Corwin Springs, Montana Weather Forecast Discussion

180
FXUS65 KBYZ 090811
AFDBYZ
Area Forecast Discussion
National Weather Service Billings MT
211 AM MDT Tue Sep 9 2025
.KEY MESSAGES...
- Above normal temperatures through Thursday.
- Repeated late day isolated/scattered showers and storms
  through Thursday, especially over the western mountains and
  foothills.
- Good chance of significant precipitation (35-70% chance
  widespread >0.5in) and cooler temps Friday-Saturday.
- Areas of Wildfire Smoke through today, decreasing for
  Wednesday.
&&
.DISCUSSION...
Through Wednesday night...
Synoptic pattern for the short term period will see an upper
ridge of high pressure with its axis over eastern Montana while a
large upper low develops over the western CONUS. As the upper low
slides into the Rockies, we will see a gradually increasing
diffluent southwest flow across our western CWA late today through
Wednesday...tapping into some Pacific and monsoonal moisture. All
the while easterly low level flow is induced across our east
bringing low level moisture into the area as well. The end result
is an increasing chance of precipitation as weak perturbations in
the mean flow track SW to N/NE over our region triggering
scattered showers and isolated storms the next couple of days.
Overall the best chances for precipitation will be over the
western mountains and foothills under the stronger diffluent
flow. While the chance for precipitation is lower over SE Montana
due to a mid level inversion under the ridge, this will be where
the highest CAPE values exist, especially by Wednesday when MUCAPE
reaches 1250-2000 J/kg from Miles City to Alzada and Baker. As
such, not expecting many thunderstorms in this area, but any that
manage to pop could become strong to severe Wednesday evening with
hail and heavy rain possible.
Expect temperatures to be above normal (normal highs this time of
year are in the upper 70s to 80 degrees) peaking Wednesday in the
mid 80s to lower 90s. Overnight lows will be mainly in the 50s.
Wildfire Smoke...The near surface winds under the ridge will keep
smoke from dispersing much today as southwest winds aloft pull in
additional smoke from wildfires in the Great Basin. However,
latest model runs do indicate the increasing southerly flow at
midweek will be push much of the smoke north of our area by
Wednesday morning. BT
Thursday through Monday...
Into Thursday, troughing moving in will promote southwest flow
and moisture advection, creating increased chances for showers and
thunderstorms through the weekend. The ensembles are still
disagreeing on timing of the better forcing moving in. However,
much of the region has about a 50-75% chance of getting at least
half an inch of rain Friday through the weekend. An additional
component to note is the increased instability Thursday through
Saturday, promoting afternoon and potentially overnight isolated
to scattered thunderstorms. With ensembles depicting another push
of increased atmospheric moisture Friday as well as slowing storm
motion, the potential for storms to produce heavy rainfall arises.
Note that there is still a noticeable amount of disagreement
between ensembles regarding system track, instability, and
resulting precipitation totals. As mentioned earlier though, much
of the region has a good chance to see at least a half an inch of
rain.
High temperatures will be in the 70s east to 80s east Thursday and
Friday before cooling into the upper 60s and low 70s for Saturday.
High will warm into the 70s across the region by Monday. TS
&&
.AVIATION...
Scattered showers and isolated thunderstorms are expected to begin
developing over the Beartooth/Absarokas around noon today, moving
onto the foothills into the afternoon. Confidence is low on any
showers making their way onto the plains. Wildfire smoke will
continue to reduce slant range visibility. TS
&&
.PRELIMINARY POINT TEMP/POPS...
Tdy Wed     Thu     Fri     Sat     Sun     Mon
-------------------------------------------------------
BIL 086 058/087 059/084 054/077 055/070 053/075 052/078
    0/K 11/H    24/T    35/T    76/T    43/W    12/W
LVM 083 048/083 050/079 044/075 045/070 044/075 044/075
    3/T 32/T    45/T    35/T    66/T    33/T    23/T
HDN 088 056/090 057/087 051/078 053/070 050/075 048/079
    0/K 10/B    22/T    35/T    86/T    53/W    21/U
MLS 085 058/090 061/088 056/082 057/074 054/075 053/080
    0/K 10/H    21/B    23/W    77/T    63/W    21/U
4BQ 083 058/088 063/088 056/078 055/071 054/072 052/078
    0/K 10/H    11/B    13/T    77/T    52/W    21/U
BHK 083 053/085 059/088 054/081 053/073 051/073 049/077
    0/K 00/N    21/B    22/W    66/T    63/W    21/B
SHR 085 051/088 054/086 049/076 047/070 045/073 046/078
    1/K 11/B    22/W    36/T    77/T    43/W    12/W
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
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NWS BYZ Office Area Forecast Discussion