645
FXUS65 KBYZ 172347
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
547 PM MDT Fri Jul 17 2026

.KEY MESSAGES...

- Scattered thunderstorms again today, a few may be strong over
  the west. Torrential rain, strong winds and hail are all threats.

- Marginal Risk (Level 1/4) of flash flooding over portions of
  central and western Montana today.

- Daily chance of showers and thunderstorms through next week with
  high temperatures mainly in the 80s and 90s, warmest this
  weekend.

&&

.DISCUSSION...

Through Thursday...

A ridge of high pressure continues to build over the region with
an upper low centered off the Washington coast. Monsoonal moisture
is streaming into the region from the south bringing PWATs of
150-200% of normal. A weak impulse moving through the flow will
bring another round of scattered showers and thunderstorms once
again this afternoon and evening. Look for convection to form over
the mountains this afternoon, lifting off to the north and east
through the evening over the plains. A few strong storms are
possible over the west with modest instability (CAPE values of
500-1500 J/kg), though shear is fairly weak (generally less than
25 kts). Very heavy rainfall, strong winds and to a lesser extent
large hail are possible with the strongest storms. SPC has a
marginal risk for severe weather for areas generally west of
Billings. There remains a marginal risk for excessive rainfall
over western areas as well.

Ridging continues over the area on Saturday, with the greatest
monsoonal moisture mainly over the mountains and areas south.
Isolated to scattered showers and thunderstorms are possible
during the afternoon and evening hours as another weak impulse
lifts through the region. A weak upper low sliding east through
southern Canada flattens the ridging even more for Sunday and
Monday, with a weak front moving through the area on Sunday and a
backdoor front for Monday. Convection looks to be confined mainly
to the higher terrain these days.

Ensembles remain in good agreement heading towards the middle of
next week in a return of ridging to the region, as well as an
increase in monsoonal moisture. This will keep a daily chance for
showers and thunderstorms in the forecast, with near to slightly
above normal temperatures. High temperatures are forecast to range
from the upper 80s to 90s most days, with some locations
approaching 100 degrees over the east on Saturday and Sunday. STP

.AVIATION...

Scattered showers and thunderstorms are expected to develop and
move northeast to east through Montana and Wyoming into tonight.
The main risk with any thunderstorm is heavy rain causing MVFR to
IFR conditions and erratic wind gusts. Isolated hail is possible
as well. The risk of strong to severe thunderstorms is greatest
around and west of KBIL through this evening. Tonight into early
Saturday morning, showers and weak thunderstorms look to linger
over eastern Montana where a low level jet is expected to develop.
Saturday will then see another round of isolated to scattered
showers and thunderstorms during the late afternoon and evening.
LA/STP

&&

.PRELIMINARY POINT TEMP/POPS...

    Sat     Sun     Mon     Tue     Wed     Thu     Fri
-----------------------------------------------------------
BIL 068/097 067/098 066/091 065/089 065/091 066/092 066/095
    60/U    21/U    10/U    11/B    21/B    23/T    32/T
LVM 057/095 057/096 057/091 056/088 056/090 057/090 057/092
    70/U    21/U    10/U    12/T    34/T    45/T    44/T
HDN 067/097 065/099 064/092 062/090 063/093 064/094 063/096
    51/U    10/U    20/U    11/B    21/B    23/T    32/T
MLS 070/100 067/100 067/091 062/087 064/092 065/094 066/097
    42/W    11/U    11/U    00/B    21/B    11/B    11/U
4BQ 070/100 068/099 067/091 063/086 064/091 065/091 065/094
    31/B    21/U    30/U    11/B    32/T    32/T    32/T
BHK 064/098 064/100 063/090 057/085 058/089 060/092 061/095
    12/T    30/U    21/N    00/B    22/T    21/U    11/U
SHR 061/095 062/096 061/091 058/089 059/090 060/089 059/092
    42/T    22/T    11/U    12/T    35/T    45/T    43/T

&&

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

&&

$$
weather.gov/billings