890
FXUS65 KBYZ 141547
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
947 AM MDT Tue May 14 2024

.UPDATE...

Upper trough was moving into the area today with two main
vorticity maximums. One was over E central WY with showers and a
few thunderstorms circulating around it, and the other was located
from S ID into NW MT. A cold front was progressing SE through the
central part of the forecast area per surface observations and
showers were developing along and behind it. Forecast soundings
had long skinny CAPE and little shear for today into tonight...so
strong storms are not expected. However any storms will produce
gusty winds given steep lapse rates and small hail is not out of
the question with freezing levels in the 4000-6000 ft range over
western and central areas. Adjusted PoPs through tonight based on
current radar trends and latest HRRR/CoNSShort/deterministic
models which lowered PoPs in the E and reduced them to likely
central, W and S. Other forecast parameters were in good shape.
Arthur

&&

.DISCUSSION...

Through Wednesday Night...

There are currently some showers moving through the region. These
will persist through the overnight before mostly coming to an end
this morning. Around 18Z today we will see precipitation chances
return to the region as a shortwave trough moves into the region.
With the surface low pressure system to the east, winds will be
from the northwest pushing showers and thunderstorms from
northwest to southeast. Instability will be limited today with
HREF soundings showing surface based CAPE values topping out in
the 500-1000J/kg range and mixed layer values remaining below
300J/kg. This will combine with shear values <25kts to create an
environment similar to Monday leading to non-severe showers and
thunderstorms. With winds out of the northwest, the most favorable
locations for precipitation will be locations in the mountains,
foothills, and Bighorn county. These areas have a 60-80% chance of
getting over 0.25 inches of precipitation with other locations in
our western and southern areas having a 30-50% chance. With this
precipitation being more upslope dependent, locations in the east
such as Miles City and Baker only have a ~10% chance. Any snow
from this will generally be above 9,000ft where some of the higher
peaks of the Bighorns and Beartooths have a 60% chance of getting
over 6 inches of snow. Temperatures will be cooler today in the
high 60s to low 70s due to the troughing and northwest winds.

Wednesday morning should be near the end of the scattered showers
and thunderstorms as we start to get upper descent behind the
trough. Models are hinting that a few isolated showers still can`t
be ruled out however. This leads to much of the region having a
30-40% chance of showers Wednesday. Temperatures will be similar
to Tuesday with most locations in the high 60s to low 70s.
Torgerson

Thursday through Monday...

Zonal to northwest flow aloft sets up over the region for Thursday
and Friday, with a couple shortwaves crossing along the US/Canada
border. Energy from the shortwaves and associated cold fronts
looks to bring isolated to scattered showers/thunderstorms
(15-40% chance) and west to northwest winds, breezy at times both
Thursday and Friday. Ensembles and cluster analysis remain in
decent agreement that larger scale troughing will set up over the
region over the weekend into early next week bringing unsettled
conditions with multiple shortwaves crossing the area.

High temperatures look to range from the 70s for Thursday and
Friday, dipping back towards normal over the weekend and Monday,
with highs in the 60s. Low temperatures in the upper 30s and 40s
are forecast most nights, coolest over the western valleys. STP

&&

.AVIATION...

Periods of showers and some embedded thunderstorms can be
expected through this evening as a couple disturbances move
through the region. In general, VFR will prevail, but any heavier
showers/thunderstorms have the potential to produce brief MVFR-
IFR, small hail and erratic wind gusts to ~30kts. Mountains will
be obscured at times through this evening due to snow, mainly
above 9000 ft agl. Arthur/STP

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Wed     Thu     Fri     Sat     Sun     Mon
-------------------------------------------------------
BIL 068 047/069 049/074 050/077 047/067 043/068 045/070
    6/T 54/T    34/W    33/T    34/T    22/W    22/T
LVM 065 043/068 045/074 049/075 043/065 040/066 041/068
    7/T 62/T    13/W    23/W    34/W    23/W    23/T
HDN 068 046/069 048/074 047/079 045/068 042/069 042/072
    6/T 64/T    43/W    33/T    33/T    22/W    22/W
MLS 071 046/069 049/070 048/075 045/065 042/068 044/072
    2/T 22/R    43/W    33/W    32/T    22/W    21/B
4BQ 070 047/067 048/071 047/077 045/067 043/067 044/071
    4/T 32/T    22/T    22/W    32/W    22/W    11/B
BHK 070 041/067 044/069 045/074 043/065 039/066 040/070
    2/W 21/B    24/W    23/W    32/W    22/W    12/W
SHR 066 044/065 043/071 045/078 044/067 039/066 040/069
    7/T 66/T    33/T    32/T    33/T    22/W    22/T

&&

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

&&

$$
weather.gov/billings