Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 221525
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
925 AM MDT Sat Apr 22 2017

.UPDATE...
Lingering sprinkles over the central zones this morning should
dissipate by late morning. There is some degree of instability
this afternoon remaining in the eastern half of the CWA. So
mentioned a few isolated sprinkles this afternoon in the east.
Other parameters tweaked a bit, but nothing notable. BT

&&

.SHORT TERM...valid for Tdy and Sun...

Upper trough was sliding out of the area as anticyclonic flow
gradually builds in today. KBLX radar has shown returns steadily
decreasing in coverage and intensity through the overnight hours.
All that is left are a few lingering light showers. Will keep a
slight chance of a light shower over mainly central zones early
this morning. Snow was diminishing over the Bighorn mountains as
well, and will cancel the Winter Weather Advisory.

Inherited forecast had patchy fog carrying over through the
morning hours. Cloud cover has limited fog formation to this
point. Clouds were breaking up a bit as of this writing and
temp/dewpoint spreads were narrow, so can not rule out some fog
formation early on. HRRR hints at patchy development over mainly
central and western zones, but clears it out around 15z. Have
trimmed the ending time of the fog to 15z. The rest of the day
should provide decreasing clouds and warmer temperatures.

The next Pacific system moves into the area Sunday with a
stronger wave approaching for Sunday night. This system will be
embedded in strengthening southwest flow and therefore, showers
should move quickly. SPC advertises at least a slight chance of
thunder Sunday afternoon and evening, with some surface to mid
level CAPE. Will keep the thunder wording in. The GFS was quite
aggressive with QPF and thus, mountain snow potential, for Sunday
night, with a farther south moving secondary wave. This could lead
to a quick 3 to 6 inches of snow in the higher terrain. The ECMWF
was not quite a heavy with liquid potential, so tempered the snow
total a bit. TWH

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


The extended forecast continues to look damp and cool as a large-
scale upper trough slowly slides eastward over the western U.S. through
the next week. Numerous disturbances should propagate through this
flow, bringing periods of shower activity to our region. Models
are keying in on Monday night for perhaps more organized rainfall
as a better-defined shortwave trough moves across. Low-level flow
turns northeasterly/easterly on the ECMWF and to a lesser extent
on the GFS...indicating some upsloping potentially enhancing
precipitation over south central MT. In addition, some instability
is present mainly over south central MT late Monday, so a few
thunderstorms are possible.

Models still show another upper low or shortwave trough tracking
over Wyoming Wednesday night, which would produce a widespread
rainfall over southern MT/north central WY. Models differ on the
track and strength of this storm system, so am keeping PoPs in the
chance range at this time.

The troughiness continues into the late week timeframe with a
continued chance of showers. If current model solutions hold,
rainfall totals could exceed 0.5 inches in some parts of south
central MT and north central WY by week`s end. RMS/TWH

&&

.AVIATION...

A few isolated showers with MVFR conditions are possible through
about 15z this morning over south central MT. Patchy fog with
MVFR-LIFR conditions is also possible over the area this morning.
VFR is then expected late this morning into the evening.
Mountains will be obscured mainly this morning. RMS/TWH

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Sun     Mon     Tue     Wed     Thu     Fri
-------------------------------------------------------
BIL 060 041/063 043/058 041/055 039/054 038/053 036/054
    0/B 03/T    53/T    65/T    45/T    54/W    33/W
LVM 059 038/057 037/055 035/054 034/051 033/052 031/053
    0/U 06/T    64/T    66/T    35/T    44/W    43/W
HDN 061 039/066 043/060 040/057 039/058 038/054 036/055
    2/W 03/T    43/T    66/T    35/T    54/W    33/W
MLS 062 042/064 044/059 038/055 038/056 038/053 036/055
    1/B 02/W    43/W    44/W    25/R    44/W    34/W
4BQ 062 039/067 044/059 039/053 036/054 035/048 035/052
    1/B 00/B    42/W    66/W    25/R    56/W    34/W
BHK 062 037/059 038/055 032/051 033/053 033/051 032/053
    1/B 01/B    43/W    33/W    24/R    44/W    33/W
SHR 058 037/065 040/056 038/052 036/053 035/047 032/050
    1/B 01/B    43/T    76/T    35/T    66/W    33/W

&&

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

&&

$$
weather.gov/billings



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