Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 201408
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
808 AM MDT Sun May 20 2018

.UPDATE...
Satellite imagery clearly shows low cloud deck west of a Ryegate
to Red Lodge line this morning which is gradually dissipating from
its eastern edge as well as around Livingston. We made some
adjustments to cloud cover and reduced coverage of patchy fog
based on this. Otherwise, looks like a beautiful Spring day with
just a chance of showers and an isolated thunderstorm or two over
the mountains. BT

&&

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

Flow aloft today and Monday will be out of the southwest. While
there are no organized waves moving through, there are still some
weak impulses of energy embedded in the flow. Most of the area
will be dry today, but the mountains could see some scattered
showers and isolated thunderstorms. Monday there will be a little
more energy moving across the area as a trough begins to dig into
the Great Basin. This will result scattered showers and isolated
thunderstorms extending a little farther off the higher terrain. A
few storms may have some small hail, however shear remain very
weak in the short-term. Organized severe convection is not
expected. Temperatures will be back in the 70s to near 80 degrees
to day and into the upper 70s to lower 80s tomorrow. Reimer

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

Active weather coming midweek, with above normal temps throughout
the extended period.

Expect periods of showers and thunderstorms across the cwa
Tuesday afternoon through Wednesday as Great Basin low slowly
fills and lifts through central MT. As this occurs, moisture will
increase courtesy of low level flow from the Gulf of Mexico, with
precipitable waters expected to reach 0.75-1.00 inches, possibly a
bit higher in our east. These are very high values for late May.
Wind shear still looks weak for the majority of our cwa, but bulk
shear values near 30 kts may support a low risk of severe storms
near the Dakotas border. That being said, biggest concern is the
potential for pockets of heavy rain and possible impacts on rivers
and streams which are already running high. Something to think
about over the coming days.

Trof lifts north Thursday then moves east Friday and Saturday,
allowing for rising heights and a drying/warming trend for the end
of the week. Cannot rule out mainly diurnal showers/thunderstorms
with weak shortwave energy Thursday and Friday, but Saturday
should be mostly dry.

Temperatures will cool slightly but remain above normal with the
increased precip chances Tuesday and Wednesday. This will be
followed by a warming trend for late week, a scenario agreed upon
by GFS/ECMWF and ensembles. If current indications are correct, we
could see the warmest temps yet of the year by next Sunday (highs
in 80s to around 90 degrees possible). Stay tuned.

JKL
&&

.AVIATION...

MVFR cloud deck west of KBIL is slowly dissipating from east to
west this morning. Otherwise, we expect VFR conditions to prevail
with some scattered afternoon showers and maybe a thunderstorm
over the mountains, some of which may affect KLVM later today. BT
&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Mon     Tue     Wed     Thu     Fri     Sat
-------------------------------------------------------
BIL 072 050/080 053/077 055/071 054/078 055/080 055/081
    0/U 02/T    33/T    67/T    33/T    32/T    21/B
LVM 067 045/074 048/073 049/067 047/075 049/076 048/077
    2/T 24/T    56/T    67/T    44/T    33/T    32/T
HDN 074 048/081 053/080 055/073 054/079 054/081 052/082
    0/U 01/U    22/T    57/T    43/T    32/T    21/B
MLS 072 049/080 056/080 057/075 056/077 056/080 056/081
    0/U 00/U    12/T    46/T    43/T    21/B    10/U
4BQ 069 046/080 053/081 057/076 055/077 055/078 054/079
    0/U 00/U    22/T    55/T    33/T    21/B    11/U
BHK 066 045/076 053/078 056/075 054/075 054/077 054/078
    0/N 00/U    14/T    55/T    43/T    22/T    10/U
SHR 069 045/077 050/078 052/072 050/076 050/078 050/080
    0/U 02/T    23/T    77/T    43/T    32/T    22/T

&&

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

&&

$$
weather.gov/billings



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