280
FXUS66 KOTX 231657
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
957 AM PDT Sun Jun 23 2024

.SYNOPSIS...
A dry cold front Today will lead 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 bringing another round
of breezy and showery conditions to the region.

&&

.DISCUSSION...

***Morning mesoscale update***: Satellite shows the dry cold front
 nosing into Okanogan and Chelan County early this morning.
 Prefrontal mountain wave clouds have formed on the lee of the
 Cascades but they are starting to slowly erode as the cold front
 overruns them. Modeled LCL to LFC relative humidities drop as low
 as 5% in central and eastern Washington this afternoon. While not
 all of the dry air aloft will not make it to the surface, it
 would not surprise me to see some stations bottom out at 10% RH
 with dewpoints in the low to mid 20s. Spokane International
 Airport has sustained winds in the 20s already and MOS guidance
 indicates this will continue for the rest of the day. The signs
 of the dry air impacting surface stations is apparent at 6000`
 and above currently. Mission Ridge and Camp Muir NWAC have
 dewpoints of 10 and -7 respectively. While that will not happen
 in our populated valley locations, it speaks to how dry the air
 is aloft. Red flag warnings are in effect from 1 to 8 pm for much
 of central and eastern Washington. Any new or existing fires will
 have the potential to spread rapidly.

Previous discussion:

Today through Monday night: Today we will see
elevated to critical fire weather conditions due to a combination
of gusty winds and very low relative humidity values. The
pressure gradient over the Inland Northwest is strengthening as a
trough nears the coastline of British Columbia, and we`re already
starting to see winds pick up. Winds will only get stronger
heading into this afternoon with sustained westerly winds of 10 to
25 mph and gusts of 30 to 45 mph expected.

Meanwhile, a dry cold front is sweeping across the region ushering
in much drier air than what we`ve seen over the past couple of days.
Relative humidity values will drop to 12 to 20 percent behind the
front for many locations. Rapid fire spread may occur with any new
and existing fires. A Red Flag Warning is in place for 1 PM to 8 PM
PDT this afternoon and evening for the Columbia Basin, Spokane area,
Palouse, Snake River area, Wenatchee area, and the Waterville
Plateau.

Temperatures today will peak in the upper 70s to low 80s, around 5
to 10 degrees cooler than yesterday. Low temperatures overnight
Sunday into Monday morning will be noticeably cooler as well (in the
40s for most places) with the dry airmass allowing heat to radiate
away from the surface more efficiently. Heading into Monday
afternoon, the pressure gradient over us will relax as we transition
to a more zonal flow pattern. Ridging will begin to build again on
Tuesday. Conditions will stay dry and skies will be clear through at
least the middle of the workweek with the exception of intermittent
shower chances over the North Cascades. /Fewkes

Tuesday through Saturday: Shortwave ridging will build across the
Northwest Tuesday before the next weather disturbance off the
West Coast approaches the WA/OR coastline. Temperatures will warm a
few degrees Tuesday into Wednesday with the frontal feature pushing
through Wednesday into Thursday. Two changes in the ensemble
guidance over the last 24 hours has been the timing of the trough
passage and the track. Wednesday evening now looks more favorable
(certain) for the trough passage to take place and the track has dug
a bit farther south into the central Oregon coast which will amplify
the southwest winds for central Washington into north Idaho as well
as increase chances for showers and storms mainly for north-central
Washington and the northern Idaho Panhandle.

Wind - Wednesday and Thursday will be breezy with southwest winds
across the Basin and into the Palouse and L-C Valley. While the
surface winds Thursday don`t look as impressive as they do for today
(Sun June 23), the hazard for breezy conditions will be felt the
same. The relative humidity Wednesday and Thursday don`t look as dry
at this time, so fire weather concerns are lower with some Limited
risk across the southern Basin. Wind gusts from Wenatchee, Moses
Lake, Pullman, Lewiston will range from 30-40 mph Thursday.

Rain/Thunderstorms - The threat for high based
showers/thunderstorms will be limited and isolated Wednesday to the
far north-central part of Washington in the Okanogan Valley and
Okanogan Highlands. Friday has trended drier for
thunderstorm/shower chances in the Spokane - Coeur d`Alene area and
the better chances remain across far northern Idaho Panhandle and
northeast Washington. Coincidentally, Thursday afternoon and evening
look better for northeast Washington and the Idaho Panhandle
including the Okanogan Valley to the West Plains and central Idaho
mountains from St Maries to Avery. Instability Wednesday through
Friday will mainly be confined to the north-central and northeast
portions of Washington and north Idaho in the higher terrain. Not a
huge moisture surge in PWAT anomalies so wind and brief rain will be
the threats to consider. /Dewey

&&

.AVIATION...
18z TAFS: A dry cold front is pushing through central and eastern
Washington this morning and will continue into north Idaho by mid
day Sunday. VFR conditions will persist with mostly passing upper
level clouds during the afternoon hours. Winds will be breezy to
gusty 25 to 30 mph out of the southwest. Some isolated areas in
central Washington will see gusts to 40 mph. Looking for
conditions to weaken after 04-06z Monday.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
High confidence in VFR conditions through the TAF period.

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

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        80  47  77  50  85  56 /   0   0   0   0   0   0
Coeur d`Alene  79  47  75  49  83  54 /   0   0   0   0   0   0
Pullman        77  45  74  48  83  54 /   0   0   0   0   0   0
Lewiston       90  54  85  56  93  63 /   0   0   0   0   0   0
Colville       78  40  76  43  83  48 /   0   0   0   0   0   0
Sandpoint      77  45  73  46  80  51 /   0   0   0   0   0   0
Kellogg        75  50  72  52  82  58 /   0   0   0   0   0   0
Moses Lake     82  47  82  52  90  58 /   0   0   0   0   0   0
Wenatchee      77  52  82  56  87  64 /   0   0   0   0   0   0
Omak           84  47  83  53  88  59 /   0   0   0   0   0   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Red Flag Warning from 1 PM this afternoon to 8 PM PDT this
     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)-Okanogan Valley (Zone 703)-
     Waterville Plateau (Zone 706)-Western Columbia Basin (Zone
     707).

&&

$$