558
FXUS65 KBYZ 211947
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
147 PM MDT Fri Jun 21 2024

.DISCUSSION...
Through tonight...

Severe Thunderstorm Watch has been issued through 02Z for
Wheatland, Golden Valley and Musselshell Counties. Watch may be
extended further S later this afternoon. Good setup for severe
weather with strong trough overhead, surface CAPES of 1000-2000
J/kg, Bulk Effective Shear 35 to 50 kt and PWAT`s around 1 inch
with higher values over SE MT. Main threats are wind gusts to 70
mph and large isolated hail of 2 to 3 inches in diameter. A
tornado or two cannot be ruled out, but 0-1 km SRH has been
decreasing with successive HRRR runs, so this is a very isolated
threat. Watch may be extended S into Yellowstone and nearby
counties later this afternoon as low clouds scatter out.

Watch also issued for Sheridan County and Big Horn County til 03Z
given an uptick in activity there. Main threats are damaging
wind gusts to 70 mph and large hail with diameter up to 2 inches.
Arthur

Saturday through Thursday...

Upper level ridging will settle in over the Northern Rockies this
weekend, resulting in hot and dry conditions with several
locations nearing record highs for Sunday. High temperatures on
Sunday will be in the 90s for much of the region with locations
along the river valley most likely to hit 100 degrees (40-80%
chance). A brief shortwave will flatten out the ridging Sunday
evening, bringing the chance for isolated showers and
thunderstorms. Westerly flow and ridging will rebuild into the new
week with high temperatures in the upper 80s and low to mid 90s.
Latest ensemble runs show a broad trough dipping into the PNW on
Thursday. With this, high temps closer to normals are forecasted
and an increase in the chance for precipitation (20-40%).

Arthur/Matos/TS
&&

.AVIATION...

Thunderstorms will increase over the area through this evening.
Due to high moisture levels, storms will contain IFR and lower
conditions. Storms may also be severe with wind gusts to 60 kt,
2-3 inch diameter hail, and a possible tornado, but this threat is
very low (5 to 15%) confidence. The severe threat will affect KBIL
and possibly KSHR. Storms will quickly decrease after 06Z
tonight. Patchy fog is possible over the region overnight as well
as localized MVFR/IFR ceilings over KBIL, KSHR and KMLS. Areas of
mountain obscuration are expected through this evening. VFR will
otherwise prevail on Saturday. Arthur
&&

.PRELIMINARY POINT TEMP/POPS...

    Sat     Sun     Mon     Tue     Wed     Thu     Fri
-----------------------------------------------------------
BIL 056/085 058/098 062/091 057/085 057/091 061/089 060/080
    61/U    01/U    11/U    00/U    00/U    11/B    23/T
LVM 051/085 053/094 056/089 051/087 052/091 055/087 053/077
    21/U    01/N    11/N    00/U    01/U    13/T    34/T
HDN 054/085 057/101 061/092 055/086 056/093 059/092 058/082
    51/U    01/G    21/U    10/U    00/U    11/U    33/T
MLS 056/082 058/096 065/088 058/083 057/090 061/090 060/083
    50/U    00/U    20/U    10/U    10/U    11/U    32/T
4BQ 056/083 058/098 066/091 058/084 057/093 061/094 061/085
    30/U    00/U    10/U    10/U    10/U    11/U    22/T
BHK 055/081 055/093 063/087 054/083 053/088 057/089 058/085
    31/U    00/U    10/U    10/U    11/U    11/U    32/T
SHR 051/083 054/096 061/094 054/085 055/091 058/092 055/084
    52/T    00/U    11/U    10/U    00/U    11/U    22/T

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Severe Thunderstorm Watch 442 in effect until 8 PM MDT this
      evening FOR ZONES 29-42-63-68-172-228.
     Severe Thunderstorm Watch 443 in effect until 9 PM MDT this
      evening FOR ZONES 57-138-169-171.
WY...Severe Thunderstorm Watch 443 in effect until 9 PM MDT this
      evening FOR ZONES 198-199.

&&

$$
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