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000
FXUS65 KBYZ 190737
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
137 AM MDT Fri Apr 19 2024

.DISCUSSION...
Today through Saturday night...

Mesoanalysis showed cyclonic flow over the region with numerous
waves in the flow. It was also unstable over much of the area with
mid-level lapse rates ranging from 6 to 8 deg C/km. Models were
not handling the QPF over NE MT well, and shortwave energy will
likely drive isolated to scattered snow showers into NE portions
of the area including KMLS and KBHK by 12Z. Also other waves will
produce isolated to scattered snow showers in the mountains. GFS
layer RH field had a decent handle on location of expected QPF, so
updated PoPs through 12Z, and used the GFS to make rest of PoP
forecast. For this morning, had 20-30% PoPs over areas N and E of
KBIL as well as over the mountains. Kept similar mountain PoPs
this afternoon, but airmass will be drying out E of KBIL, so
decreased PoPs from W to E through 00Z Saturday. Area will be
under cold advection and good mixing again today, resulting in
highs in the 30s to mid 40s and breezy conditions E and S of KBIL.
Went with NBM 90th percentile for wind gusts. Will continue to
highlight the FWF with gusty winds.

Cyclonic flow persists over the area tonight, but airmass will be
drying out. Kept 20% evening PoPs over the mountains. It will be a
chilly night with lows in the teens and 20s. Winds will quickly
diminish early this evening. Shortwave ridging will move across
the forecast area Saturday and Sat. night with dry weather. It
will be warmer on Sat. with temps in the upper 40s to lower 50s
with much less wind. Low temps Sat. night will be in the 20s.
Arthur

Sunday through Thursday...

Sunday will be mild ahead of an upper low moving across southern
Canada. High temperatures will be in the mid 60s to lower 70s,
aided by mixed west to southwest winds. The upper low will drive a
cold front through late Sunday afternoon and evening, turning
winds to the northwest and increasing gusts to 30-40mph, as the
front moves through. The cold front will tap into increasing mid
level moisture for an increasing chance (30-50%) of showers along
and behind the boundary Sunday afternoon and night. The mountains
will have higher chances of precipitation (snowfall) at 60-80%.
Temperatures look warm enough that all lower elevations will
receive rainfall, with snow over the mountains (1-4 inches).

The upper low over southern Canada will drop southeast across
northeast Montana and into western North Dakota on Monday. this
will bring cooler air to the area (especially Monday night over
the east), along with another shot of showers (20-40% chance).
Northwest winds will gust Monday afternoon with 850mb winds
30-40kts (strongest east). These winds will be limited to a
certain degree by ascent, with the wave dropping down, but NBM was
still projecting gusts of 35-45mph with a 40-70% chance of seeing
gusts above 35 mph over central and eastern zones. High
temperatures will be held to the mid to upper 50s, and with the
gusty winds, will feel colder than that.

Tuesday will start a warming trend that will continue into
Thursday as ridging builds in. Highs will be in the lower to mid
60s on Tuesday, with upper 60s to mid 70s Wednesday and Thursday.
The chance of showers will increase on Thursday as the ridge
breaks down and southwest mid level flow brings some moisture in,
along with shortwave energy. Some cape develops on Thursday as
dewpoints creep back into the lower 40s. This may lead to a
thunderstorm Thursday afternoon and evening over southern
locations. TWH
&&

.AVIATION...

An area of mainly mid level clouds will be over western and
central locations of southern Montana and northern Wyoming today.
An isolated rain/snow shower can not be ruled out this morning
into early afternoon over these locations, but this will be very
few and far between. The better chance of showers will be over
southeast Montana (impacting KMLS). Some of the precipitation may
produce local MVFR conditions, but VFR is still expected to
prevail. Mountains will be obscured at times in snow showers.
Winds will be breezy with gusts of 20-30 knots east of KBIL. TWH


&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Sat     Sun     Mon     Tue     Wed     Thu
-------------------------------------------------------
BIL 042 024/050 029/067 038/058 034/063 039/073 046/071
    1/B 00/U    02/R    52/R    00/U    01/B    25/R
LVM 041 020/050 030/065 031/055 030/062 037/070 042/066
    1/U 00/U    02/R    31/U    00/U    02/R    35/R
HDN 043 021/053 026/070 037/060 033/066 038/076 044/074
    1/B 00/U    01/B    52/R    10/U    01/B    24/R
MLS 039 023/048 026/068 038/056 034/060 039/072 045/073
    3/J 10/U    00/B    43/R    10/B    00/B    12/R
4BQ 039 020/048 027/071 039/058 035/062 039/073 046/073
    2/J 00/U    00/U    32/R    10/B    00/U    12/R
BHK 036 018/047 024/065 036/055 032/056 034/068 041/070
    3/J 10/U    00/U    43/R    11/B    00/B    12/R
SHR 041 016/049 024/068 033/055 031/062 035/071 041/071
    1/B 10/U    00/B    43/R    10/U    01/B    24/R

&&

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

&&

$$
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