606
FXUS66 KOTX 181746
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
1046 AM PDT Thu Jul 18 2024

.SYNOPSIS...

Strong high pressure will begin to amplify over the Inland
Northwest during this period continuing our string of hot weather
which began around July 5th. The heat will likely peak this
weekend with widespread triple digit high temperatures and
possible records. There are hints the heat will finally relent by
the middle of next week.

&&

.DISCUSSION...

Today...Slow moving upper level shortwave, currently centered
just north of Spokane will continue to eject slowly NE during the
next several hours. Isolated thunderstorms will still be possible
near the shortwave as well as along a narrow band stretching from
Lookout Pass toward Lewiston. Most of the lightning will occur in
northern portions of Pend Oreille County as well as northern
Bonner and Boundary Counties in an area of the greatest
instability (MUCAPE values in excess of 500 j/kg, and weak forcing
from the shortwave.

Otherwise we expect to see the upper level ridge rebounding today
as a trough rebuilds just west of 130w. This amplification will
bring several degrees of warming compared to what we experienced
yesterday. That equates to highs in the mid 90s to 104 for most
valley locations. However unlike yesterday where we saw partial
relief from variable cloud cover, today should be much sunnier and
thus potentially feel hotter. Based on these temperatures we decided to
expand the heat advisories into north Idaho to join the rest of
eastern Washington. These will be in effect at least through the
weekend.

Tonight through Friday night...The offshore trough will begin
to nudge toward the Cascades. This could bring a slight cooling
trend to the Cascade Crest area, but little cooling elsewhere.
Highs will once again peak in the mid 90s to the lower 100s with
little cloud cover. Meanwhile overnight lows will be in the mid
50s and 60s.

From a fire weather perspective, the daytime relative humidity
values will drop into the teens to lower 20s with poor overnight
recoveries in the mountains and mid-slopes. This suggests any
ongoing fires (or new ones from this lightning event) have the
potential to exhibit strong growth. The sunshine today will also
potentially perk up local fires in the Cascades and the numerous
ones over Oregon. This will result in increased smoke production,
but for now the HRRR smoke models are keeping most of the surface
based smoke near the Pioneer fire north of Chelan. The only
saving grace is winds will be relatively light for most locations
save the Wenatchee Valley and Waterville Plateau late this
afternoon and evening when we could see wind gusts possibly up to
20 to 25 mph. fx

Saturday to Wednesday: The region will continue to warm through
this weekend as a ridge amplifies over the northern Rockies,
before it starts to lose influence heading into the new work week
and temperatures start to moderate, maybe even closer to seasonal
norms. Highs push into the 100s over much of the region Saturday
and Sunday, with Sunday being the warmest day. By Monday an
onshore flow begins to push cooler air up toward the Cascade crest
and knock temperatures down a couple degrees everywhere, though
still with highs largely in the 100s. Models hint at the chance
for showers Monday and Tuesday as the offshore trough starts to
push inland. However 2/3 of the models keep the better chances
around the fringes of our CWA, so the forecast largely remains
dry. If chances are increased, right now the chances remain best
near the Cascades though north-central WA. Winds start to increase
as the trough shifts inland too, especially near the Cascades and
central WA. Models are still marginal or very localized where
wind speeds and RH may converge to product critical fire weather
conditions from Monday through Wednesday, but it definitely will
be monitored. Highs trend toward the 90s and even upper 80s by
midweek. /Solveig

&&

.AVIATION...
18Z TAFS: The Inland NW expect VFR conditions to prevail as high
pressure builds into the region. The only exception will be some
hazy conditions from increasing smoke from the regional fires
this afternoon/evening, including the Pioneer Fire near Lake
Chelan. The HRRR smoke model suggests this will drift N-NW late
today and tonight and should remain out of the KEAT area.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
With the exception of smoke near wildfires confidence is high for
continued 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        98  64  98  65 102  66 /   0   0   0   0   0   0
Coeur d`Alene  95  62  96  63  99  65 /   0   0   0   0   0   0
Pullman        93  58  94  59  98  63 /   0   0   0   0   0   0
Lewiston      103  70 103  70 107  71 /   0   0   0   0   0   0
Colville       97  54  97  54 100  56 /   0   0   0   0   0   0
Sandpoint      93  58  94  58  99  60 /   0   0   0   0   0   0
Kellogg        92  67  95  68  98  71 /   0   0   0   0   0   0
Moses Lake    100  62 100  61 104  68 /   0   0   0   0   0   0
Wenatchee     101  70  99  69 103  76 /   0   0   0   0   0   0
Omak          102  65 102  65 106  68 /   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-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.

&&

$$