Area Forecast Discussion
Issued by NWS Great Falls, MT

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229
FXUS65 KTFX 240917
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
317 AM MDT Sat Jun 24 2017

.SYNOPSIS...

An upper level ridge of high pressure will gradually build over
the Northern Rockies through the weekend. Slightly unstable
northwest flow aloft ahead of the ridge will bring a few showers
to the region on Saturday, but mostly dry conditions on Sunday as
the ridge axis moves overhead. Afternoon high temperatures will
continue to warm a few degrees each day with hot conditions
expected by Monday.

&&

.DISCUSSION...

Today through Monday...Main player in short term forecast
continues to be an upper level ridge along the West Coast. Ahead
of this ridge, a slightly unstable northwest flow aloft will
continue to affect North Central Montana today. Main impacts of
this flow will be mid-level clouds and a few light rain showers or
sprinkles continuing into this evening. Meanwhile, Southwest
Montana will remain generally dry and mostly clear. By late
tonight the upper ridge axis will begin to shift eastward bringing
mostly clear skies along with dry and warm conditions on Sunday.
Temperatures continue to increase on Monday as the thermal ridge
shifts into the state leading to hot conditions. However, as the
ridge continues to shift eastward, flow aloft over the state
becomes southwesterly late Monday with an increasing chance for
showers and thunderstorms as unstable air advects into the region.
mpj

Monday Night through Friday...A cold front associated with a surface
low over central Alberta passes through the forecast area Monday
night. A weak shortwave aloft will aid in developing scattered
showers and thunderstorms along the front Monday night through early
Tuesday morning.  A large and closed upper level low develops over
western Canada on Tuesday, then drops into the high plains through
the end of the week. This change to a generally northwest flow aloft
will maintain slightly cooler than average temperatures, with
periods of rainshowers and afternoon thunderstorms.  PN

&&

.AVIATION...
Updated 0425Z.

Northwest flow aloft will remain in place over the Northern Rockies
and Northern High Plains through the 2406/2506 TAF period. VFR
conditions will prevail, however, lowering ceilings to around 5000ft
AGL are expected to occur at the KCTB, KHVR, and KLWT terminals
after 12z Saturday. Ceilings at the KCTB terminal may approach MVFR
for a brief period during the early morning hours on Saturday, but
confidence is to low to mention at this time (outside of using
SCT030). Some mountain obscuration is possible, especially along the
Northern Rocky Mountain Front. Otherwise, winds are expected to be
light and variable. - Moldan

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  73  47  81  54 /   0  10   0   0
CTB  72  45  80  51 /  10  10   0   0
HLN  77  50  84  55 /   0   0   0   0
BZN  75  44  82  49 /   0   0   0   0
WEY  71  37  77  39 /   0   0   0   0
DLN  75  45  81  52 /   0   0   0   0
HVR  75  46  82  53 /  10   0   0   0
LWT  69  44  77  51 /  10   0   0   0

&&

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

$$

weather.gov/greatfalls



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