Special Weather Statement, NWS Missoula, MT

Area Forecast Discussion
National Weather Service Missoula MT
121 PM MDT Tue Sep 28 2021

.DISCUSSION...Showers and isolated thunderstorms will continue
through the afternoon, while under the influence of an unstable
atmosphere due to the trough that is passing through the region.
Drier air will enter the region tonight as the current trough
departs so showers will have a decreasing trend overnight. Cloud
cover is forecast to remain in many places overnight, but
Wednesday will start with chilly temperatures due to a much
cooler airmass in place.

Cloud cover is expected to decrease during Wednesday with high
temperatures warming to a few degrees below normal.

Model guidance agree that high pressure will build into north-
central Idaho and western Montana on Thursday. Thursday morning is
showing up as the coldest of the week with most of the valleys in
western Montana forecast to be near or below freezing.

Confidence continues to increase for a quick moving shortwave
trough passage on Friday. Showers, increased winds, and slightly
cooler temperatures are the main weather conditions that will
associated with the disturbance.

Most of the extended models show a warming trend and dry
conditions for this weekend and to start next week.

&&

.AVIATION...A band of stratiform precipitation associated with
an upper level trough passage continues to push across the
Northern Rockies airspace this afternoon. This band of
precipitation will push across the Continental Divide by 28/2300z,
with scattered showers developing in an unstable atmosphere
through 29/0300z this evening. Terrain obscurations will continue
into the evening as snow levels have fallen to around 6,000 feet
and ceilings area wide continue to hover in the 4k to 5k AGL
range. Stratus clouds will continue to linger across the area
tonight, particularly across mountainous terrain.

&&

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

Special Weather Statement
National Weather Service Missoula MT
245 PM PDT Tue Sep 28 2021

IDZ007-282230-
Orofino/Grangeville Region ID-
245 PM PDT Tue Sep 28 2021

...A strong thunderstorm will impact portions of central Idaho County
through 330 PM PDT...

At 245 PM PDT, Doppler radar was tracking a strong thunderstorm over
Kooskia, or 7 miles southeast of Kamiah, moving east at 15 mph.

HAZARD...Winds in excess of 30 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Kooskia and Syringa.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 4614 11603 4621 11598 4616 11572 4604 11578
TIME...MOT...LOC 2145Z 289DEG 13KT 4616 11592

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...30 MPH