An upper low moved across Wyoming producing a deep, upslope flow against the Bighorn Mountains and adjacent foothills, which resulted in heavy snow amounts.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS BYZ wrote it up.
An upper low moved across Wyoming producing a deep, upslope flow against the Bighorn Mountains and adjacent foothills, which resulted in heavy snow amounts.
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 Billings, MT wrote its last area forecast discussion before the first event at Apr 3, 12:51 PM MST, 4 hours 9 minutes earlier.
Area Forecast Discussion
National Weather Service Billings MT
151 PM MDT Mon Apr 3 2023
.DISCUSSION...
This afternoon through Wednesday night...
No major changes to the going forecast this afternoon. Current
highlites look to be in good shape. Did not see a need to upgrade
going highlites for wind at this time as winds should stay mainly
below Blizzard thresholds and the strongest winds should arrive
after the snowfall tapers off in the east. That said, it wouldn't
take much of a shift to the west to change that assessment so
can't completely rule out needing a Blizzard Warning at some
point going forward.
Upper low track remains consistent running from near Salt Lake
City this evening and crossing southern Wyoming and into central
South Dakota by tomorrow evening. This track will favor strong
lift along the MT/WY border starting tonight and continuing into
tomorrow evening, with some enhanced lift over far SE Montana as
the low tracks further north into South Dakota by mid day
Tuesday. Additional enhanced lift will occur in the up-slope
favored northern slopes of the Beartooth mountains as gusty
easterly winds tonight turn northerly tomorrow. These will be the
areas favored for heavy snowfall. There will be a fairly sharp
gradient to less or no snow as you go further north from the
border, with an inch or two along I-90 and I-94 and potentially no
snow along the northern portions of our northern counties from
Musselshell east to Custer.
Expect easterly winds to increase tonight with 15 to 30 mph speeds
common. Models are showing some easterly gusts in the 30 to 40 mph
range in the Big Timber to Livingston area around midnight
tonight. During the day tomorrow winds will turn northerly and
become gusty along the Bighorn foothills and areas east and north
into the Dakotas. could see a period with gusts in the 30 to 40
mph range in these areas as well tomorrow, but generally winds
will be under 30 mph.
As system moves into the eastern Dakotas on Wednesday snow will
taper off across the area. Winds will likely reach their peak over
SE Montana on Wednesday afternoon as snow ends. Expect significant
blowing and drifting snow to continue into Wednesday evening
before diminishing with the winds overnight.
Lows tonight will drop into the teens to mid 20s. Highs tomorrow
will range from 25 to 35 with the colder temperatures occurring
where snowfall is heaviest. Lows Tuesday night will be mainly in
the teens, with winds helping to hold temperatures above the
single digits. Wednesday will see westerly winds and clearing
central and west pushing highs into the lower 40s. Further east
clouds and snow will hold the lower 30s. Downslope winds will keep
temperatures in the mid to upper 20s for all but the far east and
Sheridan foothills where teens will hold on. Chambers
Thursday through Sunday...
Shortwave ridging is expected to drop through the area and may
bring scattered, light showers Thursday. The ridge will flatten
and the pattern will become more unsettled Saturday, bringing a
chance of scattered showers. The mountains have the best chance
(35-60%) of seeing more than a trace. Another ridge is expected
Sunday, bringing drier conditions to the region.
Temperatures will warm up through the week with highs in the mid
40s to lower 50s Thursday to 50s and 60s for the weekend. With
this warming trend, the biggest concern will be keeping and eye on
possible ice jams as ice will start to break up in streams and
rivers and stream inflow will increase from melting snow. Archer
&&
.AVIATION...
Snow showers will increase throughout the day causing conditions
to drop to MVFR/IFR more frequently, especially after 00Z. Expect
mountain obscuration. Archer
&&
.PRELIMINARY POINT TEMP/POPS...
Tue Wed Thu Fri Sat Sun Mon
-----------------------------------------------------------
BIL 024/031 020/042 027/050 034/059 039/061 040/062 039/067
46/S 21/U 20/U 00/B 01/B 21/B 10/B
LVM 020/030 015/038 022/044 033/051 037/053 038/056 039/061
67/S 11/B 10/N 01/B 12/W 21/B 00/B
HDN 023/031 018/041 021/049 027/059 033/061 037/061 035/067
57/S 41/B 30/U 00/B 11/B 21/B 10/B
MLS 022/029 017/037 020/049 028/059 035/063 040/061 037/067
14/S 30/B 10/B 00/B 00/B 20/B 00/B
4BQ 023/027 016/035 017/044 025/054 032/062 040/061 037/065
89/S 61/Q 10/U 00/B 00/B 21/B 10/U
BHK 018/024 012/031 013/042 025/053 030/058 035/056 033/060
38/S 71/Q 10/B 00/U 00/B 21/B 10/U
SHR 020/025 011/032 012/037 022/048 030/052 034/053 032/059
++/S 80/B 10/U 00/B 00/B 21/B 10/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory in effect from 6 AM Tuesday to 6 AM
MDT Wednesday FOR ZONES 32-33.
Winter Storm Warning in effect from 6 PM this evening to 6 AM
MDT Wednesday FOR ZONES 36-37.
Winter Storm Warning in effect from 6 PM this evening to
midnight MDT Tuesday night FOR ZONES 56-66-67-138-169-171.
Winter Weather Advisory in effect from 6 PM this evening to
midnight MDT Tuesday night FOR ZONE 58.
WY...Winter Storm Warning in effect from 6 PM this evening to
midnight MDT Tuesday night FOR ZONES 198-199.
&&
weather.gov/billingsThe national radar mosaic for the moment the first event began.
2 winter storm. Local standard time, as filed.
New snowfall amounts ranged from 8 to 20 inches.
Snowfall amounts of 20+ inches were reported across the area.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2023Every state in 2023This day in weather historyWarnings in Wyoming, April 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: 1086614, 1086613.