091
FXUS65 KBYZ 171618
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
1018 AM MDT Tue Jun 17 2025

.KEY MESSAGES...

- Scattered showers and isolated thunderstorms today.

- Quieter weather pattern through Thursday.

- Active pattern by the end of the week.

&&

.UPDATE...

Isolated to scattered showers, and isolated thunderstorms were
ongoing over the Bighorn Mountains, spreading east into southeast
MT this morning. Weak shortwave energy sliding west to east
through the region today will bring isolated to scattered showers
and thunderstorms over the area, increasing in coverage this
afternoon, decreasing into the evening. Can`t rule out a strong
storm or two, but widespread severe thunderstorms are not
expected. Have updated PoPs and precipitation amounts through
tonight to account for latest trends and hi-res guidance. STP

&&

.DISCUSSION...

Today through Wednesday...

Isolated showers will continue this morning, increasing to
scattered showers and isolated thunderstorms by afternoon.

Conditions are much less favorable for severe storm development
compared to the last few days. CAPE values will generally be
around 500 to 800 J/kg and shear values only around 20 to 30 kts.
Moisture is also decreased, with PWATs around 0.75 inch (near
normal) rather than 1+ inches. That said, any stronger cells that
do develop may produce small hail and gusty winds.

This evening into Wednesday, upper level ridging will build in,
leading to dry conditions by late this evening and highs
increasing from 70s today to 80s Wednesday. Archer

Thursday through Monday...

Ensembles are in good agreement that we will be under a strong
upper ridge Thursday leading to a mostly dry and rather warm day
with highs in the 80s to near 90 degrees (10 degrees above
normal) for many locations.

However, a large upper low will be moving into the Pacific NW and
pushing the upper ridge axis to our east late Thursday through
Friday. Mid level winds will back to the southwest in response and
send a short wave disturbance across our area Thursday evening
leading to a chance of isolated to scattered thunderstorms across
our west. The pattern then clearly transitions back to an active
weather pattern Friday and into the weekend as the upper low moves
into the northern Rockies. Look for potentially active weather
across the western and northern portions of our CWA (mainly west
and north of Billings) through Saturday. By Sunday, the energy
within the upper trough splits off and lifts northeast into
Saskatchewan and sends cooler air into our area with a good chance
of showers/thunder. Highs for Sunday may only be in the 60s for
the plains. Freezing levels may drop to under 8500 feet, so a
trace of snow is even possible in the high country Sunday evening
(think Beartooth Pass). The southern split trough axis to the west
keeps southwest mid level flow over our area for a chance of
showers into Monday. Highs will still be on the cooler side of
average, with readings in the mid 70s. There is a risk the flow on
Monday could send some Canadian wildfire smoke back into our
area. BT

&&

.AVIATION...

Isolated to scattered showers/thunderstorms over northern
WY/southeast MT this morning are expected to spread into western
areas as well this afternoon/evening. Brief MVFR conditions are
possible with the heaver cells, including gusty winds to 35 kts
and small hail. Expect occasional mountain obscurations. BT/STP

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Wed     Thu     Fri     Sat     Sun     Mon
-------------------------------------------------------
BIL 076 055/086 057/088 059/086 056/081 050/066 045/071
    2/T 00/U    00/U    32/T    22/T    44/W    32/T
LVM 075 048/084 050/086 052/084 049/076 041/062 037/069
    3/T 10/U    01/U    43/T    33/T    55/T    33/T
HDN 075 051/086 054/089 058/089 057/083 052/067 046/073
    3/T 10/U    00/U    32/T    21/U    43/W    32/T
MLS 079 055/087 057/091 063/087 062/085 052/067 046/069
    2/T 10/U    10/U    53/T    31/U    43/W    32/W
4BQ 075 053/084 057/090 060/087 062/087 054/070 047/068
    4/T 20/U    00/U    21/U    10/U    22/W    42/W
BHK 077 052/084 054/089 058/083 057/084 053/069 045/068
    2/T 00/U    00/U    32/T    21/U    32/W    32/W
SHR 070 048/081 053/089 055/086 054/084 049/069 041/070
    6/T 20/U    00/U    11/U    11/U    33/T    43/T

&&

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

&&

$$
weather.gov/billings