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000
FXUS66 KOTX 220452
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
952 PM PDT Sun Apr 21 2024

.SYNOPSIS...
Mild and dry weather returns for the start of work week with 60s
and 70s by Tuesday. A subtle cooling trend arrives Wednesday into
Thursday with breezy winds and small chances for mountain
showers. Unsettled weather continues late Thursday through the
weekend with better chances for precipitation across the lowlands.

&&

.DISCUSSION...
Tonight through Tuesday: The upper level trough to the northeast
of the Inland Northwest will continue to move eastward as upper
level ridging begins to amplify and shift in from the west. Radar
this afternoon shows light rain showers across northeast
Washington and north Idaho as a trailing weak shortwave passes
through southeastern British Columbia. A tight southwest surface
pressure gradient that has brought breezy conditions across the
region has begun to weaken this afternoon and will continue to
decrease over the next couple of hours.

Decreasing winds this evening and clear skies will allow temperatures
to drop near to slightly below freezing regionwide. We have issued
a frost advisory for areas around Moses Lake and northeastern Nez
Perce county where growing season has begun and models indicate a
70-80% chance for frost development tonight.

Models show some continued influence from the upper level trough
across far north Idaho Monday afternoon for isolated light shower
development. Ridging will center over the Inland Northwest Monday
night as an upper level low approaches the northern British
Columbia coast. Tuesday will be the warmest day of the week under
this ridge with highs in upper 60s to mid 70s.

Wednesday: A closed upper level low will move inland British Columbia
early Wednesday with a weak cold front pushing across the Inland
Northwest. There is strong agreement that precipitation will
remain in the mountains, although there is a small subset (9%) of
ensembles that depict a more southern track of the upper level
low, which would result in more widespread light precipitation
over eastern Washington. Regardless, this system will bring subtle
cooling along with breezy southwest winds on Wednesday.

Thursday through Sunday: Weather will become more active late
Thursday evening into Friday as surface low approaches the
Washington coast and an upper level trough digs along the western
US. Models are in good agreement for precipitation to expand into
the eastern third of Washington, but differences in the overall
strength and track of the shortwave result in high uncertainty in
the total amounts. Right now, the NBM is giving the eastern third
of Washington a 40-50% chance of a tenth of an inch of rainfall
during the 72 hour period from 5 AM Thursday through 5 AM Sunday.
For the Idaho Panhandle, this chance increases to 70-80% for a
tenth and a 50-60% chance for two tenths. /vmt

&&

.AVIATION...
06z TAFS: Anticipate VFR conditions across the TAF sites through
06z Tuesday with bands of cirrus during the daytime hours and
wind speeds under 10kts.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence in
VFR conditions and forecast details. Given the dry airmass, chances
for valley fog near rivers remain low by early Monday 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        32  59  35  69  42  65 /   0   0   0   0  10  10
Coeur d`Alene  32  57  34  68  41  64 /   0   0   0   0  10  10
Pullman        32  55  34  66  42  62 /   0   0   0   0  10  10
Lewiston       38  63  39  73  47  70 /   0   0   0   0  10  10
Colville       28  61  31  69  38  66 /   0   0   0   0  10  10
Sandpoint      33  56  34  66  40  63 /  10   0   0   0  10  10
Kellogg        34  55  37  67  44  63 /   0   0   0   0  10  10
Moses Lake     33  64  36  72  43  70 /   0   0   0   0   0   0
Wenatchee      36  62  42  69  47  66 /   0   0   0   0   0   0
Omak           33  65  38  71  45  69 /   0   0   0   0   0  10

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Frost Advisory from 2 AM to 8 AM PDT Monday for Lewiston Area.

WA...Frost Advisory from 2 AM to 8 AM PDT Monday for Moses Lake Area.

&&

$$