Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 200552

Area Forecast Discussion...Updated
National Weather Service Billings MT
1052 PM MST Mon Feb 19 2018


Quick update to temperatures and cloud cover late this evening.
Areas from Billings west have seen considerable clearing in the
past few hours allowing temperatures to plunge into the teens and
20s below zero already. Harlowton currently at -20. Some mid
clouds lingering int he Livingston and Big Timber areas but those
areas are well into the teens below zero as well. With back edge
of thin cloud cover at Billings and already around -7 degrees lowered
temperatures to around -17 degrees at the airport, and will
probably go several degrees colder on the west end. Adjusted cloud
cover lower as we go through the night to go along with current
trends and latest model thoughts. Chambers


.SHORT TERM...valid for Tue and Wed...

Light snow continued across portions of southeast Montana into
the mid afternoon with areas of flurries as far west as
Yellowstone County. Dynamic support aloft will continue to slide
slowly southeast this evening and overnight. So we look for
precipitation winding down from west to east overnight. The
southeast corner up into Fallon county are the only areas which
may see around an additional inch of snow from late afternoon
through the night. Other locations will see flurries to maybe a
dusting of new snow tonight.

The trof axis finally slides by us Tuesday morning. Our main
forecast issue is potential wind chills early tomorrow. Model
progs are slow to dissolve the cloud cover overnight, but do
suggest sky cover will begin to break up toward 12Z in the western
CWA. At that time we see winds shift to the southwest late tonight
and pick up a bit hitting 7-12 kts. As a result, it appears wind
chills by sunrise may be 20 to 30 below zero over our western CWA.
Course this is an issue for children waiting for buses etc. We
will issue a wind chill advisory from midnight to noon Tuesday for
these areas. Areas further east will have less wind and air
temperatures may not bottom out thanks to lingering low clouds.
Highs on Tuesday will be mainly single digits above zero.

Lower elevations will remain dry Tuesday through Wednesday.
However, the flow aloft remains cyclonic and proggs show some
energy dropping south out of Canada into the Northern Rockies.
This may generate some snow showers over our western mountains
Tuesday night into Wednesday, but this should be of little
relative impact or accumulation. Look for another cold night
Tuesday night and highs on Wednesday still only in the single
digits and teens. BT

.LONG TERM...valid for Thu...Fri...Sat...Sun...Mon...

Only minor changes to the extended forecast this afternoon, as
mainly dry conditions and below average temperatures persist
through the latter portions of workweek.

Several reinforcing trofs in western CONUS will keep high
temperatures from rising very quickly through the work week, only
reaching mid 20s by Friday. Meanwhile, low temps a few degrees
above and below zero are expected through Friday. Temps will Jump
into the mid 30s on Saturday, as downslope flow develops ahead of
an approaching weather maker for Sunday evening and Monday.

Western mountains looks good for additional snow into the Cooke
City area through the latter portions of the workweek, as moisture
continues to stream into the region. Models continue to advertise
mainly dry conditions over the lower elevations until
Sunday/Monday time frame. Would not be surprised to see a few
light snow showers slipping off the mountains at times, but would
not anything of significance. AAG



MVFR to IFR conditions are expected to continue to improve to VFR
from northwest to southeast through the evening as the storm
system moves out of the area. Cloud cover may be slow to clear,
and could hang around in the east through mid day Tuesday,
although VFR conditions should prevail before that point.



    Tue     Wed     Thu     Fri     Sat     Sun     Mon
BIL 917/006 910/013 907/020 901/027 012/034 016/033 013/034
    11/U    01/B    01/U    11/U    12/J    22/S    21/B
LVM 917/010 905/017 901/023 005/029 016/036 018/034 015/036
    11/U    01/B    11/B    11/B    13/J    43/S    22/S
HDN 916/006 914/012 909/020 907/025 007/033 012/031 009/034
    21/U    00/B    00/U    11/U    01/B    22/S    21/B
MLS 910/003 916/007 912/014 909/018 004/027 007/025 005/029
    31/B    00/U    00/U    10/U    01/B    11/B    21/B
4BQ 911/003 918/011 911/018 907/023 006/030 011/029 009/033
    41/B    00/U    01/U    11/U    01/B    11/B    21/B
BHK 909/003 914/009 911/018 908/018 005/028 009/026 004/029
    61/B    00/U    00/U    10/U    01/B    11/N    21/B
SHR 915/006 917/013 909/021 906/027 006/033 012/032 008/034
    31/B    00/U    01/U    11/U    01/B    21/B    21/B


MT...Wind Chill Advisory in effect until noon MST Tuesday FOR
      ZONES 28-29-34-35-40>42-63-65-66.


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