797
FXUS66 KOTX 201232
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
532 AM PDT Sun Apr 20 2025

.KEY MESSAGES...

- Isolated to scattered thunderstorms over extreme eastern
  Washington and in the Idaho Panhandle Today (Easter) and over
  northeast Washington and in the Idaho Panhandle on Monday.

- Chilly temperatures with frost expected Monday night into
  Tuesday. This includes the Moses Lake Area and Lewiston-
  Clarkston Valley which are now within their growing season.

&&

.SYNOPSIS...
Today through Monday will see seasonable temperatures along
with chances for showers and isolated to scattered thunderstorms.
Frosty conditions with chilly overnight temperatures expected
Monday night into Tuesday morning. Warm and dry conditions return
toward the middle of the week then turning unsettled again at
the end of the work week into next weekend.

&&

.DISCUSSION...
Today through Monday night: A shortwave weather disturbance will
drop down out of BC this afternoon to deliver widely scattered
showers across the Inland Northwest. Instability parameters are
marginal for thunderstorms, but this wave looks to pack enough of a
punch that it should be enough to produce at least isolated
thunderstorms over extreme eastern Washington and into the Idaho
Panhandle. Best chances for thunderstorms today at a probability of
near 25% will be over the northern mountains from the Okanogan
Highlands over to the northern Panhandle; however, even the Columbia
Basin generally east of a line from Wilbur to Lind will see a 15%
chance for thunderstorms. It will take some time for the surface to
heat up to reach convective temperatures with thunderstorm
initiation expected to be after 2:00 PM. Potential for convection
and thunderstorms will continue into the evening hours follow the
leading edge of the shortwave as it pushing into the Idaho Panhandle
and western Montana around midnight. Thunderstorms will be capable
of producing dangerous cloud to ground lightning, small hail, gusty
outflow winds, and heavy downpours. Keep these thunderstorm threats
in mind if planning Easter Holiday celebrations outside. Potential
will increase mid to late afternoon. The sound of thunder means that
you are close enough to be struck by lightning, and the best place
to retreat to for safety is inside a building. A great resource
for learning about lightning safety is at
weather.gov/otx/Lightning

The longwave trough of lower pressure will shift a bit more east on
Monday with the Inland Northwest under the backside. The cold pool
aloft will be mainly over the Idaho Panhandle and northeast
Washington by then. This will be the focus for more diurnally forced
covective showers. Models are also showing another shortwave
dropping down out of BC the looks to generally just clip the
Northeast Mountains to the Northern Panhandle. This would be the
focus for isolated thunderstorms. Monday doesn`t look quite as
favorable as today though with the disturbance not as robust.
Probability for thunderstorms will range from around 10-20% in the
afternoon. Surface based CAPE of 200-400 J/kg will be present across
the Central Panhandle Mountains and can`t rule out isolated
thunderstorms across this area as well. Similar hazards are expected
with thunderstorms on Monday as with today just with less coverage.

Today and Monday will be breezy days. Strongest westerly winds with
gusts up into the 25-35 mph range will be through the Cascade
gaps out onto the Waterville Plateau. Today looks breezier than
Monday. Temperatures will be a bit cooler under the trough of
lower pressure with highs in the 50s to low 60s. Drier air push
in late Monday into Monday night and weakening winds will result
in chilly overnight temperatures into Tuesday morning.
Widespread frosty conditions can be expected Tuesday morning,
and sensitive vegetation should be covered to prevent
frost/freeze damage. /SVH

Tuesday through Saturday: Conditions look to turn drier again for
the middle of next week. Daytime temps to be near normal for
Tuesday, then expected to warm to above normal for Wednesday,
Thursday, and potentially beyond. The warmest day of the period is
currently expected to be on Thursday, when readings will be about 4
to 10 degrees above average. Extended range models bring increasing
chances for precipitation with a low pressure system for Friday and
Saturday, though finer details in this scenario are likely to evolve
in the coming days. /KD

&&

.AVIATION...
12Z TAFS: Patchy valley fog this morning in extreme northeast
Washington and into the Idaho Panhandle. KDEW may see temporary
visibility restrictions down to around 1SM and KCOE may also see
a low stratus deck with brief IFR conditions through 15Z.
Diurnal heating will then result in a developing cumulus field.
Cumulus may result in brief MVFR conditions for the Spokane-
Coeur d`Alene corridor (KGEG to KCOE) and points northward;
otherwise ceilings are expected to be above 4 kft agl with
mountain obscurations. Breezy west to southwest winds across the
exposed areas of the basin with gusts to 20-25 kts that includes
KEAT-KEPH-KMWH-KGEG-KSFF-KPUW.

A shortwave disturbance dropping down out of BC will result in
widely scattered showers with embedded thunderstorms primarily
east of a line from KMWH to KOMK. Not enough thunderstorm
coverage to include TSRA in TAFs at this time. Any
thunderstorms that do develop will be capable of gusty outflow
winds, small hail, and brief heavy downpours. Convection will
continue into the evening with potential for thunderstorms
waning overnight.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Continued high confidence
in VFR conditions across central WA, and the Lewiston area
through Sunday evening. For KGEG/KSFF/KCOE/KPUW the HREF model
is carrying a 10-30% chance of MVFR CIGS Sunday morning so kept
prevailing CIGS VFR. Low to moderate confidence in thunderstorms
today with best chances between KOMK to KSZT at a 20-40%. /SVH

&&

.Preliminary Point Temps/PoPs...
Spokane        36  55  31  59  35  64 /  30  10   0   0   0   0
Coeur d`Alene  34  53  31  57  32  62 /  50  40  10   0   0   0
Pullman        37  51  32  55  33  60 /  40  30   0   0   0   0
Lewiston       42  60  36  61  38  65 /  40  20   0   0   0   0
Colville       31  56  31  60  33  64 /  60  20  20   0   0   0
Sandpoint      36  53  32  55  32  60 /  70  60  40  10  10  10
Kellogg        37  49  32  53  35  58 /  70  70  20  10  10  10
Moses Lake     37  61  33  63  36  67 /  10   0   0   0   0   0
Wenatchee      39  60  37  62  39  66 /  10   0   0   0   0   0
Omak           35  60  34  63  35  67 /  10   0   0   0   0   0

&&

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

&&

$$