887
FXUS65 KBYZ 010337
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
937 PM MDT Tue Apr 30 2024

.UPDATE...
Just some minor tweaks to POPs this evening. Differential
vorticity in the upper cyclonic flow continues to generate some
light showers (mtn/fthl snow) over the western third of our CWA
(mainly west/southwest of Billings), and this should continue to
be the case through the night. Do not expect much more than a few
hundreths of liquid at the lower elevations. BT


&&

.DISCUSSION...

Rest of Today through Thursday Night...

The breezy conditions ongoing across the region will subside
through the evening hours today. Outside of the wind, isolated to
scattered showers have developed over the Beartooth/Absaroka
mountains and foothills. This activity will continue through the
evening hours before decreasing overnight. Billings could see a
light shower with the activity this evening, but the chance
remains low at 15 percent. While Billings would see rain, the
foothills could see light snow as wet bulb temperatures remain
near freezing. Any snow that falls does not look to be impactful.

Unsettled weather will continue Wednesday and Thursday across the
region with the upper low influence remaining over the region.
Wednesday will see a 20-70% chance of precipitation, and Thursday
will see a 40-80% chance of precipitation. The best chances each
day reside over the mountains where a couple inches of snow is
expected (70-80% chance of at least 3 inches / 20-30% chance of at
least 8 inches). Over the lower elevations south and west of
Billings, the cooler temperatures with drier air near the surface
will allow for a rain/snow mix Wednesday through Thursday. While
an inch or two of snow on grassy surfaces is possible along the
immediate foothills (40-70% chance), snow impacts will be little
to none. Liquid precipitation totals over the rest of the lower
elevations Wednesday through Thursday are hard to pin down given
the spotty nature of this activity, but chances for a total of
0.25 inches or more are low outside of the mountains and
foothills. Locally higher amounts are possible under stronger
cells though.

On that note, there is enough weak instability for a mention of
thunder west of Billings and over the mountains Wednesday and
mainly east of Billings Thursday. Any activity that gets going
will be weak.

Breezy conditions will prevail Wednesday and Thursday with 15-30
mph gusts Wednesday, strongest over the western foothills, and
20-35 mph gusts Thursday. Temperatures will remain cooler than
normal as well, with highs in the upper 40s and 50s both days.
Arends


Friday through Tuesday...

On Friday, an unstable northwesterly upper flow pattern will be
over the Northern Rockies. This pattern will facilitate additional
rounds of scattered showers over the area but moisture will be
limited (indicated by negative precipitable water anomaly values)
so precipitation amounts will also be low, generally a few 0.01"
or less. The probability of precipitation (PoP) is 20-70%,
greatest in he mountains. Snow levels will be 4000-4300 feet
Friday morning, so a light accumulation of snow, one inch or less,
is possible mainly in the Red Lodge foothills and in the
mountains. The chance of Red Lodge receiving at least one inch of
snow is about 25%.

Friday night into Saturday, upper air shortwave ridging will move
into the region and cause dry weather. In addition, weak surface
high pressure will move southeastward from Canada into the
northern Plains and contribute to low-level winds turning
southeasterly. This low-level southeasterly flow will contribute
to warming on Saturday.

Saturday night into Monday, models generally agree on an upper
trough/low moving east/northeastward somewhere in our region.
Models differ, though, on the track of this system, with some
taking a more northern track that would give our area less
precipitation and more wind, and others taking a more southern
track that would give our area more precipitation and less wind.
Accordingly, NBM shows increasing PoP values from west to east
Saturday night into Sunday night, with PoPs reaching 30-60% Sunday
night and again on Monday, greatest in the mountains. NBM shows
that the probability of reaching at least 0.25 inches of
precipitation from this system ranges from about 25% in
southeastern Carbon County to near 60% in the Bighorn Mountains
and over 60% in the Crazy and Beartooth/Absaroka Mountains. So,
much of the area does have at least a 25% chance of receiving at
least 0.25 inches precipitation. Snow should be confined to the
mountains above 6000 feet.

Monday night into Tuesday, models show large-scale upper air
trough over western North America, but differ on the smaller-scale
details. Some model solutions show a period of dry weather during
this time from shortwave ridging. Others show more disturbances
moving through with additional periods of showers. In accord with
these solutions, NBM has a 20-40% chance of showers Monday night,
then a 20-60% chance of showers on Tuesday, greatest in the
mountains. Precipitation in the mountains above 5500 feet will
fall as snow.

High temperatures will generally be in the 50s Friday, then 60s to
lower 70s Saturday, 60s to lower 80s Sunday, and 50s-60s Monday
and Tuesday. Saturday through Tuesday, the warmest air will be in
southeast MT. RMS

&&

.AVIATION...


VFR will prevail during the TAF period. Look for westerly wind
gusts of 25-35kts across lower elevations, affecting all TAF
sites this afternoon. Winds will decrease by evening. In
addition, a weak disturbance from the west will bring scattered
rain/snow showers to the area, first to areas west of KMLS and
K00F late this afternoon-tonight, then to much of the area on
Wednesday. Mountains will be frequently obscured in snow showers.
JKL/RMS

&&

.PRELIMINARY POINT TEMP/POPS...

    Wed     Thu     Fri     Sat     Sun     Mon     Tue
-----------------------------------------------------------
BIL 035/053 035/053 033/057 034/067 045/073 046/066 043/066
    13/O    26/O    33/W    00/B    13/W    44/W    23/W
LVM 030/048 030/051 029/055 031/064 041/065 039/059 037/061
    42/S    36/T    33/W    01/B    25/W    44/W    24/W
HDN 033/055 033/055 031/057 031/071 043/077 046/069 042/068
    13/R    47/R    33/W    10/U    12/W    44/W    32/W
MLS 034/055 034/053 034/054 032/066 044/079 048/068 044/066
    02/R    35/R    22/W    10/U    01/B    34/W    32/W
4BQ 033/057 034/054 032/054 032/070 045/080 048/068 043/066
    02/R    44/T    12/W    10/U    01/B    34/W    32/W
BHK 029/055 031/054 031/051 029/064 040/073 044/066 039/063
    02/R    46/T    23/W    11/U    02/W    45/W    32/W
SHR 029/053 028/052 028/053 029/068 041/076 042/066 038/064
    16/T    56/O    35/W    10/U    02/W    44/W    22/W

&&

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

&&

$$
weather.gov/billings