342
FXUS65 KBYZ 221849
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
1249 PM MDT Wed Jul 22 2026

.KEY MESSAGES...

- Scattered thunderstorms capable of producing very heavy rainfall
  this afternoon and evening, especially near the mountains and
  foothills. Burn scars are at risk of seeing flash flooding and
  debris flows.

- Isolated thunderstorms and a bit warmer Thursday. Risk of heavy
  rain is lower.

- Friday into early next week is looking hotter and drier, with a
  return of triple digit temperatures expected. Slight chance
  (10-20%) of thunderstorms each day. Fire concerns will increase.

&&

.DISCUSSION...

Through next Wednesday...

Deep monsoonal moisture continues to lift out of the great basin
and mesoanalysis shows pwats of 1.10-1.20" across the region.
Despite the anomalously high moisture, "cooler" low level east
winds keep a mid level cap in place at lower elevations thru much
of the day. Convection will develop over the mountains by 19-20z
(there is some beginning upstream near the Tetons). CAMs show
convection struggling to spread off the foothills even by this
evening, but given weak synoptic ascent and expectation of outflow
boundaries within this very moist air mass, there should be some
activity of lesser coverage spread over the lower elevations. Main
risk of today`s storms is of course heavy rain capable of
producing flash flooding, and this includes burn scars such as
Robertson Draw and East Side near Red Lodge, and Elk along the
eastern slopes of the Bighorns. A Flood Watch remains in effect
from 1pm to 2am. Expect activity in the south to go thru late
evening and even into the overnight hours, per slowly tracking
shortwave across northern WY.

Showers and weak t-storms should linger into early Thursday over
our S/SE, but we will see large scale subsidence spread over the
area behind the departing wave. As a result, CAMs and lower
resolution models have trended drier for tomorrow. However, pwats
will remain anomalously high for another day (still >1") and feel
the potential for a few diurnal showers and weak t-storms is a bit
underdone by the models. Temps into the lower 90s really should
release some surface-based instability.

Friday will be hotter and drier w/ breezy mixed west winds, due to
ridge flattening from a weak shortwave energy in southern Canada.
This is looking like the first of several days of hotter & drier
weather supported by a strong stagnating ridge over the
intermountain west. Ensembles and cluster analyses show high
confidence here. Look for above normal temps through at least the
middle of next week, meaning highs generally ranging from 95-105F
each day through next Wednesday. Monsoon moisture spreading thru
the ridge should yield a low risk (10-20% chance) of diurnal high-
based t-storms each day. In fact, today`s models have trended more
supportive of daily convection. Any storms will be non-severe but
could produce erratic winds, and with pwats still in the
0.75-1.00" range could also cause localized moderate rainfall.
Impacts from Friday into next week will be twofold. Heat related
impacts will be of concern with the triple digit highs and warm
nighttime lows offering little relief. Also, with min RHs expected
in the low-mid teens and poor nighttime recoveries, fire concerns
will also increase over time especially in areas missing out on
rainfall this week. Fire concerns will be exacerbated by periods
of breezy mixed winds along with a daily risk of lightning. This
will be something to monitor over the coming days. The 8-14 day
outlook from CPC shows high confidence in warmer than normal
temperatures persisting into early August.

Finally a comment on this Saturday, July 25th...the only day in
July on which the Billings airport has not reached 100F in its
period of record (back to 1934). Smoke shouldn`t be a factor as
the SW flow takes PacNW smoke to our north. However, the ridge is
looking a bit dirtier, and in fact there is confidence in water
vapor transport in the afternoon leading to some diurnal
convection over our west. Thus, increasing cloud cover could limit
temperatures by mid-late afternoon. Current forecast at KBIL is
103F. Stay tuned.

JKL

.AVIATION...

Showers and thunderstorms will increase this afternoon over the
mountains and foothills, moving from west to east into the
overnight hours. The best chance (50-80%) is over the mountains
and along the MT/WY border. Isolated showers and thunderstorms
will linger into Thursday morning before again increasing over the
mountains and foothills in the afternoon. Localized visibility
reductions due to pockets of heavy rain are possible. Wildfire
smoke from the Pacific NW may produce slant range visibility
reductions at times, but surface visibility reductions are not
expected. Archer

&&

.PRELIMINARY POINT TEMP/POPS...

    Thu     Fri     Sat     Sun     Mon     Tue     Wed
-----------------------------------------------------------
BIL 067/093 069/101 069/103 069/100 068/097 067/097 067/096
    22/T    01/G    12/T    41/U    20/U    21/U    21/U
LVM 058/092 059/100 060/099 059/098 058/095 057/095 058/095
    52/T    11/N    12/T    32/T    21/U    21/U    11/U
HDN 065/094 064/104 066/106 066/103 066/098 065/099 065/098
    22/T    00/G    11/G    31/G    21/U    21/U    11/U
MLS 066/095 068/105 069/107 073/103 070/099 068/100 069/099
    01/B    00/G    10/G    30/G    21/U    21/U    11/U
4BQ 065/090 065/101 068/105 071/102 069/098 067/097 068/097
    42/T    10/G    10/G    20/G    21/U    22/T    22/T
BHK 060/092 063/102 065/106 069/103 066/099 063/098 064/097
    00/B    00/N    00/G    21/G    21/U    22/T    22/T
SHR 061/087 059/099 061/103 064/099 063/095 061/095 061/095
    64/T    10/U    01/G    11/U    22/W    22/T    11/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Flood Watch in effect through late tonight FOR ZONES
      56-64>67-138-139-169>171.
WY...Flood Watch in effect through late tonight FOR ZONES 198-199.

&&

$$
weather.gov/billings