Damaging Winds in Montana, August 11 to 12, 2024

Area Forecast Discussion
National Weather Service Billings MT
119 AM MDT Sun Aug 11 2024

.DISCUSSION...
Through Monday...

Satellite imagery shows trof axis moving thru central MT and
clearing west of Butte & Dillon. Waves of showers w/ embedded
thunderstorms will continue to impact our forecast area until
subsidence arrives from the west (12z in our far west to 20z in
our far east). As forcing shifts east, models continue to show
700mb winds turning easterly ahead of the trof, setting up a
period of frontogenesis in a region of high precipitable waters
(near 1"). As a result, heaviest rain from now through mid
afternoon will be east of Rosebud County (0.30-0.60" and locally
higher). Western areas can expect localized amounts to 0.10", but
most locations will see less than that today. As the wave moves
east a subsidence inversion will develop in our west, but there
may be enough surface heating to allow for very modest surface-
based cape this afternoon...so will keep isolated pops across the
west half of our cwa thru 00z, though admittedly the latest CAMs
show very little in the way of diurnal development. Eastern areas
should see precip taper off completely in the early evening.

Building ridge will bring dry conditions tonight through Monday
morning. A healthy rainfall today and persistent easterly winds,
followed by clearing skies tonight, yields a fair risk of fog
and/or stratus in Fallon & Carter Counties late tonight into early
tomorrow (roughly 06-15z). This will be something to monitor.

By late Monday, the next shortwave arrives in the backing SW flow
aloft, bringing the next dose of scattered showers &
thunderstorms to our west.

Temperatures today will remain quite a bit cooler than normal,
with highs ranging from the upper 60s in our far east to lower 80s
along western foothills. Monday should be the warmest day we've
seen in several days w/ highs returning to seasonable levels (mid
to upper 80s for most).

Skies will remain hazy due to lofted smoke from wildfires over the
western U.S.

JKL

Monday night through Sunday...

SW flow will prevail over the forecast area Monday night through
Wednesday, when the clusters had a decent wave moving through the
area. Continued 20-30% PoPs from KBIL W Mon. evening on the back
side of the departing ridge. Best instability, shear and moisture
were from KBIL E, so a stronger storm is not out of the question
around KBIL. For Tuesday, MLCAPES increase to 1000-2000 J/kg over
the far eastern zones, with Bulk Effective Shear of 30-40 kt.
PWAT's from KBIL E will be 1-1.25 inches from KBIL E through
Tuesday night. PoPs increase again Tue. afternoon from 20-30% in
the E to 60% over and near the western foothills. Best chances
for strong to severe storms will be over the far E. Storms may
also produce heavy rainfall. Scattered showers and thunderstorms
will continue Tue. evening and into the overnight hours. The wave
will bring more showers and thunderstorms to the area Wednesday
afternoon where high CWASP values in the E supported possible
strong storms. Highs on Tue. will be near normal, while Wed. will
be slightly cooler.

Clusters had ridging over the region Thursday and Friday. PoPs
will be in the 20s and 30s and temps will be near normal. For the
weekend, clusters had SW flow or upper ridging. NBM had low PoPs
over the area. Temps will remain near normal. Arthur

&&

.AVIATION...

Showers and embedded thunderstorms capable of producing local
MVFR-IFR in heavy rain will impact areas east of KBIL today, while
western areas see VFR in scattered showers and a few weak
thunderstorms. Shower activity will taper off in the late
afternoon and early evening. Look for clearing and widespread VFR
tonight. The only exception is potential fog near the Dakotas
border late tonight. Wildfire smoke will continue to reduce slant
range visibility at times. JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Mon     Tue     Wed     Thu     Fri     Sat
-------------------------------------------------------
BIL 079 055/088 060/087 059/085 058/086 058/086 058/088
    3/T 01/B    23/T    34/T    12/T    22/T    11/U
LVM 081 050/087 052/083 050/080 048/083 049/084 050/085
    2/T 03/T    36/T    55/T    13/T    23/T    22/T
HDN 077 051/089 057/088 057/085 055/087 056/087 057/089
    5/T 00/U    12/T    34/T    11/U    21/U    11/U
MLS 072 053/083 060/090 060/085 058/085 059/086 060/086
    8/T 10/U    13/T    43/T    11/U    12/T    21/U
4BQ 072 052/082 061/090 060/085 058/087 059/087 060/087
    8/T 10/U    12/T    33/T    21/U    22/T    11/U
BHK 070 048/079 055/087 056/084 056/085 055/085 056/084
    8/T 20/U    13/T    53/T    11/U    12/T    21/U
SHR 078 048/088 055/088 053/083 052/085 053/085 053/087
    5/T 01/B    13/T    35/T    22/T    12/T    11/U

&&

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

&&

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