Flash Flood Warning 2, NWS Missoula, MT

780 
WGUS75 KMSO 112146
FFSMSO

Flash Flood Statement
National Weather Service Missoula MT
346 PM MDT Wed Sep 11 2024

IDC059-112156-
/O.CAN.KMSO.FF.W.0002.000000T0000Z-240911T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lemhi ID-
346 PM MDT Wed Sep 11 2024

...FLASH FLOOD WARNING FOR THE MOOSE FIRE BURN SCAR IS CANCELLED FOR 
NORTHWESTERN LEMHI COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Thunderstorms remain in the forecast throughout the night, 
so stay alert for additional heavy rainfall in the area.

A Flood Watch remains in effect until 900 PM MDT for portions of 
east central Idaho and west central Montana.

&&

LAT...LON 4531 11413 4528 11413 4525 11421 4529 11428
      4535 11430 4538 11428 4540 11419

$$

Area Forecast Discussion
National Weather Service Missoula MT
134 PM MDT Wed Sep 11 2024

.UPDATE...As atmospheric conditions have evolved, warmer
temperatures and higher dew points are being observed. The
decision was made to issue flash flood watches for all counties
south and east of Missoula. We are concerned for debris flows from
burn scars, running water in urban areas built along hillsides,
and ponding of water in low lying areas. Please keep apprised of
current conditions.

&&

.AVIATION...Rain and embedded thunderstorms will overspread the
Northern Rockies region today, with rain becoming heavy at times
by this afternoon. Rain will continue through Thursday, lowering
visibility and ceiling heights at all terminals, particularly this
evening as the low makes its way into central Idaho. In doing so,
wrap around precipitation will increase and snow levels decrease,
causing snow above elevations of 6500 feet. Expect rain, fog,
mountain snow and obscurations to persist well into Thursday.

&&

.PREV DISCUSSION... /ISSUED 100 PM MDT Wed Sep 11 2024/

..Wet Weather System Today Through Friday, Mostly Beneficial
Rain With Some Hydrological Concerns and High Elevation Snow...

DISCUSSION...The forecasted wet weather system has begun with a
line of showers currently from the Camas Prairie ID, through
Lincoln County MT. We expect as the low pressure strengthens today
that line will negatively pivot on its axis and precipitation
will fill in throughout the Northern Rockies.

First, there is a chance for stronger storms, mainly from Lemhi
County, ID through southwest MT. The atmosphere is marginal in its
ability to produce these storms, but it is important to keep in
mind for outdoor plans that outflow wind gusts up to 40 mph are
possible along with locally heavy rains.

In general, precipitation forecast amounts remain unchanged and
there is high confidence in widespread beneficial rainfall. Just
in the last hour with simply virga and light showers, visibility
from smoke has improved and we expect continued improvements in
visibility and air quality over the next 24 hours.

How much rain you ask? It is near 100% probable for at least
0.50" widespread by Friday evening. The probability for at least
1" of rain is 40% in far northwest MT and 60-90% everywhere else.
One inch not enough, well in the Mission and Flathead Mountains,
Bob Marshall Wilderness, and Glacier National Park, 2 inches of
rain is 50 to 60% probable.

High elevation snow is also in the forecast above 6500 feet for
Lemhi County ID, the Eastern Clearwater, southern Bitterroot and
Sapphire, and Mission Mountains, along with the Bob Marshall
Wilderness and Glacier National Park. If you have back country
plans in these locations please plan for wet and cold conditions.

After a brief appearance of near normal mid-September temperatures
Saturday and Sunday, our next weather maker approaches Monday
night. Current weather models are showing a more southerly track,
however there is some confidence of much cooler temperatures,
widespread rain, and high elevation snow.

AVIATION...Rain and embedded thunderstorms will overspread the
Northern Rockies region today, with rain becoming heavy at times
by this afternoon. Rain will continue through Thursday, lowering
visibility and ceiling heights at all terminals, particularly this
evening as the low makes its way into central Idaho. In doing so,
wrap around precipitation will increase and snow levels decrease,
causing snow above elevations of 6500 feet. Expect rain, fog,
mountain snow and obscurations to persist well into Thursday.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Flood Watch until 9 PM MDT this evening for Bitterroot/Sapphire
     Mountains...Butte/Blackfoot Region...Missoula/Bitterroot
     Valleys...Potomac/Seeley Lake Region.

     Winter Weather Advisory from 6 AM Thursday to 6 AM MDT Friday
     for Bitterroot/Sapphire Mountains...Butte/Blackfoot Region.

     Winter Weather Advisory from 6 PM Thursday to 6 AM MDT Friday
     for West Glacier Region.

     Winter Weather Advisory from noon Thursday to 6 AM MDT Friday
     for Potomac/Seeley Lake Region.

ID...     Flood Watch until 9 PM MDT this evening for Eastern Lemhi
     County...Western Lemhi County.

     Winter Weather Advisory from 6 AM Thursday to 6 AM MDT Friday
     for Eastern Lemhi County...Western Lemhi County.

&&