786
FXUS65 KBYZ 161128 CCA
AFDBYZ

Area Forecast Discussion...CORRECTED
National Weather Service Billings MT
528 AM MDT Thu Jul 16 2026

.KEY MESSAGES...

- A few strong to severe thunderstorms are possible this afternoon
  and evening, primarily west of Billings. The main threats are
  heavy rain, strong winds, and large hail.

- Anomalously high moisture remains over the region into the
  weekend; daily chance of afternoon/evening thunderstorms.

- High temperatures will be highest over the weekend, in the 90s
  to near 100.

&&

.UPDATE...
Area of nocturnal showers and weak t-storms from near Sheridan to
south of Miles City, activity supported by a mid level wave in a
region of negative showalters, is finally dissipating. Further
west where skies have been mostly clear, satellite imagery shows
fog along the Musselshell River near Roundup and the Clarks Fork
from Bridger to Laurel. It is expanding to the northeast of Laurel
and could impact Billings before sunrise. Any fog will of course
erode quickly after sunrise, but just the fact that there is fog
in mid July tells plenty about how moist this air mass is. The
dewpt is currently 66F at Billings. Otherwise, water vapor imagery
shows moisture plume from the southwest lifting from eastern NV
to south central MT. We will remain within a region of anomalously
high pwats and thus expect another round of showers and
thunderstorms this afternoon and evening. High res models show
development beginning over our SW mountains at 18-19z. Mid levels
are still warm and forecast soundings continue to show capping at
lower elevations for much of the day. It is possible that initial
convection struggles to spread off the mountains, but this should
change by evening with a hint of easterly low level jet and
another shortwave embedded within the SW flow aloft. Today`s
storms should be a bit less widespread than the past two days, but
they will produce locally heavy rain and erratic wind gusts.
Steep low level lapse rates and a water-logged profile above 700mb
is highly suggestive of wet microbursts. Something to watch
today. Temps should reach the upper 80s to mid 90s today (hottest
east) and with the high dewpts it will feel humid.

Have expanded area of fog thru 15z this morning and adjusted onset
of pops/wx this afternoon. SPC`s day1 outlook shows a marginal
risk of severe weather from Billings westward, and a slight risk
further west but including parts of Park County. Shear is weak so
very heavy rain and gusty winds are the primary risks, but cannot
rule out a hail report either. JKL

&&

.DISCUSSION...
Thursday through Wednesday...

Upper level ridging, with occasional shortwave disturbances, is
expected to continue into next week. Monsoonal moisture will
continue to stream into the region, with PWATs around 140-180% of
normal into Saturday. As a result, daily afternoon and evening
showers and thunderstorms (40-60% chance) will continue through
Saturday. The main threat with any stronger storms that develop
will be localized very heavy rain. With the continued high
moisture, WPC continues to have a Marginal risk (level 1 of 4) for
excessive rainfall that may result in flash flooding over much of
the west each day through Saturday.

For this afternoon and evening, SPC has issued a Marginal risk
(level 1 of 5) across western Montana and a Slight risk (level 2
of 5) over portions of Montana mainly from Livingston west and
north. In addition to heavy rain, large hail up to half dollar
size and strong winds up to 65 mph are the main threats with any
severe storms.

Sunday into Monday will see (comparatively) drier air over the
region, with PWATs near normal over much of the area to around
130% of normal along the Wyoming border. This will limit
precipitation to mainly over the mountains and foothills Sunday
and Monday. By Tuesday, monsoonal moisture looks to move in again,
resuming afternoon and evening shower and thunderstorms chances
(40-60%).

Highs today will be generally in the upper 80s to low 90s. Friday
into Saturday will see the ridge briefly shift north, increasing
highs to 90s to near 100 for the weekend. Then, the ridge flattens
some and shifts back south late Sunday into Monday, allowing
temperatures to fall to near normal, in the mid 80s to low 90s.
Archer

.AVIATION...

Issued 10z. Satellite imagery at 0945z shows valley fog forming
along the Musselshell River near KRPX and the Clarks Fork from
Bridger to K6S8. Fog may eke into KBIL early this morning and this
will be monitored. Reductions to MVFR or lower are expected with
any fog thru ~14z. Look for another round of scattered
thunderstorms this afternoon and evening, beginning around 18z
over the mountains and tracking eastward over the plains in the
late afternoon/evening. Local MVFR/IFR in heavy rain and erratic
wind gusts of 25-45kts can be expected with today`s storms. JKL

TS Potential Times:
KLVM: 19Z-03Z
KBIL: 23Z-06Z
KSHR: 19Z-06Z

JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Fri     Sat     Sun     Mon     Tue     Wed
-------------------------------------------------------
BIL 091 066/094 066/095 067/097 066/092 065/088 064/087
    2/U 42/T    62/T    41/U    10/U    23/T    42/T
LVM 090 057/090 057/093 058/095 057/092 058/084 056/085
    3/T 34/T    63/T    41/U    01/U    25/T    55/T
HDN 093 065/096 065/096 066/097 064/093 063/090 062/088
    2/U 52/T    62/T    31/U    10/U    13/T    42/T
MLS 095 067/095 069/099 069/099 066/093 064/089 064/088
    1/U 21/B    62/T    31/U    11/U    11/B    33/W
4BQ 094 067/095 069/099 068/097 066/092 064/087 063/086
    1/U 32/T    33/T    51/U    21/U    22/T    53/T
BHK 094 063/093 063/095 065/097 062/091 059/086 059/085
    1/B 11/B    43/T    42/T    11/U    11/B    33/T
SHR 091 060/093 061/095 062/094 059/091 059/087 058/085
    4/T 53/T    44/T    44/T    32/T    35/T    56/T

&&

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

&&

$$
weather.gov/billings