868
FXUS65 KBYZ 290305
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
905 PM MDT Tue May 28 2024

.UPDATE...

Current forecast in good shape for tonight, no changes
anticipated. Low level jet over eastern half of the forecast area
will keep winds stirred up overnight resulting in warm overnight
temperatures in the 50s and maybe a few lower 60s in the higher
hills east of Hardin. Will continue with a 20 percent chance for
a shower or thunderstorm along the western mountains and foothills
tonight. Gusty winds will be the main impact from any
thunderstorms that do make it over the divide, but most of this
activity should stay west of the forecast area tonight.

Made some adjustments earlier to the forecast for Wed/Wed night
to give a better idea of location/timing of storms that could
generate stronger sub severe wind gusts and hail. Continue to see
hints in the HREF and in the NCAR severe probabilities of some
longer helicity tracks in areas outside the Marginal/Slight Risk
areas, as far west as the Billings area for tomorrow
afternoon/evening. Conveyed this to SPC for their consideration of
pulling the Marginal Risk further west with the 06z Outlook.
Strong wind gusts continue to be the main threat for tomorrows
convection, with locally heavy rain the secondary threat. Small
hail can be expected with just about any storm tomorrow with
freezing levels dropping through the day. Chambers

&&

.DISCUSSION...

Through Wednesday night...

This evening through overnight, isolated showers and
thunderstorms are expected west of Big Timber. Southerly winds
over the region will increase moisture overnight into Wednesday,
raising PWATs to 0.75 to 1 inch.

Late Wednesday morning, the chance of showers and thunderstorms
will increase and spread east, with a 50-60% chance of precip and
a 35-45% chance of thunderstorms west of Billings by midday. By
Wednesday evening, the chance of precip increases to 70-90% across
the forecast area. The chance of thunderstorms increases to
50-60% over Fallon and Carter counties, and a 40-50% chance over
the rest of the area.

The SPC has issued a Slight Risk of severe thunderstorms for
Wednesday for Fallon and Carter counties, where CAPE values are
expected to be highest. However, stronger shear is expected over
Billings to Sheridan, so despite lower CAPE values, a severe
thunderstorm can`t be completely ruled out in this area. The main
threat with any storms is high winds. Small hail is also possible,
and any storms that develop a longer track may produce some large
hail. Additionally, the WPC has issued a marginal risk for
Excessive Rainfall across the forecast area due to the locally
heavy rainfall possible with thunderstorms.

Late Wednesday evening through overnight, showers and
thunderstorms will decrease. Snow levels are expected to drop to
around 6000 ft Wednesday night, so lingering showers will bring a
40% chance of at least 3 inches of snow over the
Beartooth/Absarokas. Archer


Thursday through Tuesday...

In the wake of a cold front, Thursday will bring cooler
temperatures, breezy west to northwest winds and mainly dry
conditions to the area. Probabilities for wind gusts of 40 mph or
greater are currently 30-50% from Big Timber north through
Harlowton, and less than 15% for other locations. Unsettled
weather can be expected into early next week as multiple
shortwaves are progged to move through the region at times
bringing chances for showers/thunderstorms. At this time, the day
with the greatest precipitation potential is Sunday (20-60%
chance, greatest along the western foothills/mountains). Ensembles
point towards warmer and drier conditions heading into midweek as
high pressure builds aloft.

High temperatures are currently forecast to range from the upper
50s to 60s on Thursday, warming into the 70s for the weekend.
Widespread 70s and 80s are forecast for by Tuesday. STP
&&

.AVIATION...

Clouds will gradually move in from the west this evening into
Wednesday. With this, isolated showers and thunderstorms are
possible near KLVM late this evening through overnight. Areas of
low- level wind shear are also possible around KSHR, KMLS, and
KBHK overnight into early Wednesday morning with strong winds
aloft, especially where surface winds remain lighter. Late Wednesday
morning, showers and thunderstorms will increase and spread east,
potentially impacting all TAF sites. East of KBIL, some storms
may be severe. Expect the strongest storms to contain erratic
winds, hail, and heavy rain. Conditions may decrease to MVFR/IFR
under heavy rain.

TS POTENTIAL TIMES WEDNESDAY:
KBIL: 20-04Z
KLVM: 18-03Z
KMLS: 22-05Z
KSHR: 20-04Z

Arends/Archer
&&

.PRELIMINARY POINT TEMP/POPS...

    Wed     Thu     Fri     Sat     Sun     Mon     Tue
-----------------------------------------------------------
BIL 053/075 045/064 044/069 046/077 052/074 053/080 056/079
    09/T    81/N    00/B    00/B    24/T    21/B    11/B
LVM 050/067 037/061 038/069 042/075 048/071 049/076 051/077
    2+/T    61/N    00/U    01/B    35/T    22/T    11/N
HDN 052/078 045/065 042/071 044/079 050/076 051/082 055/082
    07/T    91/B    01/B    00/B    23/W    21/B    11/B
MLS 055/083 048/064 043/071 044/079 053/077 052/080 056/082
    03/T    81/N    01/B    00/U    12/W    21/B    11/B
4BQ 055/085 048/064 042/071 045/080 053/077 053/082 056/082
    04/T    80/U    11/U    00/U    12/W    21/B    11/B
BHK 050/083 045/062 039/067 041/077 051/077 049/079 053/077
    04/T    80/N    01/B    10/U    13/W    21/B    21/U
SHR 051/080 042/062 040/070 042/079 048/075 049/081 052/081
    08/T    82/W    11/U    00/U    13/T    21/B    11/B

&&

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

&&

$$
weather.gov/billings