Issued Sunday May 11, 2025 7:50 P.M. PDT
Tonight…Showers with isolated thunderstorms possible in the evening. Some thunderstorms may produce torrential rainfall, hail, frequent lightning and strong winds. Snow level lowering to near 6000 feet after midnight. Local snow accumulations of 1 to 2 inches possible above 6500 feet. Patchy fog developing towards dawn. Lows in the 40s with mid 30s around 6000 feet. Light wind except gusty winds possible near thunderstorms. Ridge top winds becoming westerly 15 to 25 mph after midnight.
Monday…Patchy early morning fog otherwise variable cloudiness with scattered to numerous showers and thunderstorms developing by afternoon. Thunderstorms may produce heavy rain, small hail, frequent lightning and gusty winds. Snow level near 6000 feet. Local snow accumulations of 1 to 2 inches possible above 6500 feet. Highs in the mid 50s to lower 60s with near 40 around 6000 feet. Southwest winds 10 to 20 mph with gusts to 25 mph across ridge tops. Gusty winds possible near thunderstorms.
Monday night…Mostly cloudy with patchy fog developing towards dawn. Rain and snow showers becoming likely towards dawn. Snow level lowering to near 5500 to 6000 feet. Lows in the lower to mid 40s with mid 30s around 6000 feet. Light wind except ridge top winds southwest 10 to 20 mph with gusts to 25 mph before midnight.
Tuesday…Rain and mountain snow showers likely with scattered afternoon thunderstorms. Snow level rising to near 6000 feet in the afternoon except locally lower beneath heavier thunderstorms. Local snow accumulations of 1 to 2 inches possible above 6500 feet. Highs in the 50s to near 60 with upper 30s around 6000 feet. West to southwest wind 5 to 15 mph.
EXTENDED OUTLOOK (WEDNESDAY THROUGH SUNDAY):
Wednesday…A chance of showers with afternoon and evening thunderstorms. Lows in the upper 30s to mid 40s with mid 30s around 6000 feet. Highs in the upper 50s to lower 60s with upper 30s around 6000 feet.
Thursday…Dry except for a chance of late day showers. Lows in the upper 30s to mid 40s with mid 30s around 6000 feet. Highs in the upper 50s to mid 60s with mid 40s around 6000 feet.
Friday through Sunday…Cool with a chance of valley rain showers and thunderstorms with a chance of high mountain snow showers. Lows in the 40s with mid 30s around 6000 feet. Highs in the upper 50s to mid 60s with lower 40s around 6000 feet.
In-Depth Weather Discussion for Northwest Montana/North Idaho/Northern Rockies
ISSUED 05/11/2025 8:20 P.M. MDT/7:20 P.M. PDT
SHORT TERM (SUNDAY NIGHT THROUGH TUESDAY):
After a good rainfall in the morning across North Idaho another shortwave is rotating into the region as of this writing on Sunday evening. This feature is associated with some good upper level jet dynamics as well as a good convergence/divergence couplet located across Northwest Montana. As of 8:00 pm.m MDT/7:00 p.m. PDT there was a radar indicated severe thunderstorm that moved across northwest Sanders County with reflectivity showing ping pong ball sized hail and 60 mph wind gusts. Have not heard of any reports of damage but the most intense part of this storm appeared to located over very rural parts of Sanders County west of Noxon and south of Heron along the Idaho line and up in the Coeur d’ Alene Mountains. Instability will remain present throughout the evening hours as the incoming shortwave helps to provide the needed lift or vertical motion through the atmosphere to generate precipitation, some of which will be locally intense. Largely this will be beneficial rainfall and even some high elevation snowfall as well with our region coming off a largely dry April. The shortwave will lift north into southern Canada with a trowal feature developing around the system which looks to provide another round of beneficial rains and high elevation snowfall into Tuesday for at least parts of the region although the exact location continues to change with each model run. Outside of this feature will be a smattering of showers and thunderstorms but thunderstorms will not be strong to severe outside of Sunday evenings potential. Instability will be present and any passing shortwave within the flow will help provide additional support to generate convection. Temperatures will actually remain below average for a few days and potentially the entire week as a progressive and fairly flat flow remains in place across our region with cooler atmospheric height and thickness values remaining in place. With the upcoming weekend featuring several notable events weather will be playing a large role. Read below for more details.
LONG TERM (TUESDAY NIGHT THROUGH SUNDAY):
Lingering instability and another passing shortwave disturbance on Wednesday will provide for additional sunshine and scattered heavy, possibly thundery downpours. There is decent confidence that a transitory shortwave upper level ridge will pass overhead sometime late Wednesday night into late Thursday afternoon offering up a stable airmass with more sunshine but an active North Pacific jet stream associated with a negative height anomaly in the Gulf of Alaska will be directing yet another strong shortwave passage into the region on Friday and lasting through the weekend. This feature will also have some decent jet support for this time of year so it looks like at least periodic rounds of rain and high elevation snowfall from Friday and lasting through the weekend. The Lost in the 50s event in Sandpoint is next weekend and it looks wet for that event as well as cool. In addition there is the annual Eagle Valley Auction over by the Libby airport which also looks a bit damp and cool. Finally and not to be missed is the “Fishmas” opener in Northwest Montana as the stream fishing opener takes place. If planning on casting a line in the water for this take the jacket and rain coat as it will likely be very cool and damp especially Saturday morning. The overall trend is for the active North Pacific jet to remain focused across our region bringing typical May weather to the Northern Rockies with periodic rounds of valley rain showers and higher elevation snow showers. After the dry April the precipitation will definitely be welcome to gardeners and farmers alike although the timing may not be the best.