688
FXUS65 KTFX 111521
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
921 AM MDT Tue Jun 11 2024

.SYNOPSIS...

Dry and breezy to windy conditions are expected over the next
couple of days while temperatures generally run above average.
Another Pacific disturbance will move through the Northern Rockies
this weekend, initially bringing scattered showers and
thunderstorms followed by cooler and windy weather.

&&

.UPDATE...

No real update to report on, the going forecast remains on track.
-thor

&&

.AVIATION...

11/12Z TAF Period

VFR conditions prevail through the TAF period for all Southwest and
North Central Montana airfields. Winds increase this afternoon
between the 16z and 18z TAF time and continue to be periodically
gusty through the end of the TAF period for North Central Montana
airfields. Winds could gust up to 36 knots for KCTB this afternoon
and evening. Southwest Montana airfields could see wind gusts
today between 15 and 25 knots. Webb

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

&&

.PREV DISCUSSION...
/ISSUED 510 AM MDT Tue Jun 11 2024/

Dry and breezy conditions are expected for much of today while
shortwave ridging passes through the region. A Pacific cold front
crosses the Continental Divide late in the afternoon and may bring
a few isolated showers and thunderstorms as it quickly races
eastward during the evening hours. Strong westerly flow aloft
associated with a trough moving through Southern Canada will then
increase surface winds along the Rocky Mountain Front tonight.
Projected H700 to H500 flow has increased some and looks to run
between 45 and 55 kts or around 3 standard deviations above
climatology according to the NAEFS (North American Ensemble
Forecast System), though peak flow most likely to occur during the
overnight hours will at least limit the overall coverage of
higher end gusts. With that in mind, forecast soundings do show
profiles conducive for mountain wave activity along the Rocky
Mountain Front and adjacent high plains for increased chances for
wind gusts exceeding 55 mph during the nighttime hours.

Deep layer mixing then encourages the windy conditions to move
eastward into the plains and valleys. Current wind exceedence
probabilities for this event suggest that peak wind gusts will
mostly fall between the 35 and 55 mph range for most locations
except along the Rocky Mountain Front and adjacent high plains
where gusts up to and exceeding 60 mph will be more common. The
primary concern continues to be difficult conditions for summer
outdoor recreation and travel; however, afternoon temperatures in
the 70s and 80s combined with the said winds and minimum relative
humidity values in the teens and 20s is expected to accelerate the
curing/drying of grassland fuels. While no fire products are
anticipated this time around, this drying process may set up fire
weather concerns in the future.

Another brief period of transient ridging aloft will bring calmer
winds and continued dry conditions for Thursday and much of
Friday before another Pacific trough brings unsettled conditions
next weekend. Although uncertainty remains with the specifics of
this system, most ensembles favor the primary circulation and
moisture staying north in Canada, which reduces the likelihood for
widespread rainfall for North-central and Southwest Montana. The
first opportunity for precipitation comes later Friday into
Saturday when southwesterly flow and a cold frontal passage
encourage a period of shower and thunderstorm development. Breezy
to windy conditions and cooling temperatures are then expected for
the remainder of the weekend with another chance for scattered
showers late Sunday into Monday. - RCG

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  85  50  77  42 /   0  10   0   0
CTB  82  46  71  40 /   0   0   0   0
HLN  87  53  82  46 /   0  10   0   0
BZN  85  49  83  42 /  10  10   0   0
WYS  75  42  77  37 /  10  10   0   0
DLN  83  48  81  43 /   0  10   0   0
HVR  87  54  78  44 /   0  20   0   0
LWT  82  48  75  42 /   0  40   0   0

&&

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

$$

http://www.weather.gov/greatfalls