Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion...updated 
National Weather Service Billings Montana
950 PM MDT Tuesday Jul 22 2014


Thunderstorm activity is winding down this evening with just one
strong storm left across southwest Powder River County and
northeast Sheridan County. The storm is moving southeast and will
be out of our forecast area of responsibility within the hour. As
a result...will be canceling the remaining Severe Thunderstorm
Watch for Powder River and Carter counties with this update.

Upper level wave responsible for this evenings severe weather is
shifting into northern Montana and the western Dakotas. Satellite
showing some clearing skies across our central and western
locations. Can't rule out an isolated shower for the remainder of
the night but dry conditions should prevail after midnight. The
exception will be a slight shower/thunderstorm chance continuing
across our four eastern counties. Have adjusted probability of precipitation and sky
cover for the above changes with the remainder of the forecast in
good shape. Updated forecast already sent. Hooley


Short term...valid for Wednesday and Thursday...

Current forecast remains on track this afternoon...with three main
pieces to the convective puzzle still in play. The first piece is
the weak shortwave and associated middle-level frontogenesis lifting
into glasgow\s forecast area. That forcing has kicked off an
isolated cluster of strong thunderstorms in northern Rosebud
County. The cumulus field is continuing to develop southeastward
toward Baker. Given that some storms have already broken the
cap...confidence is slightly higher that more storms could develop
toward Baker this afternoon. The second piece is a weak wave
moving across northern Wyoming...which has been perturbing the
cumulus field near Cody and across the Big Horn Mountains. This is
the wave that could force some strong to severe storms as it moves
across northeast Wyoming and southeast Montana. The third piece of
the puzzle is the weak wave lifting into southwest Montana.
Currently...thunderstorms are developing over southwest Montana
near Virginia City to Butte. As this wave continues to round the
ridge axis expect showers and thunderstorms to develop eastward
toward Billings by this evening. Convective activity will diminish
this evening as the wave shifts into the Dakotas.

For tomorrow...the ridge axis builds into the forecast area.
Rising heights over the forecast area along with warm advection
around 700 mb will make for one of the hottest days we have seen
this year. This should also help to keep most portions of the
forecast area dry. Certainly cannot rule out some isolated
thunderstorms especially across far eastern Montana where the
low-level moisture remains in place. However it will be difficult
to break the cap tomorrow with such warm 700 mb temperatures in

Thursday will rival Wednesday in terms of heat across the
forecast area. Deep southwesterly flow ahead of an approaching
Pacific trough and cold front will Foster downslope and
compressional warming. This could push many locations close to 100
degrees again. The main concern will be critical fire weather
conditions with strong winds developing behind the cold front. At
this point we chose to stick with strong wording the severe weather potential statement and fire
weather forecast and to forego a Fire Weather Watch. Model
consensus actually keeps the track of the 500 mb low slightly
farther north than the GFS...more in line with the NAM and ec.
This more northern track decreases the magnitude of the wind
field over the Billings County warning area and thus keeping US below critical
fire weather conditions. Will continue to monitor the latest model
trends to see if any fire weather highlights become necessary.

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

Dry and warm weather will prevail during the long term period. The
large-scale flow aloft over the United States will amplify by this
weekend with a deepening trough in the eastern parts of the nation
and a well-established western trough. The result is northwesterly
flow aloft over southern Montana and north central Wyoming with highs in the
80s f Friday through sun over the lower elevations. Mixing on Friday may
result in gusty winds that day...but then the height gradient will
relax over the weekend with light easterly low-level flow expected
to be in place by early next week when the 500-mb ridge will build
eastward once more. That scenario could yield some isolated storms
during the early and middle part of next week...but our confidence
in coverage is low so outside of the mountains we have a dry fore-
cast in place. Otherwise...700-mb temperatures will rise back into
the +12 to +14 c range again by Monday and highs will likely
rise above 90 f again by early next week. Schultz



Partly to mostly cloudy skies along with VFR conditions will
prevail for the remainder of the night. The exception will be the
possibility of an isolated thunderstorm containing very heavy rain
and strong winds resulting in MVFR to IFR conditions across
southeast Montana through midnight. isolated shower
will be possible. Hooley


Preliminary point temp/pops...

Wednesday Thursday Friday Sat sun Monday Tuesday
bil 063/098 066/098 057/084 057/084 058/086 059/089 061/091
11/b 11/u 11/u 11/u 11/u 11/u 11/u
lvm 055/099 056/091 049/082 048/083 049/087 051/089 055/090
11/u 11/north 10/u 01/u 11/u 11/u 11/u
hdn 059/100 062/101 057/086 056/086 057/087 057/091 059/092
21/b 11/g 11/u 11/u 11/u 11/u 11/u
mls 065/098 067/097 059/084 058/084 058/085 059/088 060/090
32/T 21/u 21/u 11/north 11/u 11/u 11/u
4bq 061/098 064/100 058/085 057/085 057/084 058/087 059/089
32/T 21/u 21/u 11/u 11/u 11/u 11/u
bhk 060/091 062/096 057/082 053/082 053/082 054/083 056/085
32/T 22/T 21/u 11/north 11/u 11/u 11/u
shr 057/098 059/098 053/084 053/084 053/084 054/087 055/087
11/u 11/u 11/u 11/u 11/u 11/u 11/u


Byz watches/warnings/advisories...



National Weather Service Glossary of Abbreviations