Area Forecast Discussion
Issued by NWS Great Falls, MT

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673
FXUS65 KTFX 250253
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
853 PM MDT Sat Jun 24 2017

.UPDATE...
850 PM Update...Updated evening forecast is out. Just a few
sprinkles left from Great Falls eastward to Lewistown. Most of
these sprinkles should diminish by 11 PM or so. Otherwise expect
clearing skies over the region for the rest of tonight. Thus I
lowered temperatures a bit for the colder locations along the
Rockies and in Southwest MT...such as Wisdom, West Yellowstone,
Elk Park, etc.

Looking ahead...Sunday should be dry, sunny and warm across the
region. Monday will be very warm and windy. Most of the
thunderstorms will hold off until Monday evening. However...a few
storms could be strong as they move through the region Monday
night. Brusda

6 PM Update...just did a quick update for light rain showers
northwest of Great Falls and southeast of Big Sandy. The rest of
the forecast is on track. Brusda

&&

.SYNOPSIS...

A northwesterly flow aloft will reside over the region
tonight...resulting in a few isolated light rain showers over North
Central MT this evening...while mostly clear skies prevail over
Southwest MT. On Sunday...an upper level ridge of high pressure will
build over the region...resulting in dry and warm conditions across
the region. It turns very warm on Monday...with afternoon highs
ranging from the upper 80s to mid 90s...with thunderstorms possible
Monday night.

&&

.AVIATION...
Updated 2325z.

As of 2330z, scattered light rain showers were being sampled across
North Central Montana via the KTFX radar. While these shower could
be producing some light rainfall amounts, the main concerns to
aviation interest are the breezy/gusty surface winds that could be
generated as the precipitation falls through relatively dry air and
subsequently evaporates. These breezy/gusty winds are most possible
at the KCTB, KHVR, KGTF, and KLWT terminals through approximately
03z. The aforementioned shower activity is expected to decrease with
the loss of daytime heating, and thus bringing an end to the
breezy/gusty wind potential. Otherwise, VFR conditions are expected
to prevail through the 2500/2524 TAF period. - Moldan

&&

.FIRE WEATHER...
There is increasing concern for the potential of critical fire
weather conditions occurring Monday afternoon through early
evening ahead of a lee-side surface trough over Blaine and
possibly northeastern Fergus County and far eastern Hill County.
Gusty southeast winds are expected ahead of this feature along
with minimum afternoon humidity levels dropping below 20 percent.
With fuels rapidly drying due to ongoing drought in these areas,
we have opted to issue a Fire Weather Watch for Fire Weather Zone
113 for Monday afternoon and early evening with this afternoon`s
forecast package. cc/Brusda

&&

.PREV DISCUSSION...
/ISSUED 525 PM MDT Sat Jun 24 2017/

This evening through Monday night...Expect mostly dry isolated
showers over north-central Montana to diminish with the loss of
daytime heating and with the associated disturbances continuing to
move south and east away from the area. 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. A sharpening surface lee trough over our far eastern
plains counties will allow for gusty winds in the afternoon along
with dry conditions, allowing for an increased threat of critical
fire weather conditions. A cold front passes associated with a
surface low over central Alberta will combine with a mid-level
disturbance and allow for some showers and possibly thunderstorms
to develop Monday evening through early Tuesday. cc/mpj

Tuesday through Friday...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 rain showers and afternoon
thunderstorms. PN

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  45  81  54  92 /   0   0   0  10
CTB  46  80  51  90 /   0   0   0  10
HLN  47  86  55  93 /   0   0   0  20
BZN  42  82  49  90 /   0   0   0  10
WEY  29  75  39  79 /   0   0   0   0
DLN  43  84  52  88 /   0   0   0  10
HVR  45  80  53  94 /   0   0   0   0
LWT  43  75  50  86 /  10   0   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...

Fire Weather Watch from Monday afternoon through Monday evening
Hill and Blaine Counties.

&&

$$

weather.gov/greatfalls



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