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Area forecast discussion 
National Weather Service Billings Montana
241 PM MDT Tuesday Mar 31 2015

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

Areas of fairly thick high cloud have kept our temperatures and mixed
winds a bit in check so far this afternoon...though as of 2 PM
temperatures are in the upper 60s to middle 70s. Latest visible imagery
shows mountain wave clouds continuing to develop in the Lee of the
beartooth absarokas in SW flow aloft. This could hinder our
prefrontal thunderstorm potential as well...but will sustain isolated wording
into the evening as the hrrr and NAM have been hinting at. Looking
west...cold front is currently a little east of Missoula with
pressure falls in excess of 1mb/hour noted from Salmon to Butte and
Helena. Some weak convection is trying to develop in this area.

Front will push into our west this evening. Timing depicted by
models is a bit slower than previously thought though pressure
fields are somewhat muddled by the convection. 300 mb jet is parallel
to front in central Montana with pressure falls as already
mentioned...and in fact pressure rises are all the way back in
Oregon now...so a slightly slower frontal passage timing seems reasonable.
Expect a front to Livingston by around 02z...Billings 04z and
Miles City/Sheridan 06z. West-northwest wind gusts to 40 miles per hour will accompany
and follow this frontal passage. Could see a little Post frontal shower
activity especially considering the middle level instability. Best
chance of showers will be over our western high terrain as
secondary pv maximum moves in from the west. The beartooth absarokas
will see a little snowfall as 700mb temperatures fall to near -12c by 12z
Wednesday. Livingston may also wet bulb down to a rain/snow shower
mix by late tonight.

As for the red flag warning will make no changes at this time.
Frontal passage and wind shift tonight will be followed by gusty
west-northwest winds through tomorrow with gusts of 35-50 miles per hour. We will be
very well-mixed on Wednesday and per very dry middle levels expect
surface dewpoints to really crash...probably single digits from Billings
west...resulting in teens for afternoon humidity despite the much
cooler airmass. Winds will begin to diminish and rhs will begin to
recover Wednesday night.

Unstable northwest flow on tap for Thursday as upper trough slides to our
east. Surface high pushing into the northern plains will actually
stabilize the airmass in our east on Thursday...but lifted indices
near zero expected west of Billings. This along with convergent
boundary layer flow will allow for a greater chance of rain/snow
showers from Billings west Thursday afternoon and evening. Mountains
will see a little more snow accumulation.

Highs in the 50s Wednesday should fall to the middle 40s to lower 50s
on Thursday as we continue to weakly cold advect as the flow turns
northwesterly. A good chance of below freezing temperatures many areas
Thursday night.

Jkl



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

The pattern for the extended period is shaping up to be cooler
and more unsettled than the pattern of recent days. A shortwave
ridge will be over the area Friday and Friday night. A departing
shortwave over east Montana will bring a slight chance of showers to that
area on Friday. Friday will have highs in the 50s under a cooler
airmass. The ridge will flatten on Sat allowing Pacific energy to
move into the area. A cold front will push S through the region.
Temperatures were somewhat uncertain due to frontal timing
differences between the models. Model compromise gave highs in the
50s to around 60 degrees. SW flow will approach the area Sat night
and will move over the area on sun. Chances for showers will be
confined to mainly western and central areas Sat through sun.
Highs on sun will be slightly lower...in the upper 40s and 50s.

For Sun night through Tuesday...models agreed on an upper trough
moving through the region. Models had dry-slotting pushing up into
the area from low pressure in Wyoming Sun night into Monday. Continued
chance probability of precipitation over most of the area during this time...but the dry
slot will need to be watched in case probability of precipitation are a bit too high.
Continued slight chance/chance probability of precipitation over the area through the rest
of the period. Had highs in the 50s for Monday and Tuesday. Tuesday looks a
little warmer than Monday due to the departing system. Arthur
&&

Aviation...

Gusty west-southwest surface winds will continue this afternoon ahead of a
cold front. The cold front will cross klvm around 02z...kbil
around 04z...kmls around 06z and kshr around 05z. Surface winds
will shift to the northwest behind the front with gusts of 25 to 35 knots.
Winds will gust in the 30s and 40s from the northwest on Wednesday.
Otherwise...there will be a slight chance of thunderstorms around
klvm...and over and near the western mountains after 21z today.
Widely scattered to scattered showers and a few evening
thunderstorms will occur over the area tonight with possible MVFR
conditions. There will be a chance of showers over and near the
mountains on Wednesday. Localized to areas of mountain obscuration this
afternoon will increase overnight and persist on Wednesday. Arthur
&&

Preliminary point temp/pops...

Wednesday Thursday Friday Sat sun Monday Tuesday
-----------------------------------------------------------
bil 042/056 033/049 031/056 033/059 034/056 035/055 033/056
31/north 13/west 31/b 01/b 22/west 33/west 32/west
lvm 035/050 027/047 025/053 031/054 028/052 030/050 028/052
54/west 24/west 31/b 12/west 23/west 33/west 32/west
hdn 040/058 030/050 028/058 030/062 033/059 034/058 031/059
31/north 12/west 21/b 01/b 21/b 22/west 32/west
mls 041/058 031/049 028/055 030/060 032/058 033/055 031/055
21/north 02/west 12/west 01/b 11/b 33/west 32/west
4bq 041/057 031/048 025/054 028/061 031/058 032/057 031/057
21/north 02/west 11/b 01/b 12/west 22/west 32/west
bhk 039/056 029/045 024/052 026/058 028/054 028/049 028/050
21/north 02/west 12/west 01/b 11/b 33/west 32/west
shr 037/054 028/047 025/052 026/059 029/057 032/055 030/055
22/west 13/west 21/b 01/b 12/west 22/west 32/west

&&

Byz watches/warnings/advisories...
Montana...red flag warning in effect until 9 PM MDT Wednesday for zones
28>42-56>58-63>68.
Wyoming...red flag warning in effect until 9 PM MDT Wednesday for zones
98-99.

&&

$$
Weather.Gov/Billings

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