Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Great Falls Montana
240 PM MDT Thu Sep 18 2014


Tonight through Saturday...a weak upper level trough and
associated surface cold front will sweep through Montana
overnight. Isolated to scattered showers and thunderstorms will
mainly impact southwest Montana and southern sections of central
Montana this evening with breezy to windy conditions expected for
much of the forecast area. Windy conditions persist through the day
on Friday, especially along the Rocky Mountain front, but do not
expect that high wind criteria will be reached. Temperatures are
expected to be cooler than those of today, and as the mid and
upper level winds shift to a more westerly direction behind the
system, the widespread smoke that has moved into the area should
clear out. Breezy conditions are expected to diminish Friday
night as an upper level ridge begins to build over the western
USA. This ridge will usher in mostly clear skies with seasonable
temperatures and light winds on Saturday. Mpj

Saturday night through Thursday...high pressure will be building
over the region Saturday night and the ridge will be over central
Montana by Sunday. Moisture will begin to move north underneath the
ridge but convection will remain south of the zones. The ridge will
begin to move east of the zones Monday and a shortwave will
approach The Rockies. The air mass will remain very dry and only the
extreme southwest should see any convection. Moisture will slowly
increase across the region Monday night and Tuesday and by Wednesday
afternoon a low pressure trof over the eastern Pacific will be
approaching the West Coast. The GFS is faster with this feature and
has it moved over the West Coast by 00z Thu. The ECMWF, slower, has
it hanging back over 135w. The GFS solution would bring moist,
unsettled flow aloft across the zones Thursday night and Friday, it
would also create an unstable air mass with showers and
thunderstorms likely lasting into the night as the trof continues to
approach The Rockies. However, with the European model (ecmwf) keeping the trof west,
and the Gem more in line with the European model (ecmwf) as well, will keep pops near
climo and wait for the models to come more into agreement.
Temperatures will remain well above normals through the period
although the GFS solution would bring significant cooling on
Thursday. Will keep more moderate temps due to the disagreement in
the models. Zelzer


updated 1730z.
Upper level trough will continue to push eastward through the
northern rockies today. Moist, unsettled flow ahead of this system
will bring a chance of showers and thunderstorms across mainly the
central and southwest portions of the region. Precipitation chances
diminish overnight but breezy to windy conditions are expected this
afternoon and again on Friday morning. Mpj


Preliminary point temps/pops...
gtf 53 75 46 73 / 10 10 0 0
ctb 47 72 42 72 / 10 10 0 0
hln 51 76 47 77 / 10 10 0 0
bzn 45 74 42 74 / 30 10 0 0
wey 37 68 33 71 / 60 20 10 0
dln 47 74 43 75 / 20 10 0 0
hvr 53 78 48 74 / 20 10 0 0
lwt 52 74 47 72 / 30 10 10 0


Tfx watches/warnings/advisories...



National Weather Service Glossary of Abbreviations