918
FXUS66 KOTX 221747
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
1047 AM PDT Sat Jun 22 2024

.SYNOPSIS...
Warm and dry conditions will occur into Saturday with temperatures
warming into the 80s and 90s. A dry cold front on Sunday will
create elevated to critical fire weather concerns over portions of
central and eastern Washington with widespread breezy to windy
conditions. This will likely be followed by temperatures cooling
back down towards normal values by Monday. Another warm up arrives
on Tuesday and Wednesday before the next weather system arrives
on Thursday.

&&

.DISCUSSION...

Today through Sunday night: A layer of mid- to high-level clouds
passing through this morning will give way to clear skies by the
afternoon as a ridge of high pressure continues to strengthen over
us. Temperatures will be 3 to 5 degrees warmer today than they were
yesterday, ranging from the low 80s to upper 90s across the region.
These will be the warmest conditions we`ve seen yet this season, so
remember to stay hydrated and take breaks in the shade or in air
conditioning as needed if you`re spending time outdoors!

Heading into tonight the ridge will shift eastward into Montana as a
trough approaches the coastline of British Columbia just to our
north. Winds will pick up as our region gets caught under the
pressure gradient between the incoming trough and the departing
ridge. Sustained westerly winds of 10 to 25 mph and gusts of 30 to
45 mph are expected.

In addition, early Sunday morning a dry cold front will sweep
through the Inland Northwest, ushering in cooler, drier air.
Relative humidity values will drop to 12 to 25 percent behind the
front with the driest areas being the Columbia Basin into the
Palouse, the West Plains, and South Stevens, Pend Orielle, and Ferry
Counties. With the combination of gusty winds through the day on
Sunday and a dry airmass in place across Central and Eastern WA, the
primary concern for Sunday will be elevated fire weather conditions.
Rapid fire spread may occur with any new and existing fires. A Fire
Weather Watch has been issued from 1 PM to 8 PM PDT Sunday afternoon
and evening.

The greatest area of uncertainty with this forecast is how low
relative humidity values will drop in the Eastern Cascade Valleys
Sunday afternoon. A marine layer west of the Cascades may seep over
into the eastern valleys keeping relative humidity values above
critical thresholds, but it`s hard to say at this point. /Fewkes

Monday through Saturday: After the dry frontal passage on Sunday,
Monday will see temperatures drop a bit further to near seasonal
normal for late June (low to mid 70Fs). The pressure gradient will
relax and breezy winds will taper off throughout the day. Given the
cooler temperatures and lighter winds, the concern for Fire Weather
should decrease as we move into early next week.

Under a zonal westerly flow through Wednesday, the Northwest will
begin to load up the next upper level weather feature. Temperatures
will gradually warm through mid week, however there are still
disagreements in just what will take place Wednesday. The spread in
forecast temperatures is quite large indicating uncertainty in the
strength and timing of an approaching weather disturbance. Current
forecast temperatures is near the 50th percentile which seems
fitting with such a large spread of model solutions. An overwhelming
65% of the ensembles bring a weak trough along the WA/Canadian
border while the remaining model guidance maintains a ridge of high
pressure centered over the Northwest. By Thursday and Friday, there
are much more certain and clear solutions indicating the frontal
system will bring a return to cooler (near seasonal normal)
temperatures and chances for showers/storms across the northern
counties of eastern Washington and north Idaho.

Thunderstorms: Wednesday, Thursday, and Friday the best chances for
thunderstorms will be north of Omak to Deer Park to Spirit Lake. The
far northern communities will see 10-15% chance for thunderstorm
activity in the afternoon and early evening hours each day. For
outdoor events late in the week and into next weekend, Spokane to
Coeur d`Alene has the potential (10% chance) for isolated
thunderstorms in the afternoon and evening hours Friday and
Saturday. There lies uncertainty still. /Dewey


&&

.AVIATION...
18z TAFS: High pressure in place over the region will result in
dry and warm weather this weekend. Today and tonight, winds will
be light at 10 knots or less under thin high clouds above 10k feet
AGL. Sunday, winds will become breezy and gusty out of the
southwest.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
High confidence in VFR conditions through 18z Sunday.
-----------------------

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        88  59  80  48  77  50 /   0   0   0   0   0   0
Coeur d`Alene  85  56  79  47  74  49 /   0   0   0   0   0   0
Pullman        86  58  78  47  74  47 /   0   0   0   0   0   0
Lewiston       96  65  90  55  84  56 /   0   0   0   0   0   0
Colville       86  50  79  41  76  43 /  10  10   0   0   0   0
Sandpoint      82  54  78  46  72  45 /   0   0   0   0   0   0
Kellogg        83  60  76  50  72  51 /   0   0   0   0   0   0
Moses Lake     94  58  83  48  82  51 /   0   0   0   0   0   0
Wenatchee      93  60  78  52  81  55 /   0   0   0   0   0   0
Omak           90  56  84  48  81  52 /  10   0   0   0   0   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Fire Weather Watch from Sunday afternoon through Sunday evening
     for Colville Reservation (Zone 702)-Eastern Columbia Basin
      -Palouse  -Spokane Area (Zone 708)-Foothills of Central
     Washington Cascades (Zone 705)-Lower Palouse  -Snake River
     (Zone 709)-Waterville Plateau (Zone 706)-Western Columbia
     Basin (Zone 707).

&&

$$