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Area forecast discussion...updated 
National Weather Service Billings Montana
631 PM MDT Tuesday Sep 23 2014

Update...
introduced isolated thunderstorms through midnight for western
areas...mainly west of a line from Roundup to Billings to the Big
Horn Mountains...to reflect current radar activity moving east
from southwest Montana. High resolution rapid refresh and arw
models seem to be handling this convection very well...and
suggests the convection will not progress east beyond that
line...with all of it dissipating by midnight. Meier
&&

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

Strong upper level ridge moving into the area Wednesday shifting
eastward on Thursday bringing near record high temperatures.
Amplitude of ridge is not too far north so moderate southwest flow
aloft moving over the Canadian rockies Wednesday and shifting
into north central Montana Thursday brings a weak downslope
pattern to the area. Cold air is not established in Yellowstone
Park yet so only expect mild winds but certainly a flow pattern to
full mixing potential. If Billings hits back to back 90s Wednesday
and Thursday it would be the first time that has ever been done
after September 23rd. Dry conditions through the period with clear
skies.Borsum

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

Main change in this forecast package was to slow down the approach
of the Pacific trough set to impact the area. This means warmer
temperatures and a drier weekend than was previously advertised.
The best chance of precipitation should now hold off until Sunday
night and Monday.

Models have dramatically slowed the evolution of the Pacific
trough currently seen on WV imagery off the West Coast. The highly
amplified trough currently in place is expected to cut off over
northern California by Saturday afternoon. The low will slowly
drift eastward toward the forecast area over the weekend before
being picked up again by the jetstream by the beginning of next
week. The result of this slowed evolution is a warmer and drier
weekend for the area...as the main push of cooler air is delayed
until trough passage on Monday. Despite this delayed push of the
coolest air...we will see a weak frontal passage on Saturday as
the northern portion of the wave split passes north of the area.
That front will break our streak of hot weather that is expected
through week\s end. Models are hinting that Sunday may even be
slightly warmer than Saturday as a warm front feature surges back
north ahead of the approaching cut-off low. Rain chances should
hold off through the weekend now...with the best chance Sunday
night into Monday as the low finally pushes across the area.

Beyond Monday...model trends have been toward a reinforcing wave
tracking into the forecast area as a ridge builds into the Golf of
Alaska. Should this pattern develop...we could see a more
prolonged push of more fall-like temperatures and showers around
through next week. Church

&&

Aviation...
VFR conditions will prevail tonight under mainly clear skies.
There is a slight chance of isolated showers and thunderstorms in
area mountains through early this evening...before tapering off
overnight...resulting in occasional obscurations. Church

&&

Preliminary point temp/pops...

Wednesday Thursday Friday Sat sun Monday Tuesday
-----------------------------------------------------------
bil 058/089 058/091 057/085 055/070 051/072 051/067 046/063
10/u 00/u 00/u 11/b 12/T 44/T 33/T
lvm 053/087 050/088 051/083 047/072 047/069 044/062 040/061
20/north 00/u 10/b 21/b 23/T 54/T 33/T
hdn 054/090 054/092 054/087 053/074 050/076 050/070 045/067
10/u 00/u 00/u 11/b 12/T 44/T 33/T
mls 056/090 057/093 058/088 055/077 054/077 052/069 046/066
10/u 00/u 00/u 11/b 12/T 34/T 32/T
4bq 054/089 056/094 058/089 055/079 054/079 054/069 045/065
10/u 00/u 00/u 11/u 12/T 34/T 32/T
bhk 052/088 054/091 056/088 054/079 051/075 051/069 044/063
10/u 00/u 00/u 00/u 12/T 24/T 32/T
shr 050/088 051/092 053/088 051/077 049/076 049/067 041/063
20/u 00/u 00/u 11/b 12/T 43/T 33/T

&&

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

&&

$$
Weather.Gov/Billings

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