742
FXUS65 KBYZ 040939
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
339 AM MDT Sat May 4 2024

.DISCUSSION...

Today through Sunday night...

The short term will start out pretty quiet as a shortwave ridge
moves into the region bringing warm temperatures and mostly clear
skies to the region. Max temperatures will be in the 60s F for
most. Today will be breezy for some today as southerly winds
funnel through the Bighorn Basin leading to elevated winds gusting
into the 20s mph from Carbon County up to Wheatland County. This
corridor has a 20-40% chance of seeing a wind gust over 30mph. Toward
the evening and overnight the strong winds will shift to
locations north and east of Billings. Winds will also shift from
being more southerly to more easterly in the evening as we start
to feel the effects of the 500mb low making its way across western
CONUS. NBM shows a 40-70% chance of getting a gust over 30mph.

Sunday will see winds pick up out of the south ahead of the upper
low as the shortwave ridging moves off to the east. Winds will be
stronger than Saturday, especially for eastern areas as Sheridan,
Fallon, and Carter Counties have 70-90% chance for wind gusts over
40mph. These strong winds will bring significant warm air
advection to the region with temperatures in the 70s and 80s F.
Increased temperatures across the region to NBM 50th percentile as
the NBM deterministic had temperatures below the 25th percentile
in some locations. This also had the effect of lowering RH values
into the high teens to low 20s for Sunday. The combination of hot,
dry, and windy conditions will lead to elevated fire concerns.
This is reflected in fire indices with the hot dry windy index
showing 95th percentile conditions for locations from Sheridan
County up through Rosebud County where RH values are lowest. The
Fosberg index is also showing values in the 50-60 range indicating
fire concerns.

Sunday will see the 500mb low move closer bringing precipitation
chances (30-60%) to southeast Montana. Lowered Pops across the
region Sunday evening as models like the GFS are delivering a dry
slot across much of the area. Saturday night into Monday morning
could see precipitation chances become more widespread although it
is hard to say given model uncertainty. By 12z Monday morning,
ensembles are generally keeping precipitation values below 0.1
inches with the only locations having a >50% chance being west of
Billings.  Torgerson



Monday through Friday...

Models remain in general agreement that a strong negative tilt upper
low will be pushing across Wyoming Monday to settle in a position
over western North Dakota by Tuesday. While details on the exact
track and strength of this weather system remain in question (EC
vs GFS solutions), we remain quite confident based on cluster
analysis that our region will see below normal temps, quite windy
conditions at times and possibly significant precipitation. Lower
elevations will see primarily rain but elevations above 6500 ft
could see substantial wet snowfall.

Monday/Monday night...Model solutions have significant
differences here with some dry slotting over our central zones by
the GFS while the EC is quite wet for our central zones and
basically most of our CWA. Our precipitation forecasts reflect a
strong lean toward the much wetter EC (stronger closed low) due
to a more consistent message among its ensemble members. The
negative tilt trough hits our eastern zones the hardest Monday,
but if the EC solution is most accurate...the central could get
hit hard to (think >0.25 liquid). W/NW winds will increase Monday
into Monday night making for a blustery and uncomfortable
time to be outdoors. High temps will be in the 50s west to lower
60s east.

Tuesday/Tuesday night...Ensembles suggest upper low will generally
settle over western North Dakota. Strong W/NW winds are generated
across the region mainly from the Snowies to Carter County. We
are muting model output of wind speeds at this time a bit, but
there is a signal from the ensembles that gusts to 50 kts are
possible (40-70% probability) in this corridor Tuesday and we will
monitor this for a possible High Wind event across our eastern
plains. Look for bands of precipitation to affect the CWA during
this time. Even worse conditions than Monday for outdoor
activities.

This dynamic low is likely to continue generating strong winds
and bands of precipitation Wednesday/Wed Night and into Thursday
before a secondary lobe of energy swings around the cyclonic flow
and sends the upper low gradually to the southeast by the end of
the work week. Highs will be in the 40s and 50s at midweek before
some warming returns us to the 50s and lower 60s Friday with just
some lingering PoPs of 20-30%.

Impacts: While our high country may see heavy wet snow at times
(30-50% chance of over a foot in the high country), the main
impacts we are concerned about are the harsh combination of wind
and rain for people caught outside and especially for young
livestock. Make sure to stay up to date with the latest forecast
for your location as details emerge. BT


&&

.AVIATION...


The next 24 hours will be dry with minimal cloud cover. The
biggest threat to aviation will be winds that start to pick up
across the region for areas west of Billings in the afternoon
before the strongest winds shift to locations north and east of
Billings in the evening and overnight. These winds will be
southerly/southeasterly and gust to near 25kts. Most impacted
airports will include K1KM and KBHK. Torgerson

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Sun     Mon     Tue     Wed     Thu     Fri
-------------------------------------------------------
BIL 065 039/076 046/057 043/058 042/053 041/056 041/065
    0/U 02/R    66/R    34/R    57/R    77/R    43/R
LVM 063 041/071 040/051 038/052 036/049 036/052 037/062
    0/B 06/T    77/R    35/O    68/O    66/R    22/R
HDN 067 038/081 046/059 042/059 040/052 039/057 040/066
    0/U 02/R    56/R    54/R    68/R    88/R    43/R
MLS 062 040/084 050/062 041/054 038/050 040/059 041/064
    0/U 01/N    48/T    76/R    78/R    77/R    32/R
4BQ 064 041/083 049/061 040/057 039/049 039/056 040/062
    0/U 01/N    57/T    64/R    57/R    77/T    43/R
BHK 059 037/078 047/062 037/052 034/049 036/057 037/061
    0/U 00/N    68/T    86/R    68/R    76/R    32/R
SHR 065 036/082 042/056 037/059 036/052 035/052 036/061
    0/U 01/N    66/R    55/R    57/R    78/R    54/R

&&

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

&&

$$
weather.gov/billings