737
FXUS65 KBYZ 081223
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
623 AM MDT Wed May 8 2024

.UPDATE...
ALl high wind warnings have expired. The winter weather advisory
for Judith Gap has expired as well.

We are getting some snow mixed in with the rain at Billings
Airport and over surrounding higher hills at this time thanks to
the strength of the dynamics involved with this system.
Accumulations should be minimal in grassy areas. We do expect
this to switch back to all rainfall by mid-morning. BT

&&

.DISCUSSION...

Today through Thursday night...

Satellite imagery showed a drifting upper low over western South
Dakota spinning waves of precipitation into Montana. The system is
very slowly weakening and 850-700 mb winds are slowly decreasing
as expected, though some gusts 50-60 mph are still possible in the
western foothills. The remaining high wind warning is valid until
6 AM and this should work out abut right.

We did replace the high wind warning at Judith Gap with a winter
weather advisory earlier last evening as precip had changed over
to snow and was creating visibility issues. We have also had some
wet snow noted in the higher hills around Billings and Roundup.
Accumulations should be limited as warmer air will be moving in
from the northeast as it wraps around the upper low...with
snow levels lifting about 1000 ft by sunrise. (ranging from 4750
in the SW Mtns to 6600 ft east). So almost all rain on the plains
by mid morning...which is why the winter weather advisory for
Judith Gap only goes to 6 Am this morning.

The high winds will be done by morning, but look for wet and
blustery conditions yet today into tonight as waves of energy and
moisture rotate around the upper low into our region as it slowly
drifts south. Upslope will also be in play on north facing slopes
of the mountains and foothills. The winter storm warnings for the
mountains are still in place until noon Thursday. The heaviest
snowfall is expected today and tonight. The chance of a foot or
more of snow on north facing slopes ranges from 75-95% above 6500
ft...and the chance of over two feet at a whopping 60%!

Precipitation will begin to slowly wind down Thursday as the
upper low opens up and moves into the central plains phasing with
energy in the Great Basin for a double barreled trough.
Precipitation is progged to linger over the southern portions of
our CWA with PoPs ranging from 60% in the foothills to 30% on the
plains by Thursday afternoon, then dwindling to less than 20
percent Thursday evening.

Look for highs today ranging from 40s west to mid 50s east. We
warm up to 50s west to lower 60s east on Thursday.

Hydro Issues...areas over our central and eastern zones have
received 1-3 inches of rainfall (more in some local spots). Some
of the rivers are rising in response and will need to be
monitored. The most notable is the Tongue River at Miles City
which is currently at 6.25 ft and forecast to rise to 8 feet by 6
AM Thursday (flood stage is 10 ft). BT

Friday through Wednesday...

High pressure building into the region looks to bring warmer and
drier conditions into the weekend, with highs in the 70s by
Saturday, lasting into at least Monday. Confidence is high for
temperatures into the 70s, with a greater than 70% chance of
exceeding 70 degrees Saturday through Monday. Uncertainty with the
overall pattern increases early next week as ensembles show
varying solutions, either ridging or shortwaves dropping into the
region from the northwest. Shortwaves would bring cooler and
unsettled conditions with chances for showers and thunderstorms. STP
&&

.AVIATION...

A large storm system will continue to bring periods of rain to the
lower elevations and snow to the mountains and immediate foothills
through the day today. MVFR to IFR conditions can be expected at
times. Mountain obscurations can be expected through the period
due to snow. Gusty west and northwest winds will decrease into
the morning hours, turning more north to northeast for most
locations. STP
&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Thu     Fri     Sat     Sun     Mon     Tue
-------------------------------------------------------
BIL 051 043/059 041/066 044/077 048/078 051/080 052/075
    +/O 85/R    20/U    01/U    01/U    12/T    23/W
LVM 046 038/054 035/064 039/072 043/075 046/075 046/072
    +/O 86/R    10/U    00/U    01/U    12/W    23/W
HDN 054 041/061 040/068 040/077 046/078 048/081 049/076
    9/R 85/R    20/U    00/U    01/U    12/T    33/W
MLS 055 041/063 042/068 044/076 048/078 050/080 051/075
    5/R 42/R    10/U    01/U    01/U    11/U    22/W
4BQ 052 039/060 043/067 042/075 047/077 050/080 051/075
    4/R 34/R    10/U    00/U    01/U    11/U    22/W
BHK 054 038/063 040/067 042/074 045/075 047/078 048/073
    4/R 22/R    10/U    01/U    01/U    01/U    22/W
SHR 048 037/056 037/065 037/072 043/075 045/076 046/074
    8/O 85/R    21/U    00/U    01/U    13/T    34/T

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Winter Storm Warning remains in effect until noon MDT
      Thursday FOR ZONES 67-68-171.
WY...Winter Storm Warning remains in effect until noon MDT
      Thursday FOR ZONE 198.

&&

$$
weather.gov/billings