227
FXUS65 KMSO 200658
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
1258 AM MDT Thu Jun 20 2024

.DISCUSSION...Southwest flow continues into Friday allowing for a
warming trend and occasional shower/thunderstorm chances. There
is just enough instability for a few showers along the Divide this
afternoon. Deep mixing will allow for afternoon gusts up to 25 mph,
gusts diminish quickly around sunset. Elevated instability and
moisture associated with a weak disturbance may bring sprinkles
early Friday morning. This increase in mid-level moisture will
enable a slight expansion in convective coverage on Friday
afternoon, mainly across western Montana. Given the deep dry
layer, any thunderstorms will be capable of gusty outflow winds.

A transitory shortwave ridge of high pressure will traverse the
Northern Rockies over the weekend, that will allow for afternoon
temperatures to run around 15 degrees above normal, with
mid/upper 80s in western Montana valleys, and low/mid 90s for
north-central Idaho. As the ridge breaks down on Sunday afternoon,
gusty westerly winds are expected. There is a 30-40% probability
of valley gusts over 30 mph. Those planning activities on area
lakes should prepare for choppy conditions. Daytime temperatures
cool a few degrees and breezy afternoon winds continue Monday and
Tuesday of next week, rain chances remain low.

Nearly 80% of ensemble clusters support a weak trough impinging
on the Northern Rockies late next week (27th-28th). Details are
somewhat scarce but a general consensus points toward daytime
temperatures returning to seasonable levels with an increase in
precipitation chances. There is only a 10% probability of
widespread, significant rains (> 0.50"), thus scattered showers
are the most likely mode.


&&

.AVIATION...Southwest flow continues into Friday with generally
VFR conditions. Patchy fog may develop this morning, mainly along
rivers. There is just enough instability for a few showers along
the Divide this afternoon. Deep mixing will allow for afternoon
gusts of 15-20 kts at terminal sites with gusts diminishing
quickly around sunset. Elevated instability and moisture associated
with a weak disturbance may bring sprinkles early Friday morning.
This increase in mid-level moisture will enable a slight
expansion of convective coverage on Friday afternoon.



&&

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

$$