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FXUS65 KBYZ 010818
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
218 AM MDT Sat Jun 1 2024

.DISCUSSION...
Today through Sunday...

Satellite imagery shows dry NW flow behind a departing wave to our
northeast. Flat shortwave ridge is building from the west, but
further upstream there is weak energy moving into the PacNW and
off the coast. These upstream waves along with a gradual increase
in pwats (to near 0.75") will bring us modest chances (20-40%) of
showers and weak thunderstorms over the weekend.

Temps today will warm the mid 70s to around 80F. By late afternoon
we should begin to see weak convection develop in our far west,
per diurnal instability (sbcapes of 250-750 j/kg) along the
foothills. This activity will remain weak but could produce some
erratic wind gusts (maybe up to 35 mph) in the early evening,
mainly W-NW of Billings where the 00Z HREF paints the highest
probabilities. The greatest chance of actual precipitation (0.10"
or less) may turn out to be late tonight into Sunday morning as
secondary wave is expected to bring a bit better forcing...along
with a Pacific cold front. As a result, Sunday will be a bit
cooler (highs low-mid 70s) w/ mixed west winds gusting perhaps
into the 20s. By Sunday afternoon the wave departs into the
Dakotas and subsidence arrives from the west. Will keep low pops
in our far east after 18z, but western pops appear too high in the
NBM given the drying/subsidence/downsloping so have scaled those
back.

One other item to note is the southeasterly low level jet expected
to develop this evening in southeast MT. HREF shows dewpts rising
to near 50F with increasing elevated instability. However,
forecast soundings per various models suggest a healthy mid level
cap in this region, and thus there is a lack of convection in the
high res models. This is nonetheless something to watch.

The recent cooler days have limited mountain snow melt, but
today`s warming should bring some modest diurnal rises through the
weekend. No hydro issues at this time.

Have a good weekend, folks.

JKL

Monday Evening through Saturday...

Model ensembles depict an upper trough digging into the Northern
Rockies Monday night through Tuesday morning, with a sfc cold
front sweeping across Montana. There is disagreement among the
deterministic models though, especially with the extent of
precipitation and the timing of the frontal passage. The latest
NBM probability for >0.25" of QPF through Tuesday morning is
10-25% for most of the forecast area outside of the mountains and
foothills. The foothills currently have a 30-50% probability of
0.25" of QPF and a 50-70% probability in the mountains. As for
the overall chance for precip, the latest forecast has almost the
entire area seeing a 60-80% in the Monday night thru Tuesday
morning timeframe. The chance for showers will diminish from west
to east, Tuesday morning.

In the wake of the frontal passage, increased winds and breezy
conditions are anticipated. Current guidance has winds in the
20-30 mph with gusts in the 30s-40s mph. The highest wind gusts
are expected to be in the western mtns and foothills.

An upper ridge begins building into the Northwest Tuesday night.
Ensembles show this ridge persisting through the extended forecast
period, bringing warm and dry conditions. High temperatures in the
low to mid 70s on Tuesday, 70s to low 80s on Wednesday, and low to
mid 80s Thursday thru Saturday.

Matos

&&

.AVIATION...

VFR will prevail today under high pressure aloft. A weak Pacific
disturbance is expected to bring scattered showers and a few weak
thunderstorms from west to east beginning around 22z in the west
(i.e. KLVM to KHWQ) and continuing eastward through tonight.
Erratic wind gusts (30 kts or less) are possible with this
activity in the early evening, otherwise VFR should prevail
through tonight.

TS POTENTIAL TIMES TODAY:
KLVM: 22-04Z

JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Sun     Mon     Tue     Wed     Thu     Fri
-------------------------------------------------------
BIL 078 052/074 055/078 050/074 053/081 053/084 056/085
    1/U 32/W    02/W    71/N    00/U    00/U    11/U
LVM 078 048/074 052/071 045/071 052/081 051/084 054/085
    2/B 33/T    17/T    71/N    00/N    01/U    11/B
HDN 080 050/076 052/082 050/076 051/082 050/086 054/087
    0/U 22/W    01/E    81/B    00/U    00/U    10/U
MLS 078 053/076 052/082 052/073 053/078 049/083 053/085
    0/U 32/T    01/B    81/N    10/N    00/U    10/U
4BQ 079 052/075 051/083 051/073 053/077 051/083 055/085
    0/U 22/W    01/B    71/B    00/U    00/U    10/U
BHK 078 051/076 050/082 049/070 049/076 047/079 049/080
    0/U 33/T    02/T    71/N    10/N    00/U    00/U
SHR 080 048/075 049/081 047/074 049/080 049/084 053/085
    0/U 12/T    01/B    72/W    00/U    00/U    11/U

&&

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

&&

$$
weather.gov/billings