A slow moving low brought an early season snow across the northern mountains of Eastern Washington. It brought snow amounts ranging from 7 to 12 inches to elevations above 3500 feet.
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The episode as NWS OTX wrote it up.
A slow moving low brought an early season snow across the northern mountains of Eastern Washington. It brought snow amounts ranging from 7 to 12 inches to elevations above 3500 feet.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Spokane, WA wrote its last area forecast discussion before the first event at Oct 31, 9:28 PM PST, 3 hours 32 minutes earlier.
Area Forecast Discussion
National Weather Service Spokane WA
1028 PM PDT Thu Oct 31 2024
.SYNOPSIS...
An active weather pattern will continue through Monday with
periods of valley rain and mountain snow. A drier pattern is
forecast for the middle to end of next week.
&&
.DISCUSSION...
Today through Saturday: An upper level low will effectively stall
over southwest British Columbia tonight into tomorrow bringing
lowland rain and mountain snow to the Pacific northwest. The wave
of precipitation is working its way northeast from western
Washington and Oregon this evening. Precipitation will hold off
long enough in most places for trick-or-treating luckily. Models
suggest the formation of a double barrel low tonight off the
Washington coast that will shift northeast into southern British
Columbia. The low pressure will keep the low levels of the
atmosphere warmer thanks to southerly flow.
The northern mountain passes (Sherman, Washington, and Loup Loup) will
be hit with snow as temperatures look to stay below freezing for
the duration of the event. Expecting a continuous light to
moderate snowfall for many hours at those passes. Sherman pass
could hit the jackpot thanks to higher elevation and the longest
duration of upslope flow through the event. There is a 25% chance
of greater than 18 inches by Saturday there. Less favorable
upslope flow for Washington Pass and Loup loup will cut into snow
totals but still expect a healthy 6 to 12” for both of them.
Stevens Pass is a wildcard for snowfall accumulations as low level
warm advection may bring a brief transition to rain during the
afternoon hours tomorrow. Some models show the lowest 50 mb above
freezing while others stay below freezing altogether. The
deterministic NBM is only showing 3” of snow for Stevens Pass
which is below the 10th percentile. Hard to put a lot of faith in
amounts that low. 4” to 8” for Stevens pass seems like a safer bet
on the spectrum of probabilistic data. As the low pressure shifts
into southern British Columbia tomorrow night, low level flow
turns northwest in the Puget sound and with very cold air aloft,
it looks like a good signature for a convergence zone to form.
This could tip Stevens over the edge of meeting winter weather
advisory criteria if they switched to rain earlier in the day
Friday.
Lowland temperatures will be far too warm for accumulating
snowfall so it will be all rain - and quite a bit of it. By
Saturday, lowland locations will see anywhere from 0.25”-1.25” of
rain…the most we have seen in a while.
Probability of 0.75” of rain or more now through Saturday morning:
Spokane: 50%
Wenatchee: 33%
Moses Lake: 45%
Lewiston: 25%
Deer Park:80%
Sandpoint: 80%
Saturday through Thursday: Unsettled weather will continue through
early next week, with periodic valley rain and mountain snow, areas
of nighttime fog, and temperatures near normal. On and off light
precipitation will continue through Tuesday, mainly over the
mountains. The snow level remain between 3500 to 4500 feet dropping
to 2500 by Monday morning. We can't rule out a rain snow mix where
temperatures are below freezing on Monday morning but no
accumulations are expected below 2500 feet. Ensembles are hinting at
ridging building back in, allowing for temperatures to warm slightly
and conditions to dry out again for the middle of next week. /KM
&&
.AVIATION...
06Z TAFS: Showers moving up northeast Washington and north Idaho
is resulting in intermittent MVFR conditions for KGEG-KSFF-KCOE.
More widespread precipitation will move into central Washington
late this evening around 09z bringing back MVFR and IFR conditions
to all of the TAF sites through much of tomorrow. High resolution
models are showing a brief break from precipitation for far
eastern Washington and the central and southern Panhandle between
20Z and 02Z. KPUW and KLWS have the best chances to see
improvement to VFR Friday afternoon.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
Confidence is high for widespread MVFR conditions across the
Inland Northwest with moderate confidence for IFR conditions for
KEAT- KGEG-KSFF-KCOE as precipitation moves in from the south.
Some model soundings suggest improvement to VFR for KGEG-KSFF-KCOE
in the afternoon but NBM probabilities (70 percent chance)
suggest conditions to remain at least MVFR through the TAF period.
-----------------------
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 35 45 38 48 31 46 / 50 60 80 100 90 40
Coeur d'Alene 33 44 38 46 32 44 / 40 60 70 100 100 70
Pullman 35 49 38 46 32 44 / 50 60 70 100 90 70
Lewiston 39 55 41 54 39 52 / 30 40 40 90 90 80
Colville 35 43 32 46 21 45 / 50 70 90 100 80 40
Sandpoint 33 41 37 43 32 41 / 30 70 80 100 100 80
Kellogg 29 44 35 42 36 40 / 30 50 60 100 100 90
Moses Lake 41 49 40 54 29 51 / 40 80 60 70 40 20
Wenatchee 38 44 36 51 35 51 / 40 60 50 70 30 20
Omak 36 44 37 52 29 50 / 50 90 80 80 30 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Winter Storm Warning until 5 AM PDT Saturday for Okanogan
Highlands-Western Okanogan County.
Winter Weather Advisory from 11 PM this evening to 5 AM PDT
Saturday for Western Chelan County.
&&The national radar mosaic for the moment the first event began.
2 heavy snow. Local standard time, as filed.
Muckamuck Snotel recorded snowfall of 7 inches.
Washington DOT reported an estimated 12 inches of snow had fallen at Sherman Pass along state route 20 and still snowing.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Washington in 2024Every state in 2024This day in weather historyWarnings in Washington, November 2024
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1223700, 1223699.