466
FXUS65 KTFX 140305
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
905 PM MDT Tue Aug 13 2024

.SYNOPSIS...

A fairly unsettled weather pattern looks to continue this week,
bringing nearly daily chances for afternoon showers and
thunderstorms to the area. Best chances for showers and
thunderstorms will be this afternoon and evening and again on
Friday as more organized weather systems move through the area.

&&

.UPDATE...

No significant updates needed to the overnight period of the
forecast.

Scattered showers and thunderstorms associated with a disturbance
in the southwest flow aloft will continue to weaken as they move
northeast over the plains of North Central Montana this evening.
Wind gusts to 35 mph and brief heavy downpours will be the main
concerns. Forecast models continue to indicate that at least a
slight chance of showers and thunderstorms will linger after
midnight in the wake of the disturbance. Another area of scattered
showers and thunderstorms will also diminish as it moves across
Southwest Montana this evening. Lingering cloudiness will likely
prevent patchy fog from forming over the plains, but partial
clearing over Southwest Montana will bring at least a chance of
valley fog there. -Coulston

&&

.AVIATION...
14/00Z TAF Period

A band of showers and thunderstorms is presently located along a
line from around KGTF-KHLN-KBZN, moving east. Primary terminal
impacts have been brief heavy rain and erratic wind gusts.
KGTF/KHVR/KLWT are expected to see additional SHRA/TSRA activity
at times through late this evening. There will be a break
overnight with a return to VFR conditions. Additional showers and
thunderstorms are expected Wednesday afternoon, but not with
enough confidence to place at specific terminals.

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

&&

.PREV DISCUSSION...
/ISSUED 550 PM MDT Tue Aug 13 2024/

Key Points:

-Daily chances for afternoon showers and thunderstorms

-Temperatures will remain near to slightly below average through
 the next week

Short term (through Friday)... Scattered to widespread showers
and thunderstorms are expected across most of North Central and
Southwestern Montana this afternoon as a decaying upper level
trough slides through the area. Current atmospheric profiles (as
of 1PM) indicate that todays storms will be capable of producing
some gusty winds thanks to the dry lower levels, and precipitation
production will be fairly efficient, with fairly warm, moist air
above the boundary layer, so some heavier rain may fall out of a
few of the thunderstorms. For the most part, I dont anticipate
this being much of an issue from a flooding standpoint, though we
will have to watch the Horse Gulch burn scar, as these storms
could produce rainfall sufficient to produce some flooding on this
burn scar.

Wednesday and Thursday will see slightly cooler temperatures in
the wake of this upper level trough as cooler air works its way
into the area from the northwest, and a few afternoon showers and
thunderstorms are expected to develop during the afternoons thanks
to some leftover instability. Unlike today, any storms should be
quite isolated and will be unlikely to produce much in the way of
gusty winds or heavy rain. There will be a better chance for more
widespread showers and thunderstorms on Friday, however, as a
shortwave trough quickly moves through the area, giving just
enough atmospheric support to enhance the ability of storms to
persist instead of the pulse type storms we will see Wednesday and
Thursday.

Extended (Sunday through next Tuesday)... Looking into the
weekend and beyond, uncertainty grows fairly quickly as we find
ourselves between an upper level ridge over the South Central US
and an upper level trough positioned over or near the Pacific
Northwest coastline. While these differences seem subtle (and they
really are), the implications for us will be rather pronounced,
as we could wind up seeing warm and dry conditions if the ridge
controls our weather, or cooler and wetter if the trough is able
to push further east and become a larger influence on our weather.
For now, the forecast calls for chances of rain each day, with
temperatures near average for this time of year. Ludwig

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  57  80  54  83 /  70  30  10  20
CTB  54  80  52  81 /  20  20  10  30
HLN  54  80  55  85 /  40  40  10  30
BZN  48  77  48  83 /  20  40  10  30
WYS  39  68  36  74 /  30  70  20  30
DLN  46  73  46  77 /  40  40  10  40
HVR  60  85  58  87 /  60  20  10  20
LWT  52  75  51  80 /  40  40  20  30

&&

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

$$

http://www.weather.gov/greatfalls