063
FXUS65 KBYZ 140239
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
839 PM MDT Thu Aug 13 2026

.KEY MESSAGES...

- Widespread precipitation is forecast today through Saturday.
  Locally heavy rainfall is possible during this period, with a
  slight risk of exceeding flood guidance for areas east of a
  Roundup to Billings to Sheridan line.

- Temperatures will be well below normal today through Saturday,
  and possibly Sunday.

- Return to average temperatures next week.

&&

.DISCUSSION...

Next 7 Days...

An upper level low pressure system / trough axis remains centered
over the Great Basin today. This is allowing for our region to get
repeated vort maxes as they migrate northeastwards. Several more
weak waves of energy will move up from the Great Basin into
Montana through the day Saturday. This will result in rounds of
showers and thunderstorms over the next 2-3 days with periods of
relatively dry conditions in the areas of AVA behind these
shortwaves.

Now that we are firmly under the shield of clouds there will be
little severe threat with any of these storms due to the lack of
CAPE and increased CIN. What remains a threat though the the
potential for locally heavy rainfall. While no storm is forecast
to have overly impressive rainfall rates, repeated showers over
the same areas could cause some localized flooding. That being
said, we have been quite dry over the past month which means that
the ground should be able to hold most of this moisture just fine
with minimal flooding concerns on a region-wide scale.

Due to the relative weak steering flow the upper level low will be
allowed to naturally retrograde over the next several days before
merging with a secondary advancing low pressure system. This will
put our area back under a ridge as it builds back in from the
Great Plains. The good news with this feature though is that it
will not be nearly as hot as the previous ridging pattern. Surface
winds will remain primarily out of the plains, limiting any
downslope effects and keeping the neer-surface environment
decently moist. Additionally, the apex of this ridge will be
roughly along the MT/SK border meaning that we could see
shortwaves ride along the ridge bringing chances for brief
cooldowns and / or precipitation. One such trough could impact the
area this time next week. WMR

.AVIATION...

A broad area of light to moderate precipitation with embedded
thunderstorms and localized pockets of heavy rain will slowly
cross the area this evening, exiting to the northeast in the early
morning hours tonight. Light upslope winds and saturated low
levels will result in low stratus and fog development across much
of the area overnight through late Friday morning, with stratus
lingering for some areas into the afternoon. MVFR/IFR conditions
can be expected with precipitation and stratus/fog overnight into
Friday morning. STP

&&

.PRELIMINARY POINT TEMP/POPS...

    Fri     Sat     Sun     Mon     Tue     Wed     Thu
-----------------------------------------------------------
BIL 058/072 057/074 055/082 057/084 058/079 056/081 056/083
    96/T    64/W    41/U    12/T    63/T    42/W    31/B
LVM 048/073 046/076 045/081 047/082 047/078 045/079 045/081
    89/T    94/T    51/U    23/T    75/T    54/T    32/T
HDN 054/074 053/076 050/083 052/087 053/081 051/083 051/085
    95/W    64/W    21/U    11/B    53/T    42/W    31/B
MLS 059/074 055/075 052/083 056/087 057/080 054/083 055/084
    87/T    22/W    13/W    11/B    53/T    32/W    32/W
4BQ 061/076 057/076 054/082 057/086 058/081 056/082 056/085
    86/W    23/W    35/T    11/B    43/T    43/W    32/W
BHK 055/076 051/075 047/081 052/086 053/080 049/081 051/084
    79/T    32/W    01/U    01/B    34/T    42/W    32/W
SHR 053/073 051/073 049/079 049/083 051/078 049/080 049/082
    85/T    77/T    52/T    12/T    35/T    44/T    22/T

&&

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

&&

$$
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