Area Forecast Discussion
Issued by NWS Billings, MT

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637
FXUS65 KBYZ 200243
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
843 PM MDT Thu Oct 19 2017

.UPDATE...

Minor update this evening to temperatures and cloud cover. Tweaked
temperatures down just a bit in area river valleys based on latest
trends. As of 7 pm some river valley locations had lost almost 30
degrees of temperature from this afternoons high temperature.
Breezy foothills conditions will hold temperatures up in those
areas. Models not handling cirrus development off of area
mountains very well. Increased cloud cover to partly cloudy in
those areas for Cirrus/ACSL development overnight. Rest of the
forecast in good shape for a quiet weather night across the area.
Chambers

&&

.SHORT TERM...valid for Fri and Sat...

We`re looking at an active end to the work week and over the
weekend as windy conditions take hold of the short term forecast.
The main forecast concerns through the next 3 days are a strong
cold front Friday afternoon and periods of strong winds,
especially along the foothill regions on Saturday night and Sunday
morning.

Wind gusts will diminish across the plains this evening as
conditions cool off. Foothill locations will see the gusty winds
lessen this evening, but the foothills will still remain breezy
overnight with 25 to 40 mph gusts anticipated. A strong cold
front enters western Montana by Friday morning and will quickly
translate east into Livingston just after noon. Ahead of this
front, southwesterly flow will rapidly increase along with strong
pressure falls across eastern Montana. The will rapidly increase
the wind gusts along the foothills back into the 50 mph range.
Expect showers to develop along and behind the front in the higher
terrain with mountain snow above 7000/8000 feet.

East of a Roundup-Billings line, the later arrival of the front
and very warm pre-frontal conditions will push temperatures into
the mid to upper 70s Friday afternoon with relative humidities
dropping into the teens. As the cold front approaches these
regions in the afternoon and evening, the fire danger will
rapidly increase immediately ahead and behind the cold front as
strong pressure rises of 2 to 3 mb/hr (very high for this region)
move in behind the front. This will produce 30 to 40 mph winds
behind the front along with wind gusts nearing 55 mph in the late
afternoon and evening hours. These conditions will allow any
fires to quickly spread, especially considering the dry conditions
eastern Montana has experienced over the last 2 weeks. With this
in mind have issued a Red Flag Warning for these eastern areas.

Winds diminish across the Plains after midnight but strong wind
gusts are expected to continue along the foothill regions through
the remainder of the short term period, especially Saturday night
and Sunday morning. Cooler conditions are anticipated Saturday but
fire conditions will remain elevated as drier air filtering into
the region will offset the cooler temperatures. Expect another
breezy day Saturday off the foothills in the afternoon with 20 to
30 mph winds across the area. By sunset, winds will lessen over
the plains but our foothill regions will see winds begin to
increase overnight as the pressure gradient across the rocky
mountain front rapidly increases. Dobbs

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

The long term can be characterized as windy with periodic
disturbances impacting the area. Very windy conditions are
expected along the foothills with breezy to strong winds
elsewhere on Sunday as pressure gradients remain very tight. With
cloud cover increasing and precipitation progged to move in from
the west, winds may be mitigated a bit, but it will still be
quite windy. Models then prog a cold front to drop in from the
north Sunday night into Monday increasing shower chances.
Conditions are progged to dry out through Monday with breezy
northwest winds over the area. High pressure is then expected to
build in over the region for Tuesday and most of Wednesday
bringing dry conditions. Gap flow winds will be possible along the
western foothills Tuesday night into Wednesday. Models then show
another cold front dropping in from the north Wednesday night into
Thursday bringing more precipitation chances.

High temperatures will range from the middle to upper 60s on
Sunday, to the upper 50s to lower 60s for Monday and Tuesday.
Highs in the upper 60s can be expected for Wednesday with
downslope winds over the area ahead of an approaching cold front,
and 50s for most places on Thursday behind the cold front. STP

&&

.AVIATION...

Surface wind gusts up to 30kts will be possible at KLVM and along
the western foothills through tonight. VFR conditions are
expected to prevail. Winds and clouds will begin to increase
across the west tomorrow morning due to an approaching cold front.
STP/Hooley

&&

.PRELIMINARY POINT TEMP/POPS...

    Fri     Sat     Sun     Mon     Tue     Wed     Thu
-----------------------------------------------------------
BIL 047/073 040/056 040/067 048/061 038/062 042/066 038/056
    02/T    20/N    21/N    21/N    00/U    01/U    31/B
LVM 044/061 037/051 045/064 044/058 035/061 038/063 034/056
    05/W    21/N    33/W    42/W    00/U    01/N    32/W
HDN 042/078 038/058 035/069 045/063 035/063 037/069 035/058
    02/T    31/N    22/W    31/N    10/U    00/U    21/B
MLS 041/079 040/056 033/069 044/061 035/059 037/067 034/055
    00/U    32/W    11/N    21/N    10/U    00/U    11/B
4BQ 044/080 039/056 032/069 045/060 034/058 036/067 034/056
    00/U    21/N    01/N    31/N    10/U    00/U    21/B
BHK 041/080 039/054 032/067 043/057 032/056 035/063 032/053
    00/U    12/W    01/N    21/N    10/U    00/U    21/B
SHR 041/078 033/055 030/069 043/059 033/060 034/068 032/056
    01/U    10/U    11/B    43/W    10/U    00/U    32/W

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Red Flag Warning in effect from noon Friday to midnight MDT
      Friday night FOR ZONES 129>133.
WY...Red Flag Warning in effect from noon Friday to midnight MDT
      Friday night FOR ZONE 274.

&&

$$
weather.gov/billings



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