658
FXUS65 KBYZ 040029
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
629 PM MDT Thu Apr 3 2025

.KEY MESSAGES...

- Snow expected this evening into Friday morning. The mountains
  and foothills will see the greatest accumulations.

- Slight chance of thunder expected through early this evening
  over far southeast MT into Sheridan WY.

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

&&

.UPDATE...

A quick update to the going forecast for current observational
and model trends. Cold front is now located from south of Baker to
near Sheridan Wyoming, moving a bit faster than previous forecast
due to convective wind enhancement. Baker recorded a strong
thunderstorm wind gust to 48 mph last hour, and now the
temperature is down to 35 degrees. Will continue to see scattered
showers and isolated thunderstorms over far southeastern Montana
through about 9pm, with the storm threat ending as the front moves
through. Precipitation type should quickly changing over to snow
late evening.

Overall the going highlites look in good shape. Snowfall is a bit
early and locally heavy at times in the Billings area, but expect
snow intensity to decrease over the next hour or so, with
additional accumulation overnight expected to be an inch or less.
That said will continue to monitor the situation for any needed
expansion of the advisory area northward tonight. Chambers

&&

.DISCUSSION...

Rest of Today through Friday night...

Line of showers and thunderstorms have developed in an inverted
trough over Rosebud County. Potential wind gusts with these storms
will be 20 to 30 mph based on radar velocity signatures. For the
18-21Z period, added thunder from the SW mountains ENE through
KBIL, KSHR and KMLS. Mesoanalysis showed 100-250 J/kg MLCAPE in
this region and lapse rates were quite steep over the area.
Effective Bulk Shear was only 20-25 kt. KBIL reported GS due to
the unstable airmass. Meanwhile cold front had moved S into the
area and at 19Z was from Roundup to K3HT. Behind the front, Judith
Gap reported 27 degs over 27 dewpoint and some moisture had
appeared on the web cam. Increased PoPs over much of the area
through 21Z and had likely PoPs for snow over Judith Gap. Front
has ushered in gusty N winds. Chances for thunder will remain from
around KBIL S and SE for the rest of the afternoon. PoPs will
increase to likely over much of the area as the front progresses S
and 700 mb frontogenesis increases behind it. Precipitation will
be in the form of rain with rain and snow or all snow N and NW of
KBIL.

Front should be through the entire forecast area by 06Z tonight,
accompanied by high PoPs along the frontogenesis band and over
areas favored by N to NE upslope flow. Precipitation will
gradually change to snow from NW to SE with mostly all snow
expected between 06-09Z. Kept a low chance of thunder S and SE of
KBIL through 03Z based on RAP forecast of low MLCAPE. Steep lapse
rates and upslope flow, combined with the frontogenesis will
allow for heavier snow showers over the upslope areas through the
evening. Gusty winds behind the front will continue into the
evening. The strong frontogenesis will be SE of the area by early
Friday morning and chance PoPs will linger over the far SE, S.
Big Horn County, NE upslope areas and Sheridan County. PoPs taper
off to the S in the afternoon. Snow totals will be an inch or less
from KBIL N and E. Expect 1-3 inches in the ongoing Advisory
areas with around 10 inches in Red Lodge and up to 18 inches in
the upslope areas of the Beartooths/Absarokas where a Warning is
in effect. 8 to 11 inches is expected over the NE Bighorns which
are under an Advisory. Will go ahead and expand the Advisory
through S. Rosebud, Powder River and Carter Counties due to a
possible band setting up in this area for 1-3 inches of snow.

Friday will be a cool day with highs in the upper 30s to mid 40s.
Friday night will be dry with lows in the teens to mid 20s. Arthur

Saturday through Thursday...

Through the weekend, NW flow will transition into ridging through
Monday. This will allow for dry conditions with above average
temperatures into the 50s and 60s during this timeframe. Early
Tuesday into Wednesday, a weak Pacific shortwave will move
through, bringing an increased chance (20-50%) for rain showers
for lower elevations. Areas 6000ft and above will likely see snow
showers (40-70% chance). The lower elevations have about a 30-50%
chance of getting a tenth of an inch of water Tuesday through
Wednesday, with the mountains at a 60-80% chance. Westerly flow
transitions back to ridging for the latter part of the week.
Tuesday through Thursday`s high temperatures remain mild with
temps in the 50s and 60s, gradually warming through the week. TS

&&

.AVIATION...


Precipitation associated with a frontal passage is expected to
move across the region through the afternoon. A few isolated
thunderstorms can be expected during this time. A rain/snow mix
can be expected for lower elevations late afternoon, quickly
transitioning to snow this evening. All sites will be subject to
IFR/LIFR conditions this evening with the transition to snow.
Expect snow showers to taper off from 12-15Z Friday. Mountain
obscurations can also be expected. TS

&&

.PRELIMINARY POINT TEMP/POPS...

    Fri     Sat     Sun     Mon     Tue     Wed     Thu
-----------------------------------------------------------
BIL 027/042 025/055 033/065 036/069 042/063 040/063 038/068
    71/B    00/U    00/U    00/U    24/R    32/R    00/U
LVM 023/041 022/053 031/060 035/063 038/058 037/056 036/065
    81/B    00/U    00/U    01/B    35/R    32/R    01/B
HDN 026/042 022/055 031/064 033/070 040/064 039/063 036/067
    81/B    00/U    00/U    00/U    24/R    42/R    10/U
MLS 025/042 024/054 031/061 031/064 038/063 040/061 039/064
    50/B    00/U    00/B    00/U    12/R    22/R    10/U
4BQ 026/039 021/050 031/059 031/064 037/062 040/061 039/063
    61/B    00/U    00/B    00/U    13/R    22/R    10/U
BHK 022/039 020/050 028/058 026/055 031/060 034/059 035/061
    81/B    00/U    00/B    00/U    12/R    22/R    10/U
SHR 022/037 016/050 026/058 029/066 034/060 034/059 033/064
    93/S    10/U    00/U    00/U    15/R    32/R    10/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory in effect until 6 AM MDT Friday FOR
      ZONES 34-36-37-58-64-65-138-139-141-169>171.
     Winter Storm Warning in effect until 6 AM MDT Friday FOR
      ZONES 56-66-67.
WY...Winter Weather Advisory in effect until 6 AM MDT Friday FOR
      ZONES 198-199.

&&

$$
weather.gov/billings