730
FXUS66 KOTX 140458
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
958 PM PDT Sat Jul 13 2024

.SYNOPSIS...
Very warm temperatures will continue through the week. A push of
breezy and dry winds Sunday afternoon will result in critical fire
weather in the lee of the Cascades, the western Columbia Basin,
and the Snake River area on Sunday. After a brief decline in
temperatures Monday and Tuesday, temperatures will rebound into
the upper 90s and 100s by Wednesday. A weak system moving into the
PNW from the southwest will lead to a 10-15% chance of dry
thunderstorms across the Cascades on Wednesday. Areas of haze and
smoke will linger over the Inland NW from local fires.

&&

.DISCUSSION...
Key points:

-Red Flag Warnings for the lee of the Cascades and the Snake River
Valley are in effect for the combination of breezy winds and very
dry conditions on Sunday.

-Heat will continue across the Inland Northwest through the week.

-Monitoring the threat for dry thunderstorms across the Cascades
 mid week.

Saturday night through Monday: The Inland Northwest remains in a
weak zonal flow aloft as a strong high pressure remains over the
southwest and a weak upper level low sits off the California coast.
This has kept temperatures very warm with highs in the 90s to low
100s across the region. A weak wave embedded in the flow will move
onshore Washington late Saturday night into Sunday morning.
Increased onshore flow will tighten the cross-Cascade pressure
gradient and bring dry and breezy winds to the lee of the Cascades
and in the lee of the Blue Mountains Snake River Area Sunday
afternoon. Sustained winds of 10 to 20 mph with gusts up to 30
percent and relative humidity values 10 to 19 percent will result in
critical fire weather conditions that can lead to rapid fire spread
on new or existing fires.

This wave will slightly cool the air mass on Monday with a
negligible decrease in high temperatures Monday afternoon. However,
this will be enough cooling to drop temperatures below Heat Advisory
criteria. This cooling will not last long as upper level ridging
will begin to rebuild on Tuesday.

Tuesday through Friday: We will be monitoring this period for the
threat of dry thunderstorms across the Cascades as deterministic
models begin to show the low off the coast of California to eject
northeastward into Oregon and Washington as a shortwave between
Tuesday and Wednesday as a longwave trough digs in the eastern
Pacific. Additionally, as this trough digs, ridging will amplify
across the Inland Northwest as mentioned earlier. Models show this
shortwave advecting elevated moisture and instability into the
region. Current probabilities in the NBM for thunderstorms across
the Cascades are low with 5 to 10% on Tuesday and and 10 to 15% on
Wednesday. Pattern recognition suggests this will be an important
period to watch over the next couple of days as the threat of
lightning followed by this extended period of hot and dry weather
will make fuels across the region more susceptible to ignition.

With regards to the heat, there is solid agreement among ensembles
temperatures will rebound into the upper 90s to low 100s across the
Inland Northwest as the longwave trough in the eastern Pacific
amplifies the ridge. Examining the clusters reveals some
discrepancies in the exact numbers Friday into the weekend as on the
placement of the center of the ridge. Regardless, temperatures look
to remain above average into the weekend with a continued threat
for heat related illnesses for anyone without effective cooling.
/vmt

&&

.AVIATION...
06Z TAFS: VFR conditions will prevail. Local reductions in
visibility are possible near and downwind of Lake Chelan due to
smoke from the Pioneer Fire. A weak weather system will move into
the region early Sunday morning will increase onshore flow through
the Cascade gaps will bring breezy winds across the region on
Sunday with the strongest winds in the lee of the Cascades.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence in
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        64  97  63  94  62  96 /   0   0   0   0   0   0
Coeur d`Alene  62  94  61  92  59  94 /   0   0   0   0   0   0
Pullman        55  92  57  89  53  92 /   0   0   0   0   0   0
Lewiston       70 103  68 101  66 103 /   0   0   0   0   0   0
Colville       54  96  54  93  54  95 /   0   0   0   0   0   0
Sandpoint      58  92  56  90  54  92 /   0   0   0   0   0   0
Kellogg        67  91  64  88  64  91 /   0   0   0   0   0   0
Moses Lake     63 100  60  98  60  99 /   0   0   0   0   0   0
Wenatchee      70  99  67  97  68  99 /   0   0   0   0   0   0
Omak           65 102  65 101  65 102 /   0   0   0   0   0   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Heat Advisory until 10 PM PDT Sunday for Central Panhandle
     Mountains-Coeur d`Alene Area-Idaho Palouse-Lewis and
     Southern Nez Perce Counties-Lewiston Area-Northern
     Panhandle.

WA...Heat Advisory until 10 PM PDT Sunday for Central Chelan County-
     Lower Garfield and Asotin Counties-Moses Lake Area-
     Northeast Mountains-Okanogan Highlands-Okanogan Valley-
     Spokane Area-Upper Columbia Basin-Washington Palouse-
     Waterville Plateau-Wenatchee Area-Western Okanogan County.

     Red Flag Warning from 2 PM to 9 PM PDT Sunday for Foothills of
     Central Washington Cascades (Zone 705)-Lower Palouse  -
     Snake River (Zone 709)-Waterville Plateau (Zone 706)-
     Western Columbia Basin (Zone 707).

&&

$$