792
FXUS66 KOTX 171020
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
320 AM PDT Fri May 17 2024

.SYNOPSIS...
It will be another windy day with gusts of 45 mph or more around
Wenatchee, Pullman, and Lewiston. Cooler weather has arrived.
High temperatures in the 60s will be common through the weekend
and into next week. Tonight will be quite chilly with the
potential for frost in our sheltered valleys of north Idaho and
northeast and north central Washington. The weekend will feature
the chance for showers. A more widespread rain event will be
possible Tuesday night into Wednesday.

&&

.DISCUSSION...

Today: It will be another windy day, but our areas of strongest
gusts will likely shift today. An upper level disturbance will
descend out of British Columbia this morning bringing a
reinforcing shot of cool air and establish a more northwesterly
pressure gradient. Yesterday`s southwest gradient directed the
strongest winds from Moses Lake into Spokane with gusts between 45
and 55 mph. High resolution models for today highlight the
Waterville Plateau and Wenatchee area as well Pomeroy, Pullman,
Lewiston, and elevations above 3000 ft in Lewis county in the
southern Idaho Panhandle. Guidance from the ECMWF ensembles and
the High Resolution Ensemble Forecast (HREF) advertise wind gusts
of 40 to 45 mph with localized gust potential to 50 mph for these
locations. A patchwork of Wind Advisories are in effect through
early evening.

There was a considerable plume of dust that originated around
Moses Lake on Thursday. High resolution models don`t produce as
much wind there today, but patchy dust will be possible near
recently worked fields on the Waterville Plateau. Early morning
rains over the Palouse and Camas Prairie may limit dust across
southeast Washington and the open wheat country around
Grangeville. As of 2 AM, Pullman got 0.15 of rain. The Camas
Prairie probably won`t get as much rain east of the Blue Mountain
rain shadow, but should get a few hundredths by mid morning before
the winds fire up.

The chilly upper level disturbance from B.C. will also generate
rain showers today across northeast Washington and the Idaho
Panhandle. A few of the showers will be capable of lightning,
brief downpours, and pea hail this afternoon before quickly
exiting north Idaho early this evening.

Tonight: It will be our coolest night in over a week. Clearing
skies and decreasing winds will allow temperatures to tumble into
the 30s and low 40s by early Saturday morning. Some of our
sheltered valleys in northeast/north central Washington and north
Idaho will flirt with freezing. Gardeners may want to protect
tender vegetation in our typical cold spots like Republic,
Mazama, Springdale, Deer Park, and spots around Colville.

Saturday: Tired of the wind? Well, Saturday will be a typical
showery and breezy spring day. Our typical breezy areas like the
Columbia Basin, Palouse, and West Plains will experience 15 to 25
mph winds...still annoying for fishermen and golfers, but
relatively low impact compared Thu/Fri. There will be a 30 to 60
percent chance of showers over the mountainous terrain of
northeast/north central Washington and north Idaho. The highest
concentration should be near the Canadian borer. Again some of the
strongest cells will be capable of lightning and small hail.
/GKoch

Sunday to Thursday: The Inland NW will remain in a somewhat active
and largely cooler than normal pattern. As Sunday starts one
trough continues to exit, then Monday a weak ridge briefly builds
in. A chance of showers will be found over much of the region on
Sunday, with the best chance for wetting rains around the northern
WA and ID Panhandle mountains. A chance for t-storms will also be
found around the region, especially those northern mountains.
Chances wanes through the night into Monday, with some risk
re-developing in the afternoon around the eastern mountains in
west-northwest flow and a subtle shortwave passing through the
ridge. Expect continued breezy conditions, especially Sunday
compared to Monday with gusts of 15-25 mph.

Then Tuesday into Thursday a deeper low moves into the region.
This looks like a wetter system, with a modest chance of wetting
rains over all but the deeper Columbia Basin and lee-side zones.
Chances are somewhat low Tuesday morning then starts to increase
over the region Tuesday afternoon and especially Tuesday night
into Wednesday. The 24-hour probability of wetting rains per
ensembles is about 50-90%, with the higher end of that range
around the Cascade crest and the Idaho Panhandle and northeast
Washington mountains. However as we head into later Wednesday into
Thursday models start to diverge over how the low evolves.
However there is enough confidence to say there will still be a
modest chance of rain, but there is less confidence there will be
wetting rains by this time. There will be some opportunities for
embedded t-storms with the instability associated with the low.
Some breezy conditions linger each afternoon, with models showing
gusts in the 10-20 mph range.

As for temperatures, there could be some pockets of frost in some
the sheltered northern valleys in morning hours Sunday and, to a
lesser extent, Monday. Otherwise lows will be in the upper 30s
and 40s. Highs will largely be in the upper 50s and 60s, with
some lower 70s in the deeper basin and L-C Valley. The exception
will be Monday as the warmest day, with highs in the mid-60s to
mid-70s, approaching near 80 in the deeper basin. /Solveig

&&

.AVIATION...
06Z TAFS: Gusty westerly winds will prevail across the Columbia
Basin, West Plains, Palouse, and southeast WA through the night
and into Friday morning with gusts of 25-35 kts. Scattered
showers will shifts from northeast WA to north ID through the
period with light precipitation. Ceilings will lower from KCOE to
KPUW and across much of north ID with light showers possible
early in the morning. Dry VFR conditions will be found across
much of central WA through the period. /rfox.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Low chances for
MVFR conditions with clouds showers over southeast WA and north ID
early Friday morning. /rfox.

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

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        63  39  63  40  60  40 /  20  10  10  30  40  10
Coeur d`Alene  59  38  61  39  56  40 /  40  20  20  30  50  10
Pullman        58  37  60  38  56  40 /  10   0   0  20  20  10
Lewiston       67  43  70  44  65  45 /  20   0   0  10  20  10
Colville       63  32  62  35  62  36 /  40  10  60  50  70  10
Sandpoint      57  37  58  38  54  39 /  80  20  50  50  80  20
Kellogg        54  39  58  40  52  41 /  80  20  30  30  60  20
Moses Lake     68  39  68  40  69  42 /   0   0   0  10  10   0
Wenatchee      64  44  64  43  66  45 /   0   0   0   0   0   0
Omak           69  39  66  40  68  42 /  10   0  20  20  20  10

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Wind Advisory until 5 PM PDT this afternoon for Idaho Palouse-
     Lewis and Southern Nez Perce Counties-Lewiston Area.

WA...Wind Advisory until 5 PM PDT this afternoon for Lower Garfield
     and Asotin Counties-Washington Palouse.

     Wind Advisory until 7 PM PDT this evening for Waterville Plateau-
     Wenatchee Area.

&&

$$