Severe Thunderstorm Warning 22, NWS Missoula, MT

445 
WWUS55 KMSO 100229
SVSMSO

Severe Weather Statement
National Weather Service Missoula MT
729 PM PDT Fri Aug 9 2019

IDC049-100238-
/O.EXP.KMSO.SV.W.0022.000000T0000Z-190810T0230Z/
Idaho ID-
729 PM PDT Fri Aug 9 2019

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHWESTERN IDAHO COUNTY WILL
EXPIRE AT 730 PM PDT...
                
The storm which prompted the warning has moved into a remote area of 
Idaho County. Therefore, the warning will be allowed to expire. Hail 
and gusty winds are still a possibility with this storm. 

LAT...LON 4541 11634 4558 11641 4576 11596 4548 11579
TIME...MOT...LOC 0228Z 253DEG 17KT 4559 11602 

$$

Area Forecast Discussion
National Weather Service Missoula MT
243 PM MDT Fri Aug 9 2019

.DISCUSSION...Widespread rain showers and isolated thunderstorms
will continue to spread from the south to north across the
Northern Rockies through the evening hours. Brief heavy rain and
occasional lightning will be the main threats this evening.

We continue to watch for the potential for strong to severe
thunderstorms developing across west-central and southwest
Montana, as well as north-central Idaho tomorrow afternoon and
evening. Thunderstorms will begin to form in north-central Idaho
in the late morning, and strengthen as they move north into
western Montana later in the afternoon. Storms that become severe
in nature will have the potential to produce strong damaging wind
gusts in excess of 50 mph. Winds gusts of these speeds may topple
trees and power lines. These strong storms can also produce large
hail in excess of 1 inch in diameter. Another impact from these
storms will be very heavy rain. Area burn scars will be
susceptible for rock and mudslides, along with flooding in some
urban locations and other flood prone areas. A Flash Flood Watch
has been issued for certain locations with these vulnerabilities.
Details can be found at our website www.weather.gov/mso. Scattered
thunderstorms will continue to move across the region through
midnight Saturday night, but these storms that move overhead after
sunset are not expected to be severe in nature.

As the upper level trough moves through the area on Sunday,
widespread rain will develop, particularly across the Idaho
panhandle and northwest Montana. Precipitation amounts of a
quarter of an inch or more will be possible in these areas.
Thunderstorms will also be possible in the afternoon, and will be
capable of brief heavy rain and small hail. Temperatures will run
roughly 15 degrees cooler than normal for this time of year.

A weak ridge of high pressure is expected over the region to start
next week, with temperatures slowly warming though still running
somewhat below seasonal normals. As the flow becomes more
southwesterly by mid week, the chance for showers and
thunderstorms will increase.

&&

.AVIATION...Rain will dissipate at KGPI, KMSO, and KBTM by
10/0200Z and a short break in unsettled weather will last through
Saturday morning. The exception will be KSMN as some isolated
storms overnight are not out of the question. Saturday will bring
active weather to all terminals in the afternoon as many
ingredients come together for strong convection. Expect a decrease
in visibility as widespread showers and thunderstorms bring heavy
rain, lightning, gusty winds, and a chance of hail to all
terminals. Storms will start at KSMN by about 10/2000Z, spread
north and northeast to KBTM and KMSO, then continue to KGPI by
about 10/2200Z.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Flash Flood Watch from Saturday afternoon through Saturday
     evening Bitterroot/Sapphire Mountains...Butte/Blackfoot
     Region...Missoula/Bitterroot Valleys...Potomac/Seeley Lake
     Region.

     Flash Flood Watch from Saturday afternoon through Saturday
     evening Flathead/Mission Valleys...Kootenai/Cabinet
     Region...West Glacier Region.

ID...     Flash Flood Watch from Saturday morning through Saturday
     afternoon Lower Hells Canyon/Salmon River Region...
     Orofino/Grangeville Region...Southern Clearwater Mountains.

&&

Special Weather Statement
National Weather Service Missoula MT
618 PM PDT Fri Aug 9 2019

IDZ006-008-100200-
Southern Clearwater Mountains ID-
Lower Hells Canyon/Salmon River Region ID-
618 PM PDT Fri Aug 9 2019

...SIGNIFICANT WEATHER ADVISORY FOR WEST CENTRAL IDAHO COUNTY UNTIL
700 PM PDT...

At 617 PM PDT, Doppler radar was tracking a strong thunderstorm 13
miles east of Imnaha, or 34 miles southwest of Grangeville, moving
northeast at 20 mph.

Nickel size hail and winds in excess of 40 mph will be possible with
this storm. Locally heavy rain will also accompany this storm.

Locations impacted include...
White Bird, Slate Creek, Copperville and Lucile.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4547 11656 4551 11656 4554 11652 4555 11652
      4558 11648 4560 11646 4565 11649 4568 11653
      4581 11632 4559 11610 4541 11656 4544 11659
TIME...MOT...LOC 0117Z 233DEG 16KT 4553 11656