302
FXUS65 KBYZ 100853
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
253 AM MDT Mon Jun 10 2024

.DISCUSSION...
Today through Tuesday Night...

Satellite imagery in the early morning hours showed an upper
trough moving through Idaho while a ridge axis shifts from
eastern Montana into the Dakotas. Radar indicated a cluster of
thunderstorms over far east central Montana being fed by a LLJ
(850 mb jet). Pockets of showers with embedded thunder were
scattered elsewhere over the region.

As the upper trough tracks across Montana today we expect to see
continued areas of showers with some thundershowers also possible.
Models have not handled placement/timing of precipitation very
well...so PoP`s are based on a blend of current trends with model
variations moving forward that look realistic given the trough
progression. The last batch of showers will be associated with the
actual trough axis and should move into our western zones around
5AM and quickly push eastward. The trough axis moves over
Billings around noon...and then to the Dakota border by 4PM.

Ahead of the trough axis we will see destabilization occur across
our east with MUCAPE of over 1000 J/kg in our very SE corner of
the state after the noon hour. Deep layer shear >30kts is also
progged to be in this area briefly before all these ingredients
shift east/southeast of our CWA with the trough axis by 4PM. So
there is a brief window where we may see some strong to severe
thunderstorms (strong winds and hail) in our SE corner and along
the Dakota border (think Fallon and Carter Counties) before it all
really takes off into the Dakotas. CAM`s generally support this
scenario with suggestion of discrete supercells possible. Neural
net models also initiate potential severe storms right along our
east/southeast border between 2-4 pm...but the better chance
remains east/south of our boders.

In the meantime, behind the trough axis brisk northwest winds
(15-30 mph) are expected to spread over our area drying us out.

By evening, any convection should be east of us and winds will
start to die down. Overnight lows will be in the upper 40s to
lower 50s.

Tuesday will see high pressure prevail with temps warming well
into the 80s. Winds will be under 15 mph for most locations. There
is a weak disturbance in the westerly flow Tuesday evening that
may produce some low/no impact showers over east central Montana
(10-20% chance) overnight.

Recent showers last evening with more this morning over the
mountains could lead to some minor flooding issues of smaller
creeks and streams in the Bearooths and adjacent foothills.
A flood advisory remains in effect for these areas. It could also
push water levels near flood stage along the Clarks Fork at Edgar
and Belfry. A flood watch remain in effect for these locations.
BT

Wednesday through Monday...

Zonal flow or weak ridging will be over the forecast area on
Wednesday. High temps will be about 10 degrees above normal...in
the 80s. Probabilities of hitting 90 degrees were in the 20s at
most climate sites, but KSHR had a higher probability at 47%. RH`s
were slightly higher than they were in previous model runs with
values across the north in the upper teens to lower 20s. ECMWF
ensemble meteograms showed gusts to at least 30 mph for KLVM, K6S0
and K3HT. Fosberg Index was in the 50s in these areas. At this
point, may just need headlines in the FWF to cover these
conditions. Will continue to watch this period. Cold front moves S
through the area Wed. night with a 20-30% chance of showers and
thunderstorms E of KBIL.

It will be dry and cooler on Thursday under zonal flow. RH`s are
progged in the upper teens in many areas. An upper ridge slides E
through the area on Friday with SW flow behind it. There will be a
20-40% chance of afternoon showers and thunderstorms mainly W of
KBIL. There were low chances in the far E. It will be windy in
KBHK and Ekalaka per the ECMWF ensemble meteograms. It will also
be hot with highs in the 80s to lower 90s, but low-level SE flow
will keep RH`s up. The highest probability for hitting 90 degrees
was in KSHR at 57%. The SE flow will increase PWAT`s to 0.75-1.00
inches, and surface CAPE E of KBIL was forecast to be around 1000
j/kg...suggestive of possible strong storms. The SW flow aloft
will bring scattered showers and storms to the entire area Fri.
evening.

SW flow continues on Saturday, with low chances of precipitation
over and near the mountains and in the far E. 20-30% PoPs
overspread the entire area Sat. evening. Saturday will be cooler
than Friday. For Sunday through Monday, clusters had differing
solutions with the next trough. Forecast had isolated to scattered
showers and thunderstorms, and highs in the 70s both days. Arthur

&&

.AVIATION...

Expect scattered showers and isolated thunderstorms across the
area through 18Z. After 18Z, more numerous showers and
thunderstorms will be E and S of KBIL, including over KMLS and
KSHR, and they will decrease from W to E late in the day. Expect
MVFR/IFR conditions in the precipitation with lower conditions
possible. A cold front crossing the area will usher in gusty W to
NW surface winds, with gusts of 25 to 35 kt, mainly from 15Z to
00Z. Gusty winds will last into the early evening in KMLS. VFR
will return to the entire area this evening. Areas of mountain
obscuration will decrease this afternoon. Arthur

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Tue     Wed     Thu     Fri     Sat     Sun
-------------------------------------------------------
BIL 082 054/085 058/086 054/080 054/087 059/081 053/074
    4/T 00/U    11/U    00/U    01/U    31/B    21/U
LVM 077 047/084 051/083 046/080 047/084 052/079 045/071
    4/T 00/B    11/N    00/U    03/T    32/T    22/W
HDN 082 053/086 057/086 053/080 054/091 058/082 053/075
    3/T 00/U    00/U    10/U    11/U    31/B    21/B
MLS 080 053/084 059/085 054/079 052/088 061/082 054/072
    5/T 00/U    20/U    20/U    11/U    41/B    32/W
4BQ 080 055/085 060/086 056/080 055/089 063/082 056/077
    4/T 00/U    10/U    20/U    11/U    41/B    31/B
BHK 077 049/082 055/083 051/078 048/084 058/082 051/075
    6/T 00/U    10/U    20/U    12/W    42/W    32/W
SHR 077 051/083 055/086 053/079 053/088 057/079 051/075
    5/T 10/U    00/U    10/U    11/B    32/T    21/U

&&

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

&&

$$
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