Area Forecast Discussion Issued by NWS Spokane, WA
000
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.
&&
$$