An unstable northwest flow aloft resulted in heavy snow to the Northeast Bighorn Mountains.
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The episode as NWS BYZ wrote it up.
An unstable northwest flow aloft resulted in heavy snow to the Northeast Bighorn Mountains.
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 16, 7:38 PM MST, 22 minutes earlier.
Area Forecast Discussion...Updated
National Weather Service Billings MT
838 PM MDT Tue Apr 16 2024
.UPDATE...
Raised PoPs for western and central zones tonight into Wednesday
morning. Radar returns have already blossomed with moderate rain
(occasionally heavy) at Livingston. This area of rainfall was
expanding north and east, and this trend will continue through
the rest of the evening. Livingston has dropped to 38F and would
expect rain to mix with snow shortly, and become all snow by
midnight. Rain moving into Billings at the present time and will
be a wet night tonight with the probability of 0.25 inches around
50%. Looking for rain to mix with snow in Billings after 2am and
becoming all snow by morning. Freezing levels will drop quickly
this evening and expect Red Lodge to not spend much time at all in
rainfall. Precipitation there should be mostly snow. TWH
&&
.DISCUSSION...
Today through Wednesday night...
Spring conditions today will depart will an approaching cold front
from the NW, associated with an upper trough building into the
Northern Rockies. Ample moisture is present with this system,
however, because of the quick hitting nature of it the highest
precip chances will be confined south and west of a line from
Harlowtown to Billings to Lodge Grass to Sheridan.
Precipitation for lower elevations will fall as rain, with
temperatures falling into the 30s and 40s for overnight lows. As
temps drop into the mid 30s, a rain/snow mix is possible as far
north/east as Billings. Current snow ratios are in the single
digits, along with above-freezing temps, snow accumulations are
expected to remain negligible. Moving into the mountains and
foothills, deep moisture with N/NW flow, initial precip in the
foothills is shown to be rain to a rain/snow mix before quickly
changing to snow as temperatures and snow levels drop. 850mb flow
tries to turn over to the N/NE a bit overnight, which could give
the mtns and foothills enhanced snowfall. However, a strong mid-
level jet may shuttle a lot of moisture over the mountains and
result in little mountain turbulence that would otherwise benefit
local topographical snow enhancement. Snow ratios in the mountains
and foothills in the 10s to 1 will result in periods of heavy
snow as well. The Winter Storm Warnings for the
Absaroka/Beartooths, Big Horns, and Pryor Mountains will begin
this evening at 6pm MDT. Latest forecasted snow amounts for these
warnings range from 10-20 inches. Models have shown higher QPF
amounts lingering in Sheridan County tomorrow, allowing for
additional snowfall in the mountains. A Winter Storm Warning will
also begin at 6pm MDT for the Beartooth and Red Lodge Foothills
where 6-10 inches of snowfall are possible. Winter Weather
Advisories will go into effect for the Western Valleys at 6pm MDT, the
Western Foothills at 9pm MDT, and the Sheridan Foothills/Southern
Big Horn County at 12am MDT. Amounts for these advisories are 2-6
inches.
With the heaviest period of snowfall occurring Wednesday morning,
locations in these Winter Storm Warnings should prepare for
hazardous commutes as roads will be slushy and slick. Models still
disagree as to how long precipitation will continue falling
tomorrow, with some models clearing it out quickly, and others
keeping periods of moderate to high chances through the afternoon.
Another note is the gusty winds much of the area has seen today,
these winds are slowly decreasing ahead of the advancing cold
front, but gusts in the 30-40mph range are expected into the
evening. Outside of travel impacts, these conditions will be
hazardous to young livestock Tuesday night through Wednesday, so
take precautions if necessary.
High temperatures Wednesday and Thursday will be in the upper 30s
and 40s, with overnight lows in the upper teens (mountains) and
20s.
Relevant snowfall probabilities can be found at weather.gov/byz
Matos
Thursday through Monday...
The main impactful weather for the extended period will be the
colder than average temperatures through the end of the week. High
temperatures Thu-Sat will be mainly in the 40s which is 10 to 15
degrees cooler than average. Average lows should be in the low to
mid 30s, but for the early extended period they will be in the low
to mid 20s with some teens sprinkled in. So, make sure to protect
tender vegetation until overnight temperatures warm up Sunday
night. These cool/cold temperatures are brought to us by an
anomalous west to east oriented trof aloft. Under the trof winds
will be generally out of the north Thursday/Friday which will keep
not only the cool temperatures, but a chance for upslope
rain/snow showers for north facing foothills locations, and maybe
a few orographically derived convective bands that could bring a
bit of precipitation off the higher terrain. None of this
precipitation looks impactful at this time.
The upper trof finally exits the area on Sunday, but another
disturbance drops in behind it from the northwest heading into
Monday. At this point precipitation with this system looks to stay
north of the forecast area, but it will increase west to northwest
winds over the area. This will help to boost highs back into the
60s to start next week. Chambers
&&
.AVIATION...
Flight conditions will continue to deteriorate over the western
mountains and foothills (KLVM) as a cold front moves into the
forecast area. By 06z the probability of ceilings under 3kft is
above 50 percent south of a K3HT to KBIL to KSHR line, with
probabilities of ceilings under 1000 feet in the 10 to 25 percent
range for the same area. By 12z areas south/west of a KRPX to K4BQ
line will be in the 35 to 60 percent range for ceilings under
3000 feet, and this will last until around 18z when ceilings will
begin to lift diurnally. Expect rain/snow mix for elevations below
4500 feet, with snow above tonight. Mountain/pass obscuration can
be expected after 03z for western mountains, and into the
Pryor/Bighorn mountains after 07z.
North/Northwest winds will remain strong (gusts 30 to 35kts) this
evening for areas east of KMLS, weakening by 06z. For areas west
of KMLS, Winds tonight will gust 15 to 25kts at times out of the
north/northwest. Chambers/TWH
&&
.PRELIMINARY POINT TEMP/POPS...
Wed Thu Fri Sat Sun Mon Tue
-----------------------------------------------------------
BIL 036/045 028/046 024/043 025/050 031/064 039/063 037/068
86/S 11/B 11/B 11/U 02/R 11/B 12/B
LVM 030/042 021/043 021/041 022/048 031/061 034/061 035/065
+6/S 21/B 11/B 11/B 12/R 11/B 12/B
HDN 036/048 027/047 023/044 023/052 027/065 037/064 037/070
66/O 11/B 11/B 11/B 01/U 21/B 11/B
MLS 038/048 028/043 023/040 021/046 027/063 038/062 037/067
01/N 11/N 00/N 00/B 01/U 11/B 11/B
4BQ 038/048 027/044 023/041 022/048 027/064 038/060 037/068
12/O 00/N 00/N 00/B 01/U 11/B 11/B
BHK 033/047 025/040 020/038 018/046 024/060 035/058 033/063
01/N 11/N 00/N 00/B 00/U 11/B 01/B
SHR 032/042 021/043 019/041 020/047 024/063 034/060 033/067
88/S 31/N 11/B 12/S 01/U 21/B 11/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory remains in effect until 6 AM MDT
Thursday FOR ZONES 34-40-64-65-141-170-172.
Winter Storm Warning remains in effect until noon MDT
Thursday FOR ZONES 56-66.
Winter Storm Warning remains in effect until 6 PM MDT
Thursday FOR ZONES 67-68-171.
Winter Weather Advisory remains in effect from midnight
tonight to 6 AM MDT Thursday FOR ZONES 138-169.
WY...Winter Storm Warning remains in effect until 6 PM MDT
Thursday FOR ZONE 198.
Winter Weather Advisory remains in effect from midnight
tonight to 6 AM MDT Thursday FOR ZONE 199.
&&
weather.gov/billingsThe national radar mosaic for the moment the first event began.
1 winter storm. Local standard time, as filed.
Area Snotels reported anywhere from 10-21 inches of snow.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2024Every state in 2024This day in weather historyWarnings in Wyoming, April 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: 1168834.