717
FXUS65 KBYZ 020739
AFDBYZ
Area Forecast Discussion
National Weather Service Billings MT
139 AM MDT Mon Jun 2 2025
.KEY MESSAGES...
- Unsettled and cooler Monday through Wednesday.
- Winter Weather Advisory in effect beginning 9AM Monday for the
Beartooth Highway. Total accumulations of 3 to 6 inches, mainly
above 7,500 feet.
- Rivers are running high and fast today, but cooler mountain
temperatures will slow snowmelt and bring decreasing flows over
the next few days.
&&
.DISCUSSION...
Through Tuesday night...
Models did a good job with the late afternoon/evening convection.
Precipitation reports show areas west of a Hysham to Red Lodge
line picked up two tenths up to six tenths of an inch of rainfall,
with radar estimates in the Boulder River drainage showing over an
inch.
Longwave trof will be over the forecast area for the next couple
of days. The most widespread precipitation with this system will
occur today, as a secondary push of cooler air pushes into the
area, while aloft jet energy flows across from the southwest.
Northerly winds today will enhance precipitation chances for the
north facing mountains and foothills. The most persistent
precipitation will fall over the northwest half of the forecast
area, while areas to the southeast will see more scattered showers
and isolated thunderstorms. Trended temperatures a few degrees
lower than NBM guidance today with short range ensembles trending
highs more in the 50s than 60s. This seems reasonable given a push
of cooler air into the area this morning along with ongoing cloud
cover and shower activity.
Latest models continue to trend drier for Tuesday with a bit more
sunshine, allowing temperatures to warm up just a bit over
previous guidance. Given recent moisture and trof overhead expect
scattered to numerous showers over areas that picked up good
precipitation amounts (>0.25in) Sun into Monday.
We have been watching the models advertise a disturbance dropping
down the west side of the trof for late Tuesday into Wednesday for
a few days now. Overall this system has trended weaker over time,
but still looks capable of bringing additional precipitation
across western and southern zones Tuesday night into Wednesday.
Precipitation amounts with this system look to be less than a
quarter of an inch, and mainly around a tenth of an inch for
lower elevation locations.
Mountain Snowfall...Snow levels are generally above 10-11kft
early this morning, but are forecast to fall into the 7-8kft range
by early this evening. Going winter weather advisory looks
reasonable for the Beartooth Pass with latest models bumping
highest totals into the 6 to 8 inch range with most of that
falling tonight into Tuesday morning. Lesser snow accumulations
are forecast for the higher portions of the Bighorn mountains (1
to 3 inches). This may impact travel over highway 14/14A mainly
Tuesday night. No plans for a near term advisory for the Bighorns
at this time, but will keep an eye on the precipitation forecast
for Tue-Wed for any increase that might necessitate one. Chambers
Wednesday through Sunday...
Another shortwave trough is forecast to quickly drop into
MT/ID/WY Wednesday morning before rapidly moving eastwards. Most
mid and long range models keep most of the precip to our south
into WY. Areas along the east side of the Bighorn and Pryor
Mountains should see the most precip from this quick hitting
system, however, the 01z NBM 75th percentile only has 0.25"
forecast for Sheridan.
The pattern remains unsettled through the end of the week as a
large parent low sets up over the Hudson Bay region allowing
several vort maxes to pivot through the region. All of these
events will be very quick hitting and pretty starved of moisture
and thus large precip totals are not expected. Pretty large
discrepancies exist regarding rainfall totals with the
operational GFS amongst the highest solutions. More winter impacts
to the mountain passes are possible, however, it is far too early
to discuss any details regarding these shortwaves.
There is good consensus between the long range models that a
return to warm temperatures will be in store for the end of the
week with many locations possibly returning to the 80s for highs
Friday/Saturday. WMR
&&
.AVIATION...
06z Discussion...
Rain showers continue across the region with some isolated
lightning in far Southeast Montana. While there could potentially
be a lull in the precipitation, widespread showers are forecast to
return before 12z. MVFR VIS is possible, however, the more likely
reduction will be MVFR to IFR CIGs at all sites in the forecast
area. Gusty winds (20-30kts) out of the north will be the theme
throughout the period as well.
While widely isolated showers remain possible through the night
tomorrow, the region should be mostly free of precipitation by
00z. Mountains will obscured for the entire period.
Additionally, a G4 geomagnetic storm is forecast by the SWPC.
This could potentially have impacts on high altitude air traffic
as well as radio communications. More information can be found at
swpc.noaa.gov. STP/WMR
&&
.PRELIMINARY POINT TEMP/POPS...
Tdy Tue Wed Thu Fri Sat Sun
-------------------------------------------------------
BIL 058 042/065 046/070 048/075 050/080 055/082 053/076
9/T 22/W 23/W 01/U 11/U 12/T 21/U
LVM 060 036/061 039/067 042/071 045/075 050/078 048/074
7/T 23/W 34/W 02/T 12/T 11/U 11/U
HDN 057 041/066 044/070 045/076 049/080 053/083 052/076
7/T 21/B 24/W 12/T 12/T 22/T 21/U
MLS 057 042/068 046/071 046/075 051/080 055/083 053/076
8/T 21/U 13/W 11/U 11/U 12/W 21/B
4BQ 057 041/065 046/065 044/071 048/077 054/080 053/074
5/T 21/U 24/W 11/U 11/U 11/U 21/U
BHK 057 039/066 041/068 042/071 046/075 050/079 049/073
7/T 10/U 03/W 11/U 11/U 12/W 21/B
SHR 057 039/060 041/064 040/070 044/075 048/078 048/072
6/T 24/W 47/T 13/T 13/T 22/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory for the Beartooth Highway today
through Tuesday night.
WY...None.
&&
$$
weather.gov/billings