Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Billings Montana
327 PM MDT Friday Aug 29 2014

Short term...valid for Sat and sun...

Shortwave ridging is building in over the forecast area late this
afternoon...resulting in mainly clear skies with some fair weather
cumulus clouds across eastern Montana in the wake of this
mornings shortwave passage. A fair evening and night is in store
for south central and southeast Montana...with near normal
overnight low temperatures.

Another shortwave is approaching the forecast area from the
west...and can currently be seen in WV imagery coming on shore in
the Pacific northwest. This wave will traverse the forecast area
during the day Saturday. Shower and thunderstorm activity will
approach Livingston by around 12z and will spread eastward
becoming more widespread and convective by the afternoon. The
strongest instability will be across far eastern Montana...near
Fallon and Carter counties...along with increasing shear into the
afternoon. Thus the threat for isolated severe thunderstorms is
possible in the early afternoon there...however...expect the
threat will quickly evolve eastward into the Dakotas given the
time of the wave. Forecast models continue to indicate some weak
instability lingering across central and western zones behind the
front on Saturday afternoon. Expect to see numerous showers and
thunderstorms from Billings west by the afternoon...with embedded
heavier elements...although storms are not expected to be strong
or severe.

Shower and thunderstorm activity will diminish Saturday night with
the wave passage and diurnal stabilization. Increasing
northwesterly flow behind the wave on Sunday will help to limit
shower and thunderstorm activity despite the cyclonic flow aloft.
Thus expecting a mainly dry day on Sunday...but wont rule out an
isolate shower or thunderstorm by the afternoon...especially near
the mountains. Another weak shortwave may be on track for
Monday...but models disagree on the track/intensity of the wave.
The GFS remains the dry solution...while the ec remains fairly
wet. This will be an important feature to watch for how it will
impact weather on Labor Day.


Long term...valid for Monday...Tue...Wed...Thu...Fri...

Models were in pretty good agreement through the end of next
week. The flow backs to the west Tuesday and southwest Wednesday.
This will be a mainly dry pattern with warmer temperatures. An
upper trough slides across northern Montana and splits Wednesday
night and Thursday. Tail end of the wave moves across the area for
a chance of showers and thunderstorms. A cold front will move
through Wednesday night and provide cooler temperatures for
Thursday and Friday. Southwest flow takes over for Friday into
next weekend but heights were on the low temperatures
will remain slightly below seasonal averages. The GFS was more
aggressive in building heights on Friday and therefore warmer so
will need to be monitored. Will keep low probability of precipitation for Thursday and
Friday with southwest flow and weak waves moving through. Twh


VFR conditions are expected tonight. A few showers and
thunderstorms will move through the mountains this evening. Clouds
will increase from west to east late tonight as a disturbance
moves in. The showers will become more widespread over the west
late tonight and early Saturday. This will impact klvm and the
mountains and foothills with occasional MVFR conditions. The
showers and thunderstorms will spread into kbil and kmls during
the day Saturday. Twh

Preliminary point temp/pops...

Sat sun Monday Tuesday Wednesday Thursday Friday
bil 057/073 054/070 051/070 050/078 052/077 051/072 047/068
16/T 62/west 12/T 11/u 01/u 22/T 33/T
lvm 052/071 044/068 044/068 044/078 045/077 046/072 046/067
27/T 62/west 22/T 21/u 02/T 22/T 33/T
hdn 055/076 053/072 052/071 051/080 052/080 053/075 051/072
04/T 52/T 12/T 11/u 01/u 22/T 33/T
mls 057/079 055/073 052/072 052/080 054/080 053/075 050/071
03/T 42/T 12/T 11/u 01/u 22/T 33/T
4bq 057/084 055/070 052/071 051/080 053/082 054/076 053/074
03/T 43/T 12/T 11/u 01/u 22/T 33/T
bhk 053/078 053/071 048/071 049/078 051/078 052/074 053/070
04/T 52/T 13/T 11/u 01/u 23/T 33/T
shr 052/080 050/070 047/070 045/080 048/080 050/075 049/072
03/T 53/T 22/T 21/u 01/u 22/T 33/T


Byz watches/warnings/advisories...



National Weather Service Glossary of Abbreviations