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Area forecast discussion...updated 
National Weather Service Billings Montana
853 PM MDT sun Jul 5 2015


Upper level trough will push through the area tonight. This will
diminish precipitation chances from northwest to southeast
after midnight. Continue to see convective development this
evening over western zones in vicinity of right rear quadrant of the
jet...and increased probability of precipitation a bit over central areas to adjust for
this. For the rest of the area lowered probability of precipitation for lower elevations
to chance category as the more persistent precipitation has
shifted south and east of the forecast area. Will continue to see
reduced visibility across the area tonight due to smoke from
Canadian wildfires that is trapped in the colder low level
airmass. Visibility could drop to 2 miles at times in some areas
due to the smoke. With the cloud cover and smoke expect a small
diurnal temperature drop tonight and left going temperature
forecast in place. Rest of the forecast on track. Will see more
sun tomorrow but trapped layer of smoke will stay with US.


Short term...valid for Monday and Tuesday...

Northwest flow aloft is becoming less cyclonic as time with
Canadian surface high pressure deepening over the region. It has
brought substantial smoke into the region which is combining with
light precipitation to reduce visibilities across the region. Should
start a drying trend overnight as a trough axis shifts east of
Montana but heights are slow to rebound tonight so still think
some clouds and light precipitation will be moving through the area.
Despite a cool night on not expect fog development but
smoke will keep hazy conditions around.

Monday a drier northwest flow is in place with the surface high
pressure beginning to shift east. A bit better mixing and sunnier
skies will bring a rebound in temperatures but still 10 degrees
below normal. Enough lingering middle level moisture to support
mountain shower activity but plains look dry.

Tuesday a surface trough will develop over the area in advance of
another surge of cooler air out of Canada. Warmer start and
sunshine should help warm temperatures but still slightly below
normal. This trough begins to pull some return flow into southeast
Montana. Shortwave associated with the next Canadian push will
give a better chance for shower and thunderstorm activity across
the western zones and could see evening or overnight thunderstorms
over southeast Montana as the wave shifts across southern Montana
overnight. NAM is a bit more aggressive than the GFS on allowing
some convection to develop but shear fields are pretty light so do
not expect severe weather. Borsum

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

Overview...somewhat modest chance of precipitation through the
extended period each day...with some uncertainty about potential
for strong thunderstorm activity Friday night/Saturday night due
to differences between models. We are most confident in a warming
trend by the end of the work week and into next weekend.

The 12 UTC models remained in agreement showing a backing of the
flow aloft from northwest on Wednesday to the southwest by next
weekend as an upper-level trough migrates into the West Coast and
Pacific northwest. That transition will be a driving force behind
the warming trend...which will push highs back above 90 f
beginning Thursday.

The evolution of ridging to the south and east of the local area
and resultant path of the Pacific-based trough by next weekend
remains uncertain. The 12 UTC European model (ecmwf) is a bit more progressive than
the 00 UTC run while the GFS continues to be the wettest solution.
Low end probability of precipitation for the plains still seem to be the best Route for
now due to uncertainty. That some stage toward next
weekend I think we should see a decent short wave in southwest
flow track over our region raising the threat of strong
thunderstorms. Bt


Scattered showers continue to move from west to east across the
area. Expect these showers to clear out from west to east
overnight...lingering towards morning around Sheridan. MVFR to
IFR are possible with these showers along with mountain
obscurations. Expect VFR conditions to develop tomorrow morning.

Preliminary point temp/pops...

Monday Tuesday Wednesday Thursday Friday Sat sun
bil 054/076 056/083 058/081 059/089 063/092 063/089 062/090
31/k 01/b 12/T 12/T 22/T 22/T 22/T
lvm 049/077 049/081 051/080 052/087 055/089 055/085 054/087
40/k 13/T 22/T 23/T 23/T 33/T 33/T
hdn 055/078 056/086 057/084 058/092 060/095 061/092 060/091
30/k 01/b 12/T 12/T 22/T 22/T 22/T
mls 055/076 055/084 058/082 059/091 063/095 065/092 064/089
30/k 01/b 12/T 11/u 22/T 23/T 22/T
4bq 056/075 055/082 057/082 059/089 062/094 063/090 062/088
41/k 02/T 33/T 11/u 22/T 22/T 22/T
bhk 054/071 051/078 055/079 056/086 060/092 061/089 060/084
30/k 01/b 13/T 11/u 22/T 23/T 22/T
shr 052/072 051/079 054/078 054/086 056/089 056/086 056/086
42/west 13/T 22/T 21/b 22/T 22/T 22/T


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