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000
FXUS66 KOTX 162141
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
241 PM PDT Tue Apr 16 2024

.SYNOPSIS...
Anticipate cool, brisk, and somewhat showery weather as a low
pressure system aloft drops over the Inland NW and lingers
through Thursday. It will be chilly early in the morning with lows
dipping below freezing for many areas and the threat of frost.
The weather gradually warms and dries by Friday into the weekend
and continues into early next week with above normal temperatures.

&&

.DISCUSSION...
An amplified upper ridge centered off the coast near 135W will
result in a broad trough with north-northeast flow over the area
through Thursday. Colder air aloft associated with the trough
combined with daytime heating will help generate convective
showers each day, mainly in the afternoon and evening hours. The
coldest air aloft with 500mb temperatures in the -30 to -34C
range will be focused over NE Washington and the Idaho Panhandle
which is where the models are generating the highest focus of
showers. The cold atmosphere and drier low levels with dew points
in the teens and 20s will support higher cloud bases with the
convection that develops, with most of the CAPE layer composed of
ice. This will support mainly graupel showers, with thunderstorms
not expected although can not rule out a stray lightning strike.

This air mass will also favor cold overnight lows for this time of
the year. For tonight areas that have begun their climatological
growing season (Wenatchee and Moses Lake area, LC valley) will see
temperatures remaining above freezing. For tomorrow night the LC
Valley and Moses Lake area will be near freezing so will have to
keep a close eye on potential frost or freeze highlights. JW

Friday through Tuesday: Conditions look to dry out for Friday and
Saturday with daytime temps warming to near daily normals. Also
expect breezy northeasterly winds on Friday with local gusts of 25
to 35 mph, especially across the Columbia Basin. Enough instability
and moisture with a passing wave will lead to a chance for mountain
showers Sunday, but most locations will remain dry. The gradual
warming trend looks to continue Monday and Tuesday, with forecast
max temperatures ~5+ degrees above normal. /KD

&&

.AVIATION...
18Z TAFS: Afternoon heating combined with cooling aloft will
destabilize the atmosphere through the afternoon over the
northern mountains surrounding Winthrop, Colville, Republic,
Sandpoint, and Bonners Ferry. Yet with a dry boundary layer
showers that develop are expected to be isolated to scattered in
nature. Given the higher cloud bases and mainly light intensity to
the showers CIGS will remain VFR, except under localized moderate
showers where snow or graupel could reduce visibility to MVFR. As
the cold pool tracks into the Spokane/Coeur d`Alene area between
1-4z there is a 20-30% chance of a brief shower impacting these
TAF sites.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: There is high
confidence in VFR conditions through the TAF period, with one
exception. As the atmosphere destabilizes this afternoon into the
early evening, the HREF shows near a 10-20% chance of visibilities
dropping to MVFR under moderate showers consisting of snow or
graupel. JW

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

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        30  54  31  55  32  56 /  20  20  20  20   0   0
Coeur d`Alene  30  52  31  53  30  54 /  30  20  20  20  10   0
Pullman        29  50  30  54  31  57 /  20  10  10  10   0   0
Lewiston       37  56  34  61  35  63 /  10  10   0   0   0   0
Colville       32  55  32  55  29  57 /  20  30  20  20  10   0
Sandpoint      31  50  33  51  31  52 /  50  30  20  20  10   0
Kellogg        33  48  32  50  29  52 /  30  50  20  30  10   0
Moses Lake     34  60  33  62  36  63 /   0   0   0   0   0   0
Wenatchee      34  58  35  59  35  60 /   0   0  10   0   0   0
Omak           34  59  33  61  34  63 /  10  10   0   0   0   0

&&

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

$$