020
FXUS65 KBYZ 261526
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
926 AM MDT Wed Jun 26 2024

.UPDATE...

Added low PoPs (~15%) further E across the area into Rosebud/W
Powder River Counties through the rest of the day as radar was
showing light echoes in response to a weak wave approaching from
the SW, jet over the area and warm advection aloft. Arthur

&&

.DISCUSSION...
Today through Thursday night...

Ridging will continue through the day today and start to break
down during the afternoon and evening. 700 mb heights and
vorticity shows a weak wave passing through Wednesday afternoon
bringing a chance of isolated showers to northern WY and southeast
MT. CAMs also show a cluster of showers and thunderstorms
entering our west early afternoon. Instability looks weak with
MUCAPE values generally below 500 J/kg (decreasing off higher
terrain) and spotty areas of 30-40 kt shear indicating the chance
for showers and isolated weak thunderstorms. A jet looks to form
with this energy over western SD bringing some low PoPs to our SE
Wednesday night, but the chance for thunderstorms remains low as
capping will likely be a limiting factor.

For Thursday, the environment is looking favorable for severe
thunderstorms capable of producing strong winds, large hail and a
possible tornado. The Storm Prediction Center has a slight risk
(2/5) for most of the region (excluding the mountains and higher
foothills where a marginal 1/5 risk exists). As troughing moves
east Thursday, an associated cold front will enter our western
zones midday and track east through the afternoon. Warm air and
moisture will be advected into the region as a result of low level
SE flow. This will result in above average atmospheric moisture
fueling instability. Beginning in our northeast, higher 0-6 km
shear values (60-70 kts) and MUCAPE values of around 1000 J/kg
will be supportive of sustained supercell like storms. CAMs
generally have these stronger cells tracking across our northern
border. The tornado threat with these storms seems to be minimal
with a lack of low level shear and LCL heights being higher than
favorable (1500-2000 ft in the NW). For the remainder of the
region, shear values of 50-60 kts and MUCAPE values up to 1500
J/kg will be possible. Any of these storms will most likely be
capable of producing strong winds (up to 70 mph) and large hail
(up to golf ball size). With above average moisture, the threat
for heavy rain cannot be ruled out under any thunderstorm. The
frontal passage and associated thunderstorms looks to exit SE MT
around 6-8 pm. Gusty NW winds (30-40 mph) and cooler temperatures
will follow the front into the evening. Isolated showers are
possible through the overnight hours.

High temperatures Wednesday will be in the 80s/low 90s. Thursday,
temps will be coolest west (70s) increasing to the east (low
90s). Low temps will be in the 50s/low 60s. TS


Friday through Tuesday...

An upper low will continue to track east along the US/Canada
border on Friday. While most of the energy associated with the low
will remain north of the area, cyclonic flow will keep shower and
thunderstorm chances in the forecast (10-40%, highest north and
west). Breezy northwest winds will wrap back into the area with
many places gusting 30-45 mph. NBM probabilities for wind gusts
greater than 40 mph on Friday range from 40-80%, highest over the
north and west. Temperatures will range from the 60s over the west
to the middle 70s over the southeast.

Ridging builds back over the region for the weekend bringing
mainly dry conditions for Saturday and most of Sunday. Highs look
to range from the 70s on Saturday to the 80s to 90s on Sunday,
highest over southeastern areas. Ensembles remain in good
agreement with another upper trough moving into the region by late
in the day Sunday, bringing shower and thunderstorm chances
through Monday (30-60% chance, highest over west and central
areas). Modest CAPE and deep layer shear over the area Sunday
afternoon and evening could produce some strong to severe
thunderstorms, so this needs to be monitored. Cyclonic flow
lingering over the area on Tuesday will bring a low chance (20%)
for showers and thunderstorms across the north. Temperatures are
forecast to range from the 70s to 80s for Monday and Tuesday. STP
&&

.AVIATION...

In general, VFR will prevail through the period. A disturbance
lifting into the region from the southwest will bring increasing
clouds today, with isolated to scattered showers and thunderstorms
moving into southwestern areas after 21Z. Local MVFR conditions
are possible with thunderstorms as well as wind gusts to 30 kts
and small hail. STP
&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Thu     Fri     Sat     Sun     Mon     Tue
-------------------------------------------------------
BIL 087 062/089 054/073 048/077 053/089 059/080 055/083
    2/T 27/T    41/N    00/U    01/U    45/T    21/U
LVM 085 056/081 046/069 042/078 049/087 052/075 047/081
    3/T 38/T    32/T    10/U    03/T    66/T    21/N
HDN 089 059/091 053/075 046/079 053/094 058/083 053/085
    2/T 26/T    52/W    10/U    01/U    45/T    21/U
MLS 085 064/091 056/073 048/074 055/092 061/082 056/082
    1/U 25/T    51/N    10/B    01/U    43/T    21/U
4BQ 088 064/094 056/077 049/077 055/097 062/084 056/084
    1/B 24/T    41/N    10/U    01/U    23/T    21/U
BHK 083 061/088 054/073 046/071 050/085 059/081 055/081
    1/U 35/T    61/N    10/B    01/N    33/T    21/N
SHR 089 058/090 050/075 044/080 053/097 057/082 050/083
    2/T 24/T    42/W    10/U    01/U    24/T    21/U

&&

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

&&

$$
weather.gov/billings