602
FXUS65 KMSO 180841
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
241 AM MDT Tue Jun 18 2024

.DISCUSSION...An upper level trough remains over the region
through this evening leading to periodic showers. A disturbance
within the trough will slide southeast across northwest Montana
this morning resulting in an uptick of showers for northwest and
west-central Montana. Snow levels will start the day around 5000
feet rising over 6000 feet this afternoon. Additional snowfall of
1-3 inches is anticipated where showers persist but overall
impacts are diminishing with winter weather highlights scheduled
to end this morning.

Thinning cloud cover and light winds tonight into Wednesday
morning will allow for areas of frost, mainly from the Mission
Valley southward to Lemhi County. Gardeners should plan to protect
any sensitive vegetation.

There is great consensus (near 100%) of a warming and drying trend
Wednesday through Friday under southwest flow. There is a 20-30%
chance of showers or thunderstorms each day, focused mainly along
the Divide. This is followed by a brief ridge over the weekend.
Under the ridge, daytime temperatures peak about 15 degrees above
normal (upper 80s western Montana valleys, low/mid 90s for north-
central Idaho).

Early next week, most ensembles (80%) support a weak trough or
zonal flow leading to an increase in daily breezes with high
temperatures dropping back to seasonable levels. Precipitation
amounts look minimal at this point.




&&

.AVIATION...An upper level trough remains over the region through this
evening leading to periodic showers. A shortwave within the
trough will slide SE across NW Montana this morning resulting in
an uptick of showers for NW and WC Montana, including airfields
KGPI, KMSO, KBTM, and KHRF. Patchy morning fog may occur where
partial clearing occurs. By this afternoon, CAPE values reach near
500 J/kg thus isolated thunderstorms are expected. Occasional
lowered ceilings and visibility reductions will occur with
precipitation episodes. Showers greatly diminish after sunset as
instability and widespread forcing subsides.



&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Storm Warning until 6 AM MDT Tuesday for
     Bitterroot/Sapphire Mountains...Butte/Blackfoot Region...
     Potomac/Seeley Lake Region.

     Winter Weather Advisory until 9 AM MDT Tuesday for West Glacier
     Region.

ID...Winter Storm Warning until 5 AM PDT Tuesday for Southern
     Clearwater Mountains.

&&

$$