Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Great Falls Montana
1140 am MDT Monday Aug 31 2015

high temperatures were increased slightly in areas not under the
influence of the Chinook Arch cloudiness. Speaking of the Chinook
Arch increased sky cover over the northern east slopes for the
rest of this morning and also this afternoon. Finally changed the
mention of areas of smoke to just patchy smoke. Blank


Aviation...updated 1740z.

VFR conditions are expected with any ceilings restricted to above
15000 feet. Gusty winds will continue over the plains then diminish
this evening. Local wind gusts near 50 kts will occur over the northwest
plains into early this afternoon. Confidence is low as to whether
there will be any visibility restrictions due to smoke during the
period and have opted to keep visibilities in the VFR category for


Fire weather...windy conditions will continue across the area
today. Temperatures will continue to trend cooler with most
locations below seasonal averages. Winds will decrease by the
evening hours with dry and near seasonal temperatures expected for
the first half of the week. Some moisture is expected to develop
across parts of the area by Wednesday.


Previous discussion...
/issued 827 am MDT Monday Aug 31 2015/
have updated to increase winds over the Rocky Mountain front and
also over eastern Glacier County for the remainder of the morning.


Previous discussion...
/issued 456 am MDT Monday Aug 31 2015/
Monday through Wednesday...breezy conditions will continue across
the area through Monday due to a decent pressure gradient behind
the the cold front and associated shortwave that moved through
the area late Sunday. Temperatures will be near seasonal averages
or slightly cooler than seasonal averages at most locations with
no significant precipitation expected through the first part of
the week. Smoke is still expected to move into the are due to the
large amount of fires in the Pacific northwest...especially in
Idaho and western Montana. Some moisture looks to move into the
area ahead of the next low pressure system on Wednesday...however
moisture amounts appear to be only minor amounts limited to the
mountains especially along the Rocky Mountain front. Suk

Wednesday night through upper level low pressure trough
will be over the Pacific northwest Wednesday night. The associated
cold front will cross the northern rockies as early as Wednesday
evening and move through central Montana by Thursday morning.
Precipitation amounts with frontal passage will generally be on the
low side. A shortwave moving through the trough will move over the
Idaho Panhandle Thursday evening and the chance for heavier precipitation
will increase, especially over the southwest zones where the airmass
will be slightly unstable. A second shortwave will move into the
Pacific northwest by Friday morning and this will broaden and keep
the trough over the western US. This shortwave will approach The
Rockies Friday afternoon and evening. Weak instability will develop
mainly over the western mountains and southwest Montana Friday and
Saturday afternoons along with a chance of afternoon and evening
thunderstorms. Some timing issues between the European model (ecmwf) and GFS begin to
develop Friday night as the European model (ecmwf) deepens and closes the low over
Washington/Oregon and the GFS continues with an open wave. The
approach of the trough will keep a threat of rain across much of
central and southwest Montana Saturday and Saturday night. The air
mass will become very moist and good precipitation amounts should be
associated with this system. The differences in the models continue
as the GFS moves the trough east of the zones late Saturday night and
Sunday...which would build high pressure and warm and dry the air
mass. However, the European model (ecmwf) keeps the low over southern Idaho Saturday
night and slowly moves it into central Montana by Monday. With these
differences, confidence in probability of precipitation and forecasted temperatures is rather low
during the Saturday to Monday period. Zelzer


Preliminary point temps/pops...
gtf 77 53 83 53 / 0 0 0 10
ctb 69 50 77 50 / 10 0 0 10
hln 79 47 85 50 / 0 0 0 0
bzn 81 45 85 49 / 0 0 0 0
wey 72 33 77 39 / 0 0 10 0
dln 79 44 83 49 / 0 0 0 0
hvr 79 50 83 50 / 0 0 0 10
lwt 78 49 82 55 / 0 0 0 0


Tfx watches/warnings/advisories...



National Weather Service Glossary of Abbreviations