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Area forecast discussion 
National Weather Service Billings Montana
312 am MDT Monday Aug 3 2015

Short term...valid for today and Tuesday...

Today will be a transition day out of the hot and dry upper ridge
that has been over the area lately. The ridge was being pushed
east by an approaching upper trough from Utah to eastern Oregon.
The trough will move into Idaho this afternoon with the strongest
energy sliding into western Wyoming. The process will keep low
level easterly winds in place. These winds were bringing in higher
dewpoints with middle to upper 40s present in southeast Montana this
morning. Dewpoints in the 50s were not far...in eastern Wyoming
and western South Dakota...and these will make their way into the
east. This will translate into higher humidity values this
afternoon. Monsoon moisture moving up with the trough will lead to
some impressive precipitable water amounts by Tuesday. The
mountains should see some convection develop this afternoon as the
trough approaches. Highs will remain very warm with 850mb
temperatures around 30c.

Models have slowed the advancement of the upper trough into
western and central zones tonight. The trough splits with the a
low cutting off over northern Wyoming. This slows the eastward
progression further and allow for the east to stay warmer on
Tuesday. Increasing clouds should keep highs out of the 90s but
the east looks now to warm back up into the middle to upper 80s.
Persistent low level east to southeast winds and monsoonal
moisture spreading in will produce precipitable water amounts in
excess of an inch from Billings east. The GFS was advertising
values near 1.5 inches. Cape values over the east rise to around
1000j/kg. Bulk shear was weak...so the organized severe threat
does not look great. Enough moisture though for a heavy rain
threat and certainly wet microburst potential with weak shear as
storms collapse. Kept the idea of high scattered to likely probability of precipitation
over the east. Increasing thunderstorm coverage will be a concern
for fire weather users...as storms should have plenty of
lightning. Storms will be wet and humidities will be above 30
percent...so will not issue a highlight at this time. A cold front
will March through western and central zones Tuesday afternoon and
evening and create gusty northwest winds. Higher humidity levels
should mitigate fire weather affects of this front but will
certainly bear watching. Highs Tuesday over western and central
zones will be held in the upper 70s to lower 80s. Twh

Long term...valid for Wednesday...Thu...Fri...Sat...sun...

Only minor changes to the extended forecast period this
morning...as models remain in good agreement for unsettled pattern
to persist over the region. Temperatures look like should hang around
seasonal average through the period...if not slightly below.

Remnant showers will exit the area into the Dakotas early
Wednesday...but another piece of will lift into the County Warning Area late in
the afternoon and Wednesday night. Precipitable waters will remain unseasonably
high and would expect another round of showers and thunderstorms.
Additionally...the east could see some potential for stronger
storms...with pretty good shear prognosticated in the area. Drier air
gets pulled into the area behind shortwave...so will see
decreasing probability of precipitation for Thursday and Friday. Chances will linger in
east however....where surface trough and better precipitable waters persist. Although
drier...kept probability of precipitation in for Thursday...but split 12h grid to reflect
decreasing potential overnight. Isolated showers are possible on
Friday as well...but looks like driest day of the period. The next
trough lifts into the region Saturday...and crossing the region
through Sunday. Aag

&&

Aviation...

VFR conditions will prevail today under strong high pressure
aloft. Easterly surface winds...less than 20 knots...will redevelop by
this afternoon. The potential for thunderstorms will increase over the
mountains and foothills by late this afternoon..and spread east
Ward through this evening and overnight. Localized MVFR conditions
are possible in heavier precipitation. Aag

&&

Preliminary point temp/pops...

Today Tuesday Wednesday Thursday Friday Sat sun
-------------------------------------------------------
bil 093 063/082 058/086 059/085 057/085 058/086 059/084
1/u 25/T 33/T 42/T 21/b 13/T 33/T
lvm 090 058/081 053/083 052/083 050/085 052/083 053/081
2/T 35/T 34/T 42/T 21/b 13/T 33/T
hdn 095 062/084 057/089 057/087 055/086 057/089 057/086
1/u 25/T 43/T 42/T 21/b 12/T 33/T
mls 094 065/088 061/087 060/084 058/085 059/088 060/085
0/u 25/T 72/T 44/T 22/T 22/T 33/T
4bq 092 062/085 058/085 059/083 058/085 058/087 059/085
0/u 26/T 72/T 44/T 22/T 22/T 33/T
bhk 088 060/087 059/083 058/080 056/082 055/084 057/082
0/u 14/T 73/T 44/T 22/T 22/T 34/T
shr 091 058/077 052/085 054/083 053/084 054/086 054/084
1/b 35/T 43/T 32/T 21/u 12/T 33/T

&&

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

&&

$$
Weather.Gov/Billings

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