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000
FXUS65 KBYZ 201948
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
148 PM MDT Sat Apr 20 2024

.DISCUSSION...
Today through Sunday night...

Today will see the region remain in high pressure up against the
Rockies as it slowly slides of to the southeast during the evening
and overnight. This will keep temperatures 5-10 degrees below
average today with most locations in the 40s. Dewpoints will be
low today as well keeping RH values in the 20s despite the cooler
temperatures. It should be a pleasant day today with clear skies
and light winds. Tonight into tomorrow morning will see gusty
winds develop along a narrow strip from the Wyoming border north
to between Billings and Columbus. The Bighorn Canyon and locations
in the downstream drainages such as Fort Smith will also see
these gusty winds. The cause of these winds is lower pressure
forming to the north and higher pressure in the Bighorn basin
combined with southerly 850mb winds being funneled out of the
basin. Many locations in these areas have a >70% chance of seeing
a wind gust over 40mph.

Tomorrow will see a change as an upper low moving along the
Canadian border brings a cold front with precipitation chances
and strong winds. Preceding the cold front will be southerly winds
bringing warm and dry conditions, especially for locations in the
east such as Miles City and Baker. Temperatures will be in the mid
60s to lower 70s with RH values in the teens and low 20s east of
Billings. Winds will be lacking however with gusts into the 20s
not being ideal for fire concerns. Due to this we have held off
on issuing any fire weather products. The cold front will move
through late afternoon into the night tomorrow bringing a 30-60%
chance for precipitation. With winds out of the North/Northwest,
the favored areas for precipitation will be the
Absaroka/Beartooth, Bighorn, Pryor, and the higher terrain areas
of Bighorn county. Precipitation values are expected to remain
light with lower elevation`s having a <20% chance of getting over
a 0.10in of precipitation and higher elevations having a 50%
chance. After the front passes many areas will see winds gust into
the 20s mph, although the stronger winds won`t come until during
the day Monday which will be covered in the long term discussion.
Torgerson



Monday through Saturday...

An active weather pattern is shaping up next week. Be sure to
monitor the forecast over the coming days.

Monday will be post-frontal, windy and cooler as trof moves from
northern MT into the Dakotas. Core of strongest 850mb flow should
be to our north, but there will be plenty of wind to mix into
along and north of a line from Forsyth to Ekalaka during the day
on Monday. 40+ mph gusts are likely (60-80% chance) in this area,
and gusts could reach 50 mph (25-35% in Fallon County). Gusts
should be 25-40 mph elsewhere. A few light rain showers could wrap
southward and eke into our northeast, but most of our forecast
area will be dry. Look for temps in the mid 50s to lower 60s, and
RHs from 18-25%. Recent cool temps and light precip, along with
cooler conditions and some cloud cover on Monday, will prevent
this from being a more concerning fire weather day.

Building upper ridge will bring the quietest weather of the week
Monday night into Wednesday. Temps will respond accordingly, with
highs getting to the lower 60s Tuesday then low-mid 70s Wednesday.
By Wednesday afternoon we could see some showers over our west, in
response to the flow backing to the SW and allowing for weak
shortwave energy from a Pacific coast trof.

Better chances of showers (and potentially a few t-storms) begin
Thursday as we undergo more significant height falls in response
to trof to our west, and pwats increase to above normal levels
(courtesy of return flow up thru the plains). Thursday will also
mark the beginning of the next cooling trend, with highs ranging
from the mid 60s to lower 70s.

The combination of an amplified trof over the western CONUS and
elevated pwats will yield a high chance of showers and cooler
temps Friday and Saturday. At the very least, consider this a
heads up if you have outdoor plans at the end of the week and next
weekend. That said, there is potential for a significant
precipitation event depending on the evolution of the western
CONUS trof. An organized low could produce an extended period
diffluence and upslope winds (i.e. WET), while a splitting trof
would be less organized and much drier. There is definitely a lot
of spread amongst the ensembles, but it should be noted that
today`s 12z operational EC and many of its ensembles trended
toward the wet GFS. If significant precip does materialize, there
is confidence for mid level temps to cool sufficiently to yield
snowfall at the higher elevations (rather than a more problematic
rain-on-snow scenario). Confidence in all of this is low at this
time, so please stay tuned.

A couple way-too-early probabilities for next Friday to Sunday:
1" of precip:  35% over mtns, 10-20% near fthls, 5-10% lower elevs
12" of snow over mountains:  25% over the Beartooth/Absarokas

JKL

&&

.AVIATION...


VFR conditions are expected today with clear skies and light
winds. Tomorrow afternoon will see some clouds make their way into
the region as a cold front moves through. Winds will pick up
tomorrow as well possibly gusting into the 20s kts for KLVM,
K1KM, KBHK, and K6SO. Torgerson


&&

.PRELIMINARY POINT TEMP/POPS...

    Sun     Mon     Tue     Wed     Thu     Fri     Sat
-----------------------------------------------------------
BIL 028/068 037/060 034/062 038/074 047/068 045/063 043/059
    01/B    50/N    00/U    01/B    34/T    34/W    35/W
LVM 028/066 030/057 028/062 037/071 043/064 041/057 039/055
    02/B    20/N    00/B    03/W    45/T    45/W    46/W
HDN 026/071 036/061 033/065 037/076 046/071 044/066 041/062
    01/B    60/N    00/U    01/U    34/T    44/W    45/W
MLS 026/068 038/059 036/059 038/072 048/071 045/064 041/062
    00/U    30/N    00/U    00/U    22/W    32/W    23/W
4BQ 026/069 039/058 036/060 037/074 048/071 045/063 041/062
    00/U    20/N    00/U    00/U    23/W    33/W    24/W
BHK 023/065 036/056 033/057 034/069 043/068 041/058 036/058
    00/U    20/N    00/B    00/B    23/W    33/W    23/W
SHR 022/067 034/058 031/061 035/073 043/067 041/060 038/059
    00/B    41/N    00/U    01/B    35/T    55/W    46/W

&&

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

&&

$$
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