Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 310313

Area Forecast Discussion...Updated
National Weather Service Billings MT
913 PM MDT SAT JUL 30 2016


Made only minor changes to the forecast this evening. Adjusted
pops, winds, and sky cover to current trends. Otherwise, showers
and thunderstorms formed this afternoon and evening as expected.
Some of the stronger showers/thundestorms produced gusty winds
with Livingston reporting a wind gust to 61 mph, Sheridan 50 mph,
and other areas in the 40 to 50 mph range as well. Isolated
showers and thunderstorms will be possible across most of the area
through the remainder of the evening, before decreasing
overnight. However, some vorticity interacting with a low level
jet expected to develop across the east late tonight may be enough
to trigger a few isolated showers late tonight into Sunday
morning. The rest of the forecast remains on track and the
previous forecast discussion and an updated aviation discussion
are below. STP


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

No major changes to the going forecast this afternoon. Weak H7-5
vort max drifting across the area from west to east is still
expected to trigger isolated thunderstorms this afternoon per latest
HRRR/RUC and NSSL-WRF. Any storms will be high based and produce
generally light precipitation and gusty winds. As with the past
few nights will see this afternoon convection dissipate quickly in
the early evening hours. Low level jet increases this evening and
becomes relatively strong overnight with boundary layer southeast
winds to 40kts over the eastern half of the forecast area. More
weak H7-5 energy along with convergence along the west edge of the
LLJ may trigger a few isolated showers overnight into Sunday

As the LLJ weakens late Sunday morning the trigger for convection
will become the surface trof which slides into southeast Montana
in response to increasing divergence aloft ahead of approaching
upper trof to the west. Juicy low level airmass over this area
will support scattered strong to severe thunderstorms, but storms
will only linger over Carter and Fallon county for a brief time
before drifting into the Dakotas. Elsewhere there will be a wind
shift to the west of the surface trof Sunday afternoon to the
northwest then north, undercutting stronger westerly winds trying
to mix from aloft. This should keep fire weather conditions just
below critical levels ahead of the main frontal passage Sunday
evening. Expect afternoon temperatures in the mid to upper 90s
most locations Sunday afternoon, with a chance for a few triple

Front passes through the area Sunday night and leaves dry westerly
flow over the area for Monday. Surface high pressure will keep
surface winds light but mixing of the warmer zonal flow above
this will allow temperatures back into the upper 80s to lower 90s
once again. Precipitable water levels of a quarter to half an inch
across the area will inhibit afternoon convection even over the
higher terrain. Chambers

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

Models continue to be consistent with the trough moving through
on Tuesday. Southwest flow aloft ahead of the front, while result
in compressional warming. Temperatures will be well into the 90s
across much of the area. This continues to look like the warmest
day in the extended. The southwest flow will also help to increase
the chance of rain. Aiding this will be a surface low over
northeast Wyoming which will help to bring in easterly flow.
Models are not an great deal of instability, but cannot rule out a
few thunderstorms especially over the mountains. The front will
move through late in the evening and overnight.

Behind the front on Tuesday, winds will continue to be out of the
northwest and breezy. Temperatures will be around 10 degrees
cooler. Conditions through the rest of the week will remain dry
and cooler was the area will remain in zonal flow. Reimer



Widely scattered showers and thunderstorms near KBIl and KSHR at
03z will shift east and gradually weaken through the night. Wind
gusts to 40kts can be expected with these showers. There is a
slight chance of showers and thunderstorms from northeast Montana
dropping toward KMLS and KBHK from around midnight on with brief
heavy rain and wind gusts to 40kts with local MVFR conditions.
Otherwise, the rest of the night should be dry. Mountains will be
partially obscured this evening with improving conditions
overnight as clouds decrease. TWH



    Sun     Mon     Tue     Wed     Thu     Fri     Sat
BIL 065/095 060/089 060/095 061/085 054/084 057/090 060/091
    21/U    10/U    12/T    21/U    11/U    11/U    11/B
LVM 054/093 048/089 051/095 050/083 045/084 048/089 051/090
    11/U    10/U    12/T    21/U    11/U    11/U    11/B
HDN 063/097 060/091 057/098 060/087 052/085 056/092 060/093
    22/W    10/U    12/T    21/U    11/U    11/U    11/U
MLS 066/098 064/091 063/098 064/086 056/084 060/091 063/092
    22/T    10/U    12/T    21/U    11/U    11/U    11/B
4BQ 064/099 064/091 062/099 065/087 055/085 059/091 062/090
    22/T    20/U    12/T    21/U    11/U    11/B    12/T
BHK 062/096 061/088 058/094 062/085 053/082 056/087 059/087
    14/T    21/U    12/T    21/U    11/U    11/U    11/B
SHR 059/096 057/090 057/097 058/086 051/085 053/089 056/089
    22/W    20/U    12/T    21/U    11/U    11/B    11/B




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