301
FXUS66 KOTX 201327
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
627 AM PDT Sat Jul 20 2024

.SYNOPSIS...
Very hot temperatures will continue through Monday with widespread
triple digit heat Sunday and Monday. A significant pattern change
will arrive on Tuesday with the arrival of a dry cold front.
Although temperatures will cool by several degrees, breezy winds
and dry conditions each afternoon will result in increase fire
risk.

&&

.DISCUSSION...
Saturday through Monday: A ridge will amplify across the western US
this weekend as a deep upper level low churns in the Gulf of Alaska.
850mb temperatures will warm to 26 to 28C in response, corresponding
to widespread highs in the upper 90s to low 100s for the Inland
Northwest. On Sunday, as the Gulf of Alaska low begins to inch
toward the British Columbia coast, repositioning the center of the
ridge slightly eastward. With the flow aloft shifting to the south,
temperatures will warm even further. 850mb temperatures around 29 to
31C across the Inland Northwest will bring widespread temperatures
in the triple digits. Heat advisories will upgrade to Excessive Heat
Warnings this afternoon as these temperatures will result in major
to extreme HeatRisk across the region. Everyone who is exposed to
the heat is at risk for heat related illnesses. Please consider
canceling outdoor activities. Warm overnight low temperatures will
result in little to no relief overnight. If you have access to air
conditioning, use it, or find a location that does. Even a few hours
in a cool location can lower risk for illness.

Sunday and Monday will need to be watched for the potential for dry
thunderstorms as a shortwave moves in from the southwest on Sunday
and as a cold front approaches the region on Monday. For Sunday, in
combination with intense heating resulting in a very unstable
atmosphere, elevated moisture and instability raises these alarms.
Models continue to show the strongest lift to our west and south
with the probability for thunderstorms remaining below 15 percent.
Some high resolution models are showing isolated showers to move
northward across central Washington Sunday afternoon, but confidence
remains too low to include it in the forecast.

As the deep low approaches the British Columbia coast on Monday,
moisture and high level clouds will spread eastward into the rest of
eastern Washington and north Idaho ahead of an approaching cold
front. The threat for thunderstorms will also spread eastward as
this mid level moisture increases elevated instability. Currently
the best chances will be across the north Cascades, the northeast
mountains, and north Idaho with a 10 to 15 percent chance. In
addition to this risk, a return to onshore flow will tighten the
cross-Cascade pressure gradient with breezy winds through the
Cascade gaps and central Washington Monday evening. /vmt

Tuesday through Friday: A cooldown is finally on the horizon! A deep
center of low pressure is on track to move into northern British
Columbia on Tuesday which will send an associated dry cold front
sweeping across the Inland Northwest, bringing some long awaited
relief from the heat. However, all good things come at a cost. With
the cooling temperatures will come an increase in winds due to a
pressure gradient setting up over our region with the area of low
pressure to our north and higher pressure to our south. Increased
winds will create potential for the numerous wildfires throughout
Eastern WA and North ID to grow and spread rapidly, especially with
vegetation being primed for burning thanks to our extended spell of
hot and dry conditions. Breezy winds will begin Monday night and
will persist through the end of the workweek. As for specifics on
temperatures, the most dramatic drop in temperatures will occur from
Monday to Tuesday. Daytime highs on Tuesday will be around 10
degrees cooler than those on Monday. For most locations, this means
going from triple digits on Monday to the low 90s on Tuesday. The
cooling trend, though more gradual, will continue through the end of
the week. By Thursday, if our current forecast pans out, Spokane
will see temperatures drop into the 80s for the first time since
July 4th! This will mark the end of what has been a record-breaking
streak of 90-degree-or-higher days. Spokane`s previous record was 15
days in a row of temperatures climbing above 90F. If our current
streak continues through Wednesday as forecasted, we`ll obliterate
that record with a whopping 20 days of 90+ degree temperatures.
/Fewkes

&&

.AVIATION...
12Z TAFS: An upper level ridge will allow VFR conditions to
continue through the period. The only exception will be some hazy
conditions from smoke near wildfires that may reduce visibilities
along Lake Chelan and in the Methow Valley.

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       100  67 106  70 102  65 /   0   0   0   0   0   0
Coeur d`Alene  98  67 102  68 100  64 /   0   0   0   0   0   0
Pullman        97  64 103  63  97  59 /   0   0   0   0   0   0
Lewiston      106  73 111  75 106  71 /   0   0   0   0   0  10
Colville       98  57 103  60 101  56 /   0   0   0   0   0   0
Sandpoint      96  62 100  65  99  60 /   0   0   0   0   0   0
Kellogg        96  72 100  72 100  68 /   0   0   0   0   0   0
Moses Lake    102  64 108  68 102  61 /   0   0   0  10  10   0
Wenatchee     102  75 108  75 102  66 /   0   0   0  10  10   0
Omak          104  68 110  73 107  65 /   0   0   0   0   0   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Heat Advisory until 11 AM PDT this morning for Central Panhandle
     Mountains-Coeur d`Alene Area-Idaho Palouse-Lewis and
     Southern Nez Perce Counties-Lewiston Area-Northern
     Panhandle.

     Excessive Heat Warning from 11 AM this morning to 8 PM PDT
     Monday for Central Panhandle Mountains-Coeur d`Alene Area-
     Idaho Palouse-Lewis and Southern Nez Perce Counties-
     Lewiston Area-Northern Panhandle.

WA...Heat Advisory until 11 AM PDT this morning for Central Chelan
     County-Lower Garfield and Asotin Counties-Moses Lake Area-
     Northeast Blue Mountains-Northeast Mountains-Okanogan
     Highlands-Okanogan Valley-Spokane Area-Upper Columbia Basin-
     Washington Palouse-Waterville Plateau-Wenatchee Area-
     Western Okanogan County.

     Excessive Heat Warning from 11 AM this morning to 8 PM PDT
     Monday for Central Chelan County-Lower Garfield and Asotin
     Counties-Moses Lake Area-Northeast Blue Mountains-Northeast
     Mountains-Okanogan Highlands-Okanogan Valley-Spokane Area-
     Upper Columbia Basin-Washington Palouse-Waterville Plateau-
     Wenatchee Area-Western Okanogan County.

     Red Flag Warning from noon to 10 PM PDT Sunday for East Portion
     of North Cascades National Park/Lake Chelan National
     Recreation Area (Zone 697)-East Washington Central Cascades
     (Zone 696)-East Washington North Cascades (Zone 698)-
     Foothills of Central Washington Cascades (Zone 705)-Methow
     Valley (Zone 704).

     Heat Advisory from 11 AM this morning to 8 PM PDT Monday for
     Western Chelan County.

&&

$$