Flash Flood in Idaho, April 14, 2024

Area Forecast Discussion
National Weather Service Missoula MT
219 PM MDT Sun Apr 14 2024

.DISCUSSION...A weak disturbance associated with the low pressure
system over the Great Basin has moved into central Idaho and
southwest Montana this afternoon. This disturbance is causing a
few showers to develop over Lemhi county, southern Idaho county
and southwest Montana. This feature will drift northward this
afternoon and evening causing scattered to numerous showers. The
greatest instability will be over Clearwater and northern Idaho
counties during the early evening hours. This instability will
allow for the development of a few stronger showers and even a few
thunderstorms. These storms will be capable of gusty erratic winds
along with some small hail. The shower activity will decrease in
coverage and intensity after sunset this evening, but a few
showers will linger throughout the night over north central Idaho
into west central Montana.

A weak cold front is still expected to move into the Northern
Rockies on Monday as a low pressure system slides southward into
British Columbia. This front will create breezy conditions across
the region, but the strongest winds are anticipated over northwest
Montana. Wind gusts up to 35 mph are anticipated for northwest
Montana which will produce choppy conditions on area lakes,
especially Flathead, so a lake wind advisory has been issued.
These breezy winds appear to linger across the region Monday night
into Tuesday as the low pressure system makes its way into the
Northern Rockies.

The low will settle over the Northern Rockies Tuesday into
Wednesday bringing colder temperatures and widespread
precipitation. Areas along the Continental Divide will receive the
bulk of the precipitation Tuesday night into Wednesday morning
with the precipitation type being mainly snow. Glacier NP and
Marias pass have a 40 to 80% chance of receiving over 4 inches of
snow Tuesday afternoon into Wednesday morning. The snow levels
will drop to the valley floor across western Montana by Wednesday
morning where a dusting to an inch of snow could accumulate on
non-paved surfaces. Maximum temperatures will drop into the 40s
to 50s for Tuesday and Wednesday which is around 10 degrees below
seasonal averages.

Around 80% of the models are showing a low amplitude ridge of high
pressure moving over the Northern Rockies by the weekend causing a
slow warming and drying trend.

&&

.AVIATION...Satellite and radar are indicating showers developing
across Lemhi County into southwest Montana this afternoon. These
storms will be increasing in coverage and intensity during the
remainder of the afternoon into the evening hours as they drift
northward. The strongest storms are anticipated to be over
Clearwater and Idaho counties. All shower activity will be capable
of producing gusty erratic winds as the low levels are fairly
dry. KSMN, KHRF and KBTM will be dealing with vicinity storms
until 15/04z. Storms are expected to start impacting KMSO around
14/23z to 15/06z.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Lake Wind Advisory from noon to 9 PM MDT Monday for
     Flathead/Mission Valleys.

ID...None.
&&