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Area forecast discussion 
National Weather Service Billings Montana
232 am MDT Wednesday Jul 27 2016

Short term...valid for tdy and Thu...

Ingredients are coming together for better chances of wetting
rains for today through Thursday. Precipitable waters have risen
to 1 inch to /1.25/ inches over the eastern part of the area and
will remain high through the period as low-level easterly flow
persists through tonight. A series of shortwaves will affect the
region, although the models were not in great agreement with the
track of the waves, which created some pop challenges. Models were
however in closer agreement with the position of an inverted
surface trough over the eastern zones.

The sref showed 1000 j/kg MUCAPE over the area today and Thu.,
With convective available potential energy around 500 j/kg tonight. The bulk effective shear was
30 kt today and tonight. Thus there could be some strong storms,
but not seeing any large severe storm potential.

Early this morning, a shortwave was crossing Montana and a second wave
was over Washington on water vapor imagery. The Montana wave will be moving
into southeast Montana at 12z today and should be gone by 18z. The Washington wave
will move into the area, but the European model (ecmwf) and WRF keep it further north
than the GFS. Forcing with the wave looked weak today. Kept low
pops over the central zones through 18z with higher pops east and
went with scattered pops in the afternoon with the highest pops E,
based on model quantitative precipitation forecast consensus. It will be cooler than yesterday
with mixing to 700-600 mb, convection and clouds.

Inverted trough sets up over the east tonight as the wave continues
moving through the region. Again, forcing was weak and models kept
the wave generally north of the area. Had scattered evening pops, then
highest pops east overnight with the surface trough. The shortwave
moves into NE Montana on Thu, maintaining an inverted trough over southeast
Montana. Again, focused the higher pops over the east. It will be slightly
cooler with limited mixing and clouds/precipitation on Thursday.
The shortwave will move into the Dakotas Thu. Night and pops will
decrease from west to east. Arthur

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

Conditions will begin to dry out and turn warmer on Friday, but
there is one final area of pv tracking thru the west-northwest flow aloft
that clips our N/E. As boundary layer moisture will remain
somewhat elevated, this could be enough for a few showers and
tstms mainly over the mountains and in our east, but will admit
there could be a slight chance across our lower elevations until
the pv exits. Friday night should be dry as ridge finally builds
behind this final shortwave. Temps on Friday should be very close
to late July normals, ie mid 80s to around 90.

Ridge builds and flow aloft backs by Saturday, allowing for
warmer air to push into our cwa from the SW, as upper trof digs
thru British Columbia into Washington. Models remain consistent in showing a surge of
monsoonal moisture and the threat of higher-based thunderstorms
beginning late Saturday in our southwest, then across our region
on Sunday. Conditions will generally hot this weekend but latest
models seem to have trended just slightly not-as-hot. 700mb temps
near +16c will get many locations to the upper 90s to near 100,
with hottest temps likely to occur on Sunday in our east.

Evolution of pac northwest and trailing Pacific shortwaves still in much
question for the first half of next week, but today's models are
hinting at a couple things. First is a drier Post-frontal day on
Monday as initial trof pushes across northern Montana and southern
Alberta/Saskatchewan, scouring out moisture behind a Sunday night
frontal passage. Then, trailing wave will bring next chance of
showers and thunderstorms by Tuesday. Given the uncertainty will
leave climo/slight pops in for both Monday and Tuesday, but again
there is a trend to suggest Monday may be a dry day for US. Temps
early next week should cool a bit from the weekend but remain warm
and pretty close to normal. That being said, gefs plumes show
plenty of spread in 850mb temps by days 6-7.

Impacts in the extended could include elevated fire weather
concerns on Sunday with potential high-based storms, hot temps and
a frontal passage. Something to monitor moving forward.

Jkl
&&

Aviation...

Line of showers/tstms near kmls-k4bq will track east thru 12z.
Additional shower and thunderstorm development is expected later
today thru tonight. Although VFR will prevail, local MVFR could
occur in the heavier showers, and mountains will be periodically
obscured. Gusty sfc winds and small hail are also possible with
any stronger storms. Jkl

&&

Preliminary point temp/pops...

Tdy Thu Fri Sat sun Mon Tue
-------------------------------------------------------
bil 087 062/084 060/089 063/096 066/097 064/090 060/091
3/T 33/T 31/u 11/u 12/T 22/T 22/T
lvm 089 053/086 052/090 055/094 058/093 054/090 051/088
3/T 33/T 31/u 12/T 22/T 22/T 22/T
hdn 089 060/086 058/090 061/097 064/099 061/093 058/093
3/T 33/T 31/u 11/u 12/T 22/T 22/T
mls 086 063/085 061/088 063/096 067/100 067/093 062/093
4/T 34/T 41/u 11/u 12/T 22/T 22/T
4bq 088 061/086 059/088 062/095 066/099 067/096 062/094
4/T 44/T 41/b 11/u 12/T 22/T 22/T
bhk 082 058/082 057/084 058/091 063/097 065/092 058/090
5/T 45/T 52/T 11/u 12/T 22/T 22/T
shr 089 057/086 054/090 056/096 059/099 059/093 056/092
3/T 44/T 41/u 11/u 22/T 22/T 22/T

&&

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

&&

$$
Weather.Gov/Billings

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