170
FXUS65 KBYZ 030828
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
228 AM MDT Mon Jun 3 2024

.DISCUSSION...
Today through Tuesday...

A shortwave trough will bring a cold front through the state later
today, bringing an increase in the probability for showers and
some thunderstorms. Widespread coverage for precipitation is
expected with a 50-90% chance for most locations. HiRes soundings
show better instability out west, with SBCAPE values up to 800
J/KG. This is sufficient for some stronger thunderstorms capable
of producing heavy rain and gusty winds. With strong winds in the
low-mid levels of the atmosphere, precipitation accumulations are
not expected to be very high, with a few hundredths of an inch of
QPF for most locations. Higher amounts are possible out west, with
some locations seeing 0.1-0.2". However, locally higher amounts
are possible with stronger storms. Expect high temperatures in
the 70s to low 80s today, with warmer temps being felt east of
Billings. Expect highs in the 70s on Tuesday in the wake of the
cold front.

The cold front is expected to depart the region Tuesday morning,
leaving behind a lot of subsidence and increasing lapse rates in
the 8-9 C/KM range. A strong 700mb jet will also be in place. As a
result of these conditions, a period of very gusty conditions are
anticipated late tonight into Wednesday morning. Much of the area
will see winds in the 20s mph with gusts approaching 50 mph. The
northwestern counties will see the strongest winds, with 30-40 mph
sustained winds and gusts approaching 60 mph. As a result, there
is a High Wind Watch in effect tonight through Wednesday morning
for Judith Gap, Southern Wheatland, Melville Foothills, and
Northern Sweet Grass. The latest NBM run gives a 50-70%
probability for wind gusts of 60 mph or greater in Wheatland
County.

Matos


Tuesday Night through Sunday...

Strong westerly winds will continue Tuesday night thru Wednesday
morning. In fact, there is a secondary (stronger?) 700mb wind
speed max arriving early Wednesday in response to another
shortwave passing to our north. Some model differences exist here,
and the GFS is stronger than the EC (as always), but even the EC
shows 700mb winds up to 55 knots. Given this and persisting steep
low level lapse rates have extended the High Wind Watch along the
western foothills through Wednesday morning. It should also be
noted that strong NW winds will be felt across our eastern plains
on Wednesday...w/ deep mixing and synoptic scale subsidence. If we
see mid level winds of 50 knots that could translate to 50 mph
gusts at the surface over a large area. Something to watch.

Tuesday night through Thursday will be dry as heights build from
the west behind departing trof, and pwats fall to around 0.50".
Look for highs in the 70s Wednesday then upper 70s to mid 80s
Thursday. Winds on Thursday will be much lighter.

Pattern for the end of the week will be characterized by a western
CONUS ridge w/ above normal heights, and a low anomaly to our
north over northern AB/SK. The transition between the two
anomalies has been a source of model disagreement over the past
few days, but confidence is increasing for the ridge being
dominant over our region allowing for a string of warmer than
normal days. Generally speaking we should see highs in the upper
70s and 80s Friday through the weekend...on the order of 10F above
early June normals. Weak upper low near Baja California will
allow for monsoon-ish moisture to wrap northward under the western
CONUS ridge, resulting in at least a low (20%) chance of diurnal
showers and thunderstorms each day...beginning only for the
mountains/foothills initially, but by the weekend the convection
could spread further north (along with elevated pwats). Overall,
the weak flow aloft suggests storms will be non-severe, but of
course could produce erratic wind gusts and chaotic outflow
boundaries. By Monday, there is some consensus for a shortwave of
some kind and a better chance of more organized showers and
thunderstorms across the region.

The upcoming warmer weather will increase high elevation snow melt
and cause rises on rivers and streams. Water levels are currently
in good shape and do not anticipate problems at this time, though
it will be something to watch as we move into our climatological
peak flows season.

JKL
&&

.AVIATION...


VFR conditions and tranquil weather will persist through midday
today. Showers and embedded weak thunderstorms will impact the
region this afternoon through tonight. MVFR is expected in the
shower activity, and mountains will be frequently obscured
beginning in the late afternoon.

Pre-frontal SW winds will gust 25-35 knots along the western
foothills today. By this evening, a Pacific cold front will bring
a shift to gusty W-NW winds. Look for gusts of 30-50 knots along
the western foothills tonight, and 20-35 knot gusts elsewhere to
the east.

TS POTENTIAL TIMES:
KBIL: 22-04Z
KLVM: 21-03Z
KMLS: 00-06Z
KSHR: 22-06Z

JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Tue     Wed     Thu     Fri     Sat     Sun
-------------------------------------------------------
BIL 076 047/074 055/079 050/083 055/084 056/083 057/082
    4/T 70/N    00/N    00/U    01/U    10/U    11/U
LVM 069 041/071 054/078 048/085 053/085 052/082 053/081
    8/T 70/N    10/N    00/U    01/U    11/U    12/T
HDN 081 046/075 053/077 046/083 053/085 054/084 055/083
    2/T 80/N    00/N    00/U    00/U    10/U    11/U
MLS 081 048/074 054/073 047/080 053/085 054/081 054/081
    2/W 80/N    00/N    00/U    00/U    00/U    11/U
4BQ 082 050/072 054/074 047/080 054/085 054/082 055/080
    1/B 70/N    00/N    00/U    00/U    10/U    11/U
BHK 081 047/071 049/072 045/078 049/083 050/078 049/077
    3/T 60/N    00/N    00/U    00/U    00/U    11/U
SHR 079 044/074 049/077 046/083 053/085 054/083 052/081
    1/B 71/U    00/N    00/U    01/U    11/U    21/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...High Wind Watch in effect from late tonight through Tuesday
      evening FOR ZONES 63-141-172-228.
WY...None.

&&

$$
weather.gov/billings