513
FXUS65 KBYZ 200750
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
150 AM MDT Sun Apr 20 2025

.KEY MESSAGES...

- Scattered showers through tonight. Rumble of thunder over the
  west possible in the evening (10-20% chance).

- More persistent precipitation (mountain snow/lower elevation
  rain) on Monday with isolated Thunderstorms possible.

- Periodic chance of showers Tuesday through the work week.

- Temperatures in the 50s to near 60 degree range through mid-
  week, warming up into the 60s Thu/Fri.

&&

.DISCUSSION...

Today through Monday night...

The current wave of precipitation, caused by a weak shortwave
ahead of the trough, will exit to the east by early afternoon.
A brief break will occur behind the first wave, then, upper level
divergence from a digging trough over the Pacific Northwest will
bring additional isolated to scattered showers this afternoon into
overnight. The best chance for precipitation then begins late
tonight through Monday as the trough moves across the region.

Currently, there is a 50-70% chance of at least 0.25" of precip
for all but the far southeastern corner of the region through
Monday night. Snow levels will gradually decrease from 7000 ft
today to around 5500 ft by Monday morning, so the western
foothills and higher hills may see a little snow, although the
chance of more than 1 inch is less than 30%. The highest snow
totals are expected over the western mountains, ranging around
6-12" with higher amounts possible over the highest peaks. Over
the Bighorn mountains, snow totals generally range from 4-8".

Enough instability will be present today and Monday for a few
thunderstorms to develop, although no strong storms are expected.
Today, the best chance will be west of Rosebud County, while
Monday will have 15-25% chance across the region.

High temperatures today and tomorrow will be in the 50s to low
60s. Archer


Tuesday through Sunday...

Cluster analysis of the 500 mb pattern suggests confidence in
an unsettled pattern across the region for the extended period.
Weak cyclonic flow Tuesday will gradually transition to a moist
southwest flow over the region by next weekend. This should
result in a chance of isolated to scattered showers (high
elevation snow) through the week, mainly over and near the
mountains, with the best chance and coverage of precipitation
for the whole CWA occurring Wed/Wed Night. Friday may be warmer
and mostly dry as ridge axis prevails over the high plains for a
short time, but southwest mid level flow will develop into our
region by Saturday which could bring Pacific moisture into our
region and an increasing chance of precipitation again.

Look for highs in the 50s through Thursday, pushing into the 60s
and lower 70s Friday and Saturday. Overnight lows will range from
30s at mid week to 40s by the weekend. BT

&&

.AVIATION...

Unsettled weather conditions to rule over the next 24 hrs. A
broken line of precipitation (lower elevation rain and mountain
snow) will continue to move west to east through the area this
morning. There is a good chance of an extensive area of MVFR
ceilings developing east of KBIL after 14Z as well. Mountains may
be obscured at times. After a brief break in the precipitation
around midday, additional isolated to scattered lower elevation
rain and mountain snow showers are expected this afternoon into
the evening. A more robust area of showers will spread across
south central Montana late this evening into Monday morning...and
will likely impact KLVM and KBIL. Flight conditions are expected
to remain mostly VFR with overcast low to mid level cloud decks
common (040-090 CIGS)...but MVFR/IFR are possible late this
evening into Monday near the foothills including the KLVM
vicinity. A rumble or two of thunder is also possible, mainly west
of KBIL late today through the evening. BT

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Mon     Tue     Wed     Thu     Fri     Sat
-------------------------------------------------------
BIL 061 040/056 035/057 036/053 037/057 040/067 044/070
    4/W 79/T    32/W    14/W    33/W    22/W    23/W
LVM 058 036/050 028/053 030/050 032/056 035/064 040/063
    4/W 8+/T    22/W    24/W    33/W    12/W    24/W
HDN 061 038/057 034/058 033/055 036/058 039/068 043/071
    6/W 5+/T    52/W    14/W    44/W    22/W    23/W
MLS 060 037/057 036/056 031/055 036/058 039/064 045/071
    5/W 29/T    32/W    01/B    33/W    22/W    22/W
4BQ 057 036/058 036/056 034/055 038/055 039/063 045/071
    5/W 08/T    31/U    12/W    44/W    22/W    12/T
BHK 057 032/060 033/055 029/055 033/056 034/060 039/066
    4/W 19/T    52/W    01/B    33/W    22/W    12/W
SHR 054 030/055 030/055 030/053 032/055 035/065 040/069
    7/W 19/T    42/W    14/W    45/W    32/W    23/W

&&

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

&&

$$
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