Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 240248
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
848 PM MDT Fri Jun 23 2017

.UPDATE...

Only minor adjustments to going forecast overnight. Main change
was to lower lows for tonight, mainly in the colder mountain
valleys along the Rocky Mountain Front and south into Southwest
Montana, as those areas should remain mostly clear. Clouds
currently along the east slopes of the Rockies seem to be being
reinforced by clouds moving south from the east slopes of the
Canadian Rockies in Alberta. Have therefore kept skies mostly
cloudy along our east slopes overnight. Only a very small chance
of a passing light rain shower over the plains. Winds also appear
to remain light overnight with high pressure at the surface.
Coulston

&&

.SYNOPSIS...

An upper level ridge of high pressure will gradually build over
the Northern Rockies over the weekend. As a result, expect a few
isolated showers over the region early this evening and again on
Saturday, while it will be mostly dry on Sunday. Afternoon
temperatures will gradually warm over the next several days, from
the mid 70s on Saturday to around 90 degrees by Monday.

&&

.AVIATION...
Updated 2235Z.

Northwest flow aloft will remain in place over the Northern
Rockies and Northern High Plains through the 2400/2424 TAF
period. VFR conditions are expected through the entire TAF
period, however, lowering ceilings to around 5000ft AGL are
possible at the KCTB, KHVR, and KLWT terminals after 12z
Saturday. Confidence in areal coverage of these lower ceilings is
low at this time, so only went with prevailing SCT for these
lowest ceilings over the aforementioned terminals.
- Moldan

&&

.PREV DISCUSSION...
/ISSUED 535 PM MDT Fri Jun 23 2017/

Tonight through Sunday...A northwesterly flow aloft continues to
reside over the region...resulting in a few light rain showers
along the divide. These showers will drift to the southeast this
evening...but should generally remain west of I-15. Otherwise
mostly clear skies will prevail...especially over Southwest MT.
Another cool/crisp night is expected, especially for the valleys
of the Southwest...thus some delicate/sensitive vegetation could
be at risk once again. On Saturday, the upper level ridge builds
a bit further north/east resulting in slightly warmer
temperatures. A few spotty light showers will once again be
possible...mostly over North Central MT. On Sunday, the upper
level ridge continues to drift further east, resulting in mostly
dry and warm conditions over the region.
Brusda

Sunday Night through Thursday...The weekend warming trend peaks
on Monday as the upper level ridge axis passes over the region.
Warm temperatures Monday afternoon will produce adequate
instability to cause scattered afternoon and evening
thunderstorms. Some of this activity could persist late Monday
evening, aided by a shortwave trough approaching from the PacNW.
A large scale trough develops over western Canada on Tuesday,
then drops into the high plains through mid-week. Diverging model
solutions provide little useful guidance regarding the passage of
shortwave features embedded within the broadly NW flow aloft.
Overall, temperatures trend cooler Tuesday through Thursday, with
slight chances for showers and thunderstorms associated with the
minor shortwave disturbances.
PN

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  43  73  47  81 /   0   0   0   0
CTB  41  72  45  80 /   0  10  10   0
HLN  46  77  50  84 /   0   0   0   0
BZN  42  75  44  82 /   0   0   0   0
WEY  31  71  36  77 /   0   0   0   0
DLN  42  75  45  81 /   0   0   0   0
HVR  44  75  47  82 /   0  10   0   0
LWT  41  69  43  77 /   0  10  10   0

&&

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

$$

weather.gov/greatfalls



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