Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 231125
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
525 AM MDT Tue May 23 2017

...Update to Aviation...

.SYNOPSIS...

High pressure ridge will bring mainly clear skies, dry conditions,
and above average temperatures in the 60s and 70s for today. A
cold front could then bring strong winds, cooler temperatures, and
scattered showers for Wednesday into Thursday. Damaging winds of
over 50 MPH may even be found across northern portions. Check out
the High Wind Highlights for the latest details. Memorial Day
weekend will start out cool with temperatures returning to near
normal. Some widely scattered shower activity is also possible at
times.

&&

.DISCUSSION...

Today through Thursday...High pressure ridging over the region
will bring mostly clear to partly cloudy skies and warm
temperatures across the forecast area on Tuesday. By this evening
an upper level low will move from the Gulf of Alaska into British
Columbia. Models are in good agreement showing a strong jet streak
on the south side of this feature reaching the western border of
my forecast area late tonight. Have gone ahead and upgraded the
High Wind Watch to a warning for the Rocky Mountain Front and
adjacent plains with sustained winds likely to exceed criteria,
especially over the plains on Wednesday. Eastern portions of the
watch were NOT upgraded at this time since it will take an extra 6
to 12 hours for strong winds to reach this area. This will give
the day shift an opportunity to view one more model run before
making a decision for this part of the forecast area. A strong
cold front sweeps through North Central Montana with this weather
system for much cooler temperatures and unsettled conditions by
Thursday. mpj

Thursday night through Tuesday...Tightly wound sfc low across
Canada will slowly pull out of the region Thursday night with
diminishing winds, but still breezy at times, expected. A
broadscale trough extending from the upper low in Canada will then
be draped across much of the CWA for Friday. The result will be
continued cooler temperatures with some scattered shower activity.
The best chances for this shower activity will be along and west
of a line from Cut Bank to Great Falls to Billings. Weak
instability could also bring a few thunderstorms, however, they
will be isolated and below severe criteria. We then find ourselves
between a ridge to our west and the large upper low to our east
in central Canada for Saturday. The result will be weakly moist
northerly flow with slightly warming temps. More widely scattered
shower activity is again possible on Saturday, with isolated weak
thunderstorms. The high to our west encroaches a little bit more
each day for the remainder of Memorial Day Weekend, bringing
warming temperatures and only isolated shower and thunderstorm
activity. This ridge then struggles to stay established on
Tuesday, with weak disturbances in nw flow possibly bringing a few
more scattered shower and isolated thunderstorm chances. As
hinted, each day in the extended will be warmer than the previous.
By Sunday into next week 70s could return to the area. Some
models are even hinting low 80s are possible during this time
frame, especially across the central and northern plains. Winds
will be nothing like Wednesday and Thursday, but may be breezy at
times through Sunday especially across the north and east. Anglin

&&

.AVIATION...
Updated 1125Z.
High pressure aloft will bring dry conditions and mostly clear skies
to Montana for widespread VFR condition through early Wednesday
morning. However, an approaching disturbance will bring increasing
westerly winds to north central Montana after 18Z with locations
along the Rocky Mountain Front becoming strong and gusty after 06Z
Wednesday. mpj

&&

.HYDROLOGY...

While significant hydro issues are not expected, we will continue
to monitor stream/river levels over the next 24-48 hours as above
normal temperatures develop beneath the upper level ridge. The
short duration of the warmer temperatures should ultimately limit
the flooding potential. That said, some streams and rivers will
likely run high through Wednesday with increased snowmelt.
Snowmelt should decrease some later this week with cooler
temperatures expected. Martin

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  77  57  62  43 /   0   0   0  40
CTB  77  51  59  40 /   0   0  10  40
HLN  80  53  67  44 /   0   0   0  30
BZN  75  47  69  38 /   0   0  10  20
WEY  67  38  66  29 /   0   0  10  10
DLN  74  47  68  36 /   0   0  10  10
HVR  79  56  69  45 /   0   0  10  40
LWT  72  52  66  40 /   0   0  10  30

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Warning from 6 AM Wednesday to midnight MDT Wednesday
night Eastern Glacier...Eastern Pondera...Eastern Teton...
Liberty...Toole.

High Wind Warning from midnight tonight to midnight MDT
Wednesday night Northern Rocky Mountain Front...Southern Rocky
Mountain Front.

High Wind Watch from late tonight through late Wednesday night
Blaine...Chouteau...Hill.

&&

$$

weather.gov/greatfalls



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