Wildfire in Washington, September 9 to 30, 2022

Area Forecast Discussion
National Weather Service Spokane WA
434 AM PDT Fri Sep 9 2022

.SYNOPSIS...
Above average temperatures along with dry and breezy winds will
keep fire weather concerns elevated through the weekend. Chances
for precipitation return by mid week with a return to seasonal
temperatures.

&&

.DISCUSSION...
Friday and Saturday: Water vapor imagery early this morning shows a
strong ridge of high pressure extending from the southwest US into
the northeast Pacific. The ridge will begin to shift into the
Pacific Northwest through the day today and encompass the entire
region by late Saturday morning. Meanwhile, at the surface, a
thermally induced surface pressure trough over northern California
will strengthen and begin to extend into western Oregon and into
western Washington. High pressure building east of the Rockies will
result in a strong north to northeast pressure gradient across much
of north Idaho and Washington. Dry, breezy to gusty winds will
continue through this morning and afternoon down the Okanogan Valley
into the Waterville Plateau and the Columbia Basin. Sustained winds
up to 20 mph with gusts 30 to 40 mph have warranted the continuation
of the Red Flag Warning across the Okanogan valley and the
extension into Columbia Basin through 8PM. These winds will
decrease to below critical values as the due north gradient
weakens, and the northeast gradient takes over this afternoon.

As the surface trough strengthens west of the Cascades this
late this afternoon and evening, a -15 to -17 mb pressure
gradient from KOTH to KGEG will support strong offshore winds
across much of the region Friday evening through Saturday morning.
Model soundings suggest that these winds will struggle to mix
down to the surface across most lower elevations overnight, with
sustained winds below 15 mph. However, strong winds near 850 mb
will be felt across mountain ridge tops in the central Cascades,
mainly above 3000 feet. Sustained winds 15 to 20 mph with gusts 25
to 40 mph will be common through the night. The combination of
these winds along with low minimum relative humidity values and
poor overnight recoveries will result in critical fire weather
conditions, therefore, a Red Flag Warning has also been issued for
the east slopes of the central Cascades from Friday afternoon
through Saturday night. Winds will begin to decrease late Saturday
morning and afternoon as the pressure gradient begins to slacken.

Sunday through Thursday: Winds will shift back to the west-southwest
on Sunday as the thermal trough cuts off and moves northward along
the Pacific Coast and the high pressure east of the Rockies weakens.
A return to onshore flow Sunday will provide much needed relief
for our friends to the west. Any smoke from new fires Friday or
Saturday may begin to migrate into the Inland Northwest during
this time. Ridging will peak over the Inland Northwest on Sunday
with temperatures warming back into the upper 80s to low 90s.
However, there is some uncertainty as increased smokiness would
keep temperatures a bit cooler than what is currently forecasted.

Fortunately, ridging won't hang around for too long as an upper level
low begins to move into the region early Monday and work to shove
it to our east. Increasing southwest flow aloft will advect
moisture from the remnants of Hurricane Kay into the region, with
cloud cover increasing late Sunday into Monday. Some
deterministic models and even a few ensemble members are
suggesting that there may be enough lift from the approaching
trough and instability to support isolated showers and perhaps and
few isolated thunderstorms across the Cascades and the northern
mountains Monday and Tuesday. Any showers or thunderstorms would
be high based with little precipitation expected.

The Pacific Northwest will remain in an unsettled pattern beyond
Tuesday with models indicating a series systems to pass through.
Significant differences among models and ensembles keep the specific
details fuzzy, but there does look to be enough agreement to suggest
the return to seasonal temperatures through the foreseeable
future along with multiple chances for measureable precipitation.
vmt

&&

.AVIATION...

12z TAFs: Smoke will continue to reduce visibilities across most
terminals today, especially along the eastern slopes of the
Cascades including KEAT. Visibility could decrease to 3SM with
localized lower visibility. North to northeast winds will be
gusty in the Basin westward towards Wenatchee and up the Okanogan
Valley for Friday afternoon.

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        77  47  83  50  88  56 /   0   0   0   0   0   0
Coeur d'Alene  76  47  82  49  87  54 /   0   0   0   0   0   0
Pullman        77  45  83  48  87  51 /   0   0   0   0   0   0
Lewiston       83  52  89  56  93  61 /   0   0   0   0   0   0
Colville       79  39  85  40  88  47 /   0   0   0   0   0  10
Sandpoint      74  43  80  45  83  50 /   0   0   0   0   0   0
Kellogg        71  49  81  55  85  61 /   0   0   0   0   0   0
Moses Lake     81  52  87  50  89  56 /   0   0   0   0   0   0
Wenatchee      81  56  85  60  89  64 /   0   0   0   0   0  10
Omak           82  51  85  53  90  59 /   0   0   0   0   0  10

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Red Flag Warning from noon today to 8 PM PDT this evening for
     Eastern Columbia Basin  -Palouse  -Spokane Area (Zone 708)-
     Western Columbia Basin (Zone 707).

     Red Flag Warning until 8 PM PDT this evening for Okanogan Valley
     (Zone 703)-Waterville Plateau (Zone 706).

     Red Flag Warning from noon today to 11 PM PDT Saturday for East
     Washington Central Cascades (Zone 696).

&&