943
FXUS65 KBYZ 030941
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
341 AM MDT Thu Apr 3 2025

.KEY MESSAGES...

- Clipper system brings next shot of lower elevation snow and
  colder temperatures this later today/this evening into Friday
  morning. Several inches of snow are possible for the mountains
  and foothills. Light accumulations are possible across the rest
  of the area.

- Snow could impact the Thursday evening and Friday morning
  commutes, mainly around the southern foothills.

- High confidence of building high pressure this weekend; expect
  warmer and dry conditions into next week.

&&

.DISCUSSION...

Through Friday night...

Light showers were lingering over central and northwestern areas
early this morning, as weak energy continued to filter through the
region. Precipitation amounts are expected to be light with any
shower. Patchy to areas of fog causing localized visibility
reductions will persist into the morning hours, before gradually
burning off.

After a mainly dry morning for most areas, a shortwave and
associated cold front are expected to drop into the area later
today and this evening, bringing cooler temperatures, gusty
northerly winds and rain/snow. Ahead of the cold front, showers
are expected to spread first into the mountains and foothills and
then out onto the plains this afternoon. Weak instability over
the region may bring a few thunderstorms to the area this
afternoon/evening with small hail and gusty winds to 30 mph with
the strongest activity. As the cold front drops south and winds
shift to the north to northeast (gusts 15 to 30 mph), rain/snow is
expected to become widespread as frontogenesis and upslope flow
increase. A band of snow is progged to settle over the southern
mountains and foothills by evening, persisting into tonight,
before decreasing into Friday. Up to an inch or two of snow can
be expected for the lower elevations, with a few inches for most
foothill locations, greatest on grassy surfaces. For the
Beartooth foothills and the Red Lodge area, this is a good setup
with upslope flow and steep lapse rates. These areas could see 5
to 10 inches of snow into Friday. For the mountains, 8 to 16
inches are forecast for the Beartooth/Absarokas, greatest on north
and east facing aspects with 5 to 10 inches of snow in the
Bighorn/Pryor mountains. Have gone ahead and issued Winter Weather
Advisories and Winter Storm Warnings for the southern mountains
and foothills from later today through early Friday morning. If
you are traveling this evening and tonight, expect changing
conditions with slushy to slick roads possible.

Drier conditions will gradually work into the area for the second
half of Friday and Friday night. High temperatures will range from
the 40s to near 50 degrees today, ahead of the approaching cold
front. Friday will see cooler conditions, with highs in the 30s to
lower 40s. Low temperatures in the upper teens to 20s are forecast
tonight and Friday night for most areas. STP

Saturday through Thursday...

Saturday will feature a high amplitude ridge moving in from the
west. This will allow temperatures to rebound back to average for
the weekend. As the ridge builds in, there is great confidence in
above average temperatures with calm weather for the second half
of the weekend and start of the work week. NBM probabilities give
Billings at 80% chance of reaching 65F as a high on Monday.

There could be brief breakdown in the ridge Tuesday into Wednesday
as all long range models show a weak shortwave trough move
through. There is some disagreement when it comes to timing with
the ECMWF lagging the GFS and Canadian. As temperatures will be
above average leading up to and throughout this event, snow will
be confined to the mountains. If the earlier solutions do end up
panning out then the possibility for some thundershowers exists
Tuesday afternoon as the SFC-3KM lapse rates are forecast to be
>8C/KM. With how far out this event is and how weak it could be,
details will certainly change.

After the shortwave exists the region, the possible rex-block and
associated ridge take over yet again which will allow temps to
potentially get 20F above average. NBM 50th percentile gives KBIL
a high of 74F for the day on Friday. WMR

&&

.AVIATION...

09z Discussion...

The main concern through 15z will be FG/BR. Currently KLVM is
reporting a CIG of 700ft AGL which is likely FG along the slopes
of the mountains. Due to the winds being light it is expected that
winds will become more of a drainage flow after 10z which should
help lift the FG as has been the trend over the past hour. If the
light easterly winds continue though, low CIGs and FG could
continue through daybreak. A similar situation is occuring at
KSHR where their CIG is at 900ft AGL and is also likely fog along
the mountain slopes. Due to the terminal being further removed
from the mountains the FG should not become an issue however,
there is still a possibility (30%) that KSHR dips to LIFR VIS
before daybreak. There is also the chance for some BR out in the
plains at places like KMLS/KBHK. This should remain patchy,
however, trends will be monitored if denser FG does end up
developing.

The next main story will be some precipitation moving
into the region after 15z. SN should start primarily in the
mountains before spreading NW to SE after 20z reaching KBIL around
23z. This will likely start as RASN before transitioning to SN
after 01z. While there may be periods of better visibility, expect
mountains to be obscured for the entire period.
WMR

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Fri     Sat     Sun     Mon     Tue     Wed
-------------------------------------------------------
BIL 048 026/042 024/056 034/066 035/071 043/067 040/068
    7/T 81/B    00/U    00/U    00/B    23/W    32/W
LVM 043 023/041 022/053 032/062 035/067 039/060 038/063
    6/J 81/B    00/U    00/U    01/B    34/W    32/W
HDN 049 025/042 021/055 031/064 032/071 040/067 038/068
    6/T 81/B    00/U    00/U    00/U    23/W    43/W
MLS 048 025/041 021/053 031/060 030/067 040/067 039/067
    5/T 61/B    00/U    00/B    00/U    11/B    31/B
4BQ 049 026/038 021/051 031/058 030/066 039/065 040/064
    3/W 71/B    00/U    00/B    00/U    12/W    32/W
BHK 046 022/037 017/049 027/054 024/057 031/063 036/064
    4/W 71/B    00/U    00/B    00/U    11/B    21/N
SHR 047 022/037 015/049 026/060 029/069 037/063 034/065
    4/W 94/S    10/U    00/U    00/U    14/W    43/W

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory in effect from 6 PM this evening to 6
      AM MDT Friday FOR ZONES 34-65-138-139-141-169-170.
     Winter Storm Warning in effect from 3 PM this afternoon to 6
      AM MDT Friday FOR ZONES 56-66.
     Winter Weather Advisory in effect from 3 PM this afternoon to
      6 AM MDT Friday FOR ZONE 64.
     Winter Storm Warning in effect from noon today to 6 AM MDT
      Friday FOR ZONE 67.
     Winter Weather Advisory in effect from noon today to 6 AM MDT
      Friday FOR ZONE 171.
WY...Winter Weather Advisory in effect from 6 PM this evening to 6
      AM MDT Friday FOR ZONE 199.
     Winter Weather Advisory in effect from noon today to 6 AM MDT
      Friday FOR ZONE 198.

&&

$$
weather.gov/billings