Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 201953

Area Forecast Discussion
National Weather Service Billings MT
153 PM MDT Sun Jun 20 2021


Tonight through Tuesday night...

An upper shortwave trough is bringing scattered showers and
isolated thunderstorms to the area this afternoon. Expect the
shower activity to become more widely scattered late this
afternoon, and diminish altogether this evening, as the trough
moves southeastward out of the area.

Rainfall amounts from this system appear to be on track with the
forecasted amounts from earlier, with a few 0.1 inch over western
foothills, to a few 0.01 inch over central areas, to little to
nothing over southeast MT. The strongest forcing for upward
vertical motion is over south central MT, west of Billings, and
over WY, and these are the areas that have received and should
receive this afternoon the greatest rainfall amounts.

Upper ridging will build over the Northern Rockies tonight through
Tuesday night and bring warmer and drier weather. High
temperatures will generally be in the 70s and 80s Monday and 80s
and 90s Tuesday. Low temperatures will generally be in the 40s to
near 50 degrees tonight, 50s Monday night, and 50s and 60s Tuesday
night. RMS

Wednesday through Sunday...

Wednesday continues to look like a possible fire weather day. Area
will be under weak ridging with a Pacific cold front moving
through and a chance of thunderstorms over the SW mountains. Also
it will be windy W, with low RH`s central and E. Temps will be up
in the 90s. Any thunderstorms that form could be strong with the
SREF showing greater than 500 j/kg MLCAPE over the W and
effective bulk shear of at least 30 kt across the area. Thus will
need to keep an eye on this period. Weak NW flow will be over the
region for Thursday with another frontal passage...this time from
the the morning. ECMWF ensemble gust charts showed windy
conditions over the E, but NBM was not as bold. Thursday will be
cooler, in the 80s, with higher humidities. There will be a chance
of showers and thunderstorms across the area into Thu. night.
Model clusters showed either NW or weak cyclonic flow over the
area Friday. This pattern will bring a continued chance of showers
and thunderstorms with temps in the 70s to 80s. Dry weather
returns for the weekend with temps climbing back into the 90s, as
upper ridging builds over the area. Arthur


Showers will affect areas mainly W and SW of KMLS, and will
decrease from NE to SW through the evening. Isolated thunderstorms
will occur, but coverage will be limited, so have downplayed them
in TAF`s. VFR will prevail, with MVFR in heavier showers.
Mountain obscurations will decrease this evening. Expect gusty N
to NW surface winds from KMLS to KSHR through early evening. VFR
will prevail overnight through Monday. Arthur



    Mon     Tue     Wed     Thu     Fri     Sat     Sun
BIL 050/083 056/092 062/094 062/084 056/081 056/089 060/095
    10/U    00/U    11/B    12/T    32/T    10/U    10/U
LVM 041/084 051/090 056/089 054/084 050/080 050/088 054/094
    20/U    00/U    21/U    12/T    22/T    10/U    10/U
HDN 048/084 053/094 060/097 059/087 054/081 053/090 057/097
    10/U    00/U    11/B    11/B    32/T    10/U    10/U
MLS 048/080 054/091 062/097 062/084 054/082 055/088 059/094
    00/B    00/U    01/B    11/B    22/T    10/U    10/U
4BQ 051/079 054/090 063/097 065/087 057/078 054/085 059/092
    10/U    00/U    01/B    11/B    33/T    10/U    11/U
BHK 043/076 051/089 059/096 059/083 053/078 052/084 057/090
    00/U    00/U    01/B    11/B    22/T    10/U    10/U
SHR 045/079 051/089 057/094 057/082 051/076 050/085 054/092
    20/U    00/U    11/B    13/T    33/T    11/U    11/U




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