Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 162352
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
552 PM MDT Wed Aug 16 2017

...UPDATED AVIATION...

.SYNOPSIS...

Mostly dry and, at times, breezy conditions will continue to be the
main themes through the upcoming weekend. Temperatures will be near
to slightly above normal. For those looking ahead to the eclipse on
Monday, much of the area looks to have mostly sunny skies. However,
there may be a bit more in the way of clouds across parts of
Southwest Montana, so stay tuned.

&&

.DISCUSSION...

The main concern over the next several days is fire weather. For a
detailed discussion regarding fire weather concerns, please see the
fire weather section below.

This afternoon, a weak shortwave is combining with weak instability
over the higher terrain of SW MT, producing isolated showers and
thunderstorms. These should quickly diminish by early evening. Later
tonight/Thursday morning, a cold front will dip south out of
Alberta. In the wake of this front, a breezy NW wind will develop,
especially across the plains. This combined with continued dry
conditions will lead to elevated to critical fire weather
conditions. Zonal flow then develops across the region, with
continued breezy conditions at times. Significantly impactful winds
are not expected, but they will likely be high enough to cause
impacts/concerns for the fire community.

Over the weekend, the models continue to advertise yet another
strong cold front dropping south out of Canada. The trend has been
for this front to come in earlier, possibly as early as Friday
night. However, it should quickly return north as a warm front, with
any cooldown being very brief.

As for the much-anticipated solar eclipse, it is looking mostly dry
for most of our forecast area. Medium range models suggest a weak
disturbance may be moving through, which may be accompanied by at
least partly cloudy skies and possibly an isolated shower or storm.
This is subject to change, though, so stay tuned. MARTIN

&&

.AVIATION...
Updated 0000z.

VFR conditions are expected throughout the forecast period. Some
breezy westerly winds will be found through the evening hours
across most sites. A scattered upper level cloud deck will also be
found this evening. Skies then go on a clearing trend tonight into
Thursday. Increased fire activity today will bring some smoke and
perhaps minor visibility reductions throughout the forecast
period. Currently have mention of smoke in the KHLN
area...although...smoke is possible from KGTF and south...perhaps
as far as KBZN and KEKS. Anglin

&&

.FIRE WEATHER...

The weather pattern over the next few days very much seems to
favor elevated to, at times, critical fire weather conditions.
Breezy conditions have developed for some areas today, although
the gusty winds haven`t been quite as widespread as originally
thought. That said, RH continues to be low to very low, with some
sites coming it below 10 percent. We`ll keep the current Red Flag
Warning going given the low RH and gusty winds in spots.

Overnight into early Thursday morning, a cold front will drop
south out of Alberta. In the wake of the front, RH will likely
come up some, but still remain at or below critical levels. In
addition, a breezy NW wind is likely. The wind potential looks a
bit better tomorrow compared to today and we have decided to
upgrade the Fire Weather Watch to a Red Flag Warning for zones 113
and 115 for Thursday afternoon/evening. In addition, we added
zone 117 to the Red Flag Warning for tomorrow, with the greatest
impacts expected across the eastern half of that zone.

Fire weather concerns look to continue into Friday and potentially
Saturday due to breezy/dry conditions. The threat on Saturday
looks a bit more conditional depending on the timing of a cold
front forecast to move through. Models have trended earlier with
the front and lower on the winds Saturday, but we`ll continue to
monitor both days closely. Of note, overnight RH recoveries are
expected to be poor for many areas over the next few nights.
MARTIN

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  55  84  51  89 /   0   0   0   0
CTB  53  81  49  86 /   0   0   0   0
HLN  54  85  52  90 /   0   0   0   0
BZN  46  83  49  88 /   0   0   0   0
WEY  41  73  37  76 /  10  10   0   0
DLN  48  82  47  85 /   0   0   0   0
HVR  56  85  52  91 /   0   0   0   0
LWT  54  81  51  88 /   0   0   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 9 PM MDT this evening Central and Eastern
Lewis and Clark National Forest Areas...Chouteau and Fergus
Counties...Eastern Glacier/Toole/Central/Eastern
Pondera/Liberty...Helena and Townsend Ranger Districts of the
Helena National Forest...Hill and Blaine Counties...Lewis and
Clark National Forest Rocky Mountain District-Rocky Mountain
Front.

Red Flag Warning from noon to 9 PM MDT Thursday Central and
Eastern Lewis and Clark National Forest Areas...Chouteau and
Fergus Counties...Hill and Blaine Counties.

&&

$$

weather.gov/greatfalls



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