471
FXUS65 KBYZ 180508
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
1108 PM MDT Tue Sep 17 2024

.UPDATE...
Latest mesoanalysis shows snow levels in the Beartooth-Absarokas
down to around 10kft, with strong 700mb frontogenesis and heavy
precip occuring. Impacts will remain above any populations (i.e.
Cooke City) but recreation in the high country will be impacted
by a period of heavy wet snow and strong westerly winds over the
next 12-18 hours. Have issued a Winter Storm Warning for the
Beartooth-Absarokas thru tomorrow. JKL

&&

.DISCUSSION...

The rest of today through Wednesday night...

An upper level low is moving into the region, bringing a chance
for strong to severe thunderstorms through around 9 pm this
evening. The SPC has highlighted much of central and eastern MT in
a slight risk (2/5) for severe weather with much of south-central
and southeast MT in a marginal risk (1/5). With any severe
storms, the main threat is large hail and wind gusts up to 65 mph,
with pockets of heavy rain also possible. PWATs are around
150-200% of normal, however, the highest expected rainfall totals
through Wednesday are generally northwest of the CWA. There is
still a 60-80% chance of at least 1 inch of rain from Rosebud
county west. Make sure you have a way to receive warnings,
especially if you have outdoor plans this afternoon and evening.

With the above normal moisture and snow levels over the west
falling to around 9,500 feet overnight, there is a 50% chance of
at least 6 inches of snow falling over the Beartooth pass through
Wednesday night.

Overnight into Wednesday, a tight pressure gradient will give way
to stronger winds, with a 50% chance of gusts of 58 mph or
greater near the area around Big Timber to Harlowton and eastward
through Golden Valley and southwestern Yellowstone counties. As a
result, a High Wind Watch is in effect Wednesday.

Lows overnight will be in the mid 40s to mid 50s. Temperatures
Wednesday will be cooler than today, with highs generally in the
60s. Archer

Thursday through Monday...

Upper low will weaken and depart quickly to the northeast
Thursday. Some light showers may linger in the morning across
southeast Montana, but otherwise this will be a dry day w/ breezy
W-NW gradually diminishing. There may be enough diurnal
instability for some late day showers over the Beartooth-
Absarokas.

Friday through Monday will be characterized by W-NW flow and what
looks to be a series of fast-moving Pacific shortwaves. There
remains plenty of uncertainty regarding the timing and strength of
these waves, and a wide spread of QPF is shown in the ensembles,
along with a fair spread in temperatures. Until this can be
worked out, a forecast of slight (20%) pops and near to slightly
cooler than normal temps will suffice for this period of time. If
there is a sharper wave it would be cold enough to produce some
high elevation snow...so something to think about if you have
outdoor plans in the mountains this weekend. Temperatures thru
the extended period look to range from the mid 60s to mid 70s, for
now, with Friday night seeing lows drop into the upper 30s to low
40s.

JKL/Vertz

&&

.AVIATION...

Widespread showers and increasing west winds will impact the
region through Thursday. Expect areas of MVFR at lower elevations,
while the Beartooth/Absaroka and Crazy mountains will be mostly
obscured. Highest gusts will be along the western foothills and
also extend eastward to KBIL tomorrow, reaching up to 50 knots.

JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Wed     Thu     Fri     Sat     Sun     Mon     Tue
-----------------------------------------------------------
BIL 053/062 053/074 050/075 047/064 045/069 047/068 046/068
    79/T    71/B    02/W    31/B    12/W    23/W    21/B
LVM 045/060 044/071 043/071 039/065 038/069 041/066 040/068
    99/W    61/B    12/W    22/W    12/W    23/W    21/B
HDN 050/062 051/074 047/075 044/067 042/070 044/068 043/067
    69/T    81/B    02/W    31/B    12/W    22/W    31/B
MLS 054/065 055/071 049/073 045/062 044/066 045/065 045/066
    67/T    81/N    11/U    21/B    22/W    22/W    21/B
4BQ 051/065 054/071 048/076 044/064 044/069 046/067 045/065
    65/W    61/B    00/U    31/U    22/W    22/W    21/B
BHK 051/066 051/071 046/077 042/064 040/068 042/067 042/068
    86/T    51/N    01/U    21/B    22/W    22/W    21/B
SHR 046/070 049/075 044/078 042/067 039/071 039/069 040/067
    25/W    51/U    02/W    32/W    22/W    23/W    32/W

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...High Wind Watch in effect from 6 AM MDT Wednesday through
      Wednesday evening FOR ZONES 34-42-63-68-141-172-228-235.
     Winter Storm Warning in effect until 6 PM MDT Wednesday FOR
      ZONE 67.
WY...None.

&&

$$
weather.gov/billings