Lame Deer, Montana Weather Forecast Discussion

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FXUS65 KBYZ 031129
AFDBYZ
Area Forecast Discussion
National Weather Service Billings MT
529 AM MDT Fri Oct 3 2025
.KEY MESSAGES...
- Still warm and dry today; elevated fire weather concerns in the
  far southeast corner of Montana (gusts 20-30 mph).
- Cool and wet system arrives Saturday, lasting through the
  weekend.
- Widespread rainfall across the plains, 30-70% chance for at
  least an inch or precipitation, greatest south.
- First significant mountain snow of the season this weekend;
  impacts to travel and outdoor recreation.
- High probability of a frost or freeze Sunday night.
&&
.DISCUSSION...
Today through next Thursday...
Satellite imagery shows a deep trof along the Pacific coast, with
SW flow aloft and above normal heights into our region. Some
shower activity last evening associated with a mid level warm
front has lifted north, and baroclinic axis is well to our west,
so the remainder of the night and this morning will be dry.
Mesoanalysis shows 700mb temp plume to +10C over Sheridan County.
This is very warm for early October and will translate to a hot
day in our south/southeast. Highs today will range from the lower
70s in our northwest to near 90F in the far southeast.
Today & Tonight: Couple things to monitor. First is the deeply
mixed S to W wind over Carter County, with gusts 20-30 mph
coinciding with the hot temps and RHs under 20% to yield elevated
grass fire concerns in the far southeast corner of MT. Second, as
the upper trof slides slowly eastward and induces height falls and
trends toward diffluence aloft over our west, we will see some
t-storm activity over/near the SW mountains and foothills this
afternoon and early evening. The calendar says October but today
will feel more like late summer. Storms won`t be severe (not
enough instability or forcing) but could produce erratic wind
gusts to ~40 mph. Tonight, as a low forms in the great basin and
heights continue to fall, the chance of showers will increase over
our west thru the night. Snow levels will remain high (>10kft)
thru 12z Saturday.
Saturday & Sunday: Confidence is high for a period of wet and much
cooler conditions this weekend. The combination of the low to our
south and an additional shortwave (and colder air) from the north
will produce widespread precip w/ upslope enhancement over the
south. The probability for at least 0.50" of precip is very high
(>80%) and the chances of 1.00" is a healthy 30-70%, greatest
south. Southern upslope areas should see 1-2" of precip with this
system. This will also be the first significant snowfall for the
mountains, and not just at the highest elevations. Expect snow
levels to fall to near 7kft Saturday night, and 5.5-6kft Sunday.
Thus, all elevations above 6kft will see accumulating snowfall. In
the case of the Beartooth-Absarokas we are looking at 12-18"
above 9kft. The Winter Storm Watch in effect for the Crazy,
Beartooth-Absaroka and Bighorn/Pryor Mountains is on track. Heads
up to anyone planning to venture into the high country this
weekend. Questions arise with the Canadian wave Sunday, as lowest
snow levels will occur with its passage into Sunday night. If
enough energy dives to our west our southern foothills (i.e. Red
Lodge and Story) could see wet snow accumulation by Sunday night.
If it slides east faster, any foothills snow will be minimal to
none. This remains something to monitor. Current probability of 1+
inches of snow at Red Lodge is 20%. Precip chances should taper
off from NW to SE Sunday night. With clearing and a ~1025mb
surface high settling in, Sunday night could yield the first
widespread frost/freeze of the fall. Billings has a 25% chance of
reaching 32F, but surrounding notoriously colder spots have
greater potential (40% or higher). Something to watch.
Monday through Friday: Our weather will quiet down considerably
next week with a transition back to upper level ridging, and
eventually a warmer SW flow ahead of the next Pacific coast trof.
Look for temps in the 50s Monday, 60s Tuesday, and mid 60s to mid
70s Wednesday thru Friday. We could see a few showers over the
mountains toward the end of the week, as flow aloft backs to the
SW, but this remains highly uncertain at this time.
Finally, it will be interesting to watch the evolution of the next
tropical storm which is expected to form off the coast of Mexico
over the next few days. Model/ensemble consensus is to take this
storm toward Baja CA and moisture to be drawn into the southerly
flow through the southwest CONUS...perhaps reaching MT/WY next
weekend.
JKL
.AVIATION...
VFR conditions will prevail through the period. Scattered showers
and a few weak t-storms are expected this afternoon and evening,
but the risk of a TS impacting a TAF site is low (

NWS BYZ Office Area Forecast Discussion