Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 221504
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
904 AM MDT Fri Jun 22 2018

.UPDATE...
Updated PoP`s to reflect current radar trends. This meant
reducing PoP`s a bit in the far west zones, and increasing them to
categorical over the central zones for the rest of the morning.
Good trowal pattern on back side of upper trough main mechanism
producing widespread showers over the central zones. This area
will shift into eastern zones this afternoon with scattered
instability showers/tstorms then filling in behind it. BT

&&

.SHORT TERM...valid for Tdy and Sat...

Early morning water vapor imagery shows an upper low over south
central MT, drier air spreading over southeast MT, and a trowal
forming over central MT. An area of showers and thunderstorms has
tracked eastward over the past several hours and is just about
out of our eastern cwa. To the west, we are seeing showers develop
associated the aforementioned trowal, mainly W and N of Billings
at 230 am but increasing in coverage.

We will remain under cyclonic flow aloft today with plenty of
instability. This will yield showers and scattered thunderstorms
across the cwa, eventually becoming most widespread across our
east as the low tracks east and our west sees increased downslope
west winds. There could be a risk of stronger storms along the
Dakotas border but it looks as if surface trof will shift east of
our cwa first...so believe stronger storms will be in the Dakotas.
That being said, small hail is a good bet with any thunderstorms
as freezing levels will be a bit on the low side for late June,
and wouldn`t be surprised if a couple storms produced marginally
severe hail. Temps today will be cooler than Thursday with highs
in the low-mid 70s.

Showers will persist well into the night across our east tonight,
as the upper low shifts slowly east. This will be followed by a
brief period of ridging and dry weather into Saturday. Tomorrow
will be a few degrees warmer than today, especially across our
east.

Next Pacific wave will evolve into a low over western MT Saturday
then drop into WY Saturday night. Ascent from this low will begin
to produce shower activity across our west as early as Saturday
morning. A good chance of showers/thunderstorms exists Saturday
afternoon and evening, with only our northeast parts possibly
excluded as ascent tracks south. Developing upslope north winds
could bring enhanced precip to our southern mountains and
foothills Saturday night. There remains some model uncertainty in
the exact track of the low, so something to watch. Have bumped up
pops/qpf across our south (i.e. Red Lodge and Sheridan), and it
could turn cold enough for some snow over the highest peaks of the
Beartooths.

JKL

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

Only minor changes to the inherited extended forecast. Fairly
progressive pattern will allow for some dry days as well as some
afternoon/evening thunder.

Upper low over northern WY should move eastward Sunday, with weak
pieces of energy bringing shower and thunderstorms to the region.
Expect to see clearing by Monday morning as ridging builds into
the region from the west. Ridging will bring the warmest temps of
the period, with highs in the mid 80s.

Another upper upper level Pacific trof, and associated cold front
moves across the region Tuesday afternoon into the night. Although
models appear to be fairly dry with this system, keep most of the
strongest energy north, but would not be too surprised to see at
least isolated showers and thunder. Have carried slight pops at
this time.

This trof flattens the flow across the region, bringing zonal flow
over the region for Wednesday and Thursday. Flow looks dry, with
only a few weak perturbations, which should not be enough to
initiate precip. Expect to see slightly cooler temps behind the
frontal passage for Wednesday, but slightly warmer Thursday.

The next trof will enter the region Thursday evening, bringing
potential for showers and thunder across the region through
Friday. AAG
&&

.AVIATION...

Numerous showers ongoing this morning over south central MT
should shift eastward to SE MT for this afternoon. Showers will
become more scattered for south central MT by early afternoon.
Thunderstorms are possible across the region today with gusty
winds, small hail, and periods of torrential rain. The
showers/t-storms will result in MVFR to IFR conditions at times,
especially over SE MT. Elsewhere, VFR should prevail. Expect
persistent mountain obscuration much of the day. AAG/RMS


&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Sat     Sun     Mon     Tue     Wed     Thu
-------------------------------------------------------
BIL 075 055/075 055/075 056/085 060/081 055/078 055/080
    7/T 23/T    44/T    20/U    12/T    21/U    12/T
LVM 072 048/071 048/073 048/084 051/080 047/077 048/077
    3/T 26/T    53/T    20/U    12/T    21/U    12/T
HDN 075 053/077 055/076 055/086 059/083 054/080 054/082
    9/T 32/T    44/T    21/U    02/T    21/U    11/U
MLS 075 058/080 057/078 059/084 061/084 057/080 057/081
    6/T 42/T    24/T    21/B    11/U    31/U    11/U
4BQ 074 056/078 056/075 057/082 058/085 057/080 057/082
    7/T 51/B    45/T    32/T    11/U    31/U    12/T
BHK 075 056/077 055/076 055/080 057/084 055/079 054/079
    6/T 64/T    24/T    32/T    11/U    31/U    12/T
SHR 071 052/075 052/071 051/080 056/082 053/079 053/080
    5/T 34/T    66/T    22/T    02/T    21/U    11/B

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.

&&

$$
weather.gov/billings


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