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Area forecast discussion 
National Weather Service Great Falls Montana
1120 PM MDT Thursday Aug 25 2016

Aviation section updated.

update forthcoming. Have dropped most pops across the southwest per
latest radar imagery and because hrrr analysis does not support
convective activity there overnight. Radar imagery does show the
weak cold front stretching southwest to northeast across much of
central Montana and which is about to move through Great Falls.
Showers have been developing across the hi-line most of the evening
and this has been corroborated by hrrr analysis. Current forecast of
showers overnight and into Friday morning across northern and
central Montana appears to be on track. Temperatures look good.


updated 0620z.
A cold front has moved through north-central Montana and will
continue advancing southward through Friday morning. Satellite and
radar imagery reveals isolated light showers with generally scattered to
broken mid level clouds across the region. Short-term model guidance
indicates a gradual increase in cloud cover over north-central Montana
through Friday afternoon. Scattered rain showers are also indicated
early Friday morning and again Friday afternoon, mainly impacting
khvr and klwt. Conditions improve from west to east Friday evening
as the upper level disturbance moves away. VFR conditions prevail in
general, although temporary MVFR are possible near rain showers. Pn


Previous discussion...issued 308 PM MDT Thursday Aug 25 2016

Tonight through Saturday...water vapor pix show a broad trof
moving east of the zones with northwest flow aloft across Alberta
and central Montana. Clouds ahead of a disturbance in this flow have
crossed the Canadian border. The air mass will be unsettled during
the night, especially across the central and northern zones, and
some showery activity is expected through Friday.
However, precipitation amounts will remain low. Extreme southwest
Montana will become unstable Friday afternoon and isolated
thunderstorms are possible. Also, most of the higher elevations
along the eastern zones will be underneath the trof during the
afternoon and a thunderstorm or two cannot be ruled out there, as
well. Winds aloft will strengthen Saturday ahead of an approaching
low pressure trof to the west. This will dry lower levels and help
keep the region stable through the day. Temperatures will remain
below normals again Friday but rise 5 to 10 degrees above normals
Saturday. Zelzer

Saturday night through Thursday...medium range models continue to
show that the upper level pattern will be dominated by a western
Canada trough for much of next week. This remains similar to
earlier forecast runs but the most recent model runs appear to be
slightly weaker with this feature and have backed off a bit on
possible shower coverage. It is also Worth noting that the European model (ecmwf)
appears to have trended toward the GFS solution that keeps bulk
of the energy associated with the upper trough in a closed low
over Southeast Alaska. As noted yesterday, both models keep
Montana beneath southwest flow aloft through the period.
Tonight's model runs suggest that shortwave energy ejecting from
the West Coast trough will likely move through Canada rather than
Montana which would help to explain the slightly lower pops that
solutions are presenting tonight. Have once again made only minor
changes to the going forecast with early to mid-week pops being
reduced somewhat and temperatures perhaps a degree or two warmer.


Preliminary point temps/pops...
gtf 46 70 51 84 / 30 20 10 10
ctb 47 68 51 80 / 60 20 10 10
hln 49 73 50 84 / 10 20 10 10
bzn 43 72 44 82 / 10 20 10 0
wey 36 66 38 70 / 20 20 10 0
dln 43 73 44 80 / 10 10 0 0
hvr 50 71 49 84 / 30 50 0 0
lwt 46 66 48 81 / 20 40 10 10


Tfx watches/warnings/advisories...



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