186
FXUS65 KBYZ 240839
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
239 AM MDT Tue Jun 24 2025

.KEY MESSAGES...

- Chance for strong to severe storms developing late afternoon and
  evening in SE Montana and northern Wyoming today and Wednesday
  afternoon.

- Thursday will be warmest day of the week with highs in the 80s
  to around 90 degrees.

&&

.DISCUSSION...

Today through Wednesday night...

Currently, a low level jet is bringing some showers and embedded
thunderstorms to far southeast MT. These showers are expected to
gradually dissipate through the morning hours. For today, a split
flow (westerly/southwesterly) will promote energy and moisture
transport from troughing from the southwest US. As a result,
strong to severe thunderstorms are possible over southeast MT and
north central WY late afternoon into the evening. Instability
(MUCAPE up to 1200 J/kg) and sufficient shear (40-50 kts) will
support an environment favorable for large hail and strong winds.
The threat for severe storms looks to end around midnight as
instability decreases, but scattered showers and thunderstorms are
expected to linger through the early morning hours in southeast
MT into Wednesday as that disturbance moves northeast. Into
Wednesday afternoon, weak departing troughing will again allow for
afternoon strong to severe thunderstorms (generally east of
Billings). Shear will be less supportive for severe storms (25-35
kts, highest over far SE MT), but instability looks to be
sufficient with MUCAPE values 1000-1300 J/kg. The best timing for
these storms Wendesday looks to be between 2 pm and 9 pm.

Highs today and Wednesday will be in the mid 70s to low 80s. TS


Thursday through Monday...

Model ensembles agree on a weak westerly flow after midweek.
Cluster analysis suggest a low amplitude upper trough will track
across southern Canada and northern Montana Friday night into
Saturday dragging a cool front across our CWA. An upper ridge is
then progged to build behind over our region early next
week...but a few recent ensemble members are trending away from
this with continued cyclonic flow across southern Canada into
Montana, creating some uncertainty for early next week. Based on
these pattern transitions, look for downslope flow warming us into
the 80s to around 90 degrees Thursday, then a slight cooling
trend into the weekend with highs around seasonal norms. Isolated
to scattered convection is possible late Thursday and Friday,
with an increasing chance of scattered thunderstorms Saturday
(generally 30-50% coverage). Temps may bounce back Monday to near
90 degrees under the upper ridge, but we will need to keep an eye
on model trends for this.

As for strength of convection in the extended...CWASP values over
50 by Saturday suggest a few seasonally strong thunderstorms are
possible with CAPE in the 750-1250 J/kg range by Saturday
afternoon. However, these values are not nearly as significant as
those last week which resulted in large hail across portions of
our CWA. Overall, typical storms for this time of year with
nothing to extreme expected at this time. However, always keep a
close eye on forecasts this time of year as environmental factors
can change significantly in a short amount of time. BT

&&

.AVIATION...

VFR conditions will prevail through much of today. Isolated
showers and thunderstorms are possible in the mountains and
terminals mainly east of KBIL. Some thunderstorms could be strong
to severe, especially in the southeast corner of MT. The
strongest storms will be capable of producing gusty and erratic
winds, as well as hail up to quarter size. Convection looks to
begin around or after 21z. Brief MVFR/IFR conditions are possible
under stronger cells. Matos

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Wed     Thu     Fri     Sat     Sun     Mon
-------------------------------------------------------
BIL 077 054/083 055/088 058/084 059/083 057/081 058/086
    2/W 31/U    01/U    11/B    33/T    21/U    00/U
LVM 075 044/081 049/084 050/083 051/081 048/081 050/086
    2/W 21/U    02/T    13/T    43/T    20/U    00/U
HDN 080 054/083 054/089 055/086 058/084 055/082 055/088
    2/W 42/T    11/U    11/U    33/T    31/U    00/U
MLS 082 058/081 056/091 060/088 060/086 058/084 057/087
    2/W 44/T    11/U    20/U    43/T    31/U    00/U
4BQ 079 057/078 056/087 060/087 061/086 058/081 058/085
    4/T 64/T    11/U    10/U    22/T    41/U    11/U
BHK 079 055/075 052/085 058/087 058/082 055/080 053/083
    2/W 67/T    21/U    21/U    22/T    31/U    10/U
SHR 077 050/079 051/086 053/086 055/083 053/080 052/084
    4/T 53/T    11/U    01/U    13/T    32/T    11/U

&&

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

&&

$$
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