Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 130550
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
1050 PM PDT Tue Mar 12 2024

.SYNOPSIS...
Scattered mountain snow showers will linger over the mountains of
the Idaho Panhandle Wednesday while mostly sunny skies are in the
forecast for central and eastern Washington. High pressure will
build over the Pacific Northwest Thursday bringing an extended
period of warm and dry weather to the region through the middle of
next week.

&&

.DISCUSSION...

As of 1045 PM: Forecast update sent to increase PoPs over NE WA
and north ID, including the Spokane/C`dA area later overnight into
Wednesday morning. Low dropping south and lingering instability,
with the support of some HREF and HRRR and other hi-res models
suggest there could be some snow showers in that time frame and
even some light accumulation is possible. Higher confidence is
toward the Idaho Panhandle. Forecast updated already sent.

.PREVIOUS DISCUSSION...
Tonight: The Convergence zone is setting up and beginning to take
shape in the Cascades. Per the latest HREF and WPC guidance, the
bulk of the heaviest precipitation associated with the convergence
zone has shifted to the south of Stevens Pass. 6-hour snowfall
totals from 6 PM through Midnight are around 5-6 inches at the
Pass and up to 10-12 inches on the south side of the Pass. The 1-
hour snowfall probabilities of 1"/hour peaks between 5 PM and 7 PM
near 70%, falling to 40% from 7 PM through 10 PM. The current
Winter Weather Advisory remains in effect through late this
evening to account for this additional push of snow accumulations.

Afternoon thunderstorms have begun to blossom (as of 1 PM) across
western Washington, northern Oregon, and now some isolated storms in
the Columbia Basin are tracking northeast. Gusty winds 25-30 MPH and
even isolated 35-40 MPH gusts will be common through early
evening when the threat for thunderstorms comes to an end.
Instability across the Basin and into the West Plains has slowly
grown over the last few hours, and we`re seeing the peak of the
daytime heating, destabilization after the clear skies this
morning, and popcorn type storms popping up. The best window will
be this afternoon through about 6 PM local time for lightning,
thunder, gusty winds, and small hail.

Wednesday will see the core of the upper level trough quickly
shifting eastward, filtering cooler air east of the Cascades along
with a drier airmass. A fairly quieter weather day, we may be
faced with early morning lingering stratus in the low-lying areas
and northern Valleys where more precipitation fell and clearing
skies allowed radiational cooling to take place.

Thursday through Tuesday: A drier and warmer weather pattern will
settle into the Northwest. Daytime high temperatures this time of
year are typically low to mid 50F and our highs forecast Saturday
and Sunday will climb about 10F degrees above normal for many lower
elevation locations from Moses Lake, Omak, the West Plains, into
north Idaho. The cluster analysis of the global ensembles is quite
confident of the ridge to maintain position over the
Northwest/British Columbia through Tuesday. By mid to late next
week, there is a small percentage (about 25%) of ensemble members
that introduce a trough pushing through the Northwest. /Dewey

&&

.AVIATION...
06Z TAFS: Winds will continue to wane. Low pressure dropping by
will continue to mean shower chances, largely as snow overnight
into early Wednesday. Chances will be found over ID and NE WA,
including near GEG/SFF/COE with chances between about 09-16Z.
Light accumulations are possible. MVFR/lcl IFR clouds are also
projected to develop around the Palouse, including PUW, with the
opportunity to expand toward the Spokane area later overnight into
early Wednesday. After 17-21Z, conditions are expected to improve
toward VFR.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
Moderate confidence is MVFR conditions are PUW. Low to moderate
confidence for low clouds/fog bringing MVFR/IFR conditions into
the Spokane area, with stratus and/or light snow.

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

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        29  47  28  50  30  53 /   0  20   0   0   0   0
Coeur d`Alene  29  43  26  48  28  52 /  30  40   0   0   0   0
Pullman        30  43  29  49  30  54 /  10   0   0   0   0   0
Lewiston       35  50  32  54  34  58 /   0  10   0   0   0   0
Colville       27  47  25  51  28  54 /  20   0   0   0   0   0
Sandpoint      31  41  27  46  29  49 /  40  30   0   0   0   0
Kellogg        31  39  27  47  30  53 /  50  60   0   0   0   0
Moses Lake     30  54  29  55  32  60 /   0   0   0   0   0   0
Wenatchee      33  51  33  54  36  59 /   0   0   0   0   0   0
Omak           31  53  32  56  35  60 /   0   0   0   0   0   0

&&

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

&&

$$


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