Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 142321
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
520 PM MDT Sat Oct 14 2017

...UPDATED AVIATION SECTION...

.SYNOPSIS...

Breezy conditions will continue across north-central Montana through
much of the upcoming week with particularly strong winds possible
on Tuesday and Wednesday. Temperatures warm to seasonal averages
or better on Sunday, then warm well above seasonal averages Monday
and Tuesday.

&&

.DISCUSSION...

Tonight through Monday Night...North-central and southwest
Montana continues to see an active large-scale jet stream pattern
transition from our south and west to our north and east today,
where it will remain for the next several days under fast west to
northwesterly flow. With the transition to the warmer side of the
jet stream, temperatures will steadily increase the next couple of
days, first to near normal readings Sunday and then above normal by
Monday and Tuesday. Within the active jet stream, smaller jet
streaks will eject from the parent jet stream and brush our northern
areas and will produce breezy/windy conditions across the plains and
higher elevations of central Montana. Strongest winds will persist
along the Rocky Mountains and adjacent Rocky Mountain Front where
winds and wind gusts will be exacerbated by persistent mountain wave
activity. By late Monday into Monday overnight, a low pressure
system developing over central Alberta will have the potential to
increase winds to the point that wind highlights may be needed. CC

Tuesday through Saturday...A strong zonal flow prevails over the
forecast area through mid-week, producing an extended period of mild
and windy conditions. A warm and deeply mixed boundary layer Tuesday
afternoon will help translate higher momentum aloft into strong
surface wind gusts. Wind gusts could reach high wind criteria,
possibly warranting high wind headlines on subsequent shifts.
Temperatures and wind speeds trend slightly lower on Wednesday as
surface pressure rises to our north over the Canadian prairies. Mild
and windy conditions return on Thursday associated with another
developing clipper system. Winds relax later Thursday night as the
clipper pulls away to the east.  The pattern changes on Friday into
Saturday. Models indicate a longwave trough crossing the PacNW, with
a substantial increase in moisture providing high chances for rain
and mountain snow mainly along and west of the Continental Divide. PN

&&

.AVIATION...
Updated 2320Z.

VFR conditions will continue over the forecast area through at least
Sunday afternoon. Gusty westerly winds will be the main forecast
issue for the period. Winds should decrease in the southwest
valleys, but gusty winds will persist over the plains. Gusts there
will generally be in the 20 to 30 kt range, but gusts along the
Rocky Mountain Front could range from 40 to 50 kt at time, likely
causing mountain wave turbulence. Otherwise, a moderate northwest
flow aloft will bring areas of mid and high clouds to the forecast
area, especially along and west of the Continental Divide.
Coulston

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  36  60  43  68 /   0   0   0   0
CTB  33  57  40  65 /   0   0   0   0
HLN  34  59  37  67 /  10   0   0   0
BZN  28  58  31  64 /   0   0   0   0
WEY  22  45  23  52 /   0   0   0   0
DLN  27  54  30  62 /   0   0   0   0
HVR  31  59  39  67 /   0   0   0   0
LWT  32  59  39  67 /   0   0   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

weather.gov/greatfalls



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