Debris Flow in Idaho, August 5, 2023

Area Forecast Discussion
National Weather Service Missoula MT
233 PM MDT Sat Aug 5 2023

.DISCUSSION...Light to moderate rain has been falling throughout
the day, mainly for areas along and south of the I-90 corridor in
western Montana. Wetting rains have been reported as far north as
Arlee in the southern Mission Valley. This precipitation shield
will slowly progress north and west through the afternoon as the
surface low begins spinning up in eastern Washington. Partial
clearing south of the precipitation shield will open the door for
the development of scattered thunderstorms this afternoon,
starting around 3PM MDT and continuing through the evening hours.
Areas with the best chance in seeing thunderstorms will be
locations along and south of I-90 in western Montana and north-
central Idaho. Occasional lightning and heavy rainfall will be the
main hazards from any convective activity.

Localized increase in easterly winds are expected this evening and
overnight along highway 93 in the Mission Valley and Flathead
Lake. Wind gusts as high as 25 mph are expected in these areas.
Take precautions if you have plans to be on the Lake.

The surface low will be slow to move out of the region, resulting
in a second surge of moisture being transported west out of the
Central Plains on Sunday. Much like today, expect light to
moderate rainfall in much the same areas in the morning, with
scattered thunderstorms in the afternoon and evening.
Probabilities for rainfall totals reaching a 0.25" or more for
today and Sunday remain around 35-45%. Chances for a wetting rain
(>0.10") for the same period is at 80% or higher. Areas that have
the least chances of receiving a wetting rain will be locations
north of Flathead Lake to Glacier National Park.

Temperatures this weekend going to into early next week, will be
around 10 to 15 degrees below normal for this time of year.
Rainshowers will also remain in the forecast going through at
least Wednesday next week.

&&

.AVIATION...Light to moderate rainfall will continue through the
afternoon for aviation sites along and south of the I-90 Corridor.
Scattered thunderstorms are still possible in these same areas
this afternoon and evening, with a 50-60% probability. Northwest
Montana, in the vicinity of KGPI will have lesser chances with a
30-35% probability. Due to the recent moisture and expected light
winds, patchy morning fog is possible in the vicinity of KMSO and
KHRF tomorrow morning.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&