000
FXUS65 KBYZ 181954
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
154 PM MDT Thu Apr 18 2024

.DISCUSSION...

Through through Friday night...

Satellite imagery shows an upper low over southern Manitoba with
chilly cyclonic flow extending westward through the northern
Rockies. Surface high near 1040mb is centered up in northern AB
currently, but we will continue to be under the influence of this
fairly cold air mass through the short-term period as the surface
high sags southward. In short, expect much below normal temps to
continue with lows tonight and Friday night in the upper teens to
mid 20s, and highs Friday mostly mid 30s to lower 40s. In fact,
the daily record low of 19F at Miles City on the 20th will be
challenged.

Brisk NW winds have somewhat overachieved today with gusts near 50
mph in an area from northern Rosebud thru Custer and Fallon
Counties. These well-mixed winds will continue thru the afternoon
then drop off quickly by sunset. Though winds tonight will become
largely decoupled in our east, gradients will support breezy NW
winds again tomorrow...beginning fairly early in the day...though
not as strong as today at 25-35 mph.

We are starting to see light snow showers develop over our west,
as expected, and there is some banding noted downwind of the
Crazy, Little Belt and Snowy Mountains. Boundary layer is quite
dry (dewpts in the single digits to lower teens) so there will
likely be a lot of virga around, but will keep 10-20 pops going
over the west half of our forecast area through the evening. In
fact, some activity may linger over the western high terrain
overnight per the mid level instability and cyclonic flow. By
Friday morning, a wave dropping thru eastern MT with moistening
shallow instability should be enough for areas of light snow for a
period of time from northern Rosebud County eastward. Otherwise,
look for a few diurnal snow showers once again over the mountains
and near the foothills Friday afternoon and early evening. Surface
high finally settles over eastern MT Friday night bringing
clearing and light winds. As already alluded to, tomorrow night
looks like the potentially coldest night of the current cool
spell.

JKL

Saturday through Thursday...

Saturday will remain cool with temperatures generally in the 40s
to low 50s. The upper troughing and high surface pressure will
gradually move off to the east, being replaced by more zonal
westerly flow. A low pressure system will form to our north in
Alberta which will bring impacts on Sunday. Breezy southerly winds
out in front of the low will build a thermal ridge, bringing
temperatures into the 60s. These winds don`t appear to be
advecting in any moisture so we will have to wait for the wave to
move in to bring the moisture needed for more widespread
precipitation chances. At this time the best chance (70%) for
precipitation will be late Sunday through Sunday night. Models are
hinting at this system having a well defined dry slot leading to
a reduction in precipitation chances before they pick back up
again on Tuesday. Low level lapse rates will be strong in the
7-8C/km range leading to the possibility of some thunder. With low
level moisture and RH values lacking, CAPE will be limited
leading to elevated non- severe convection being most likely.
Overall precipitation with this system is expected to remain light
with most of the area having a <20% chance of getting over 0.25
inches of rain.

The passage of the cold front will bring windy conditions and a
cooldown for Monday and Tuesday morning with highs in the mid to
high 50s and lows in the upper teens to mid 20s. Winds on Monday
will be out of the northwest and gust into the 30s mph for most.
After the passage of the low and upper troughing we move into a
more westerly downsloped flow leading to higher temperatures and
lower RH values. By the time we get to Wednesday and Thursday,
southeast Montana will have a 50-70% chance of seeing high
temperatures greater than 70 degrees. Torgerson

&&

.AVIATION...

Isolated light snow showers/flurries will impact the region late
this afternoon and evening. VFR will prevail, but cannot rule out
local MVFR especially close to the foothills, and the mountains
will be obscured at times. NW winds will be brisk with gusts of
25-40 knots until sunset, greatest east of KBIL. On Friday, areas
of light/snow flurries from KMLS to KBHK may produce MVFR,
especially in the morning. Mountains will be obscured at times in
light showers. Winds tomorrow will once again be breezy with
gusts of 20-30 knots east of KBIL. JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Fri     Sat     Sun     Mon     Tue     Wed     Thu
-----------------------------------------------------------
BIL 025/043 024/050 030/065 039/057 033/062 038/071 045/070
    10/B    00/U    03/R    63/R    00/B    02/R    24/R
LVM 020/041 019/050 030/063 032/054 031/060 036/068 042/067
    11/B    00/U    04/R    42/R    00/B    02/R    24/R
HDN 023/043 020/052 028/068 038/059 033/064 037/073 043/074
    00/B    00/U    01/B    73/R    11/B    01/B    23/R
MLS 023/040 020/048 027/066 040/055 033/059 037/070 044/072
    02/J    00/U    00/B    54/R    10/B    01/B    12/R
4BQ 022/040 020/049 028/068 039/057 033/059 037/071 044/073
    00/B    00/U    00/U    53/R    10/B    01/B    12/R
BHK 020/038 018/046 024/063 036/054 031/055 034/066 039/069
    02/J    00/U    00/U    55/R    11/B    01/B    12/R
SHR 018/040 017/048 024/067 033/055 028/059 034/069 040/070
    11/B    10/U    01/B    53/R    10/U    01/B    24/R

&&

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

&&

$$
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