241
FXUS65 KBYZ 150314
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
914 PM MDT Mon Jul 14 2025

.KEY MESSAGES...

- Strong cold front arrives tonight with gusty northerly winds
  through the day Tuesday. Much cooler Tuesday and Wednesday
  (60s).

- Good chances for widespread significant rainfall (0.5-1.0 inch)
  Tuesday through Wednesday.

- Seasonal temperatures return Thursday and Friday becoming above
  normal for the weekend.

&&

.UPDATE...
Convection since mid afternoon has produced plenty of erratic
winds and outflow boundaries, with gusts mostly 30-45 mph. The
exception was a rogue 58 mph gust at the western Livingston DOT
station in around 8pm. Much of the activity (which is still
ongoing east of Billings) is a result of a weak shortwave moving
across northern WY, but we are starting to see additional showers
and weak t-storms develop over our west. This convection is a sign
of ascent from the approaching Canadian trof (currently dropping
thru southern BC) and a surface cold front which has reached the
northern tier of our forecast area. Mesoanalysis shows widespread
steep mid level lapse rates (up to 8.5C/km), even on the cold side
of the surface front, so expect scattered elevated showers and
some embedded t-storms to continue to develop thru the night. Late
tonight, we will likely see low stratus surge from the north and
become enhanced in the upslope areas as winds shift to the N-NE.
An oddly cool air mass for the middle of July, for sure. Tuesday`s
high will almost certainly be tonight`s midnight temperature.
Overall the forecast is in good shape. Have made some wind and
pop/wx adjustments per current activity, especially raising
frontal gusts to the 30-40 mph range tonight.

JKL

&&

.DISCUSSION...
Through Wednesday night...

An unseasonable upper trof drops down into the ID Panhandle late
tonight, and moves slowly southeast through the area tomorrow and
Wednesday. This is going to bring a period of much below normal
temperatures and a strong chance for significant rainfall to the
region.

Energy from the southwest will spread across the area late this
afternoon into this evening ahead of the aforementioned upper
trof. This will trigger isolated to increasingly scattered
thunderstorms starting over the western mountains and moving
eastward across the forecast area through the evening. This
activity will start out very high based and mainly dry (more wind
than rain) but as the cold front arrives mid to late evening
storms should become wetter, mainly over the eastern half of the
forecast area. A marginal risk (mainly for severe thunderstorm
wind gusts 40 to 60 mph) covers most of the forecast area through
this evening.

A strong cold front arrives mid to late evening, with timing into
Billings and Miles City around 10pm-midnight. The contrast
between the cold air moving in from the north, and hot
temperatures in place over southern Montana will bring a period of
gusty north wind to the area. Gusts over 40 mph will be possible
and over 30 mph widespread for most of the night post frontal. Low
level moisture will build in behind the front as well, with
stratus cloud cover filling in across the area around sunrise
along with increasing light rain/drizzle activity.

Tuesday looks damp across the area with low clouds holding in
through the day. However, the more significant precipitation holds
off until late afternoon into Tuesday evening when stronger jet
energy shifts over the area adding to the upslope wind generated
lift already in place. The heaviest precipitation looks to fall
Tuesday night through Wednesday morning. EFI is showing a strong
shift of tails signal in the precipitation fields for Wednesday
across the area, peaking at a very strong 5 over central zones.
This is indicative of a number of ECMWF ensemble member posting
very high precipitation values relative to the rest of the
ensemble over the area. WPC has posted a marginal excessive rain
outlook for the area Tuesday and Wednesday to cover the Tuesday
night early Wednesday heavier precipitation period.

Current NBM precipitation amount probabilities thru Wednesday:
Location      0.25in    0.50in   1.00in

Livingston     90%       70%      15%
Billings       95%       85%      45%
Miles City     95%       88%      57%
Baker          93%       85%      58%
Sheridan WY    95%       84%      47%

So, everyone is looking at a very high chance for picking up at
least a quarter of an inch with this system, and near to better
than 50% for getting an inch + for all but the far western
foothills (Livingston).

Temperatures will be well below seasonal levels both Tuesday and
Wednesday. Tuesdays highs will probably not break any cold record
highs due to the highs occuring right around midnight as the front
is moving through. But Wednesdays Cold High Temperature Records
are mainly in the mid to upper 60s which is in the ballpark to
break a few daily records. Once cloud cover begins to break up
Wednesday night there might be a chance for a record low in a few
places.

Despite the cold temperatures in the forecast for the lower
elevations, snow levels stay relatively elevated with this system.
While a few flakes may make it down to 9500 feet (36 degree
line), accumulating snow is expected to stay above 11000 feet.
This should bring minimal impacts to the Beartooth Highway. Those
hiking or recreating in the high country should be prepared for
cold wet conditions over the next 48 hours at all elevations, but
especiall over the highest terrain. Hypothermia is a definite
danger in these conditions for those caught unprepared. Chambers

Thursday through Tuesday...

Upper trof shifts east of the area on Thursday. This will allow
temperatures to rebound toward more seasonal values in the lower
to mid 80s Thursday afternoon. Combination of residual moisture
from the Tue/Wed precipitation event plus a return flow
southeasterly wind capturing plains moisture keeps a chance for
afternoon/evening showers and thunderstorms in the forecast
Thursday.

Another Canadian trof drops into southern Canada and northern
Montana Friday. Right now the main impact with this system will be
to shove another shot of northerly winds through the area keeping
temperatures in the lower 80s Friday afternoon. Friday
precipitation chances are low (10-30%) and may be underdone
overall given at least weak energy over the area and wind shift
convergence at the surface. Will have to see if precipitation
chances increase for this period, especially if the upper trof
jogs southward just a bit over time.

Flat flow to weak ridging build into the area behind the Friday
system. Under this pattern temperatures build back into the 85 to
95 degree range for highs, with 20 to 30 percent chances for
afternoon/evening showers and thunderstorms each day.

A large upper low takes hold over the PacNW Sunday into Monday and
could bring more unsettled conditions to start next week. Chambers

&&

.AVIATION...

Scattered showers and thunderstorms will continue through the
overnight. Convection will be high based with more wind than rain
through mid evening, becoming wetter in the late evening. Erratic
wind gusts of 40kts can be expected near storms. Cold front will
usher in gusty (25-35kt) north- northeast winds as it arrives late
evening into the overnight hours. As the cold air builds in
expect stratus to develop with MVFR ceilings becoming common
before sunrise Tuesday. Areas of light rain/drizzle may further
reduce flight conditions at times Tuesday morning into the
afternoon hours. Mountain obscuration will become predominant by
sunrise for all area mountains. Chambers/Torgerson

&&

.PRELIMINARY POINT TEMP/POPS...

    Tue     Wed     Thu     Fri     Sat     Sun     Mon
-----------------------------------------------------------
BIL 059/063 054/064 051/082 059/082 060/090 061/093 062/088
    38/T    97/T    10/U    11/U    11/U    11/U    11/U
LVM 053/065 047/066 046/085 050/086 051/090 052/090 053/086
    49/T    94/T    01/U    12/T    11/U    11/B    11/B
HDN 060/066 053/064 049/084 057/083 058/090 059/093 059/089
    37/T    97/T    10/U    21/U    11/U    21/U    11/U
MLS 061/066 052/063 050/079 057/083 058/088 063/092 063/089
    47/T    97/T    20/U    31/U    11/U    21/U    21/U
4BQ 064/068 054/060 051/079 058/082 059/086 063/091 063/088
    25/T    98/T    20/B    31/U    21/U    21/U    21/U
BHK 056/065 048/061 044/074 052/082 053/083 057/087 059/086
    37/T    87/T    21/B    41/U    11/U    22/T    21/U
SHR 059/069 050/064 047/084 053/084 053/089 056/092 057/089
    27/T    97/T    10/U    11/U    21/U    11/U    11/U

&&

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

&&

$$
weather.gov/billings