514
FXUS65 KBYZ 020941
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
341 AM MDT Thu May 2 2024

.DISCUSSION...

Today through Friday...

Satellite imagery shows an upper low to our north over southern
SK and broad cyclonic flow across the region. Upper air analysis
shows cold air aloft...500mb temps around -30C.

There are several features at play over the next 36 hours. First,
a weak shortwave is departing far southeast MT so light precip in
this area will be exiting soon (before sunrise). Next, to our west
there is a well-defined shortwave along thew WA/OR coast moving
to the southeast. This wave will track thru the northern great
basin and WY today and Friday...south of our forecast area so
impacts will miss us. Third and most importantly is a trowal
wrapping southward thru northern MT (the forcing for ongoing
snowfall in north central MT). We are seeing clouds increase over
Wheatland to Musselshell Counties and in this area light snow will
begin soon (Judith Gap camera remains dry at 08z). All told,
almost the entire cwa is dry at this time, but that will be
changing over the next several hours.

Scattered rain/snow showers will impact our region again today,
with enough shallow instability to produce a few weak t-storms and
almost certainly some graupel where any stronger cells develop.
Showers will move from NW to SE and be of greatest coverage over
our east. As surface high noses in from the NW late today, veering
winds should produce a brief period of upslope enhancement along
our southern foothills in the late afternoon and evening. Wouldn`t
be surprised to see Red Lodge pick up a quick inch of snow during
this time. Temps today will obviously remain chilly with highs in
the mid 40s to mid 50s. Expect breezy NW winds w/ widespread
gusts of 25-35 mph.

Shower activity will diminish this evening but moisture from the
NW will continue to produce a few light showers over north and the
mountains. We remain under the cool/cyclonic NW flow on Friday,
but with temps aloft warming. As a result, shower activity
tomorrow will be more isolated and less robust than today. Do not
see a risk of thunder on Friday. Temps will again be much below
normal (upper 40s to mid 50s). Mixed NW winds will also be lighter
than today, though still somewhat breezy in our east.

JKL

Saturday through Thursday...

.KEY MESSAGES...

- Potential for long duration spring storm Sunday through
  Wednesday
- Strong winds will accompany this system leading to the potential
  for cold rain and strong winds impacting young livestock

Saturday and Sunday will feature upper ridging and the warmest and
driest period of the long term. This will lead to temperatures on
Saturday being in the mid to upper 60s for most before
temperatures increase into the 70s on Sunday. Later in the day
Sunday, an upper low from the Pacific will start to impact the
region. Precipitation chances will spread across the region from
west to east. Strong southerly winds will be present for eastern
portions of the forecast area such as Baker. NBM shows much of the
area having a >60% chance of seeing a wind gust over 30mph on
Sunday.

Sunday night into Monday, ensembles show the low strengthening,
possibly into the 980s mb over the area leading to stronger winds
and increased precipitation chances. Monday will see winds move
from southerly to westerly as the low moves off to the east. NBM
gives most of the region a >50% chance of getting a wind gust of
over 40 mph on Monday. For Tuesday, 700mb winds will be strong
out of the west, potentially over 50kts. This will lead to a
potential downsloping situation for locations west of Billings
putting more uncertainty into precipitation chances. Tuesday will
see wind speeds similar to Monday.

Late Monday through the rest of the period, more uncertainty in
the upper level pattern leads to less confidence in precipitation
chances. The longer the low holds itself together and doesn`t
break down, the more precipitation the region will receive. This
solution is currently favored by 60% of ensemble clusters. Strong
winds will persist on Wednesday on the backside of the low.
Temperatures Monday through Thursday will be in the 50s F. The
combination of prolonged precipitation chances and strong winds
could lead to hazardous conditions for young livestock. Currently
the NBM has a 60-70% chance of <=0.25 inches of precipitation from
early Monday through early Thursday. A few thunderstorms can`t be
ruled out throughout this period.

This will be a long duration event with a lot of uncertainty in
precipitation timing and amounts. As we move closer to the event,
more defined periods of precipitation will likely be identified.
Currently there is higher confidence in the strong winds than
there is in precipitation chances and amounts. Keep an eye on the
forecast as it is likely to change. Torgerson

&&

.AVIATION...

Scattered showers and isolated weak thunderstorms will impact the
region again today in a NW flow aloft. This activity has the
potential to produce local MVFR/IFR and a combination of rain,
snow and graupel. NW winds will gust 20-30kts today but locally
higher gusts (to ~35kts) are possible with any t-storms.
Mountains will be frequently obscured in snow showers. As for the
showers` timing, activity will spread in from NW to SE between
09-18z. Showers will diminish in coverage this evening, though
mountains will continue to be obscured at times in light snow
showers through tonight. JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Fri     Sat     Sun     Mon     Tue     Wed
-------------------------------------------------------
BIL 052 033/054 032/067 045/074 045/058 043/061 041/057
    5/T 22/W    00/B    03/R    56/R    33/R    34/R
LVM 052 029/053 029/064 042/067 040/055 037/054 035/052
    4/W 32/W    00/B    15/T    66/R    34/O    45/O
HDN 054 030/055 029/070 043/080 045/061 041/062 040/058
    6/T 22/W    00/U    03/R    56/R    43/R    44/R
MLS 051 032/051 029/067 045/080 051/064 042/059 041/056
    6/T 43/W    00/U    02/R    46/T    53/R    34/R
4BQ 055 030/053 029/068 046/081 050/063 041/059 040/056
    3/T 32/W    00/U    02/T    46/R    42/R    33/R
BHK 052 028/049 026/064 042/075 049/065 038/056 036/053
    5/T 53/W    00/U    01/N    56/T    54/R    34/R
SHR 054 026/052 027/068 042/078 042/059 038/060 035/055
    3/W 32/W    00/U    03/R    56/R    33/R    44/R

&&

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

&&

$$
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