755
FXUS65 KTFX 131727
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1127 AM MDT Mon May 13 2024

...Aviation Section Updated...

.SYNOPSIS...

One final warm day is expected today before a cold front brings
cooler and potentially smokier conditions to the area for midweek
and beyond. For today, expect a few showers and thunderstorms to
pop up this afternoon, mostly across Southwestern Montana with
just a few across the plains. A more widespread round of showers
and thunderstorms is expected on Tuesday as a cold front pushes
through the area.

&&

.UPDATE...

Visible satellite and radar imagery this morning shows a line of
showers have developed from the northeast side down to the western
side of Glacier National Park. These showers are likely (30%) to
continue to develop and move eastward along the Rocky Mountain
Front later this morning. Minor adjustment to probability of
precipitation for the Rocky Mountain Front in the next 2 to 3
hours for rain shower development. Otherwise, the forecast remains
on track for today with more showers and a few thunderstorms this
afternoon and evening. Webb

&&

.AVIATION...
13/18Z TAF Period

Concerns this TAF period include increasing westerly to
northwesterly winds this afternoon primarily across the plains,
widely scattered showers and thunderstorms this afternoon into the
overnight across most areas, and low VFR to MVFR ceilings across the
plains tomorrow morning associated with additional showers. Overall,
the scattered nature of showers and thunderstorms this afternoon as
well as limited confidence with respect to timing of any
thunderstorms at terminals has led to the exclusion of thunder
mentions in TAFs at this time. Trends will be monitored this
afternoon, with thunder mentions being introduced as confidence in
the situation grows. Any showers or thunderstorms will carry a gusty
outflow threat. -AM

Refer to weather.gov/zlc for more detailed regional aviation
weather and hazard information.

&&

.PREV DISCUSSION...
/ISSUED 515 AM MDT Mon May 13 2024/

-A few thunderstorms are expected today, with the best chances
across Southwestern Montana

-Wet weather expected Tuesday, with cooler temperatures for the
rest of the week

Short term (through Tuesday)... Upper level ridging responsible
for the warm temperatures that we have had over the weekend will
begin to shift to the east today, but not before allowing for one
final day of warm temperatures in the 70s across North Central and
Southwestern Montana. As this ridge moves east, a shortwave
trough will begin to slide into the area from the west, which,
combined with the warm temperatures, will help kick off a few
showers and thunderstorms across the area, first across
Southwestern Montana with a few showers popping up across the
North Central plains. While these showers and storms should be
fairly run of the mill type cells, though forecast model soundings
across the plains do support the development of some disorganized
outflows that could produce wind gusts to 40 mph or so. Most of
these showers will dissipate after sunset, with just a few
lingering through the overnight.

A second, more widespread, round of showers and thunderstorms
will move through the area on Tuesday as a cold front pushes into
the area from Canada. Like tomorrow, most of these showers and
storms should be fairly benign, with just a few areas of breezy
winds as the storms pass. Behind these storms, noticeably cooler
air will work into the area, keeping highs in the low to mid 60s.
In addition, this cooler air will potentially be accompanied by a
return of widespread smoke and haze from the wildfires that have
begun to resurrect across Western Canada, but we will need to get
a bit closer to get a better grasp on how much smoke will work
into the area.

Extended (Wednesday through next Monday)... Expect seasonable
weather through the second half of the work week as upper level
ridging over the eastern Pacific keeps our upper level flow
westerly to northwesterly with a few weak disturbances moving
through the area. For the most part, these disturbances will
mostly just result in some periods of gusty winds Thursday and
Friday as a few rounds of cooler air work their way into the area,
but areas along and north of US 2 could see a few periods of light
rainfall Thursday and Friday as these disturbances move through.
Looking towards the weekend, there seems to be some consensus that
a slightly more notable trough will work its way into the Northern
Rockies, which could help spur some more widespread rain and
mountain snow to at least parts of the area for the weekend.
Ensembles diverge for the start of the new work week, though the
overall pattern appears to remain unsettled as we head into next
week. Ludwig

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  75  46  61  44 /  40  40  80  30
CTB  73  46  62  41 /  40  60  60  20
HLN  77  50  66  46 /  20  20  70  30
BZN  74  43  64  41 /  30  60  70  40
WYS  65  36  57  34 /  60  70  70  20
DLN  72  41  64  42 /  30  30  40  10
HVR  78  48  66  44 /  50  40  40  20
LWT  72  45  58  41 /  20  40  80  40

&&

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

$$

http://www.weather.gov/greatfalls