435
FXUS65 KBYZ 261951
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
151 PM MDT Sun May 26 2024

.DISCUSSION...

Today through Tuesday night...

A 500 mb shortwave trough is moving southeastward over central and
eastern MT this afternoon. The wave is bringing increased winds
aloft to the area. Surface heating is facilitating steep low-
level lapse rates that are allowing the winds to mix down to the
surface. Strongest wind gusts to 35-45 mph this afternoon-early
evening will be in our western foothill locations from Livingston
to Big Timber northward to Harlowton. For much of the rest of the
area, expect wind gusts in the 20-35 mph range.

As the wave passes the area, there is a 20-40% chance of showers
south of Big Timber-Billings-Miles City. Drier air is moving in
with this wave so showers will not be able to drop as much
rainfall as they did yesterday or early this morning.

The wave will exit MT to the east late this evening. In its wake,
any showers and gusty winds will diminish over our area.

A 500 mb ridge will then dominate our weather overnight into
Tuesday night with mainly dry conditions. Warmer air moving in
aloft will contribute to warmer temperatures on Monday and then a
change to low-level southeasterly winds will cause further
warming on Tuesday.

By Tuesday night, the 500 mb ridge will have moved far enough
eastward that areas west of Billings will be under cyclonic
southwesterly flow that will produce a few isolated-scattered
showers and thunderstorms (20-30% chance) in the western
mountains and adjacent foothills.

Low temperatures will generally be in the 30s and 40s tonight then
40s Monday night and 50s Tuesday night. High temperatures will
mainly be in the 60s and 70s Monday and 70s to lower 80s Tuesday.
RMS

Wednesday through Sunday...

Wednesday will see ridging in the area with high 70s and low 80s
across the region. Locations were there is snowmelt concerns will
see tempeatures generally in the 60s with lows Wednesday morning
being in the 40s. These locations are currently above normal in
SWE due to recent late season snowfalls. NOHRSC average modeled
snowpack temperature is showing temperatures near 32F for all but
the highest peaks indicating the snowpack is ripe for melting.
This could lead to a quick snowmelt being exacerbated by 0-10cm
soil moistures above 80th percentiles and even 90th percentiles in
some regions. However, current hydrographs show streams and rivers
that have handled recent heavy snowfall and precipitation without
much issue. The warmup with above normal temperatures also looks
to be brief as a system comes through late Wednesday/early
Thursday lowering temperatures. Taking all of this into
consideration, it is likely that streams and rivers near the
foothills will see rises but major flooding is not expected though
much uncertainty remains. Streams will see the quickest response
with peak river levels usually occuring a couple days after peak
heating. Individuals along waterways should be prepared for high
water levels.

Looking at the WPC Clusters, there is a lot of uncertainty in how
the troughs for next week will evolve with disagreement in
whether they will be slower moving and deeper or more progressive.
It is difficult to discern between the two waves on the clusters
but generally the stronger and deeper the troughing the more
rainfall we can expect. Overall, Wednesday morning through Friday
morning most of the region will see a 40-70% chance for >0.25
inches of precipitation. Wednesday will see some ingredients
necessary for severe weather. GFS soundings are currently showing
CAPE values in excess of 1,500J/kg and 0-6km shear over 50kts.
This combined with an upper level trough and PWAT values of
0.8-1.0 will bring the potential for some severe thunderstorms. Rainfall
for Wednesday through Thursday is not expected to have much
impact on flooding if current precipitation totals continue.
Thursday we will be under upper troughing, although temperatures
will be near normal. Saturday will see a downsloping pattern
return with temperatures in the 70s. Sunday will see temperatures
warm even more with mid 70s to low 80s across the region.
Torgerson

&&

.AVIATION...

Most of the region will continue to see winds gusting into the 20s
and 30s with some 40s for locations in western gap areas until
around 03Z Monday. Midlevel cloud will persist today through this
evening before we get clearing Monday. Torgerson

&&

.PRELIMINARY POINT TEMP/POPS...

    Mon     Tue     Wed     Thu     Fri     Sat     Sun
-----------------------------------------------------------
BIL 044/072 047/080 053/079 048/064 043/068 046/073 048/079
    00/U    00/U    06/T    74/W    23/T    11/U    11/B
LVM 038/071 043/079 050/075 041/059 037/065 040/072 044/077
    00/U    01/U    29/T    75/T    23/T    11/U    11/B
HDN 041/072 043/081 052/081 048/066 041/069 043/074 048/081
    10/U    00/U    04/T    74/W    32/W    11/U    11/B
MLS 046/071 044/078 055/084 050/067 043/069 046/074 048/079
    10/U    00/U    02/T    62/W    32/W    11/U    10/B
4BQ 046/069 045/079 055/086 050/067 043/069 046/072 048/080
    10/U    00/U    02/T    52/W    32/W    11/U    11/U
BHK 042/069 042/075 049/080 049/067 041/068 043/072 045/077
    11/U    00/U    02/T    62/W    32/W    11/U    11/U
SHR 040/069 043/079 051/083 046/064 038/067 041/072 046/079
    20/U    00/U    03/T    64/T    33/T    21/U    11/B

&&

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

&&

$$
weather.gov/billings