A shower set up over the Okanogan Highlands and brought a brief heavy snow shower.
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The episode as NWS OTX wrote it up.
A shower set up over the Okanogan Highlands and brought a brief heavy snow shower.
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 Mar 23, 9:40 PM PST, 2 hours 26 minutes earlier.
Area Forecast Discussion
National Weather Service Spokane WA
1040 PM PDT Thu Mar 23 2023
.SYNOPSIS...
The passage of a cold front Today will bring periods of rain and
mountain snow to the Inland Northwest. Motorists should be
prepared for winter driving conditions over the Cascades
particularly overnight tonight into Friday morning. The weather
Friday into early next week will feature rain and snow showers,
with cooler than average temperatures. Temperatures will moderate
closer to normal by the middle of next week.
&&
.DISCUSSION...
Today and tomorrow: A decaying wave from Central WA/Eastern OR has
brought a wave of showers to the region this morning. Clearing was
evident on GOES-West imagery this morning in Central Washington
which has expanded into Eastern Washington. That has allowed for
some marginal destabilization leading to graupel showers from the
Spokane area to the Waterville Plateau which will shift northeast
for the next couple hours. Showers have continued in the
Panhandle as forcing from the shortwave is still evident in
mesoanalysis fields and is being aided by southwesterly upslope
flow.
Later this evening the cold front passage will occur bringing our
second wave of precipitation. The cold front has came ashore in
Western Washington and Oregon, which makes the timing of the
front from approximately 3-5 PM in Central Washington, 5-8 PM in
Eastern Washington, and 8-11 PM in the ID Panhandle. Snow levels
will fall to 500-1500 feet after the passage of the front, which
will bring low end snow chances. The best chances for some grassy
accumulations in the lowlands tonight are at Sandpoint, Coeur
d'Alene, and Pullman. Spokane has a 40% chance of a trace,
Pullman: 70%, Sandpoint: 90%. Sandpoint has a 60% chance of less
than 1" of snow with this round, while most other lowland
locations have a near 100% of less than 1" of snow.
High res models are indicating a potential PSCZ forming tomorrow
morning bringing additional snow chances to Stevens Pass.
Deterministic NBM is denoting a band of higher QPF (0.25"-0.75")
along highway 2 tomorrow late morning through the evening. At this
time, the best chance for snowfall is between Stevens/Snoqualmie
which would be relatively un-impactful, but there are some HREF
members that bring a burst of snow over Stevens Pass.
*Splitting this into 2 different times for the PSCZ:
-From 11AM to 5PM tomorrow with this band, there is an 80% chance
of >1" at Stevens Pass, 35% chance of >2", and a 5% chance of
>4"...
-From 5PM to 11PM tomorrow (when instability builds) there is an
80% chance of >1" at Stevens Pass, 50% chance of >2", and a 10%
chance of >4". Overall, the storm total snow probability of >6"
is 95%, 85% chance of >8", 40% chance of >12%, and a 1% chance of
>18". /DB
Saturday through Thursday: Spring time is definitely here given the
cool (pun intended) upper level weather features and some sunny
days with just enough instability to give us daily showers with
rain and/or snow and potential for graupel. Our cold (-36C at
500mb) upper level trough will provide that support for daily
mountain snow showers and valley/lowland rain/snow and graupel
showers. Saturday through Monday will feature these afternoon
isolated showers with relatively steep lapse rates and keep our
daytime temperatures as well as overnights near seasonal normal
for this time of year. However, overnight temperatures may support
slick roads and some light accumulations on grassy surfaces,
though daytime road temperature trends have been seemingly too
warm (40-50+F) for road accumulation.
Late Monday through Wednesday the models are in a bit of disarray
and therefore the range of temperatures, precipitation amounts,
and types vary with a little more uncertainty. The previous
discussion handled this well. The colder scenario which accounts
for 38% of the ensemble solutions is largely driven by a slower
arrival of the upper level trough. This would also bring a higher
amount of snow to places east of the Cascades like Wenatchee to
Chelan, the Waterville Plateau and the southern part of the
Okanogan Valley. The range of snowfall for example ranges from 0
inches (10th to 25th percentile) to 3 to 5 inches (75th to 90th
percentile). This will largely be dependent on where the Low
becomes positioned.
Another element will be winds. Right now neither the global
ensembles or the shorter range NBM probabilities speak to chances
of sustained winds over 20 mph nor gusts above 35 mph, but the
more anomalous piece of this will be the easterly component of
the winds Monday through Tuesday as the upper level low slides
south. The range of wind gusts for Wenatchee (picking one location
to speak to here) are anywhere from 18 to 32 mph with a mean gust
of 25 mph. I'm not sold on these values, but this will be
something to watch as we move forward in time. Other areas on the
Waterville Plateau and western Basin will be places to watch for
and keep an eye on with regard to wind. /Dewey
&&
.AVIATION...
06Z TAFS: A cold front is currently moving through Eastern WA
bringing mountain snow and valley rain/snow showers for through
11Z. Breezy southwest winds and mixed precip chances are
forecasted for KSFF- KGEG-KPUW-KLWS-KCOE. KCOE could see a longer
period of snow/rain lasting through 00Z. Intermittent MVFR stratus
may develop through the night as the cold front and associated
showers pass through.
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 31 45 28 44 29 45 / 40 30 20 30 10 20
Coeur d'Alene 30 43 28 41 27 43 / 70 50 30 30 20 20
Pullman 30 42 28 41 28 42 / 70 40 40 40 20 20
Lewiston 35 49 33 48 32 48 / 70 20 30 20 20 10
Colville 30 45 26 44 27 45 / 50 50 20 40 10 30
Sandpoint 31 40 28 40 29 41 / 70 70 30 50 30 60
Kellogg 30 38 28 38 27 38 / 70 70 40 70 20 60
Moses Lake 32 51 29 50 28 50 / 10 10 10 10 10 10
Wenatchee 32 47 30 46 30 48 / 20 10 10 10 10 10
Omak 32 48 29 46 29 47 / 30 30 10 20 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Winter Weather Advisory until 5 AM PDT Saturday for Western
Chelan County.
&&The national radar mosaic for the moment the first event began.
1 heavy snow. Local standard time, as filed.
Observer reported 6 inches of snow 10 miles west of Wauconda.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Washington in 2023Every state in 2023This day in weather historyWarnings in Washington, March 2023
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: 1089535.