Area Forecast Discussion
Issued by NWS Great Falls, MT

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510
FXUS65 KTFX 182302
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
502 PM MDT Wed Oct 18 2017

UPDATED AVIATION

.SYNOPSIS...

Breezy west to southwest winds will increase late today and tonight
across North Central Montana with windy and warmer conditions
returning Thursday. Dry and windy conditions will raise fire
concerns across Central Montana Thursday. The next front moves
across the region with showers across Southwest Montana Friday,
cooler temperatures, and windy conditions through Sunday.

&&

.DISCUSSION...

Tonight through Friday...Transient high pressure exits the region
today with the next upper trough moving from the Gulf of AK toward
the BC coast. Winds aloft will increase from the SW again later
today and tonight. Gusty SW winds will persist across North-Central
MT during the period with the strongest winds along the Rocky Mtn
Front. Southwesterly flow aloft allows for temperatures to surge
back to well above average Thursday as well. The upper level trough
moves inland Thursday night and Friday with a surface front moving
east across the forecast area by Friday afternoon. Precipitation
will increase along areas near the Continental Divide Friday with
showers also possible across Southwest Montana. Temperatures cool
about 10 to 15 degrees for Friday and Saturday.

Friday night through Wednesday...Look for spotty, light showers to
persist following the passage of the cold front through the
overnight hours Friday night and into Saturday. As colder air
filters in from the north, temperatures will likely continue to
drop, along with freezing-levels leading to the potential for
accumulating snow for higher elevations of south-central and
southwestern MT, especially along the Madison, Bridger and Gallatin
Ranges. This system will quickly depart early Saturday leaving
behind clearing skies with cool afternoon highs. However, by
Saturday night clouds will begin to increase from the west as
another quick moving system swings across just north of the
MT/Canadian Border. Behind this system, models continue to
confidently illustrate the development of a strong jet aloft, which
will push eastward across the Northern Rockies into the early hours
on Sunday. This will likely yield yet another high wind event across
most of the CWA beginning Sunday morning, with the peak of the event
being in the afternoon hours. Given forecast H7 wind speeds ranging
between 55-75kts across the Plains, and even higher along the Rocky
Mountain Front, strong winds aloft will have no trouble transferring
to the surface via sufficient boundary layer mixing. Having said all
of that, I have adjusted forecast wind speeds reflect a more
realistic possibility of high winds following the jet aloft, timed
with the best diurnal mixing in the afternoon hours. Looking at the
synoptic pattern as we get into next week, long-range models have
persistently been advertising the development of a re-enforcing
ridge across the Southern Pacific coastline, which will reflect
increasing heights across the majority of the western US. As strong
ridging amplifies along the entire west coast, this will transition
the upper-level flow more from the northwest and aid in the
development of a dominant surface high across the northern Rockies.
This will likely keep temperatures near, to slightly above normal
while staying dry through the middle part of next week. KLG


&&

.AVIATION...
Updated 2302Z.

VFR expected next 24-hours. Westerly flow aloft will become
southwesterly as a high pressure ridge exits to the east and a
trough aloft approaches from the Pac NW. Just a few rain/snow
showers will affect central and northern portions of the Continental
Divide. Breezy southerly to southwesterly surface winds are expected
over North-Central MT and at/near KEKS through the period, while
instances of low-level wind shear, mountain wave activity, and
turbulence are likely.
Jaszka

&&

.FIRE WEATHER...

Breezy west winds this afternoon will continue into Thursday.
Additionally, afternoon temperatures will warm into the mid/upper
70s with humidity falling into the low teens over the eastern
portions of the region. Thus a Red Flag Warning is in effect for
this region. More seasonable temperatures and slightly higher
humidity move back into the region on Friday. However, it will
remain windy most days from Friday through early next week.
Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  52  73  48  58 /   0   0   0  40
CTB  45  65  42  55 /   0   0   0  10
HLN  42  70  43  55 /   0   0   0  40
BZN  40  71  43  58 /   0   0   0  70
WEY  28  57  33  48 /   0   0   0  70
DLN  38  67  42  51 /   0   0   0  60
HVR  49  73  43  62 /   0   0   0  20
LWT  47  74  45  59 /   0   0   0  40

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 11 AM to 7 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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