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FXUS65 KMSO 181854
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
1254 PM MDT Thu Jul 18 2024

...Excessive Heat Continues Friday through Early Next Week...

.DISCUSSION...A weak circulation moving through the high pressure
ridge currently over the Northern Rockies brought about lightning
overnight through this morning, but is now shifting to the north
and east. In its wake, we expect a few isolated thunderstorms to
develop across southwest Montana (along and south of Granite and
Silver Bow County), with a few ridgetop storms developing along
the Montana and Canada border as well. Overall, the thunderstorm
threat will lessen greatly as we head into Friday and high
pressure re-amplifies.

Model consensus remains strong in several days of excessive heat
occurring Friday and continuing into next week. Temperatures will
soar into the 100-115 degree range for much of central Idaho and
western Montana valleys. Midslopes and ridgetops will also feel
the heat, with high elevation temperatures ranging in the 70s to
80s during the day. As we have mentioned previously, wildfire
smoke may inhibit full daytime heating, which would keep the most
extreme temperature values from occurring. While that potential
still very much exists, with such prolonged excessive heat
expected, and overnight low temperatures remaining in the 60s to
70s, we elected to issue both Heat Warnings and Heat Advisories to
cover a large portion of western Montana and central Idaho. For
more information on your exact area and any heat impacts expected,
please visit www.weather.gov/missoula.

Heat safety for both humans and animals alike will be of utmost
importance during this time and should not be taken lightly. With
the influence of smoke in the air around the region, degraded air
quality will only add to the stress on the body during this time,
and those with sensitivities to both heat and poor air quality
should exercise special care to ensure they remain well.

When will relief come? We`re still looking at the high pressure
ridge finally shifting east by the middle of next week, with a
low pressure center moving inland from the Washington coast by
Friday. Temperatures will cool a few degrees each day beginning as
early as Tuesday (July 23), but any major improvement will depend
solely on the timing and track of the low pressure.


&&

.AVIATION...Isolated thunderstorms accompanied by 15-25 kt gusts are
expected along the Divide this afternoon diminishing this
evening. Otherwise, hot and dry conditions will continue into the
weekend, winds will be light aside from the typical afternoon
gusts of 15-20 kts. High density altitude will continue to be a
concern given the abnormally hot temperatures. Smoke from regional
and local wildfires will create hazy skies and localized
visibility reductions.




&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Excessive Heat Warning from 1 PM Friday to midnight MDT Tuesday
     night for Kootenai/Cabinet Region...Lower Clark Fork Region.

     Heat Advisory from 1 PM Friday to midnight MDT Tuesday night for
     Flathead/Mission Valleys...Missoula/Bitterroot Valleys...
     Potomac/Seeley Lake Region...West Glacier Region.

ID...Excessive Heat Warning from noon Friday to 11 PM PDT Tuesday for
     Lower Hells Canyon/Salmon River Region...Northern
     Clearwater Mountains...Orofino/Grangeville Region...
     Southern Clearwater Mountains.

&&

$$