456
FXUS66 KOTX 071150
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
450 AM PDT Mon Apr 7 2025

.SYNOPSIS...
Morning rain will give way to afternoon showers, thunderstorms,
and breezy winds. Strong wind gusts will be possible near
thunderstorms in the afternoon. Cool and showery conditions
continue on Tuesday with breezy winds. A warming and drying trend
will return Wednesday into Thursday.

&&

.DISCUSSION...

...WIND GUSTS UP TO 50 MPH POSSIBLE NEAR SHOWERS AND
THUNDERSTORMS MONDAY AFTERNOON...

Today - Tuesday: A transition in our weather pattern is occurring
this morning as a deep trough carves into the NW. The leading
upper- level front with ties to a rich moisture plume is slowly
working its way through Central WA at this hour and will shift
eastward toward the WA/ID border the next few hours and through
the Monday morning commute. Rainfall amounts so far in the East
Slopes have ranged from 0.10-0.30" with the exception of Wenatchee
proper (only 0.01") due to downsloping effects off Mission Ridge.
The slow movement of the rain is due to midlevel flow paralleling
the front or generally southerly. This will change early Monday
morning as a more robust shortwave swinging through the longwave
trof swings on to the Oregon coast and eventually through the
Inland NW.

As steady rains shift east Monday morning, upper-levels cool
destabilizing the atmosphere leading to showers and thunderstorms
Monday afternoon and evening. Convective activity will become
better organized as the aforementioned shortwave makes its way
through. Model CAPES have increased in the last few runs with
values now between 300-500 J/kg and a few pockets in excess of 500
J/kg where sunshine is more prevalent. Consequently, just about
every location across the Inland NW will come with a chance for
showers and thunderstorms. Latest hi-res models suggest convection
will start in the Cascades and drift northeast through Central WA
between noon and 3PM Monday. At or around 3PM, focus will shift
back south toward the WA/OR border around Pendleton-Walla Walla
with new storms firing and tracking into Southeastern WA and into
the Idaho Panhandle. This includes most areas along and south of
I-90 from Ritzville to Wallace.

Cold air advection ongoing with the incoming trof and southwest
to northeast pressure gradients drawn to a 995-998 low in southern
Alberta will produce modest 85H winds of 25-35kts. Any showers or
storms producing downdrafts will tap into these winds and when
combined with a storm motion of 15-20 mph...be capable of
producing brief gusts of 40-50 mph. Winds of this nature can
result in tree damage. This is the main concern with any cells
today though brief heavy downpours (rain/small hail) and lightning
will also be possible. Numerous CAM models have been advertising
local wind gusts of 40-43kts particularly with the convection in
Central WA between Wenatchee and Omak and again over southeastern
WA and lower Idaho Panhandle but would not rule out a few cells
capable of these brief wind gusts sneaking through NE WA and N ID.

An additional shot of cooler air will arrive Tuesday evening into
Tuesday night with breezy conditions continuing through the
night. Scattered showers will impact the Cascade crest and much of
E WA and N ID. Snow levels will crash toward 3000-4000 feet with
snow showers returning to the Cascade passes and briefly Lookout
Pass. A disturbance pivoting through W WA will lead to a heavier
concentration of snow showers over the Cascade crest with several
inches of snow possible at Stevens Pass by Tuesday morning. HREF
has a 100% chance for at least an inch, 60% chance for 2 inches,
at 20% chance for 3 inches so motorists should be prepared for
winter travel conditions if traveling overnight into early Tuesday
morning.

The weather will remain cool, breezy, and unsettled on Tuesday with
widely scattered showers and a few weak thunderstorms. Afternoon
convection will be capable of an additional quarter of an inch of
precipitation in some areas and wet snow in the mountains. Wind
gusts of 20-30 mph will be common throughout the day and locally
upwards of 35 mph or stronger near any showers/storms. High
temperatures cool back into the 50s.

Wednesday- Thursday: There is good agreement in the ensemble members
for high pressure to build over the NW as one trof departs and
another tracks across the E Pac. A few showers will linger over
the mountains on Wednesday but confidence is high for drier
conditions region-wide Wednesday night into Thursday. The
strongest warm air advection at the surface will arrive Thursday
with temperatures jumping roughly 10F from WED to THU back into
the 60s to lower 70s.

Friday - Sunday: Low amplitude flow across the N Hemisphere continues
late next week and into the weekend supporting the idea that the
ridge will not last long and the next trough will swing inland.
Per the latest WPC cluster analysis, this is supported by all
members with the main differences resolving the depth and timing
of the trof. At this time, looks to be a 50/50 split if it arrives
Friday or Saturday. NBM is advertising shower chances by as early
as Thursday night but this could very well change in the coming
days toward a later timing. The incoming system comes with a bit
more westerly flow component which will focus the main shower
chances outside the lee of the Cascades. I would anticipate breezy
winds as we exchange air masses again. Not seeing much in the way
of temperature departures from normal but with PWATS dropping back
near 0.30", would be on the lookout for near freezing temperatures
by Sunday if you have sensitive plants. /sb

&&

.AVIATION...
12Z TAFS: Light rain is spreading across the region and recently
reached the WA/ID border. There is a 60-80% chance for periods of
MVFR cigs with the rain and shortly after for most terminals
across the Inland NW. Wenatchee and Lewiston only come with lowest
probabilities 20-40% due to local downsloping effects. As rain and
MVFR depart east, focus will shift toward renewed showers and
thunderstorms between 19-02z with activity starting in Central WA
19-20z and expanding southeast toward Pullman 22-23z as the next
shortwave lifts into the region. There is a 20-40% chance for
thunderstorms at all terminals during this time-frame (lowest at
KEAT-KMWH) which was left out of the 12z TAF issuance. Lightning
and heavy downpours of rain/small hail will lead to local MVFR
cigs under showers. Of greater concern will be gusty outflow winds
of 40-50 mph. Highest probabilities for these winds will be over
SE WA and NC ID generally south of the I-90 corridor but would not
rule out brief gusts 30-40 mph for Omak, Republic, Deer Park, and
Sandpoint. On a larger scale, winds will be breezy to start with
with gusts 20-30 mph so any convection will create these enhanced
gusts. The threat for thunderstorms moves out 02-03z with
additional showers and continued windy conditions Monday night.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence
for precipitation through Monday morning with moderate to high
confidence for ceilings lowering to MVFR between 16-20Z given 70%
probabilities via the latest LAMP guidance. Confidence is moderate
to low for convective cells to move over any particular terminal
19-02z but moderate that where these cells exists, there will be
gusts 30-40 mph and local gusts 40-50 mph./sb


-----------------------
Confidence descriptors:
Low - Less than a 30 percent chance
Moderate - 30 to 70 percent chance
High - Greater than a 70 percent chance

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        59  37  55  37  57  37 /  90  40  40  60  10   0
Coeur d`Alene  56  37  54  37  55  34 /  90  60  50  80  20   0
Pullman        56  35  53  36  55  38 /  90  60  40  60  10   0
Lewiston       64  42  61  41  63  41 /  90  70  30  60   0   0
Colville       57  35  55  34  56  33 / 100  60  50  70  10   0
Sandpoint      52  38  51  38  53  33 / 100  80  70  90  40   0
Kellogg        53  38  49  39  51  36 /  90  70  70  90  50   0
Moses Lake     64  39  59  36  63  40 /  70  10  20  10   0   0
Wenatchee      61  39  56  37  61  41 /  70  20  40  10   0   0
Omak           63  38  58  36  62  37 /  90  30  40  30   0   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&

$$