Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Glasgow Montana
344 am MST Monday Mar 2 2015
Short term...for northeast Montana...today through Wednesday...
Water vapor imagery and 500 mb height field show the highly
amplified weather pattern...especially across the western states.
The atmosphere near northeast Montana has lately been in a relatively
benign and more transitional pattern.
A strong cold front set to push through the area tonight looks to
change that. As an upper level trough from northern Canada quickly
pushes the trough axis and its associated cold front straight down
the Front Range and High Plains regions...a sudden drop in surface
temperatures will not be far behind. Compared with Monday...daytime
temperatures are expected to be around 25 degrees colder on
Tuesday with nighttime temperatures 10 to 15 degrees colder. With
the gusty winds expected...confidence is quite high that
conditions will be right for a Wind Chill Advisory beginning this
evening and continuing through early Wednesday morning. There
seems to be just enough forcing for ascent and moisture to squeeze
out some snow with this frontal system as well...but amounts are
expected to be on the lighter side...generally 1 inch or
less...with maybe up to 2 inches for our far western zones.
Some lingering light snow showers will be possible again on
Tuesday as the cold core of Arctic air squeezes out any remaining
moisture. Accumulations will be light.
Upper-level ridging will return to the region from the west later on
Wednesday for a sudden rise in temperatures through the latter
part of the week under a mainly dry weather pattern. Bmickelson
Long term...Wednesday night through Monday...
The northwest flow aloft will transition from an Arctic origin to
a Pacific origin between Wednesday and Thursday. This will bring a
warming trend to northeast Montana. The Arctic air mass moves to
the east Wednesday night as a warm front moves through the area.
The warming will be aided by Chinook winds on Thursday which will
result in temperatures being as much as 30+ degrees warmer than on
Wednesday. At this point...the frontal passage is expected to be
dry. The mild and dry weather will continue on Friday with a
shortwave ridge in the northwest flow aloft.
European model (ecmwf) and GFS have significant disagreements on the track of a
shortwave trough across the region Friday night and Saturday. The
European model (ecmwf) wants to take the wave through western Montana and Idaho
while the GFS wants to take through Saskatchewan and North Dakota.
At this point... it looks like either scenario bring a weak cold
front through northeast Montana with the moisture tracking either
to the west or to the east of the forecast area. Will keep
forecast dry with slightly cooler temperatures on Saturday.
Northwest flow aloft continues Sunday and Monday with models
timing waves differently. Not much in the way of moisture at this
point. Will maintain dry forecast. Forrester
Synopsis: a cold front over central and southern Alberta this
morning will move south today and across northeast Montana this
afternoon. Northwest winds 20 to 25 knots are expected behind the
Flight category: VFR with increasing middle and high clouds this
morning ... MVFR level low clouds spreading from northwest to southeast after
21z this afternoon. Conditions will improve to VFR by 06z tonight.
Llws: between 12z-18z in the pre-frontal environment there exists
a good threat of low level wind shear between 015-020 mainly east of kggw.
Ceilings and vsby: VFR through most of the period with MVFR ceilings
moving in after 21z from northwest to southeast. Isolated to scattered snow
showers are possible 21z to 06z. Ceilings will improve to low VFR
Wind Chill Advisory from 7 PM this evening to noon MST Wednesday
for central and southeast Phillips...central and southern
McCone...northern Phillips...northern valley...Petroleum...