Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 290504
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1100 PM MDT SUN AUG 28 2016

Aviation Section Updated.

.DISCUSSION...
Have made minor adjustment to the Wx grids this evening. Current
forecast looks in good shape. Mid and high clouds have thinned and
will continue to do so through the overnight hours. No precipitation
is expected overnight and temperatures look good.

&&

.AVIATION...
UPDATED 0500Z.
Areas of thin high clouds continue to cross the area on a westerly
flow aloft. Surface winds will be light, becoming generally
southeasterly on Monday across north-central MT. VFR conditions
prevail. PN

&&

.PREV DISCUSSION...ISSUED 337 PM MDT SUN AUG 28 2016

Tonight through Tuesday...High pressure aloft will strengthen
over the forecast area into Monday morning, causing skies to
become mostly clear. Surface high pressure behind a weak Canadian
cold front will also bring cooler air into the area overnight,
for lows closer to normal. The resulting northerly winds will
also help clear out smoke over the plains. However, the front
will not quite make it into Southwest Montana, and the westerly
and southerly winds ahead of the front will continue through the
remainder of the period, which will keep smoke in that area. The
high pressure ridge axis will shift to the east of the area Monday
afternoon through Tuesday, putting the area under a warming
southwest flow aloft. A disturbance in the flow may bring a few
weak thunderstorms with gusty winds mainly to North Central and
Central Montana from late Monday afternoon into Monday night. Weak
instability may bring a few storms to the Continental Divide area
again Tuesday afternoon. Breezy southerly winds at the surface
will also help warm temperatures to around 10 degrees above
normal through Tuesday.
Coulston

Tuesday Night through Sunday...Forecast model solutions continue
to evolve during this period, with some marked changes from
previous runs. Overall, conditions during this period will be
largely influenced by the broad upper-level trof that develops
along the BC/US coast during the first half of the week. Still
expect a handful of weak disturbances to propagate through the
southwest flow pattern ahead of the trof axis, with some isolated
to scattered showers and thunderstorms developing Wed- Fri.
Rainfall amounts with this precipitation still look quite light,
with local amounts being less than 0.1 inch each day where precip
occurs. Model run-to-run consistency is relatively good through
Fri, but significant changes are indicated over the weekend. Most
notably, the main trof is now forecast to track more across
southern Canada, with less moisture and energy coming through the
Northern Rockies. As such, models have backed off somewhat on the
widespread light rain for our region that was going last most of
Sat. We`ll still see areas of rain, but precip coverage and
duration have been reduced. Models do remain in decent agreement
on steadily cooler temperatures from Thurs onward, as cooler air
follows each disturbance and a much cooler Canadian airmass
arrives behind the main trof axis on Sat. After highs in the 80s
through midweek, most sites will be in the mid 70s on Fri and
down to the upper 60s and low 70s by Sun.
Waranauskas

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  50  88  56  91 /   0  10  20   0
CTB  46  84  51  87 /   0  10  20  10
HLN  54  89  56  91 /   0  10  20  10
BZN  49  88  50  91 /  10   0   0  10
WEY  41  78  43  78 /  20   0   0  10
DLN  49  86  50  87 /  10  10  10  10
HVR  49  87  56  92 /   0   0  20  10
LWT  51  84  55  90 /   0   0  20  10

&&

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

$$

weather.gov/greatfalls



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