Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 210322

Area Forecast Discussion...Updated
National Weather Service Billings MT
922 PM MDT Thu Jul 20 2017

Made some minor adjustments to PoPs to push isolated evening
activity just a little farther north off the foothills. Shower
activity over south central zones will be very limited as
strongest shortwave energy was moving into northeast Wyoming at
this time. Also adjusted PoPs a bit over southeast Montana to
focus the higher PoPs over the far southeast. Convection was
stubborn over northeast Wyoming and was trying to creep back into
the far southeast corner of the state. Also adjusted temperatures
down a couple of degrees over the east as current conditions were
a little ahead of guidance. TWH


.SHORT TERM...valid for Fri and Sat...

Convection has been forming off the Beartooth Mountains and have
already begun pushing into Big Horn County as of 230 PM. This has
been the trend that the CAMs have been advertising. Meso-analysis
shows that CAPE values along the Dakota borders are getting to
around 2000 J/kg, and shear values are 40 to 50 knots through 6
km. Recent runs of the HRRR are still pointing towards stronger
convection developing later this afternoon in eastern Montana then
moving into the Dakotas. The convection currently in Big Horn
County will increase as it moves into the better environment.

A cold front will move through overnight and should be to around
Miles City by 6 AM tomorrow. This has will keep winds breezy
across Musselshell, Treasure, and northern Rosebud counties.
Tomorrow 850mb winds remain strong out of the northwest. With
mixing tomorrow afternoon, areas from Roundup to Broadus are
going to gusty winds with relative humidity values in the teens.
Have extended the current Red Flag to until 9 PM tomorrow for
Musselshell and Northern Rosebud, and have added Custer, the rest
of Rosebud, and Powder River Counties. Saturday will be dry, as
ridging builds back into the area. Reimer

.LONG TERM...valid for Sun...Mon...Tue...Wed...Thu...

No significant changes. The riding continues Sunday and most of
Monday keeping conditions dry. A low in southern Canada will bring
a weak cold front across the area. This will shift the ridge to
the east. This put the area in southwesterly flow. This will
result in some scattered PoPs each afternoon. The GFS ensemble is
not showing much in the line of moisture with any of this
activity. With the increase flow of monsoonal moisture,
temperatures will be slightly cooler. Reimer


Isolated showers and thunderstorms will continue to weaken
through the night and be confined to areas south of a KBIL to
KBHK. Otherwise, clouds will decrease. A cold front will push
through southern Montana and northern Wyoming tonight and switch
winds to the northwest. Some gusts to 25 mph are possible with the
frontal passage. TWH


    Fri     Sat     Sun     Mon     Tue     Wed     Thu
BIL 064/090 059/090 061/095 065/095 065/092 066/090 065/092
    20/U    00/U    00/U    11/U    21/B    22/T    11/U
LVM 054/086 049/088 051/092 056/093 056/089 058/087 055/089
    20/U    00/U    00/U    01/U    21/B    22/T    22/T
HDN 064/091 058/092 058/097 062/098 063/095 064/092 062/095
    20/U    00/U    00/U    11/U    11/B    22/T    22/T
MLS 068/091 060/091 062/096 068/099 067/094 067/093 066/095
    10/U    00/U    00/U    01/U    11/B    12/T    21/U
4BQ 065/090 059/091 060/094 066/098 066/095 065/091 064/093
    30/U    00/U    00/U    01/U    11/B    12/T    22/T
BHK 066/091 056/089 056/091 063/096 062/092 062/089 061/091
    31/U    00/U    00/U    01/U    11/B    12/T    22/T
SHR 062/086 054/089 054/093 058/095 058/092 059/090 058/090
    30/U    00/U    00/U    11/U    11/B    22/T    22/T


MT...Red Flag Warning in effect until 9 PM MDT Friday FOR ZONES
     Red Flag Warning in effect from 9 AM to 9 PM MDT Friday FOR
      ZONES 131-132.


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