A very 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.
A very 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 Mar 12, 8:50 PM MST, 4 hours 10 minutes earlier.
Area Forecast Discussion...Updated
National Weather Service Billings MT
950 PM MDT Tue Mar 12 2024
.UPDATE...
Not getting any reports of measurable snowfall or even rain yet
this evening as precipitation has been of the scattered
inconsistent variety. I do not anticipate much if any impactful
weather until later tonight at which time winds respond to upper
low diving into Idaho and turn northerly with some cold air
advection. Cross sections indicate foothills (Red Lodge) may not
get much going until mid to late Wednesday morning when upslope
saturates through mountain top level and upward motion increases.
Will not change any advisory timing so not to create confusion,
just know significant precipitation and snowfall may hold off
until late tonight and possibly not until well into Wednesday
morning for some areas. BT
&&
.DISCUSSION...
Tonight through Wednesday night...
Bands of showers were moving through the forecast area in unstable
WSW flow this afternoon with decent PWAT's of .3-.4 inches. Areas
of upper divergence from a jet and orographics were aiding lift.
Updated late day PoPs to take slight chances further E based on
radar trends. With no CAPE and sheared looking cumulus on
satellite, will leave out thunder.
Upper jet will provide divergence to the area tonight with SW flow
aloft. A Pacific cold front with decent 700 mb frontogenesis will
cross the area. Lapse rates will remain steep and PWAT's will be
around .35 inches. Low temps will generally range through the 30s
with 20s in the mountains. An upper low drops SW of the region
during Wednesday and low to mid-level flow becomes more NNE over
much of the area. A secondary push of colder air moves in from the
N Wednesday night, drying out much of the area.
A mix of rain and snow will spread E across the area tonight,
giving the foothills, KLVM and Paradise Valley around an inch of
snow. PoPs will range from 20-30% E to 70% W. Snow is likely over
the southern mountains. PoPs will favor N to NE upslope areas on
Wednesday and will range from 40-80%. Expect precipitation type to
be snow S and W of KBIL with a mix of rain and snow from KBIL E in
the morning. Precipitation will then be rain from KBIL SE, with a
mix, or all snow, elsewhere. Mixed precipitation will decrease
over the area Wed. night. High temps Wed. will reach the 40s to
lower 50s and mins Wed. night will be in the mid to upper 20s.
Timing of accumulating snow in the Advisories looked good for
KLVM, Paradise Valley, the foothills and the NE Bighorns. Did have
higher QPF based on latest models which resulted in higher snow
amounts in some areas. Concerned about I-90 Wed. morning, with a
few inches of snow expected in S. Big Horn and KSHR areas. Also
concerned with accumulating snow on Lame Deer Divide, so issued an
Advisory from 12Z Wed. through 06Z Thursday for these areas.
Roads will become less slushy during the day but should refreeze
Wed. evening. While probabilities for snow amounts of 2 inches or
greater in the low-elevation Advisory areas were 20-40%, the low
snow totals will create adverse impacts during the commuting
times. Arthur
Thursday through Tuesday...
A closed low off in the southeastern US will continue to create
troughing early Thursday. With troughing beginning to retreat
Thursday, a weak jet over the east will allow for snow showers to
continue that morning mainly for the higher elevations (30-50%)
as well as the Bighorn foothills (15-25%). Ensembles have a couple
of backdoor fronts pushing through as the ridge tries to build in
with a push of moisture Friday night into Saturday. Ensembles are
keeping QPF confined the mountains at this time, so around a
20-40% chance of precip exists. Ridging Sunday through the rest
of the forecast period should provide warm and dry conditions for
the region.
High temperatures will be in the 40s/50s Thursday through Sunday,
warming into the 50s/60s Monday and Tuesday. TS
&&
.AVIATION...
Isolated rain/snow showers are moving through the region and will
continue to do so tonight. With this activity, periods of MVFR
conditions are possible along with areas of mountain obscurations.
Expected mountain obscurations to continue through Wednesday as
periods of snow continue over the mountains and foothills.
TS/Arends
&&
.PRELIMINARY POINT TEMP/POPS...
Wed Thu Fri Sat Sun Mon Tue
-----------------------------------------------------------
BIL 036/049 029/047 028/056 036/053 027/051 032/066 037/067
45/O 21/B 10/U 01/B 10/U 00/U 00/U
LVM 032/040 027/043 023/051 031/049 029/051 032/059 034/060
67/S 51/B 10/U 01/B 00/B 00/U 00/U
HDN 033/050 027/047 024/057 033/053 023/049 027/066 033/068
46/O 22/S 00/U 01/B 10/B 00/U 00/U
MLS 034/052 027/043 024/054 031/046 020/041 022/058 031/060
31/B 00/E 00/U 00/N 00/U 00/B 00/U
4BQ 036/049 029/042 023/055 032/049 022/042 022/061 034/065
34/R 11/E 00/U 00/N 00/U 00/U 00/U
BHK 030/054 024/039 021/051 028/043 016/037 017/053 028/057
21/B 00/E 00/U 00/N 00/B 00/B 00/U
SHR 031/042 027/042 019/051 028/048 025/046 024/061 032/063
49/O 62/S 10/U 01/B 11/B 00/U 00/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory in effect until midnight MDT
Wednesday night FOR ZONES 56-64>66.
Winter Weather Advisory in effect from 6 AM Wednesday to
midnight MDT Wednesday night FOR ZONES 58-138-169.
Winter Weather Advisory in effect until 6 AM MDT Thursday FOR
ZONE 171.
WY...Winter Weather Advisory in effect from 6 AM Wednesday to
midnight MDT Wednesday night FOR ZONE 199.
Winter Weather Advisory in effect until 6 AM MDT Thursday FOR
ZONE 198.
&&
weather.gov/billingsThe national radar mosaic for the moment the first event began.
1 winter storm. Local standard time, as filed.
Around a foot of snow occurred across the Northeast Bighorn Mountains.
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, March 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: 1161362.