058
FXUS65 KMSO 171841
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
1241 PM MDT Wed Jul 17 2024

.DISCUSSION...Moisture circulating around a low pressure system
in Oregon and Washington will shift into Idaho and western Montana
today. So far, lightning has been observed in eastern Oregon and
eastern Washington, with the potential for lightning to occur as
it moves inland this afternoon. That being said, the amount of
high-based (vertically integrated) wildfire smoke, and near-
surface wildfire smoke, will present a challenge and could inhibit
convective development. If it does so, that would mean less of a
potential for lightning throughout the day today as smoke
stabilizes the atmosphere. The one area with less smoke in the
air is northwest Montana, which is where instability will be
greatest as we head into the evening and overnight hours. Because
of this, northwest Montana stands a much better chance of
receiving thunderstorms with little precipitation, and an
increased chance for lighting, overnight tonight as the low moves
through. Gusty winds will accompany thunderstorm and shower
activity, with widespread gusty winds of 20 to 25 mph expected
throughout the day Thursday.

Keeping the regional smoke in mind, forecast models show additional
high-based smoke ushering into the Northern Rockies from the west
and southwest Thursday through the weekend. With the
reamplification of the high pressure ridge expected Friday through
Sunday, it is likely the smoke will remain in the forecast and
have an impact on how hot temperatures become over the weekend.

There are two scenarios that could play out regarding this
weekend`s heat:

Scenario 1: Smoke will thin enough to allow for maximum heating
potential across central Idaho and western Montana. If this
happens, we could see some of the hottest daytime temperatures of
the season so far for many valley locations of both central Idaho
and western Montana. And in some cases, all time record highs
could be in jeopardy.

Scenario 2: Smoke continues to thicken, or remains thick enough,
to inhibit the full heating potential across the region. This
would cause temperatures to be about 10 to 20 degrees cooler than
the maximum potential in the forecast.

We`ll be keeping a very close eye on this. In the meantime,
continue to take care of yourself and others, especially those
with sensitivity to extreme heat.

By mid next week, the high pressure ridge looks to break down,
allowing for more unsettled weather in the form of thunderstorms
and possible showers, along with lightning and gusty winds. Cooler
temperatures are also likely to follow.

&&

.AVIATION...Smoke from regional and local wildfires will create
hazy skies and localized visibility reductions. A spoke of energy
ahead of the low-pressure center off the Oregon coast is forecast
to pass through the region later today, bringing the threat of
gusty winds and lightning through tonight. The main focus for
storms overnight will be in northwest Montana. Smoke will continue
to impact visibility through the day Thursday, with breezy west
winds of 20 knots to persist after 18/1800Z.


&&

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

$$