Area Forecast Discussion
Issued by NWS Billings, MT

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115
FXUS65 KBYZ 171636
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
936 AM MST Sat Feb 17 2018

.UPDATE...
Isentropic lift increasing over the central zones this morning
producing flurries in the Billings area. This band should continue
to translate eastward later this morning with fairly light
accumulations if any. Updated forecast. borsum

&&

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

Today through Monday... Disturbance dropping through northwest
flow over the region overnight brought up to a few inches of new
snow, mainly across eastern areas. Snow showers will gradually
diminish into the morning across central and eastern zones as
forcing wanes. Snow begins to increase across western areas today
as warm air advection associated with the next disturbance lifts
through the area. Winds increase along the western foothills late
this afternoon and evening as the surface pressure gradients
tighten. Have gone ahead and issued a Wind Advisory for the
Livingston and Nye areas from late this afternoon into tonight
where southwest to west wind gusts up to 70 mph are possible. Snow
spreads east across the area tonight, with most of the
precipitation across our northern zones, and for areas north of
I-94. While models have remained somewhat consistent in more of a
northerly track with this system limiting snow amounts for
southern areas, there still remains some uncertainty in whether or
not precipitation spreads south overnight tonight as a surface
low dives south and east into Wyoming causing winds to turn
northerly. Snow looks to diminish into Sunday morning as cold air
surges back in from the north. For this initial period of
accumulating snowfall, have gone ahead and issued Winter Weather
Advisories for our northwest and northern zones, starting late
this morning in the west, and 5pm in the east, going through
Sunday morning. In general, 2 to 5 inches look possible, with the
highest totals found from Musselshell County and areas west. This
will need to be monitored for any additional highlites. The Winter
Storm Warning for the western mountains continues with periods of
moderate to heavy snowfall expected. Total snow accumulations for
the mountains will range from 1 to 2 feet by Sunday morning. An
upper low digging over Idaho will cause flow to turn southwesterly
aloft, with Pacific moisture overrunning the cold air near the
surface on Sunday. This will set up another period of accumulating
snowfall Sunday evening through Monday. Given the fact that
models show 850 mb temps going below
-20C late Sunday night, snow totals may be mitigated a bit due to
a lack of a dendritic growth zone.

Temperatures will range from the 30s west, to the 20s east today,
with highs on Sunday mainly in the teens. Temperatures will
struggle to make it above zero for many areas on Monday. Low
temperatures will range from the single digits to lower teens
tonight, with single digits to teens below zero Sunday night. STP

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


No major changes to the extended forecast. General northerly
cyclonic flow over the area will keep unsettled and cool
conditions in place. Pacific influence will increase through the
period displacing arctic air on Tuesday with a warming trend
toward the freezing mark for highs late in the period. There are
several weak disturbances that could produce some light
precipitation at times, but no strongly forced systems and
downslope component to the wind field looks strong enough to limit
precipitation across the lower elevations. West facing mountain
slopes though will see better chances of snow through the period.
Chambers
&&

.AVIATION...

There will be a slight chance of snow showers over the area
through 18Z. Snow showers will be accompanied by MVFR conditions.
After 18Z...snow will increase mainly N and W of KBIL accompanied
by MVFR/IFR conditions. WSW surface winds will increase at KLVM
this afternoon and evening with gusts to 50 kt this evening. Snow
continues this evening across the N and W, including KMLS and
KLVM, with MVFR/IFR and locally lower conditions. The snow will
move S through the area after 06z with a cold front. Expect
MVFR/IFR conditions and a shift to gusty N winds. Snow will
continue mainly S and W of KBIL Sat. morning. Western mountains
will be obscured through the period and the NE Bighorns will
become obscured late tonight. A mountain wave potential exists for
KSHR from near 00z through tonight. LLWS is expected in KSHR
tonight. Arthur

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Sun     Mon     Tue     Wed     Thu     Fri
-------------------------------------------------------
BIL 030 008/014 906/001 917/006 905/023 007/028 008/031
    2/S 57/S    85/S    21/B    10/U    11/E    11/B
LVM 038 012/018 909/004 917/007 904/025 012/030 014/035
    5/O 68/S    85/S    21/B    11/N    22/J    21/B
HDN 031 009/015 904/001 916/007 909/021 003/026 004/029
    2/S 46/S    85/S    31/B    10/U    11/B    11/B
MLS 022 006/012 906/901 916/002 911/014 901/019 001/022
    3/S 92/S    75/S    21/B    10/U    11/B    11/B
4BQ 028 011/017 903/002 914/005 911/017 002/024 004/027
    2/S 44/S    86/S    31/B    10/U    11/B    11/B
BHK 020 006/012 906/001 914/001 914/013 000/021 001/023
    1/B 83/S    65/S    31/E    10/U    11/B    11/B
SHR 032 015/021 906/003 916/007 911/023 002/026 004/031
    2/S 48/S    86/S    41/B    10/U    01/B    11/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory in effect until 9 AM MST Sunday FOR
      ZONES 28-29-41-42-63.
     Winter Weather Advisory in effect from 5 PM this afternoon to
      9 AM MST Sunday FOR ZONES 30>33.
     Wind Advisory in effect from 3 PM this afternoon to 2 AM MST
      Sunday FOR ZONES 65-66.
     Winter Storm Warning in effect until 9 AM MST Sunday FOR
      ZONES 67-68.
WY...None.

&&

$$
weather.gov/billings



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