  10  20  20
Omak           59  89  60  93  62  88 /  10   0   0   0  10  40

&&

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

$$