428
FXUS65 KBYZ 240837
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
237 AM MDT Sat May 24 2025

.KEY MESSAGES...

- Periodic scattered showers, some late day thunderstorms, and
  seasonable temps through the weekend.

- Memorial Day Forecast: Mostly sunny with a chance of
  showers/thunderstorms in the afternoon and evening for most
  locations; high temps in the lower 60s to mid 70s (coolest along
  MT/DK border).

- Temps pushing 80 degrees by Thursday for most locations.


&&

.DISCUSSION...
Today through Sunday...

Weak perturbations in the mid level flow were producing isolated
showers overnight, mainly within an inverted surface trough
extending from central Wy into east central MT. In the meantime,
low clouds and fog were impacting the MT/Dakota border area. A
Dense Fog Advisory was issued for the Carter County area through
9 AM this morning.

An upper trough axis extending from western Montana southwest to
Calif will shift very slowly east through the weekend. This will
provide synoptic scale forcing across our region and combine with
mid level moisture riding the southwest flow ahead of the trough.
This will produce scattered to numerous showers today, mainly
over the southern half of our CWA, with convection coverage the
greatest across the Bighorns region into SE MT. Cooler and more
stable air mass over our far east should prevent any deeper
convection along the MT/DK border. Progged MUCAPE today ranges
from 500-800 J/kg, but effective bulk shear remains limited to
under 30kt. So a few strong storms are possible with small hail
today, but would not expect anything severe. Most of the
convection will diminish this evening as the sun sets, but a few
showers will probably linger overnight due to proximity of upper
trough.

Mid level moisture is a little more limited for Sunday as northern
branch of upper trough drops southeast. So showers/thunderstorms
Sunday should be a little less in coverage than today, and not as
strong with MUCAPE a little less. Any lingering shower activity
Sunday night will likely be limited to higher terrain along the
MT/WY border as upper trough axis stays south/southeast of our
CWA and we remain on the northern periphery of the mid level
moisture fetch.

High temps this weekend will range from the upper 50s along the
MT/DK border to upper 60s and lower 70s elsewhere. BT



Monday through Friday...

For Monday, upper trough lifts into the Dakotas creating a
cyclonic flow over the upper midwest, while upper ridge develops
over the Rockies. Drier air is progged to move into our forecast
area, except the far eastern zones which will be affected by the
cyclonic flow influence to our east. We suspect we will see some
shower/thunderstorm activity over the MT/DK border area for
Memorial Day, with some isolated activity over the higher terrain
in the west as well. Ensembles suggest a trough moving into the
Rockies Tuesday into Wednesday, but is superseded and weakened by
large scale ridging over the western CONUS. So look for moderate
chance of convection in our west Tuesday, decreasing at midweek to
isolated activity. Temps will remain above normal, and even warm
to near 80 by latter part of work week. With this, mountain
snowmelt can be expected to increase again later next week. BT
&&

.AVIATION...

Areas of fog and low cloud decks (IFR/LIFR) are expected through
early morning in Eastern MT (impacts possible at KMLS/KBHK/KEKA)
through 14z.

Scattered showers return for much of the forecast area after 15Z
with the highest concentration around KSHR. Isold/Sct
thunderstorms are possible, especially 18Z-03Z. Thunderstorms
could produce brief MVFR/IFR conditions, however, VFR will prevail
for the period. Mountains will be partially obscured at times. BT

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Sun     Mon     Tue     Wed     Thu     Fri
-------------------------------------------------------
BIL 068 046/072 047/073 050/073 051/074 051/079 053/082
    3/T 22/T    11/U    14/T    22/T    11/U    22/T
LVM 068 042/069 044/073 048/071 047/074 047/078 051/079
    3/T 21/U    13/T    36/T    22/T    12/T    23/T
HDN 068 045/071 045/073 047/073 049/074 049/079 051/082
    3/T 33/T    12/T    13/T    22/T    11/U    22/T
MLS 068 046/068 049/069 048/072 048/074 049/078 052/081
    3/T 22/W    12/W    22/T    22/T    11/U    22/T
4BQ 062 047/064 049/064 048/069 047/070 047/075 050/078
    5/T 23/T    33/W    22/T    22/T    11/U    12/T
BHK 060 041/062 044/062 043/065 043/069 044/073 046/077
    2/W 22/W    23/W    32/T    22/W    11/U    11/U
SHR 063 041/065 042/068 044/070 045/070 045/075 047/077
    7/T 34/T    23/T    15/T    34/T    22/T    23/T

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Dense Fog Advisory in effect until 9 AM MDT this morning FOR
      ZONE 37.
WY...None.

&&

$$
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