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Area forecast discussion...updated 
National Weather Service Billings Montana
947 am MDT Tuesday Jul 26 2016

Update...
zonal flow across the area this morning with several shortwaves
embedded in the flow to generate lift. One wave was exiting the
east this morning and taking convection into the western Dakotas.
Have trimmed back pops for this morning as the wave exits. A
second, weaker, shortwave is progged by the models to slide across
the area this afternoon. This will generate enough lift for a few
showers and storms, but the stronger lift will come this evening
with the third shortwave. High resolution models bring the third
stronger wave into the west and central early this evening and
then swing it across the east overnight. Could be another late
night of convection over the east. Twh

&&

Short term...valid for tdy and Wed...

An area of showers and thunderstorms was rapidly moving east
into southeast Montana early this morning per radar imagery. The precipitation
was being caused by a strong shortwave crossing the state as seen
on water vapor imagery. A few other showers were seen north and northwest of
kbil. The area of thunderstorms was forecast to reach the far
eastern zones around 12z, where MUCAPES were in the 1000-2000 j/kg
range. So, will keep an eye on these for any strengthening. Sseo
and NSSL WRF were doing well with precipitation early this morning
and showed reflectivity over the far east through at least 15z. Thus
have continued pops over southeast Montana through 18z. The sref showed a good
probability of 1000 j/kg of MUCAPE over the region today with some
cape of 2000 j/kg possible over the east. Bulk effective shear will
be 30-40 kt across the area. Precipitable waters will increase to
1 to /1.25/ inches thanks to low-level easterly flow. Isolated
strong to severe storms are possible across the area given the
above, but the best chances will be over the four eastern
counties...combining the above information with spc's marginal
outlook. It will be cooler today given mixing to 700 mb combined
with increased cloud cover/precipitation.

The higher MUCAPES shift into the east tonight per the sref with
30-40 kt of shear continuing over the area. Along with continued
high precipitable waters, there will be jet divergence due to the
left-front quadrant of a jet moving over the area. Went with high
chance pops this evening, with a continued chance for severe
storms in the E, then had chance pops over the NE half of the area
overnight, based on model consensus.

More shortwaves continue moving across the area on Wed. Through
Wed. Night. There was low probability of 1000 j/kg MUCAPES over
the NE zones with continued 30-40 kt of shear across the area.
High precipitable waters will continue due to low-level southeast flow.
More jet divergence will cross the region Wed. Night. The eastern
zones will be the focus for the best precipitation chances through
Wed. Evening. Had chance pops across the area late Wed. Night due
to enhanced forcing with the jet. Wednesday will be cooler with
highs in the 80s. Arthur

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

Another shortwave in west-northwest flow aloft will bring more showers and
thunderstorms Thursday into Thursday night, with best chances in
our east where pwats will remain at or above an inch. Flat ridging
will begin to build in for Friday but there are some model
differences here, and one final weak area of pv may clip our area
before the ridge builds in fully. Have extended pops to go thru
the day in our far east, but it is possible that isolated storms
will impact our cwa further west per another day of easterly sfc
winds and relatively high boundary layer moisture. Temps Thursday
and Friday will be near normal with highs in the 80s to near 90,
with Friday being the start of a warming trend.

Ridge builds more aggressively thru the northern rockies and High
Plains for the weekend as next trof pushes toward the Pacific northwest.
Models still showing a monsoonal surge up the Great Basin bringing
US a chance of higher-based thunderstorms, especially by Sunday.
This flow out of the SW will also mean warmer temps and it now it
looks like Sunday could be the warmest day, with 700mb plume to
near +17c, which definitely gets 100 degrees in the conversation,
though cloud cover and convective chances could be a factor. Have
raised highs a bit both Saturday and Sunday getting the latter
into the mid to upper 90s.

At some point we will have a Pacific frontal passage and although
the current consensus is for that to occur Sunday night, models
are in modest disagreement with respect to the fate of the
aforementioned pac northwest trof and how aggressively it breaks down the
ridge. Will introduce some cooling for Monday but with a continued
chance of T-storms. The weekend heat and frontal passage will also
have to be watched with regard to fire weather. Jkl

&&

Aviation...

A couple of disturbances will work across the area today and
generate showers and thunderstorms. The stronger disturbance will
move into the klvm, kbil, kshr this evening and then into the
kmls, kbhk areas overnight. These storms will produce local MVFR
flight conditions, and mountains will be occasionally obscured.
Twh

&&

Preliminary point temp/pops...

Tdy Wed Thu Fri Sat sun Mon
-------------------------------------------------------
bil 091 063/088 062/086 061/088 062/095 065/097 063/090
2/T 42/T 33/T 31/b 11/u 12/T 22/T
lvm 091 053/089 053/087 051/090 055/093 057/093 054/089
2/T 32/T 33/T 31/b 12/T 22/T 22/T
hdn 093 062/089 059/088 058/089 060/096 062/098 061/092
2/T 42/T 33/T 31/b 11/u 12/T 22/T
mls 093 065/087 063/086 061/088 062/094 066/098 066/091
2/T 43/T 34/T 42/T 11/u 12/T 22/T
4bq 094 063/089 061/086 060/088 060/094 064/099 066/093
2/T 33/T 34/T 42/T 11/u 12/T 22/T
bhk 089 059/083 058/081 057/084 058/090 062/094 063/090
3/T 55/T 34/T 52/T 11/u 12/T 22/T
shr 091 057/089 057/088 054/089 056/094 058/098 060/091
2/T 32/T 34/T 41/b 11/u 12/T 22/T

&&

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

&&

$$
Weather.Gov/Billings

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