449
FXUS65 KBYZ 080825
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
225 AM MDT Sat Jun 8 2024

.DISCUSSION...
Today through Sunday...

Satellite imagery indicated weak cyclonic flow over our region
with an upper jet stretched NW to SE across northern MT and into
the Dakotas. Mid level cloudiness and some light showers or
sprinkles were noted in NE MT under the jet dynamics.

Look for some isolated to scattered light showers or sprinkles
across our eastern zones this morning related to the 500mb jet.
Later, we have a slight chance of showers over the mountains
thanks to shallow upslope flow (easterly) and diurnal instability.
Isolated activity may linger tonight over the mountains and along
the MT/WY border area due to some weak energy in the flow
pattern. Highs today will be a little cooler than yesterday due to
the easterly surface flow, with readings in the mid to upper 70s.
Lows tonight will be in the upper 40s to lower 50s.

For Sunday...the flow pattern will be transitioning as mid level
flow turns from cyclonic to westerly with high pressure building
over the southern Rockies. This opens the door to some weak
perturbations in the backing wind flow over SW MT. So look for
an increasing chance of showers and thunderstorms over our western
mountains later in the day. Increasing cloud cover will also mean
somewhat cooler temps. Highs Sunday will range from around 70
west to mid 70s east.

Runoff season is in full force. At this time, no rivers are
forecast to exceed flood stage, but water levels are elevated.
Somewhat cooler temps the next few days will mean rivers leveling
off a bit. However, flows will remain fast and cold. Please use
caution near waterways. A flood advisory remains in effect for the
Big Goose Creek near Sheridan in WY due to some minor flooding.
BT

Sunday night through Saturday...

SREF and Clusters showed an upper trough approaching the region
Sunday night and crossing the forecast area Monday through Mon.
evening. An accompanying cold front moves E into the area Sun.
night and crosses the area on Monday. MLCAPES from the SREF were
around 500 j/kg Sun. night and 500-1000 j/kg in the SE on Monday.
Bulk Effective Shear will be around 40 kt Sun. night and Monday.
CWASP numbers have come up again E of KBIL Mon. afternoon to near
60. PWAT`s will be 0.75-1.00 inch through Monday. Chances of at
least 0.50 inches of precipitation were 30-40% in the western
mountains and 15% in KLVM through Monday. Chances for showers and
thunderstorms spread E through the area Sun. night, with the
highest chances W of KBIL around 60%. Chances for showers and
thunderstorms continue Monday with highest chances in the
mountains. Cannot rule out some stronger storms Sun. night across
the area, while best chances for stronger storms on Monday will
be in the SE.

Upper ridging moves through the area on Tuesday with dry weather
and temps in the low to mid 80s. Zonal flow will be over the
region on Wednesday with highs in the low to mid 80s and low RH`s.
ECMWF ensemble had wind gusts into the 30s for western areas, so
will need to monitor for possible fire weather concerns. Zonal or
SW flow will be over the area Thursday with similar temps/RH`s to
Wednesday.

Poor Cluster agreement for Friday, with ridging in most Clusters,
but an approaching trough in one of the Clusters. Precipitation
chances are low with highs in the 80s. Clusters had differences
with the trough on Saturday. It will be a little cooler with low
chances of precipitation in the afternoon. Arthur

&&

.AVIATION...

VFR conditions will prevail through today. Isolated showers are
possible over the higher terrain after 21Z into the evening. BT
&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Sun     Mon     Tue     Wed     Thu     Fri
-------------------------------------------------------
BIL 077 053/073 055/078 054/085 058/086 055/082 056/085
    0/U 11/B    45/T    10/U    10/U    10/U    12/T
LVM 079 048/070 052/075 049/082 052/083 049/081 051/082
    1/U 13/T    66/T    11/U    11/U    11/U    12/T
HDN 078 053/075 057/078 052/086 055/086 053/084 056/086
    0/U 11/B    44/T    10/U    20/U    10/U    11/B
MLS 073 050/071 056/075 050/084 057/083 053/082 055/085
    1/U 11/B    44/T    10/U    20/U    10/U    11/U
4BQ 077 053/075 059/077 052/085 059/085 056/085 057/086
    1/U 11/B    23/T    10/U    20/U    10/U    11/B
BHK 070 046/069 053/073 048/081 054/083 051/081 051/082
    1/B 01/B    35/T    10/U    20/U    10/U    11/U
SHR 077 049/075 054/075 050/083 054/085 053/082 053/085
    1/U 22/T    34/T    20/U    10/U    10/U    12/T

&&

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

&&

$$
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