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Area forecast discussion...updated 
National Weather Service Billings Montana
906 PM MDT Wednesday Aug 27 2014

Update...
airmass stabilizing with diurnal cooling and activity over
northeast Wyoming has stopped moving northwestward. Updated
forecast to remove evening probability of precipitation. Borsum

&&

Short term...valid for Thursday and Friday...

An upper low over southern Wyoming was spreading clouds northward
into southern Montana. A few showers have developed over the Big
Horn Mountains...with more cumulus development working northward. Jet
forcing slides east pretty quickly this evening...so would
anticipate the forcing to do the same. Will linger low probability of precipitation over
the big horns and that should be it. Will have to watch convection
over northeast Wyoming...as it has been creeping northward toward
far southeast Montana. Will keep that area dry for now and rely on
jet energy keeping it south and east.

Thursday will be dry and little warmer as middle level westerly flow
increases. Would expect middle to upper 80s most locations. Models
swing a shortwave into western zones Thursday evening. Weak
instability will be present as precipitable water amounts increase
to around .75 inches. Introduced probability of precipitation for the west Thursday
evening for this and spread them into central zones and part of
the southeast Montana overnight as the shortwave swings across.

Will linger low probability of precipitation through day Friday and hit the east harder
as the shortwave does not clear the state until late Friday
afternoon. Clouds and showers...along with a cold frontal passage
at 850mb...will cause a cooler day for Friday. Small scale ridge
will slide in behind the wave Friday night and this will clear
things out ahead of the next system for Saturday. Twh

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

The main feature of interest during the long term will be a 500-mb
trough passage Sat and sun. The surface cold frontal passage which
will accompany that trough is slated for Sat...and the 12 UTC runs
of the GFS...European model (ecmwf) and NAM all suggest the front will push through
far southeastern Montana during the peak in diurnal heating. If that is
the case...then MLCAPE of 1000-1500 j/kg with 0-6-km bulk shear on
the order of 35 knots would support a risk of strong to severe storms
in far southeastern Montana for a time Sat afternoon or evening. We are
not confident in the frontal timing though /if it is faster...then
the storm risk will be relegated to the Dakotas/. Shower and storm
chances will also exist in the Post-frontal regime Sat through Monday
with cyclonic flow aloft...but they will be dropping with time. We
expect below-normal temperatures behind the front...beginning over
south central Montana on Sat and across the whole area sun and Monday. The
Heights aloft are expected to rise again by Tuesday and Wednesday...allowing
for a warming trend again in that time frame. Schultz

&&

Aviation...

VFR conditions will prevail over the region tonight through Thursday.
Arthur
&&

Preliminary point temp/pops...

Thursday Friday Sat sun Monday Tuesday Wednesday
-----------------------------------------------------------
bil 057/087 059/080 056/075 054/071 048/073 050/076 051/080
00/u 22/T 13/T 32/T 22/T 21/u 12/T
lvm 050/086 051/080 050/073 046/068 043/071 044/076 045/079
00/u 22/T 13/T 32/T 22/T 21/u 12/T
hdn 056/088 057/082 056/079 054/073 050/075 051/078 052/082
00/u 22/T 12/T 32/T 22/T 21/u 11/u
mls 059/087 059/080 058/080 056/073 051/075 052/077 054/080
00/u 23/T 13/T 32/T 22/T 21/u 12/T
4bq 058/087 058/081 057/084 055/072 050/074 051/078 053/083
10/u 03/T 12/T 32/T 22/T 21/u 11/u
bhk 055/083 055/078 055/080 054/071 048/072 050/075 050/080
00/u 04/T 24/T 43/T 22/T 21/b 12/T
shr 053/087 053/081 053/081 051/070 046/072 047/077 048/083
00/u 02/T 12/T 22/T 22/T 21/u 11/b

&&

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

&&

$$
Weather.Gov/Billings

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