Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 250933

Area Forecast Discussion
National Weather Service Billings MT
333 AM MDT Sun Jun 25 2017

.SHORT TERM...valid for Tdy and Mon...

Heights rise across the region today with surface high pressure
moving from eastern Montana into the Dakotas. Surface low still
easterly under this regime so temperatures will be warmer but
slightly below normal around 80. Narrow band of clouds along the
back door cold front in the central zones will shift east and
dissipate during the morning so expect a dry day with fairly light

Ridge moves into western Montana and eastern Idaho tonight but
the apex of the ridge is not too far north into Canada so strong
flow aloft induces leeside troughing along the Canadian front
range. This feature is not looking quite as strong as last night
and do not necessarily expect surface winds to become to southerly
in response so have lowered temperatures slightly since downslope
factor may not be as pronounced.

Monday the ridge axis moves across the state and is weakened as
energy flows through it. Leeside trough amplifies and promotes
better mixing but latest runs continue trend of showing winds and
downslope to be not quite as strong in the central and western
zones so have lowered temperatures a couple of degrees. Southeast
Montana is an exception to this with strong southeasterly winds
developing but this actually advects cooler air back into the area
with Bufkit showing inversions keeping temperatures closer to 80.

Stronger disturbance moving into northwest Montana pushes a cold
front through the western half of the area overnight Monday.
Models develop thunderstorm activity along the front and move it
into the western mountains.

Fire concerns for Monday due to warmer temperatures and low
humidity along with gusty winds. Does not look like a significant
event because temperature and wind forecasts have trended down
slightly and cold frontal passage will be at night...but still
will certainly bring conditions that support increased fire
behavior. borsum

.LONG TERM...valid for Tue...Wed...Thu...Fri...Sat...

Still looks like a rather unsettled period in the extended due to
a progressive flow. Models were in fairly good agreement in
timing numerous shortwaves into the area until Saturday.

On Tuesday, a jet will move E into WY, placing the forecast area
in the left-front quadrant. The upper ridge shifts E out of the
area as a shortwave moves in from the W. The shortwave was progged
to exit the area late Tue. night. Models were similar in cold
front timing, bringing the front into the E by 18Z. The front was
forecast to be E of the area by 03Z. Precipitable waters Tue.
afternoon and night will rise to above an inch over the central
and E, bringing the possibility of heavy rainfall. The GEFS plumes
had a range of CAPEs over the area with a cluster of CAPEs above
1000 j/kg over KBIL. Shear across the area looked supportive of
possible strong storms. Noted SPC placed the far SE portion of the
area in a Marginal Risk for severe storms. Given the above, strong
storms look possible. Will further refine the risk with future
model runs. For PoPs, have spread them W to E across the area
post-frontally on Tuesday, and decreased them late Tue. night.
Highs on Tue. will range from the upper 70s W to near 90 E.

Another jet dives SE into the region in an upper trough late on
Wed., bringing more divergence to the area. Accompanying shortwave
moves through the area Wed. night, then the models had some timing
differences on Thursday with the wave. Had PoPs over much of the
area Wed. and Wed. night with models disagreeing on QPF
amounts/placement. Wed. will be a bit cooler than Tuesday. The
flow will be cyclonic to NW over the area Thursday through Friday.
Had thunderstorms chances over the area on Thursday, then dried
out the area through Friday. Highs looked seasonable both days.
There will be brief ridging on Sat. with drier weather, then the
progressive unsettled flow brings another chance of precipitation
for Sat. night and Sunday. Nudged toward Climo PoPs for these
periods. High temperatures will be slightly above normal. Arthur



VFR conditions will prevail over the area today through tonight.



    Tdy Mon     Tue     Wed     Thu     Fri     Sat
BIL 080 054/090 063/084 055/080 053/077 053/079 055/083
    0/U 00/U    13/T    31/B    22/T    11/B    11/U
LVM 079 048/087 055/078 046/076 045/074 044/078 048/080
    0/U 00/U    25/T    33/T    22/T    11/B    12/T
HDN 081 052/092 060/087 054/083 053/079 052/081 054/087
    0/U 00/U    12/T    41/B    22/T    11/B    11/U
MLS 080 052/089 063/089 056/084 055/080 053/080 055/084
    0/U 00/U    02/T    42/T    21/B    11/B    11/U
4BQ 078 046/088 062/089 055/082 053/079 052/079 053/084
    0/U 00/U    02/T    32/T    32/T    11/B    11/B
BHK 076 044/081 056/088 053/081 051/077 050/076 051/080
    0/U 00/U    02/T    42/T    22/T    21/B    11/B
SHR 076 047/087 056/084 052/077 049/075 048/077 050/082
    0/U 00/U    13/T    44/T    33/T    22/T    11/U




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