331
FXUS65 KBYZ 010159
AFDBYZ

Area Forecast Discussion...Corrected
National Weather Service Billings MT
759 PM MDT Sun Jun 30 2024

.UPDATE...

Corrected to remove Severe Thunderstorm Watch at the bottom.

Severe Thunderstorm Watch 492 has been allowed to expire at 8 PM
MDT this evening as the threat has subsided in the west. In the
east, thunderstorms are growing in coverage as they move to the
northeast. Updated the forecast to account for this growing
activity. Arends

&&

.DISCUSSION...

Rest of Today through Monday Night...

There are no big changes to today`s thunderstorm potential
outside of the SPC`s Slight risk for severe thunderstorms getting
pulled west through Livingston this morning.

Showers and thunderstorms, some becoming strong to severe, are
still expected to form around the western mountains and move
east/northeast through central Montana this afternoon and evening.
By midnight, this activity is expected to be moving into the
Dakotas. While isolated showers and weak thunderstorms are ongoing
west of Livingston early this afternoon, the main event looks to
get started in the west around 2-4 PM MDT. The latest model
guidance continues to suggest thunderstorms will track north of
Billings this evening, but there remains a chance (30%) that
Billings could still see a thunderstorm. With any thunderstorm
that forms today, wind and hail are the main threats, with heavy
rain and frequent lightning being secondary threats. The wind
threat is the most concerning at this time with gusts up to 75 mph
possible. As common with storms out here, these strong winds will
likely also be felt outside of the storm itself, so areas like
Billings could see increased winds without ever getting a storm
overhead. In addition, today`s storms are following a cold front
so locally enhanced winds from convection along the front is
certainly a concern. One thing to note, as thunderstorms move into
east central Montana this evening, some could intensify as they
move into a better environment.

After today`s activity, periods of showers and weaker
thunderstorms look to develop tonight through Monday. With this
activity, a few stronger storms are possible in southeastern
Montana Monday afternoon. This activity will be limited by weaker
instability though, so the threat for severe weather remains
marginal. Monday night into Tuesday morning, snow levels are
expected to drop around 10,000 feet in the mountains. This could
lead to wet light snow at the highest peaks of the
Beartooth/Absaroka Mountains, including the Beartooth Highway.
Arends

Tuesday through Sunday...

Active weather will persist for much of the extended period. In
fact, current indications are that an unsettled NW flow will last
thru next weekend...a change from how things looked the past few
days.

Broad troffing/cyclonic flow and below normal heights will result
in a daily chance (30-50%) of showers and thunderstorms Tuesday
thru Thursday. The progressive nature of the flow will limit
severe potential, but w/ seasonably low freezing levels just about
any thunderstorm will produce small hail. Temps should max out in
the 70s Tuesday & Thursday, but may eke into the lower 80s
Wednesday per a brief period of pre-frontal warming. The 4th of
July may turn out to be the coolest day of the week (low-mid 70s)
and could also have breezy NW winds along with showers on the back
side of a shortwave. That said, shower chances and wind should
decrease in the early evening, resulting in comfortable (if not a
bit chilly) conditions for Independence Day celebrations.

Freezing levels should fall enough to produce a risk of snow
showers Wednesday night into Thursday over the highest elevations
of the Crazy & Beartooth-Absaroka Mountains. GFS/EC show wet bulb
zero heights to 9.5-10kft, which if accurate would mean snow
showers over Beartooth Pass above Vista Point. Something to be
prepared for if you have outdoor recreation plans in the mountains
this week. Latest snowfall probabilities for 1+ inches over the
Beartooths are non-zero.

Friday should trend warmer & drier as heights start to build, but
additional energy in the NW flow may bring a few showers
(especially in the east and southern mountains). To highlight
today`s biggest change to the extended forecast, ensembles then
show a strong Pacific coast high building far enough west to allow
for more shortwave energy to drop out of western Canada into our
region this weekend. There is plenty of spread here, of course,
but it should be noted that the cluster analyses show highest
probability of solutions on the cooler & wetter side. So, look for
more potential showers & thunderstorms next weekend, w/ temps no
warmer than normal (and possibly cooler). Overall this is shaping
up to be a very comfortable start to July, with any potential "dog
days" heat pushed back until after the 8th or 9th.

JKL


&&

.AVIATION...


For the remainder of the afternoon, look for scattered strong
thunderstorms to develop west of KBIL, possibly affecting
KLVM-K6S0-K3HT with brief MVFR, strong wind gusts and possible
hail before 00z. Thunderstorms associated with a cold front will
arrive around 00z for KBIL and progress eastward between 00z and
06z. Primary hazards w/ these storms are strong wind gusts (45-65
knots) and hail, potentially impacting KBIL-KMLS-KBHK this
evening. The potential for thunderstorms is much lower in far
southeast MT and near Sheridan (but this will need to be watched).
Additional showers and some embedded weaker tstorms are expected
late tonight and Tuesday. Mountains will be occasionally obscured.

TS POTENTIAL TIMES TODAY:
KBIL: 23z-03z (20% chance, risk of strong wind & hail)
KLVM: 20z-06z (40% chance, risk of strong wind & hail)
KMLS: 02z-06z (40% chance, risk of strong wind & hail)
KSHR: 22z-03z (10% chance, low risk of strong wind)

JKL


&&

.PRELIMINARY POINT TEMP/POPS...

    Mon     Tue     Wed     Thu     Fri     Sat     Sun
-----------------------------------------------------------
BIL 060/079 056/079 055/081 053/075 053/083 057/085 058/083
    35/T    44/T    14/T    55/T    21/U    12/T    12/T
LVM 052/075 048/075 048/077 046/073 046/082 051/084 051/082
    75/T    63/T    13/T    44/T    21/U    12/T    12/T
HDN 057/079 055/079 051/082 051/075 049/083 053/085 054/084
    25/T    54/T    14/T    55/T    21/U    12/T    12/T
MLS 061/078 056/078 054/082 055/073 054/081 057/085 057/083
    74/T    13/T    14/T    56/T    31/U    12/T    11/U
4BQ 061/079 056/077 053/084 054/073 053/080 056/085 056/083
    37/T    34/T    03/T    55/T    22/W    12/T    11/U
BHK 059/079 053/077 052/081 051/072 051/078 053/082 053/082
    45/T    13/T    03/T    56/T    32/T    12/T    11/U
SHR 055/075 050/076 048/081 048/073 047/080 051/083 051/082
    28/T    76/T    22/T    44/T    22/T    12/T    12/T

&&

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

&&

$$
weather.gov/billings