000
FXUS65 KTFX 192317
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
516 PM MDT Fri Apr 19 2024

Aviation Section Updated

.SYNOPSIS...

After one more widespread hard freeze tonight and Saturday
morning, a warming trend begins this weekend, with above average
temperatures returning early next week. A passing weather systems
will bring windy conditions Sunday and Monday, but little in the
way of precipitation is expected until the second half of the work
week.

&&

.DISCUSSION...

Current satellite/radar imagery depicts lower level clouds and
areas of light snow/flurries over the plains and scattered
mountain cloudiness over the higher terrain of the southwest. The
combination of cloud cover with -15 to -20C H700 temperatures is
keeping this afternoon`s temperatures mostly in the lower/middle
30s for northern areas and only slightly warmer farther south.
Partial clearing will take place tonight, paving the way for one
more widespread hard freeze.

Ridging aloft then moves in and commences a warming trend for the
weekend into early next week. Despite the moderating
temperatures, a closed low and attendant trailing cold front is
still expected to temporarily displace the ridge on Sunday and
bring a period on gusty westerly winds and perhaps a few hit or
miss showers. H700 to H500 winds, supported by cold air advection
aloft, will reach and exceed the 40 to 50kt range. The stronger
winds will initially be confined to the eastern slopes of the
Northern Rocky Mountain Front Sunday morning, but will quickly
spread eastward onto the plains by the afternoon hours with the
passage of a Pacific cold front and efficient diurnal mixing.

Current probabilistic guidance only supports higher end chances
(70% +) for wind gusts in excess of 55 mph along the Rocky
Mountain Front and the adjacent high plains, but the set up
described above should result in routine gusts in the 40 to 55 mph
for most Central/North-central locations and gusts in the 30s and
40s in Southwest Montana. The inherited High Wind Watch was left
as is for now and the situation will be monitored over the next
day or so for any potential upgrades/expansion and or shifts in
timing. The stronger winds do raise some fire weather concerns,
with RHs forecast to be in the 20s during the period of strongest
winds, but recent moisture is expected to preclude any widespread
elevated fire weather risks.

Ensembles remain in good agreement with upper level ridging
moving into the Northern Rockies during the first part of next
week for continued moderating temperatures, little or no
precipitation, and diminishing winds; however, lingering stronger
35 to 45 kt H700 winds and moisture associated with the exiting
low pressure system will result in gusty northwesterly winds and
even a few showers on Monday, especially for the eastern portions
of North-central MT.

Temperatures peak on Wednesday in the 60s and 70s in spite of an
approaching Pacific trough displacing the ridge of high pressure
to the east and replacing it with a more unstable southwesterly
flow. This will introduce shower and thunderstorm chances to most
locations Wednesday afternoon and evening. Ensemble members
diverge on forecast solutions for the second half of the workweek,
with some members bringing a closed mid-level low along the
Canadian border for overall drier and windier conditions and some
keep the low farther north and more or less maintain troughing
over the Pacific NW and southwesterly flow aloft in place. Either
way, temperatures will steadily cool closer to normal heading into
next weekend. - RCG

&&

.AVIATION...
516 PM MDT Fri Apr 19 2024 (20/00Z TAF Period)

VFR conditions have developed for all airfields that is forecasted
to continue through the TAF period. Low VFR conditions continue for
North Central Montana airfields due to low and mid-level clouds, but
should improve to few high clouds and clearing skies through the
overnight period beginning around the 3z time period. Mountain
obstruction is likely to continue through the overnight hours into
the 12z timeframe. Webb

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  15  52  31  58 /   0   0   0   0
CTB  14  48  27  51 /   0   0   0   0
HLN  18  56  34  60 /   0   0   0   0
BZN  17  54  29  64 /   0   0   0  10
WYS  13  51  22  56 /   0   0   0  20
DLN  17  54  33  63 /   0   0   0   0
HVR  15  52  28  61 /   0   0   0   0
LWT  16  47  27  58 /   0   0   0  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Watch from Sunday morning through Sunday evening for
East Glacier Park Region-Eastern Glacier, Western Toole, and
Central Pondera-Northern High Plains.

&&

$$

http://www.weather.gov/greatfalls