Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 251522
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
922 AM MDT Mon Mar 25 2024

.UPDATE...

Shortwave crossing the area this morning was producing snow
showers that were reducing visibilities to less than a mile in
spots. Areas of patchy fog, sometimes dense, were also occurring.
The dense fog, based on webcams, was along I-90 in S. Big Horn
and Sheridan Counties. Issued an SPS til 10 am MDT to cover the
fog. Updated PoPs to increase them into the evening across the
area based on radar and model trends. Not expecting more than half
an inch of snow in any given area. Use caution if traveling today
as visibilities could be greatly reduced in snow showers. Arthur

&&

.DISCUSSION...
Today through Tuesday Night...

There are currently light snow showers in some upslope areas west
of Billings. Looking at cameras across the region these may be
causing some reductions in visibility. Little to no accumulation
is expected. There is not much upper level forcing for these
showers. RAP analysis reveals 850mb and 700mb winds are in a
northerly direction and low level RH values are high leading to
light snow in upslope areas. High RH values and easterly surface
winds will lead to fog potential across the area from Sheridan to
Musselshell County and locations to the west. Some webcams are
showing fog currently, especially Bozeman Pass. HRRR model was
also indicating fog for parts of the area increasing confidence in
some patchy fog. For these reasons, put patchy fog in the
forecast until 18z today.

Low temperatures will not get as cold as was expected a few days
ago across much of the area. The main threat has shifted east with
most locations now looking at teens for lows Tuesday morning and
20s for Wednesday morning. The upper troughing and associated
surface high pressure will stay farther to the east with locations
east of a line from Forsyth to Broadus having a >80% chance of
seeing temperatures in the single digits Tuesday morning.
Locations along the Dakotas border have a >60% chance of getting
below zero Tuesday morning. These areas will get the worst of it
again Wednesday morning, with Fallon County having about a 30-50%
chance of getting below zero. It remains to be seen how fresh
snowpack on the ground could affect temperatures as this is
something models can struggle with. High temperatures will remain
well below normal today with temperatures near freezing for many
and low 20s in the far east. Wednesday we will start to warm as a
northwest flow sets up and upper ridging starts to make its way
into the region. Highs Wednesday will be in the mid 40s in the
west with decreasing values as you go east with mid 20s near the
Dakotas border. Torgerson


Wednesday through Sunday...

Ridge will build over the region Wednesday into Thursday bringing
us downslope warming and temps returning to seasonably mild
levels. Look for 40s to mid 50s Wednesday then 50s to lower 60s
Thursday. Lee side troffing appears to become favorable for a
brief period of enhanced gap winds at Livingston & Nye Wednesday
night into Thursday morning. We are quickly getting out of the
"gap wind" season but feel 40 mph gusts are a fair possibility.

Pacific shortwave emerging from the SW flow aloft (as ridge axis
shifts east) will bring some mountain snow and scattered lower
elevation rain showers Thursday afternoon and evening. A cold
front will be associated with this shortwave and it appears
Thursday will be the warmest day of the week.

Friday through next weekend offers a few interesting
possibilities, with a deepening western CONUS trof/low, but what
the weather pattern ultimately evolves into is very uncertain at
this time. A few scenarios: (1) A closed low cuts off over the
southwest and we are left with a drier and weaker Pacific flow,
and low chances of showers. (2) Prior to the low cutting off, an
additional shortwave lifts out of the southwest bringing us a
chance of rain/snow at lower elevations, especially the foothills
given expectation of upslope winds. (3) The low cuts off quickly
but an additional shortwave dropping out of western Canada brings
us rain/snow showers and breezy NW winds. (4) Energy dropping out
of western Canada phases with the southwest low, passing just to
our west, allowing for a period of moist upsloping and a greater
chance of wet snow for our lower elevations. All of these
scenarios are plausible and ensembles/cluster analyses show
tremendous spread in solutions. All of that said, the forecast for
Friday through the weekend shows cooler temps and a 20-50% chance
of precipitation each day. This is something to watch over the
coming days.

A few noteworthy probabilities:
-50 mph gusts at Livingston Wed night & Thu:  40%
-4" of snow in Beartooths/Absarokas Thu & Thu night:  55%
-2" of snow at lower elevations Fri-Sun:  20% east to 50% west
-2" of snow along foothills Fri-Sun:  50-70%
-8" of snow in mountains Fri-Sun:  60-85% (highest in Beartooths)

JKL
&&

.AVIATION...


Widespread low clouds w/MVFR to local IFR ceilings will persist
through the day east of the mountains. Localized fog may also
produce visibility reductions, and there will be areas of light
snow and flurries. Overall flying weather should slowly improve in
the afternoon and evening. Mountains will be occasionally
obscured. Upslope fog or low stratus may form from KBIL westward
tonight as low level easterly winds persist, but this is of low
confidence at this time. JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Tue     Wed     Thu     Fri     Sat     Sun
-------------------------------------------------------
BIL 032 017/040 025/054 034/060 035/050 028/041 027/048
    9/J 13/S    10/U    03/W    43/W    46/S    55/O
LVM 039 020/046 026/051 036/055 031/048 028/042 027/049
    9/J 25/S    20/N    16/W    54/W    45/O    44/O
HDN 032 013/039 020/055 028/062 033/052 025/043 025/048
    9/J 12/S    10/U    02/W    53/W    45/O    55/O
MLS 026 006/028 011/045 025/055 031/046 024/040 025/043
    4/J 20/B    00/U    01/B    32/W    23/S    34/O
4BQ 025 005/031 013/048 026/059 033/050 026/042 027/045
    4/J 20/B    00/U    00/B    21/B    34/O    44/O
BHK 022 902/024 004/040 020/050 026/045 022/039 022/042
    4/J 20/U    00/B    00/B    32/W    23/S    34/S
SHR 032 011/041 021/051 026/061 032/050 026/043 025/047
    4/J 21/B    10/U    01/B    33/W    55/O    55/O

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.

&&

$$
weather.gov/billings


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