Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Great Falls Montana
450 PM MST sun Feb 19 2017
Updated aviation section
Tonight through Monday...skies are generally clearing across the
forecast area this afternoon with subsidence following the passage
of a shortwave trough. Scattered rain and mountain snow showers
linger over the forecast area but are expected to dissipate while
exiting to the northeast this evening. Additional new convection
is observed upstream over Idaho. Some of this activity could move
into the western and Southwest Mountains during the evening hours.
Subtle ridging aloft with weak warm advection maintains generally
fair and mild weather for Monday.
Monday night through Wednesday..another atmospheric river sends a
surge a Pacific moisture into the region amid a strong southwest
flow aloft. Most of the accumulating rain and mountain snow will
remain along and west of the Continental Divide, though areas of
light precipitation are expected to move across central Montana at
times. A period of strong winds are expected Tuesday afternoon
across much of central, southwest and south-central Montana. This
is a somewhat atypical path for strong winds as the surface low
tracks through north-central Montana with a lightning of the 700 hpa
gradient. If this feature arrives during the daytime, boundary
layer mixing will help bring these strong winds to the surface.
Temperatures trend cooler on Wednesday as this system weakens and
cooler air begins to move into the Pacific northwest.
Wednesday night through Sunday...a northerly flow develops
bringing a return to more normal late-winter temps areawide. This
northerly flow will likely be accompanied by enough moisture for
periods of snow at times through next weekend.
VFR conditions are mostly expected through the next 24 hours.
However, the moist southwest flow aloft will continue mainly
mountain rain and snow showers. A disturbance in the flow will
continue to bring isolated to scattered showers (with the
possibility of a thunderstorm that could produce gusty winds) to the
southwest Montana terminals through around 04z. Clouds and showers
will generally decrease after 04z as the disturbance exits the area.
Another surge of moisture will then bring a chance of showers to
southwest Montana once again after 18z.
Preliminary point temps/pops...
gtf 32 52 39 54 / 20 20 20 30
ctb 27 43 31 44 / 10 10 20 40
hln 23 43 30 46 / 30 30 40 30
bzn 23 43 32 47 / 40 40 50 40
wey 19 35 31 37 / 70 90 90 90
dln 26 43 36 46 / 20 40 60 40
hvr 30 50 34 51 / 20 10 10 40
lwt 29 52 36 55 / 30 20 20 30