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Area forecast discussion 
National Weather Service Billings Montana
1021 am MDT Wednesday Jul 23 2014

no update to the forecast this morning as the forecast thinking
remains unchanged.



Short term...valid for today and Thursday...

Convection which impacted southeast Montana yesterday evening has
exited into western South Dakota. Ridge is strengthening over our County Warning Area with
latest 500 mb analysis showing heights to 594dam at 2am...and an
impressive 600dam over Colorado. We will be drawing hot air out
of this ridge and 700mb temperatures to near +17c will have a serious
impact on our convective chances today. Low level moisture and southeast
flow will remain in our east...where cape/shear values could
easily support severe weather if not for the capping middle level
warm air. With high heights/anticyclonic flow aloft and lack of
any shortwave activity have removed thunderstorm chances for our east
today. Kept isolated chances in our east and far north tonight as
heights will begin to fall and there should be ridge runner
convection to our north...and cannot completely discount an isolated
storm in far North/East parts of our County Warning Area. Elsewhere on west side of
ridge axis today...we will be hot and better mixed...mixing dry
air that is...note the -10c 700mb dewpt at slc at 00z yesterday.
We could see a few thunderstorms in our northwest near western Montana shortwave
activity and slightly cooler air aloft. In our central parts
including Billings and Sheridan...expect convective cloud bases of
14-15kft if we break the cap. This might be enough for virga and
if lucky an isolated sprinkle...but will keep precipitation out of the

As for temperatures will be the hottest day yet of
2014 and some places will reach 100f. This may include Billings
and Sheridan and have tweaked temperatures up slightly in spots.
Livingston daily record of 101f will be approached especially if
SW winds are mixed out...which they should.

Main forecast issue on Thursday revolves around fire weather as
Pacific trough breaks down the current ridge. Cold frontal timing will
be the key and models remain different here...though the European model (ecmwf)
and NAM have trended a bit slower in their 00z runs. That being
said...the NAM still introduces strong cold advection and northwest winds
in the must stress the uncertainty. Though the GFS is
the hottest model and has been consistently is possible
that nighttime and early morning convection to our north could
speed up the onset of low level cold advection in our area...
something the GFS would miss. That being said...if the GFS is
correct...we will see temperatures over 100f in our east/southeast. So
will stay with a somewhat middle ground for temperatures in the 90s to
near 100f...along with gusty/veering winds during the afternoon and
evening...and rhs in the teens as we continue to draw dry air out
of the Great Basin. All of these conditions would be dangerous for
any existing fires and potential new starts...and will continue to
highlight in the fwf/hwo/graphic.

There also is a greater confidence in at least isolated thunderstorm activity
on Thursday...especially in central and east parts. Surface frontal
passage and brief period of qg forcing warrants a mention of
thunderstorms...and there might be a window of potential severe storms in
our far east or northeast...though it is also possible that any
severe weather ends up to our N/NE.

Strong cold advection will bring relief to the heat Thursday night
and expect low temperatures to drop into the 50s...maybe 40s in our west.


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

Dry and warm weather will continue over the region for Friday
through the early part of next week. A dry zonal flow will be over
southern Montana on Friday with energy from from a closed upper
low aloft staying well north of our area. A ridge of high pressure
will build in from the west over the weekend and this will keep
the area dry. Ridging will keep high temperatures in the 80s.
Temperatures climbing back into the 90s Monday through Wednesday
as a thermal ridge builds over the area. GFS bringing a weak
trough through the ridge Tuesday and Wednesday while the ec
maintains strong ridging over the area. Given model
inconsistency...will keep just isolated probability of precipitation for the Southwest
Mountains. Precipitation over the mountains will be a few mountain
showers and thunderstorms. Plains look to be dry at this time as
700 mb temperatures rise to above +12c with build ridge. Richmond



VFR conditions will prevail over southern Montana and north central Wyoming
today. The air mass will be very unstable...but capped today over
southeastern Montana so the probability of strong storms is low...only
20 percent...and likely relegated to after 00 UTC. Schultz


Preliminary point temp/pops...

Today Thursday Friday Sat sun Monday Tuesday
bil 099 066/098 057/085 057/084 058/086 058/090 061/091
1/b 12/T 11/u 00/u 00/u 11/u 11/u
lvm 100 056/091 047/082 048/083 049/087 051/090 054/091
1/b 11/north 10/u 00/u 01/u 11/u 11/b
hdn 100 062/101 055/086 056/086 057/087 056/091 059/092
1/b 12/T 11/u 01/u 10/u 11/u 11/u
mls 098 067/097 058/084 058/084 058/085 058/087 061/089
1/b 22/T 21/u 10/north 00/u 11/u 11/u
4bq 098 064/100 058/085 057/085 057/084 057/087 059/089
1/b 12/T 21/u 10/u 00/u 11/u 11/u
bhk 091 062/096 056/082 053/082 053/082 052/083 055/085
1/north 22/T 21/u 11/north 11/u 11/u 11/u
shr 099 059/100 053/085 053/084 053/084 053/089 055/090
1/b 11/u 11/u 11/u 01/u 11/u 11/u


Byz watches/warnings/advisories...



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