417
FXUS65 KBYZ 281513
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
913 AM MDT Sat Jun 28 2025

.KEY MESSAGES...

- Chance of late day showers or storms over southern portions of
  the region through tonight.

- Mostly dry conditions expected for Sunday and Monday.

- Turning warmer this week with many locations in the 90s by
  Tuesday and Wednesday.

- Chance of showers and thunderstorms begins to increase again by
  the middle of next week.


&&

.UPDATE...

Quick update for lingering convection over northeast zones from N.
Rosebud east into Fallon county. 700mb frontogenesis combined with
moderately unstable and moist mid level air is generating weak
convection with a few lightning strikes thrown in across this
area. Hi-res models aren`t handling this very well, and looking at
satellite there continues to be additional development on the west
end of this area that will progress east over the next few hours.
As a result added mention of isolated to scattered light showers
and thunderstorms through noon. As the lower atmosphere mixes out
in the next few hours the airmass should mix in some more stable
air and allow this activity to dissipate. Next up will be mountain
induced showers and thunderstorms over the Beartooth/Absaroka
mountains that will progress eastward through this evening, riding
along a stalled out surface boundary. Best chances for
precipitation will be along and south of I-90 in the west and
US-212 in the east. Severe threat looks to be southeast of the
forecast area this afternoon/evening, but a strong storm can`t be
ruled out over far SE Montana, so stay weather aware if you have
outdoor plans today. Chambers

&&

.DISCUSSION...

Today through Sunday Night...

Isolated showers and perhaps a stray thundershower will linger
over far east central Montana (northern Custer, Fallon Counties)
through the early morning before finally exiting to the east.

A weak surface high will settle into eastern Montana stabilizing
things through much of the day. In the meantime, a low amplitude
trough moving across southern Canada will drag some impulse
energy across our CWA late in the day and into the evening with
weak upper jet dynamics setting up over the region. CAMs initiate
isolated convection over our Beartooth/Absaroka range later in
the afternoon which gradually propagates eastward growing in
coverage (20-30%) as it engages better ingredients of moisture
and modest shear over the southern third of our CWA through the
evening and overnight. The best buoyancy and instability is
pushed to the south by the time the better ascent reaches
Southeast Montana. Therefore, we are not expecting any severe
thunderstorms, but isolated garden variety storms are possible in
the aforementioned areas.

Cyclonic flow behind the Canadian system prevails Sunday, but low
level moisture is pushed out of our CWA for the most part as PWAT
values drop below 0.70 inches by Sunday afternoon. This leaves
most of the area void of any decent MUCAPE, but isolated showers
or a thundershower may develop over and near the Big Horns. SKies
clear out completely Sunday night.

Look for highs mainly in the lower 80s this weekend. Overnight
lows will range from upper 40s to mid 50s. BT

Monday through Saturday...

Upper level heights will begin to increase Monday as troughing
moves off to the east and ridging moves in from the west. This
will lead to dry conditions for Monday. Starting Tuesday, surface low
pressure over the western United States will lead to southerly
winds over the high plains. This will allow moisture to make its
way into the region with the ECMWF Ensemble indicating PWAT
anomalies around 120% of normal.

Late next week, the ridge may begin to breakdown, though this is
uncertain at this time. A potential ridge breakdown and successive
upper level waves moving over the region is leading ensemble
systems to indicate more active weather. Daily shower and
thunderstorm chances (20-50%) look to begin Tuesday and continue
through the long term.

Upper level ridging will bring temperatures of 5 to 10 degrees F
above normal in the mid 80s to mid 90s F Monday through
Wednesday. The potential weakening of the upper level ridge
indicates slightly cooler temperatures in the 80s F to end the
week. Torgerson


&&

.AVIATION...

Low chances (15%) for showers and isolated weak thunderstorms
will exit the region by 18Z Saturday. These showers and
thunderstorms have the potential to bring MVFR conditions. VFR
conditions will prevail throughout the day today. After 00z
tonight, shower and thunderstorm chances (30%) will return, mainly
for locations from Bighorn County and east. This will bring low
chances for MVFR conditions. Torgerson

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Sun     Mon     Tue     Wed     Thu     Fri
-------------------------------------------------------
BIL 082 058/082 055/087 060/092 062/093 062/090 062/086
    2/T 20/U    00/U    01/U    11/B    32/T    32/T
LVM 080 047/079 047/085 054/090 055/089 056/085 054/082
    2/T 10/U    00/U    01/U    22/T    34/T    44/T
HDN 082 057/082 053/088 059/094 061/094 062/092 061/088
    1/U 20/U    00/U    11/U    11/B    32/T    42/T
MLS 085 058/083 055/087 061/095 064/096 067/093 065/089
    2/T 20/U    00/U    01/U    21/U    32/T    42/T
4BQ 082 058/080 055/084 061/092 062/092 065/091 065/086
    0/U 31/B    00/U    11/U    21/U    31/B    42/T
BHK 083 055/080 051/083 055/089 059/089 061/088 061/085
    2/T 20/U    00/U    01/U    21/U    32/T    42/T
SHR 082 052/077 049/084 055/091 057/090 058/087 056/083
    1/U 32/T    00/U    11/U    12/T    23/T    33/T

&&

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

&&

$$
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