712
FXUS65 KMSO 291942
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
142 PM MDT Wed May 29 2024

.DISCUSSION...An upper level wave, seen in water vapor over
north- central Washington State will fire off scattered showers
and thunderstorms across northwest Montana this afternoon through
midnight tonight. There is a threat for lightning in this region
if you are planning on going out during this time. Make sure you
have a safe place in mind to retreat to if a storm approaches.
Also the tightened wind gradient has brought steady southwest
winds of 20 to 25 mph on Flathead Lake, so there is a lake wind
advisory in effect through 9 pm MDT this evening.

The broad trough over the region has brought in a seasonably cool
air mass. As a result, areas with some clearing at night will
cool off and have the potential for frost. For tonight, the focus
is mainly in northwest Montana, and Thursday night it includes
northwest and west central Montana as well as much of the Camas
Prairie in Idaho. Those with sensitive plants should take
precautions to protect them for the next few mornings.

By the weekend, temperatures warm back up to near average with
mild weather and only some isolated afternoon showers, mainly over
the mountains.

Next Monday, ensembles are showing the possibility of an
atmospheric river impacting the region. There is quite a wide
spread in the ensembles, as there often is with these types of
systems. There is an 80 to 90 percent chance of picking up at
least 0.10 inches of rain across western Montana, and for central
Idaho it`s over 90 percent. The median forecasts are coming in
with 0.25 to 0.50 inches across western Montana and 0.65 - 1.00
inches for much of central Idaho. The high end forecasts in
western Montana are peaking out at around 1 inch and in central
Idaho over 2 inches. The highest probabilities and amounts are
focused in the higher elevations south and west of Grangeville, ID
and include Elk City, Red River, and Dixie in Idaho. Right now,
the mainstem river forecasts do not approach flood stage, but a
possible impact may be small stream flooding across north-
central Idaho during this period.

Beyond Monday, the preponderance of models show a strong ridge
building through next week leading to an extended period of warmer
temperatures with a day or two of thunderstorms mixed in.

&&

.AVIATION...The region is in the base of a trough this afternoon
and evening causing cool, breezy conditions and some mid-level
ceilings. An embedded shortwave will bring a chance for
thunderstorms across northwest Montana between 29/2000z and
30/0600z (midnight tonight). The impacts will be lightning, and
gusty winds. As the trough moves east tonight and tomorrow, winds
will decrease tomorrow and VFR conditions are expected under
moderate zonal flow into the weekend.



&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Frost Advisory from 3 AM to 8 AM MDT Thursday for
     Kootenai/Cabinet Region...Lower Clark Fork Region.

     Frost Advisory from 3 AM to 8 AM MDT Friday for Kootenai/Cabinet
     Region...Lower Clark Fork Region.

     Lake Wind Advisory until 9 PM MDT this evening for
     Flathead/Mission Valleys.

ID...None.
&&

$$