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Area forecast discussion
National Weather Service Billings Montana
252 am MDT Tue Oct 22 2019

Short term...valid for tdy and tonight...

Strong shortwave energy was moving across central British
Columbia this hour. This wave will bring active weather to the
forecast area today and tonight. Ahead of the wave, the surface
pressure gradient will tighten and set up a gradient favorable for
strong from Livingston to Nye. Not a classic gap flow event here,
as the atmosphere is much to unstable for that, but the gradient
does support strong winds developing ahead of destabilizing lower
to mid levels. Strong mid level winds get in there for mixing
potential this afternoon too, with 700mb winds progged to 55kts
this afternoon. Guidance has taken a jump upward at Livingston for
wind gust potential to 60 mph. Will issue a Wind Advisory for
Livingston and Nye from late morning through late evening.

Winds will also become quite strong from Big Timber northward to
Harlowton and Judith Gap. Href has 700mb winds increasing to
60-65kts in these locations this afternoon. Surface pressure
gradient gets aligned correctly to mix these down. Shortwave
energy does float through there for overall ascent, but the GFS
hints at pockets of subsidence and mountain wave activity off the
crazies and snowies. Believe ascent from shortwave activity will
limit the 65kts potential from mixing down, but that is a lot of
wind to hold up for the entire afternoon. Will go ahead and issue
a High Wind Warning from Big Timber to Harlowton. Will include
Judith Gap in the warning too to line up with warnings to the
north from the Great Falls office. Winds should remain strong into
the early evening, then back off mid to late evening.

Snow showers will spread into the mountains today as the
shortwave approaches. The plains will pick up showers too as the
shortwave moves in this afternoon and tonight. 850-700mb lapse
rates get to 8.2c/km this afternoon and the GFS even advertises
some cape. Will keep the mention of isolated thunder by previous
shifts. Areal coverage of showers will be greatest over the east
during the evening, and along the foothills overnight. Will have
to watch low level flow to see if the rain/snow showers hang up
over the foothills, as can happen in northwest flow aloft.
Precipitation will likely change to snow late, with some light
accumulation possible. Twh

Long term...valid for Wed...Thu...Fri...Sat...sun...Mon...

Cold front dropping south through the region Wednesday morning
will bring cooler temperatures and breezy northwest winds along
with rain and snow showers over the area. A few inches of snow is
possible over the mountains with minor accumulations elsewhere.
Showers will gradually decrease from west to east Thursday night
as high pressure builds in from the west. Drier and warmer
conditions are then forecast for Thursday and Friday as high
pressure continues to build over the northern rockies. Strong
winds still look possible for the western foothills on Friday with
high pressure to the west and Lee-side troughing over central
Montana. Guidance continues to prog a strong Canadian cold front
dropping into the region on Saturday with precipitation
overspreading the area. Cool cyclonic flow then remains over the
region into next week with potentially another system dropping
into the area by Monday/Tuesday. While precipitation amounts
remain uncertain, snow accumulations are possible for the
mountains and foothills. Temperatures look cold enough for some snow
accumulations over the lower elevations as well. Still aways out,
but something to monitor.

High temperatures look to range from the upper 30s to the 40s
Wednesday, before rebounding back into the 50s Thursday and 60s
for Friday. Colder temperatures return to the area over the
weekend as the Canadian cold front drops south through the region.
Highs in the 40s and 50s Saturday will continue to drop Sunday
into next week with 30s and lower 40s most places. Low
temperatures in the 20s to lower 30s can be expected most
nights/mornings through the weekend with some locations possibly
reaching the teens next week. Stp

&&

Aviation...

VFR flight conditions will prevail most of the day. Expect
scattered showers by this afternoon and evening, most numerous
east of kbil and over the mountains. Some of the heavier showers
could produce brief MVFR conditions. Mountains will be obscured
for much of the day with snow showers. West to southwest winds
will increase this morning at klvm. Winds will also increase from
Big Timber to Harlowton this afternoon. Winds gusts to 50kts can
be expected in these locations into the evening. Twh

&&

Preliminary point temp/pops...

Tdy Wed Thu Fri Sat sun Mon
-------------------------------------------------------
bil 060 038/047 029/052 038/066 041/052 027/039 021/034
2/T 63/S 20/b 00/north 16/west 52/S 23/S
lvm 055 034/045 025/051 034/062 038/048 024/037 016/032
5/T 76/S 10/north 00/north 26/S 53/S 23/S
hdn 058 037/047 026/051 034/066 038/053 026/039 019/036
4/T 75/S 20/b 00/u 15/S 52/S 23/S
mls 053 035/045 029/049 034/065 041/052 027/038 020/036
5/T 75/S 30/b 00/u 13/west 32/S 23/S
4bq 053 033/043 027/046 031/064 037/055 025/037 019/035
4/T 86/S 40/b 00/u 03/west 52/S 23/S
bhk 050 030/041 028/044 031/061 038/052 024/037 018/035
2/T 66/S 30/b 00/u 03/west 32/S 22/S
shr 054 033/043 023/047 028/064 035/054 023/035 015/032
4/T 66/S 40/b 00/u 04/S 74/S 33/S

&&

Byz watches/warnings/advisories...
Montana...High Wind Warning in effect from noon today to 10 PM MDT this
evening for zones 63-141-172-228.
Wind Advisory in effect from 9 am this morning to 10 PM MDT
this evening for zones 65-66.
Wyoming...none.

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