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Area forecast discussion...updated 
National Weather Service Billings Montana
835 PM MDT Tuesday Oct 21 2014

Update...
frontal passage through Yellowstone County this hour with strong
pressure rises behind front. Have made some updates through the
evening adjusting for downslope flow off higher terrain and
placing highest probability of precipitation to Billings east. Some lightning noted in the
east and added this to the forecast through remainder of evening
as well. That said...I do not expect many locations to get more
than a couple of hundreths at best. Best forcing exits our
forecast area after midnight. Reduced probability of precipitation across the forecast
area for latter part of the night. Should be sunny behind system
for tomorrow with 500mb heights building over Montana. Strongest
winds so far this evening were in Livingston area with a 57 miles per hour
gust. Big Timber and Reedpoint both had 43 miles per hour gusts...Logan
Airport hit a 43 miles per hour gust as well with 46 recorded here at our
office on the Westside. Bt

&&

Short term...valid for Wednesday and Thursday...

Surface observation showing the cold haev moved through Livingston within
the past hour as pressure rises are observed just west of
Billings. However...the main thrust of the front is in the vicnity
of Bozeman. A few thunderstorms have develope along and just ahead
of the front across Gallatin County and northern Park County and
are quickly moving to the north and northeast. Clouds will
continue to increase slowly eastward through this afternoon and
evening. Will continue with just a slight shower chance and an
isolated thunderstorm along and west of a Sheridan-Billings-
Roundup line this afternoon with increasing chances this evening
as better dynamics are just behind the front. Precipitation chances will
shift east during the overnight hours but the strongest dynamics
look to move to the north of our forecast area across northeast
Montana. Main impact with this system will be gusty winds along
and especially behind the front. However...the system does not
look as windy as last weeks frontal passage. 700mb winds are only
25 to 35 kts tonight throughw wednesay with 850mb winds 25 to 35
kts tonight and 20 to 25 kts Wednesday. As a result...gusts across
the area are expected to be 30 to 40 miles per hour with a few possibly close
to 50 miles per hour.

The system will quickly exit into North Dakota by early afternoon
Wednesday but stil enough instability and troughiness to warrant a
slight shower chance during the morning acros the east. Next
system approaching the Pacific northwest Wednesday afternoon will
allowing ridging to quickly build across Montana during the
afternoon and overnight hours. Although ridging begins to build
during the afternoon....high temperatures will be about 10 to 15
degrees cooler today but still slightly above normal for this time
of year. By Thursday...a surface low will move across southern
Canada resulting in Lee-side troughing and a downslope surface
flow across our area. Mostly sunny skies combined with a downslope
flow will allow temperatures to warm back above normal with
readings in the upper 60s to lower 70s. Hooley

Long term...valid for Friday...Sat...sun...Mon...Tue...

Models are in very good agreement through the extended period
lending good confidence to the forecast. Changes to the going
forecast are of a minor nature. Overall a more progressive fall
pattern is starting to develop pushing systems through the area
every few days...though still no strong low pressure systems on
the horizon that could bring significant precipitation.

Zonal flow on Friday has a decent moisture feed associated with
it for possibly a few mountain showers and extensive cloud
cover...but downslope should keep lower elevations mainly dry.
Ridging develops aloft Saturday ahead of a strengthening West
Coast trough. This will bring dry and warmer conditions for
Saturday but as the upper trough slowly approaches will see
precipitation chances increase Sunday and Monday. However a
significant downslope gradient and the progressive nature of this
system will prevent more than a 20 to 30 percent chance for
precipitation for the lower elevations...though it could be
significantly higher for mountain locations where strong pulse of
Pacific moisture moves over the area. Temperatures will drop from
the 70s Saturday toward more seasonal levels as the upper trough
kicks through the region Sunday and Monday. Brief ridging develops
on Tuesday for slightly warmer temperatures before another shot of
Pacific moisture pushes over the area middle week. Chambers
&&

Aviation...

Expect VFR conditions for the rest of tonight and through the day
tomorrow. A cold front has moved through Livingston...where winds
will slowly decrease. Across the rest of the area...as the front
moves through...gust 35 to 40 miles per hour will be possible. Expect winds
to remain gusty for a few hours following the front...before
decreasing to 10 to 15 miles per hour. Reimer
&&

Preliminary point temp/pops...

Wednesday Thursday Friday Sat sun Monday Tuesday
-----------------------------------------------------------
bil 045/065 042/070 047/066 041/073 044/057 036/055 035/058
21/b 00/u 00/b 00/u 12/west 21/b 11/b
lvm 040/061 039/067 043/065 041/072 041/055 031/053 032/055
31/b 00/north 01/b 10/u 13/west 21/b 11/b
hdn 043/067 038/073 043/070 038/074 040/060 034/057 032/059
21/b 00/u 00/b 00/u 11/b 21/b 11/b
mls 045/065 037/072 043/069 041/070 042/062 033/054 031/056
51/b 00/u 00/b 00/u 01/b 21/b 11/b
4bq 044/065 037/071 042/069 040/073 042/061 034/054 031/056
41/b 00/u 00/b 00/u 01/b 21/b 11/u
bhk 044/062 035/070 040/067 038/067 041/059 032/050 029/052
31/b 00/u 00/b 00/u 01/u 21/b 11/u
shr 041/065 034/072 040/071 037/076 038/060 030/055 027/057
21/b 00/b 00/b 00/u 11/b 22/west 11/b

&&

Byz watches/warnings/advisories...
Montana...none.
Wyoming...none.

&&

$$
Weather.Gov/Billings

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