814
FXUS66 KOTX 072147
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
247 PM PDT Mon Apr 7 2025

.SYNOPSIS...
Cool and showery conditions along with possible thunderstorms with
gusty winds will continue into Tuesday. A warming and drying
trend will return Wednesday into Thursday before conditions turn
cooler, showery, and breezy for the end of the week.

&&

.DISCUSSION...
Tonight through Tuesday Night: A closed low in the Gulf of Alaska
will continue to send mid level disturbances into the region. A
100-120 kt upper jet will remain over Oregon through Tuesday
putting Washington and North Idaho on the cold and conditionally
unstable side of the jet. One disturbances will track across
Eastern Washington and North Idaho late this afternoon into the
evening. This combined with surface based instability with SB cape
of 500-1000 J/KG will trigger isolated to scattered coverage of
thunderstorms across the region. Gusty outflow winds are the main
threats with CAM`s models continuing to show potential gusts of
40-50 MPH. CAM`s show the highest potential for these brief gusts
across the Columbia Basin, north and east across the Palouse and
Spokane/Coeur d`Alene area between 4 PM - 7 PM. Models show
convective activity persisting into the late evening over NE WA/N
Idaho due to lift with the passing wave with a drying trend
overnight into Tuesday morning as the wave exits and the lower
atmosphere stabilizes. Tuesday afternoon another disturbance moves
through the region for another round of showers, and the
potential for isolated thunderstorms. Models show less instability
Tuesday afternoon with SB CAPE of 200-500 J/KG, but with some
added lift from the passing wave isolated thunderstorms are
possible.

Finally, snow showers will be on the increase tonight in
the Cascades as snow levels drop from 4500 feet to 3000-3500 feet
overnight. This will result in rain changing to snow over Stevens
Pass with 3-5" into Tuesday morning. Snow levels also come down
over Lookout Pass into Tuesday morning but as they do snow
showers will be on the decrease with less than 1" forecast. Snow
levels climb back up to 4000-5000 feet Tuesday afternoon before
dropping back to 3000-4000 feet Tuesday Night. Drying aloft
Tuesday night should keep mountain accumulations on the light side
as moisture becomes more limited as snow levels drop. JW

Wednesday through Thursday: A high pressure ridge builds in over the
region with a warming and drying trend. The ridge will be transitory
with only a brief warm up. Lingering showers continue over the Idaho
Panhandle Wednesday afternoon as diurnal heating results in weak
instability. There is only a 15 to 30 percent chance for showers and
mainly over the higher terrain. The ridge strengthens over the
region Wednesday night with a dry and seasonably warm day for
Thursday. High temperatures will be 10 to 15 degrees above normal
topping out in the mid 60s to low 70s.

Thursday night through Monday: Confidence is high that the ridge
axis will shift east at the end of the week. There is some
uncertainty with how quickly this will occur. About 70 percent of
the model ensemble members brings in a moderately deep trough of
lower pressure by Friday with good cold air advection that results
in temperatures cooling back to near normal. Moisture with the cold
front is lacking and doesn`t look to be a good precipitation
producer except at the Cascade crest where between a quarter and a
half of an inch of precipitation is possible. Winds aloft won`t be
particularly strong, but good cold air advection looks to produce a
breezy day across the exposed areas of the Columbia Basin Friday
afternoon.

A more robust shortwave trough of lower pressure will push across on
Saturday. This disturbance is interesting in the sense that it looks
like it will strengthen east of the region with a deep surface low
forming in northeast Montana by Saturday night. This will tighten of
the westerly gradient with winds a bit breezier across the Inland
Northwest by the afternoon on Saturday. Cyclogenesis will be far
enough away to the east that the strongest winds in the westerly
gradient will miss us. Snow levels will drop Saturday night with
light snow expected over the mountains as well.

Shortwave ridging then looks most likely later in the weekend into
early next week. This would decrease the potential for precipitation
and warm temperatures back up into the lower 60s. The forecast is
uncertain this far out with a large spread in the ensemble model
guidance with how deep and progressive the trough will be. /SVH

&&

.AVIATION...
18Z TAFS: A cold front delivering stratiform rain and gusty winds
will shift into the ID Panhandle through 20z with convective
showers forming behind the front through the afternoon. In
addition, 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 18z 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: 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. JW


-----------------------
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        37  55  36  56  38  68 /  40  60  50   0   0   0
Coeur d`Alene  38  53  36  54  35  67 /  70  60  70  10   0   0
Pullman        36  54  36  54  40  68 /  70  50  50  10   0   0
Lewiston       43  61  41  63  42  74 /  80  50  60  10   0   0
Colville       36  53  33  55  34  65 /  70  70  50  10   0   0
Sandpoint      38  50  37  53  34  63 /  80  70  90  20   0   0
Kellogg        38  50  39  52  38  66 /  80  70  70  30   0   0
Moses Lake     40  59  36  62  40  69 /  10  40  20   0   0   0
Wenatchee      39  56  37  61  42  66 /  20  60  20   0   0   0
Omak           39  57  35  59  39  66 /  50  60  30   0   0   0

&&

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

$$