703
FXUS65 KTFX 192344
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
544 PM MDT Sun May 19 2024

.SYNOPSIS...
Showers, thunderstorms, small hail and snow will all decrease over
the area tonight, as drier air moves in for a few hours. However,
expect showers and thunderstorms to redevelop over Southwest MT on
Monday, with the showers becoming more widespread on Tuesday. A
spring storm will affect much of the area Wed and Thu, with
periods of heavy rain and mountain snow expected. Generally, below
normal temperatures are expected for most areas this week.

&&

.DISCUSSION...
Tonight through Tuesday...Expect a variety of weather conditions
over the CWA tonight, with rain, snow, thunderstorms and small
hail all diminishing this evening, as the main upper level trof
moves off to our east. No significant impacts are expected from
the weather this evening. Most snow or small hail accumulations
will only occur on grassy areas. Much of the area starts out dry
tomorrow morning, but a slow moving upper level disturbance moves
into Southwest MT by mid day, producing scattered
showers/thunderstorms by late morning and then continuing into
Tuesday. Again, this thunderstorm activity is expected to be on
the light side for most storms. Afternoon temperatures will warm
up a bit for Monday and Tuesday, with near normal afternoon
temperatures expected on Tuesday.

Wednesday into Friday...A spring storm is expected to affect much
of the CWA for the middle portion of the week. There is a 50
percent chance of 0.25 to 0.75 inches of liquid at lower
elevations and 1 to 1.50 inches in the mountains. There is less
than a 10 percent chance of getting over 2 inches of liquid in the
mountains at this time. The heavy rain could cause some impacts in
the Monarch and Neihart areas. Additionally, snow levels look to
be around 7000 feet. There is a 50 percent chance of over 8
inches of snow in the mountains of Northwest Beaverhead County and
the Tobacco Root Mountains, and about a 30 percent chance over
the Rocky Mountain Front and the Kings Hill area. Thus winter
statements are likely for portions of the CWA for this event. This
system is slow, and it will take almost 2 days to move through
the CWA. Below normal temperatures are expected during this time.
There is also a small concern that snow levels could lower to near
valley floors during the morning hours on Thurs/Fri, which could
impact some bigger lower elevation cities.

Saturday and Sunday...Some forecast models show the potential for
a 2nd spring storm to move through the CWA, while other models
have lighter precipitation. Never the less, below normal
temperatures and the chance for precipitation is looking likely
for most areas at this time next weekend. Brusda

&&

.AVIATION...
20/00Z TAF Period

North-central and Central Montana (KCTB, KHVR, KGTF, KLWT, KHLN):
Scattered showers and thunderstorms will continue across north-
central and central Montana through the rest of the evening with a
chance for some lightning and small hail, particularly for KGTF and
KHVR. There will be a lull in the precipitation overnight into early
Monday morning before another round of showers moves through the
area starting after 20/19Z. Periods of MVFR will be possible with
heavier showers as well as periods of mountain obscuration around
KHLN.

Southwestern Montana (KEKS, KBZN, KWYS): A chance of showers will
persist through much of the TAF period with the potential for
mountain obscuration after 20/14Z. During the overnight hours, rain
is expected to transition to a rain/snow mix with periods of MVFR
conditions possible in heavier showers.

-thor

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

&&

.HYDROLOGY...
A flood watch has been issued for the Kings Hill, Monarch and
Neihart areas from Wednesday night into Friday. There is a 50
percent chance of 1 inch of liquid from this event in this area.
There is a 10 percent chance of 2 inches of liquid. Some of the
precipitation will fall as snow, especially for elevations above
7000 feet, which will help, but for areas lower than 7000 feet,
impacts could develop fairly quickly given how saturated the soil
is and how full the creeks/streams are currently in this region.

At this time, other areas of North Central and Southwest MT should
be able to handle the expected rainfall, but there is the
potential that additional flood statements might be needed. Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  33  59  36  65 /  20  50  20  30
CTB  33  57  34  63 /  30  60  10  20
HLN  36  61  38  66 /  20  60  20  30
BZN  31  56  32  62 /  20  70  40  40
WYS  26  50  28  52 /  30  70  60  60
DLN  34  54  31  59 /  40  60  30  20
HVR  35  61  37  66 /  30  40  10  20
LWT  31  54  33  59 /  20  60  20  40

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Flood Watch from Wednesday evening through Friday morning for
Little Belt and Highwood Mountains.

&&

$$

http://www.weather.gov/greatfalls