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000
FXUS65 KBYZ 221531
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
931 AM MDT Mon Apr 22 2024

.UPDATE...
Light precip has exited to our east and we are in the dry slot
associated with upper low to our north. Winds are increasing and
we are already seeing gusts over 40 mph at Big Timber and Rock
Springs. When all is said and done, strongest gusts today (35-45
mph, locally near 50 mph) will be in an area north and east of
Hysham and in particular the far northeast corner of our forecast
area. Pwats are analyzed to be 0.25" or less this morning and this
will translate to afternoon humidity mostly 14-19% once we mix
(which will be soon). Already seeing dew points in the teens most
locations and could see single digits a bit later today. Forecast
is in good shape, with a focus on the elevated grass fire risk in
our northeast. Have increased winds and lowered dew points/RHs in
spots. High temps will be upper 50s to lower 60s most places. JKL

&&

.DISCUSSION...
Today through Tuesday night...

A cold front has pushed through the area. This, combined with
lowering heights as a deepening trough slides across southern
Canada and a weak shortwave cutting across southern Montana, was
producing scattered showers east of Billings. These showers will
exit the area by 6 am, so will not include in the morning
forecast. The main weather maker today will be the upper low over
southern Canada mentioned above.

The upper low will drop into north central North Dakota this
afternoon. A tight surface pressure gradient and 850mb winds
25-35kts will produce wind gusts 30-45mph (strongest over Custer
and Fallon counties). Baker has a 75% chance of gusts exceeding
40mph, with Miles City at 40%. That chance at Baker goes down to
40% when looking at the chance of exceeding 45mph. Billings has a
35% chance of gusts exceeding 35mph, but only a 5% chance of
exceeding 40mph. Temperatures will be cooler today but seasonal,
with highs in the upper 50s to lower 60s. These cooler
temperatures will help to somewhat limit fire weather concerns.
That being said, green up over eastern zones, although
progressing, has been slower than western and central zones, with
less precipitation over the past two weeks. Will issue a Rangeland
Fire Danger Statement for Rosebud (mainly for the northern part
of the county), Custer, Fallon and Carter counties today.

Winds will die down this evening but clouds will increase over
northeast zones, with ascent approaching around the upper low to
the northeast. Models do produce light showers that approach
Fallon county late evening and overnight tonight. Will keep
showers out for now (lined up with what NBM provides) but will
have to keep a close eye on this as the time gets closer. Tuesday
will be less windy as the surface pressure gradient relaxes.
Models bring energy across through the day, but mid level capping
should prevent cumulus from getting deep and would expect flat mid
level clouds with little precipitation. Temperatures will be very
similar to today with highs in the upper 50s to lower 60s. Warm
up will start on Wednesday. TWH

Wednesday through Monday...

An active weather pattern is shaping up for the second half of
this week into the weekend. Be sure to monitor the forecast over
the coming days.

Wednesday will be warm and dry as temperatures warm into the 70s
under a flat upper ridge. Luckily, winds look to be light outside
of a few 20-25 mph gusts along the western foothills, so fire
conditions are not a great concern. By Wednesday evening and
night, flow aloft will begin to back out of the SW as the upper
ridge axis slides east. This will open the door to Pacific energy
and moisture which will introduce the potential for showers across
the west late Wednesday into early Thursday morning (15-50%
chance, highest over the mountains). This will mark the beginning
of a transition period to the more active weather pattern.

Thursday will still be warm, especially in eastern MT, as
temperatures warm into the 60s to lower 70s. Lowering heights
associated with a deepening western CONUS trough will bring
increased precipitation chances to much of the region, mainly
during the afternoon (15-90% chance, highest over the mountains
and lowest over Fallon, Custer, and Northern Rosebud Counties). A
few weak thunderstorms are also possible Thursday in far
southeastern MT and along the Beartooth/Absaroka mountains and
foothills, but chances remain low. This is the point in the
forecast where the uncertainty increases.

Friday through Sunday feature periods of increased precipitation
chances (overall 30-90% chance, highest over the mountains and
lowest over Fallon, Custer, and Northern Rosebud Counties once
again). With this, how the upper level flow develops plays a
critical role in the extent of precipitation across the region.
The latest ensemble runs of the GFS and ECMWF have backed off on
precipitation over southeastern MT, but have focused in on the
heaviest precipitation falling Friday through Saturday over the
western and central mountains and foothills. Over the lower
elevations, precipitation type should be all rain, especially
during the day. Temperatures will be cooler Friday through Sunday,
but still near seasonal with highs in the 50s to lower 60s. If
the pattern does materialize in favor of the heavier
precipitation, it still looks like there will be enough cold air
aloft for all snow in the higher elevations.

Monday looks to be warmer and drier, but a lot of uncertainty
remains on how the upper level flow will respond after this
weekend. Arends

&&

.AVIATION...

Expect widespread VFR and brisk W-NW winds across the region
today. Gusts will reach 25-40 knots, strongest along the western
foothills and from KMLS to KBHK. Winds will diminish this evening.
VFR will prevail thru tonight. JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Tue     Wed     Thu     Fri     Sat     Sun
-------------------------------------------------------
BIL 060 034/061 037/075 047/069 048/058 043/056 040/060
    0/N 00/U    01/U    24/R    46/R    47/R    44/R
LVM 057 029/059 036/071 044/066 041/054 038/052 035/057
    0/N 00/B    01/U    37/T    58/R    67/R    45/R
HDN 061 032/064 035/076 045/072 046/062 043/059 039/062
    0/N 00/U    00/U    13/R    45/R    46/R    44/R
MLS 060 034/061 038/073 046/072 046/067 043/059 039/061
    0/N 00/U    00/U    11/B    12/R    24/R    32/R
4BQ 059 035/061 038/074 047/073 046/066 043/057 039/061
    0/N 00/U    00/U    01/B    33/R    34/R    43/R
BHK 058 032/059 035/071 044/072 043/065 038/057 036/056
    0/N 00/B    00/B    02/R    22/R    24/R    33/R
SHR 059 030/061 033/073 042/068 043/059 038/055 037/057
    0/N 00/B    00/U    14/T    66/R    57/R    54/R

&&

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

&&

$$
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