489
FXUS65 KMSO 181813
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
1213 PM MDT Wed Sep 18 2024

.DISCUSSION...The low pressure system that brought widespread
beneficial rainfall to the region, has moved into eastern Montana
this afternoon. Cool temperatures with mostly cloudy conditions
will be the result for the rest of the day.

A mostly dry west to northwest flow will develop over the
Northern Rockies for the rest of the week and weekend. A weak
ripple in the flow Friday will aide in an increase in westerly
winds during the afternoon, with a 60-70% probability for gusts
reaching 20 mph throughout western Montana and north-central
Idaho. Those probabilities lower to 30-40% for widespread gusts
of 25 mph. Those planing to recreate on Flathead Lake Friday
afternoon between 3PM and 9PM should keep that in mind.

The increase in wind Friday will also help with drying of the
atmosphere and with partial clearing skies during the overnight
hours, there will be increasing probabilities for areas of frost
both Saturday and Sunday mornings. As it stands now, widespread
frost probabilities are higher (30-40%) Sunday morning for the
more populated valleys of western Montana. As for north-central
Idaho, those outside of the higher elevated valleys (Orofino,
Kamiah, & Grangeville) the probability for frost is less than 10%.

All the ensemble clusters depict a weak shortwave trough by
Monday, that will bring a general 20 to 30 percent chance for
showers. Temperatures will be seasonable to start the week, then a
gradual warm-up ensues mid-week, with 85% of the clusters showing
a ridge of higher pressure with dry conditions.


&&

.AVIATION... As the upper low departs, skies will gradually clear
tonight allowing for patchy fog in the valleys lasting into
Thursday morning. Otherwise, VFR conditions will be common on
Thursday with afternoon gusts of 15-20 kts at terminal sites.



&&

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

$$