662
FXUS65 KTFX 181815
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1215 PM MDT Tue Jun 18 2024

.SYNOPSIS...

Widespread precipitation pushes off to the east this morning, with
another round of precipitation with a few thunderstorms arriving
this afternoon. Daily precipitation chances remain through the
forecast period, with better chances arriving Friday. Temperatures
gradually warm up, becoming well above average by the weekend.

&&

.UPDATE...

Noon... Allowed the Winter Weather Advisories to expire at noon.
High elevation snow showers will be around this afternoon and
evening, but impacts are expected to be more isolated in nature.
-AM

815AM... The only significant update this morning was to cancel
the Winter Weather Advisory for the Southern Rocky Mountain Front
a bit early. Otherwise, remaining Winter Weather Advisories will
continue through the remainder of the morning.

Precipitation trends from being stratiform to more convective in
nature this afternoon, with showers and a few thunderstorms
becoming numerous across the region by mid afternoon. With snow
levels gradually rising through the day today, the expectation is
that impacts from snow should largely diminish after noon. -AM

&&

.AVIATION...
18/18Z TAF Period

The primary concern this TAF period will be for lingering low
clouds, as well as numerous showers and scattered thunderstorms
developing this afternoon and early evening. Confidence in
timing/location of any thunderstorms was too low to warrant a
thunderstorm mention in TAFs at this time, but will be monitored
through the afternoon for amendments. The greatest uncertainty this
forecast period will be for fog development around daybreak
tomorrow. Clearing skies and recent precipitation will be favorable
for fog, but the length of clear skies prior to daybreak will
ultimately determine who does and who does not get fog. Mountains
are likely to be obscured through the evening. -AM

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

&&

.PREV DISCUSSION...
/ISSUED 511 AM MDT Tue Jun 18 2024/

Today...Widespread rain and mountain snow showers will slowly push
off to the east along with the main upper level wave this morning.
Snow levels at 4,500ft to 5,000ft can accumulate a few more inches
of snow early this morning(mainly on grassy surfaces).
As the sun comes up, snow levels will rise back to 6,000-7,000ft.
This combined with widespread snow moving out of the area, I`ve kept
the Winter Weather Advisories to expire this morning (6am for
Central/Southwest MT mountains and 12pm for the Northern Continental
Divide). Wind chills will be cold this morning. Lower elevations is
forecasted for wind chills to drop into the 20s-30s while mountain
locations can drop into the teens. Another upper level disturbance
from Canada will push south into the region this afternoon,
producing more scattered to widespread showers. A few thunderstorms
is also expected with showers this afternoon. These showers can
bring up to another 0.1-0.25" of moisture. Showers will taper down
during the evening, ending around midnight.

Wednesday and Thursday...Northwest flow aloft will transition to
southwest flow aloft over the next few days. The southwest flow will
help bring in warmer air and help moderate temperatures closer to
normal averages. There will be upper air disturbances passing
through that will produce isolated showers/thunderstorms (primarily
across Central/North Central MT). Precipitation amounts look to be
light. The NBM 75th percentile in precipitation amounts shows the
CWA receiving up to a 0.1" of moisture for both days.

Friday...A small shortwave trough passing through will bring better
chances for scattered/widespread precipitation, primarily for
central and eastern portion of the CWA. There`s a 40-60% from
Central Chouteau, Judith Basin, and Hill Counties and to the east of
receiving 0.25" of precipitation.

Saturday and beyond...By the weekend, temperatures will be well
above normal across the region. We will be monitoring locations
across the CWA reaching 90 degrees for the first time this year on
Sunday. The climatological average for the first 90 degree day of
the year happens on June 23rd for Great Falls and Bozeman, June 26th
for Helena, and June 12th for Havre. NBM probabilities are showing a
50-60% for high temperatures reaching 90 degrees around the Helena
and Bozeman area, and 30% for the Great Falls area. The beginning of
next week brings more low chances for precipitation daily. -Wilson

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  59  37  67  41 /  80  50  30   0
CTB  54  31  64  38 /  80  40  30   0
HLN  61  40  72  46 /  70  40  20   0
BZN  55  33  68  39 /  50  50  10   0
WYS  50  25  62  32 /  60  20  10   0
DLN  55  31  66  37 /  40  40   0   0
HVR  60  41  68  45 /  60  50  30   0
LWT  55  34  65  41 /  90  30  40  10

&&

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

$$

http://www.weather.gov/greatfalls