Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 192233
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
333 PM MST Sat Jan 19 2019

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

First item to address is the wind threat in the gap flow areas of
the foothills and across I-90. Livingston airport has had a gust
to 68 mph this afternoon with a gust over 60 mph near Nye 60 mph
this morning. The wind in these areas is still expected to let up
later this evening as the pressure gradient lets up. The midnight
end time to the Wind Advisory looks good.

Active weather pattern across our region the next few days.
Currently, we are under an unstable northwest flow in the mid
levels. There is some weak lift being generated by a minor
disturbance shifting over the area, which was mostly east of
Billings at midafternoon. We do not expect much if any
accumulations from this feature. Additional instability and
disturbances are expected to produce areas of snow to the
southwest mountains and nearby lower elevations overnight as a
warm front pushes toward the area. Several inches of snow are
possible in the high country by morning. While a mix of scattered rain
and snow showers are expected at the lower elevations.

Sunday...A mid level warm front will lift north through the area
pushing a band of precipitation through the western zones and
north into east central Montana. Look for the precipitation to
transition to a rain/snow mix during the day, gradually decreasing
as the warm front lifts north. We generally expect an inch or
less of accumulation for the lower elevations. There is also the
possibility that some of the precip could be mixed, with warm air
moving in aloft. Have left any mention of freezing rain or sleet
out of the forecast for now, but future shifts will continue to
monitor this possibility. By Monday morning, winds will turn
around to the north as a cold front drops into the area and an
upper trough moves into the region. The chance of snow will
increase, especially over the mountains and foothills.

This is where there is some inconsistency in the models. The GFS
solution keeps most of the energy in the split flow well to our
south. However, the ECMWF wraps the upper low up further north
over Wyoming leading to stronger and deeper upslope and
instability, particularly over the Big Horns region. This solution
is supported by the FV3 (experimental GFS) and some ensemble
members.

With all this in mind we have continued to opt for a blend of
solutions until things look more clear. Thus, our snow graphic on
our website will not show any significant changes from the days
earlier version. BT

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


A short break from the precipitation will occur on Tuesday and
into Wednesday as dry weather and no precipitation will accompany
an upper level ridge. During this period, a strong pressure
gradient from Idaho Falls to Lewistown will bring about high wind
speeds from the southwest for the Livingston-Big Timber-Nye areas
that may meet at least advisory-level criteria, as gusts above 50
mph are likely.

As the ridge breaks down, cyclonic northwest flow will likely take
its place. As with previous discussions, much uncertainty still
exists between the models and ensembles from Wednesday and on,
especially in the temperature, relative humidity, and QPF fields.
Scattered precipitation is likely across south-central and
southeastern Montana, but due to the large spread in surface and
850 mb temperatures, it is uncertain whether is will be freezing
rain or snow. At this time, freezing rain is expected during the
day on Wednesday and as the night approaches, it will turn into
snow, with minor accumulations expected. Going into Thursday,
drastic cooling may take place in far southeastern Montana, but
again, the spread of temperatures is too large to be certain how
much they will decrease by.

The pattern of high winds to light precipitation will again occur for
Thursday and into Saturday. More high wind speeds look to occur
around Livingston from Thursday afternoon and into Friday morning.
Following this is another round of precipitation that seems to
have good forcing supportive of more than minor accumulations,
and this is expected to occur from Friday afternoon through
Saturday morning. Going into Saturday, temperatures may increase
back into the 40`s. Again, much uncertainty lies with the forecast
going past Wednesday, so continue to check in for mid-to-end of
the week weather conditions.

Vertz


&&

.AVIATION...


VFR conditions will prevail through the night at all terminals.
Starting around 09z, mixed precipitation is expected to impact and
be in the vicinity of KBIL, KLVM, and KSHR, possibly producing
slick runways and bring about IFR conditions. The precipitation
will move out of the area by late Sunday morning, but lowered
ceilings will follow that could keep MVFR conditions at the
previously stated terminals. Snow showers will continue to
obscure mountain areas over the next 24 hours. Southwesterly
surface winds will continue to gust up to 45 kts through the
evening. Vertz
&&

.PRELIMINARY POINT TEMP/POPS...

    Sun     Mon     Tue     Wed     Thu     Fri     Sat
-----------------------------------------------------------
BIL 032/043 028/035 019/035 027/040 023/037 023/039 028/042
    34/O    15/S    20/B    14/W    42/W    33/W    11/B
LVM 034/046 029/036 015/036 024/038 023/037 023/040 025/044
    36/O    35/S    21/N    24/W    32/W    22/W    11/N
HDN 028/044 025/035 018/036 022/040 019/036 018/038 023/042
    32/S    15/S    40/B    24/W    53/J    34/J    21/B
MLS 024/041 024/032 018/034 022/037 017/027 014/029 017/040
    22/O    33/S    21/B    13/J    32/J    32/J    22/J
4BQ 027/042 025/034 019/033 021/038 018/030 014/031 017/040
    32/R    15/S    41/B    13/W    43/J    34/J    32/J
BHK 021/038 020/028 015/032 021/035 013/024 009/027 013/037
    11/B    23/S    31/E    12/J    13/J    32/J    22/J
SHR 028/045 025/034 014/036 016/038 017/034 015/037 020/044
    22/S    07/S    51/B    14/W    52/J    34/J    21/B

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Wind Advisory in effect until midnight MST tonight FOR ZONES
      65-66.
WY...None.

&&

$$
weather.gov/billings


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