Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 241225
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
625 AM MDT Sun Sep 24 2017

.UPDATE...
Weak energy ejecting from main upper low has diminished. Next push
of forcing over our area is tonight. High resolution models
trending toward the drier GFS solution if anything for today.
Therefore, have updated to reduce PoP`s and cancel the Winter
Weather Advisory in the Big Horns. The best shot of any
accumulation now seems to be later this evening (after current
expiration time) rather than rest of today. BT

&&

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

We have an unusual difference in model solutions that has
developed for the short term forecast. The GFS proggs are on the
dry side this morning over our eastern sections. Other models keep
the precipitation coming this morning. 00Z run of the GFS seems
like the odd man out and with the cyclonic pattern and jet
placement as it is on satellite, we will side with the wetter
solutions today.

That said...central Rockies upper low will continue to dominate
our weather pattern over the next couple of days as it slowly
shifts northeast and fills in. Best chance for precipitation will
be today east of a Miles City to Sheridan line as stronger jet
dynamics slice across the region. Most of the precipitation may be
on the lighter side by this afternoon as lapse rates will not be
quite as steep as recent days, but some narrow bands or pockets of
moderate rain are still possible due to the jet dynamics aloft.

Despite upper low shifting through to the northeast we will still
be in a cyclonic pattern with increasing northwest flow in the mid
levels by the latter part of Monday. This means we will be slow to
warm up to seasonal norms until later in the work week. BT

The Winter Weather Advisory for the Bighorn mountains continues,
mainly above 7500 feet through tomorrow. Otherwise any snow
accumulations will amount to a dusting in the foothills or higher
ridges. BT

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


An upper low can produce isolated showers over far eastern MT
Tuesday morning. Forcing is very weak so any rainfall would be
light. Then as this low moves northeastward into North Dakota, E
MT will have a dry afternoon. Northwest flow behind the upper low
can bring a few showers to the higher terrain in the afternoon
mainly west and north of Harlowton.

The rest of the extended period looks mild and dry as an upper
ridge builds in from the west and dominates our weather. High
temperatures will generally be in the 60s Tuesday through Thursday
and then reach the lower 70s Friday and Saturday. RMS

&&

.AVIATION...

LIFR to MVFR conditions and light rain will persist through this
morning east of KBIL to KSHR and east to the Dakota border.
Patchy fog producing LIFR conditions is possible over south
central MT as well with plenty of moisture near the surface from
recent precipitation...but confidence in the fog developing is
low. Mountains will be obscured for much of the day today. RMS

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Mon     Tue     Wed     Thu     Fri     Sat
-------------------------------------------------------
BIL 051 038/058 039/065 044/066 044/068 044/070 046/071
    2/W 21/B    01/B    11/B    11/U    00/U    00/U
LVM 052 030/058 035/063 035/065 037/066 037/070 040/069
    1/B 11/U    01/B    11/B    10/U    00/U    00/N
HDN 051 038/057 037/067 042/068 042/070 042/072 043/072
    3/W 22/W    11/B    11/B    11/U    00/U    00/U
MLS 051 040/054 039/065 042/069 045/068 044/071 045/072
    4/W 22/W    21/B    00/U    11/U    00/U    00/U
4BQ 047 040/052 038/063 040/067 042/067 042/069 044/070
    4/W 45/W    21/B    11/U    11/U    00/U    00/U
BHK 049 039/052 039/061 040/067 042/067 040/067 043/069
    4/W 33/W    22/W    00/U    10/U    00/U    00/U
SHR 044 036/052 035/062 037/064 037/067 039/069 041/069
    4/W 43/W    21/B    11/B    11/U    10/U    00/U

&&

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

&&

$$
weather.gov/billings



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