Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 160322
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
922 PM MDT Sat Jul 15 2017

.UPDATE...

No major updates. The only update involved matching precipitation
chances to current trends and increased POPs slightly in eastern
Montana overnight. Low level jet in eastern Montana tonight will
help some of this convection persist through the evening. As
advertised the ridge crashing disturbance will come through the
area in pieces through Sunday. The first one, currently helping to
produce another round of showers to our west, will move through
overnight. As this disturbance interacts with the low level jet
over eastern Montana, it could yield a few showers or storms
overnight (as indicated by the GFS) so increased POPs slightly in
these areas. Previous discussion is below, but the next piece of
the disturbance will move through Sunday, which will kick off
another round of showers and thunderstorms. With better dynamics
in place with this system, stronger storms are anticipated with
one or two possibly being severe. Dobbs

&&

.SHORT TERM...valid for Sun and Mon...

Already have scattered thunderstorms over the mountains and
foothills this afternoon. Latest Hi-Res CAM models continue to
indicate a spread of this activity northeastward across the area
this evening with the potential for isolated wind gusts to 50 mph.
Pre-frontal trof will move into the area overnight tonight from
the west and will provide an additional focus to continue isolated
showers and thunderstorms overnight into tomorrow morning. Storms
over eastern zones will feel the effects of a strong pre-frontal
low level jet that will develop early in the evening so can`t rule
out a stronger storm or two east of Hysham/Hardin overnight with
gusty winds and lightning remaining the main threat. Expect
another warm night across the area for those that do not get
rainfall, with lows in the 65 to 75 degree range in the lower
elevations.

Tomorrow`s set up remains pretty much unchanged with the pre-
frontal trof holding over SE MT and main front moving into the
area in the early afternoon hours as an upper level low crashes
the upper ridge and moves across southern Canada. Models continue
to indicate a squall line of stronger thunderstorms will develop
along the cold front and push through the area during the
afternoon and early evening hours. Wind gusts of 40 to 60 mph seem
reasonable with this scenario with isolated stronger gusts
possible. Will see significant lightning with these storms as
well. Upgraded going Fire Weather Watch to a Red Flag Warning from
noon to midnight tomorrow.

Will see isolated showers and storms linger in some areas into the
overnight hours Sunday into Monday, but Monday morning starts out
dry. Temperatures Monday look to be about 10 to 15 degrees cooler
than Sunday. Will see scattered showers/tstms develop a bit later
than normal on Monday, mainly in the evening hours stretching
into the overnight period as right rear quad jet energy moves
across the area. Chambers

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

Ensembles were in fairly good agreement through the period. Ridge
was flattened over the area Tuesday and Wednesday, with energy
moving through the ridge. Ridge builds on Thursday, then gets
suppressed again for Friday and Saturday. Jet will move through
the area through Wednesday. Inverted surface trough was forecast
over SE MT on Tue., then a weak front pushes S through the area on
Wednesday. The NAEFS table showed that precipitable waters will be
over an inch over the E through Wednesday. Thus had slight chance
to chance PoPs over SE MT through Wednesday, with seasonable
temperatures on Tuesday, and slightly warmer conditions for
Wednesday.

Went with more slight chances over SE MT Thursday and Friday with
a low-level jet in this region. BRN and MLCAPE values showed that
storms could be strong in these areas, so will keep an eye on
model trends. Temperatures will be several degrees above normal
both days. Airmass looked drier on Saturday, so kept the forecast
dry, but this is subject to change, given that it`s so far out in
time. Arthur


&&

.AVIATION...

Isolated thunderstorms will move through southeast Montana through
0600UTC and over the mountains through 0800UTC. A weak storm or
two may move across the plains overnight. Expect VFR except near
the heaviest cells. borsum


&&

.PRELIMINARY POINT TEMP/POPS...

    Sun     Mon     Tue     Wed     Thu     Fri     Sat
-----------------------------------------------------------
BIL 068/094 062/086 058/089 063/092 063/094 065/094 063/091
    24/T    32/T    31/U    11/U    01/U    10/U    11/U
LVM 060/088 054/084 050/088 054/092 054/092 055/092 053/089
    34/T    33/T    41/U    11/U    01/U    10/U    01/U
HDN 069/096 064/088 061/091 060/094 062/096 062/096 060/093
    24/T    42/T    31/U    11/U    02/T    10/U    01/U
MLS 074/099 067/090 064/090 065/094 065/095 066/097 065/094
    23/T    31/U    32/W    11/U    12/T    21/U    11/U
4BQ 070/099 066/090 064/091 064/094 065/095 065/095 064/093
    22/T    32/T    42/T    22/T    12/T    11/U    11/U
BHK 068/098 065/089 062/087 061/090 061/091 062/093 061/092
    22/T    41/B    33/T    22/T    12/T    22/T    11/U
SHR 065/093 061/085 059/090 058/092 057/093 058/093 056/090
    23/T    33/T    31/U    11/U    12/T    11/U    01/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Red Flag Warning in effect from noon Sunday to midnight MDT
      Sunday night FOR ZONES 127>133.
WY...Red Flag Warning in effect from noon Sunday to midnight MDT
      Sunday night FOR ZONE 274.

&&

$$
weather.gov/billings



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