335
FXUS65 KBYZ 061337
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
737 AM MDT Sun Apr 6 2025

.KEY MESSAGES...

- High confidence in warmer and dry conditions through Monday.

- Occasional lower elevation rain showers and mountain snow
  showers Tuesday afternoon and Wednesday (40-80% chance); snow
  accumulations of 2-5" over west aspects of the Beartooth-
  Absarokas.

- Windy Tuesday and Wednesday with wind gusts of 30-40 mph for
  most of the area, and a 50% chance of 50 mph wind gusts in the
  western foothills.

- Dry and warm Thursday and Friday.

- Precipitation potential returns (15-40% chance) Friday night
  and Saturday, though there remains a lot of uncertainty.

&&

.DISCUSSION...
Through Monday Night...

A strong high amplitude ridge has squarely built into the western
CONUS which will allow for continued quiet weather. Temperatures
should have no issue getting 10F above average today with the
early April sun angle unimpeded by any clouds. Towards midday,
some scattered mid-level clouds could quickly move through the
eastern half of the CWA which would keep high temps around 60F
closer to the Dakotas. As temps warm today, SFC-3km lapse rates
will exceed 8C/KM, especially for the middle of the CWA from
Roundup down through Sheridan. This will allow, albeit fairly
weak, 700mb winds to easily mix down and produce some winds gusts
over 15mph this afternoon. These gusts will likely be amplified
as they flow along the eastern side of the Bighorns and thus
Sheridan could see some gusts up to 25mph between noon and 6pm.

Monday will be quite similar to today, however, being that it is
the second day fully under the ridge, highs could reach 70F for
many locations in the center of the CWA. As we mix out the sfc
inversion, the weak 700mb winds should yet again cause some breezy
conditions during the afternoon. With the 700mb flow predicted to
be westerly by this time, some gaping of these winds in the
western foothills is expected. Even with the gap flow, the 700mb
winds will be too weak to see any gusts over 35mph.

The next shot for precipitation comes with a weak shortwave trough
moving into the area Monday night. The only locations likely to
see precip before sunrise Tuesday will be the western mountains
with a slight chance for any location west of Billings.
WMR

Tuesday through Saturday...

WPC clusters of 500 mb heights show that ensemble model solutions
are in good agreement on the large-scale pattern through
Thursday, then begin to diverge on Friday.

Tuesday into Tuesday night, 500 mb shortwave trough will move
eastward across Montana. This trough, along with the left exit
region of a 300 mb jet streak, will bring some weak large-scale
ascent to the area and facilitate the development of showers. The
time period of greatest chance of precipitation is Tuesday
afternoon into the evening, when the chance is 30-90%, lowest in
Carter County and greatest in the Beartooth/Absaroka Mountains.
There is also a 15-20% chance of a thunderstorm in the southern
mountains and areas southeast of Billings due to some weak
instability in the atmosphere. Precipitation potential appears
limited with this system, as the system will be moving quickly
and any convection would be weak. NBM shows precipitation amounts
could range from near nothing (10th percentile) to about 0.20
(eastern MT) to 0.50 (south central MT) to 0.65 inches (Crazy and
Beartooth/Absaroka Mountains) (90th percentile). Snow levels will
decrease from about 6700-7800 feet Tue. morning to 5900-7700 feet
Tue. afternoon to 5000-5900 feet early Wed. morning. Snowfall
amounts in locations above these snow levels will be 2-5 inches.

Later Tuesday night, the chance of precipitation decreases to
about 20-40%, as there will be competing effects between weak
shortwave ridging that would inhibit shower development and
northwesterly flow that tends to facilitate some shower
development. Any precipitation during this time would be light
(less than 0.10 inch).

Wednesday, 500 mb flow will be northwesterly over our area with
weak disturbances moving through the flow and facilitating
additional showers. Chance of precipitation ranges from about 20%
near Miles City to 60-70% in the mountains and in southern Big
Horn County, where northwesterly winds flow upward along the
terrain. Precipitation potential is less than on Tuesday, with
NBM 90th percentile QPF mainly 0.20-0.25 inches or less, with the
greater potential amounts in areas southeast of Billings and the
Bighorn Mountains, and the lower potential amounts in areas
northwest of Billings.

Tuesday and Wednesday will also be windy with the 500 mb
disturbances bringing increased winds aloft, anywhere from 25 to
40 kt at 700 mb per LREF 10th to 90th percentile values. These
winds will probably mix down to the surface during the daytime,
and produce 30-40 mph wind gusts for much of the area. For the
western foothills, there is about a 50% chance of 50 mph wind
gusts as those stronger 700 mb winds mix down to the surface. Be
prepared for strong crosswinds if you will be traveling with a
high-profile vehicle in the western foothills.

500 mb ridge will move into the area Wednesday night into
Thursday, which will bring drier conditions and lighter winds.

Friday into Saturday, models differ on movement of the 500 mb
ridge, with some clusters moving it eastward more quickly and
others doing so more slowly. The faster solutions would give a
pattern favorable for showers in southwesterly flow aloft and a
shortwave trough earlier, perhaps as early as Friday afternoon in
our western areas. The slower solutions would cause the chance of
showers to begin later, Friday night into Saturday. In accord
with these scenarios, NBM shows a 15-20% chance of showers in the
western foothills Friday afternoon then 15-30% over south central
MT and the Bighorn Mountains Friday night and 15-40% over south
central MT and north central WY Saturday. Precipitation amounts
during this time again appear light, with NBM 90th percentile QPF
ranging from around 0.10 inch over southeast MT to 0.25 inches in
much of south central MT and north central WY.

High temperatures will generally be in the 50s and 60s Tuesday-
Thursday then 60s and 70s Friday and Saturday. RMS

&&

.AVIATION...

13z Discussion...
Strong high pressure aloft will bring widespread VFR through the
next 24 hours. Occasional 15-25 knot SW-NW wind gusts will impact
the region today. Expect winds to shift to light easterly to the
east of KBIL this evening. JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Mon     Tue     Wed     Thu     Fri     Sat
-------------------------------------------------------
BIL 065 036/070 044/063 038/060 037/065 040/074 046/070
    0/U 00/U    17/W    44/W    10/U    11/B    22/W
LVM 059 035/065 040/055 035/054 032/064 040/071 044/066
    0/U 00/B    37/W    34/W    00/U    12/W    23/W
HDN 064 033/071 040/064 036/061 035/064 038/075 044/072
    0/U 00/U    17/W    65/W    10/U    11/B    22/W
MLS 063 033/068 041/064 038/059 040/062 038/072 045/072
    0/U 00/U    04/W    42/W    10/U    00/B    21/B
4BQ 060 032/067 040/065 039/059 040/060 037/072 046/073
    0/U 00/U    04/W    53/W    10/U    00/B    11/B
BHK 060 028/059 033/062 035/058 035/061 033/068 041/069
    0/B 00/U    03/W    33/W    10/U    00/B    11/B
SHR 059 030/067 037/063 033/057 032/059 035/072 042/071
    0/U 00/U    06/T    55/W    10/U    01/B    12/W

&&

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

&&

$$
weather.gov/billings