Forecast Discussion

Issued 05/11/2026 7:10 p.m. MDT / 6:10 p.m. PDT

SHORT TERM (MONDAY NIGHT THROUGH WEDNESDAY):

     Upper level ridge will continue to migrate across the Northern Rockies overnight into the day on Tuesday with the surface thermal trough following as well. For much of the day on Tuesday the ridge axis along with the thermal trough will remain across Central Washington before shifting east of the region overnight Tuesday into Wednesday as a compact but somewhat dynamic upper level closed low approaches the Oregon coast. Temperatures will warm considerably on Tuesday with enough mixing from a northeast gradient to help the warmer air aloft to mix down to the surface and most valley locations will likely see their warmest day of the year on Tuesday. High temperatures will average nearly 20 degrees above mid May climate seasonal climate averages. The approaching upper level low will need to be watched carefully as our region will be in the favored northeast quadrant of the upper level low with favorable diffluent flow aloft. If the low shifts a bit further north then we could see our first outbreak of elevated convection fire off overnight Tuesday into early Wednesday morning. This would likely feature quite a bit of lightning and thunderstorm activity with locally heavy rains and hail possible with this convection. The moistening of the atmosphere through airmass modification will then make surface based convection more likely on Wednesday especially by late in the day which is when CAM models are showing the most organized shower activity across our region. Preliminary rainfall amounts range between about a quarter to a half inch but some areas could see less and others possibly considerably more especially if a thunderstorm moves overhead. Temperatures will drop 15 or so degrees on Wednesday due to all of the cloud cover and showers around. In addition, surface pressure falls will take place east of the Continental Divide along with surface pressure rises along the West Coast. This will create a tight thermal gradient from the southwest across the Northern Rockies with gusty southwest winds developing on Wednesday.

LONG TERM (WEDNESDAY NIGHT THROUGH MONDAY): 

     Still a fair amount of uncertainty in the extended forecast period with a rather robust zonal North Pacific jet residing to the south of a rather cold upper level low in the Gulf of Alaska. Where this feature sets up will largely influence how much precipitation we get this upcoming weekend with outcomes ranging from a few showers and breezy to windy conditions to rather wet and yes snow up in the mountains. This weekend is a rather busy one with several activities ongoing throughout our region with the annual Lost in the 50s event in Sandpoint and the annual Eagle Valley community auction in Libby. For now have simply included a chance of showers for the Friday through Sunday period although it is not likely to be raining the entire time. Again keep this in mind if you are planning an early season backcountry trip as snow levels could be down to near 5500 feet this weekend. By next week the pattern looks to modify a bit with slightly higher heights and a bit of warming but by and large temperatures remaining near seasonal averages for mid May which is lower to mid 60s in the valleys and near 50 up in the mountains.         

Issued 05/04/2026 5:35 p.m. MDT / 4:35 p.m. PDT

SHORT TERM (MONDAY NIGHT THROUGH WEDNESDAY):

     Upper level ridging has returned just off the West Coast with an unseasonably cold upper level trough residing across the central and eastern half of North America, a typical positive phase of the PNA pattern. Our region remains under the far western portion of the upper level trough or if you prefer the far eastern portion of the upper level ridge. Either way a northerly flow aloft resides across our region. Surface high pressure has followed the cool airmass that has spilled south out of Canada across Central Montana east of the Divide. This is what has caused the breezy east to northeast winds seen across the region on Monday. These winds will continue to relax some although will remain a bit breezy in the typical areas (favored canyons, Purcell Trench, Clark Fork River Valley, portions of Lake Koocanusa and of course higher elevations). Depending on high cloud cover and winds temperatures will drop down to the lower 30s in our typical cold pocket valleys. We have not entered the official start of the growing season anywhere here in the Northern Rockies and I realize many people may have already started gardens outside. Simply know that this is almost a month too early so precautions should be taken for any sensitive plants especially after Monday night as with clearer skies, dry air and light winds valley locations will likely see a return to at least a risk of frost. Dry and settled conditions should prevail on Tuesday with lighter winds. By Wednesday an approaching shortwave disturbance looks to trigger enough lift and instability in the atmosphere in the afternoon and evening hours to kick off a few showers and thunderstorms. Hard to say exactly where these will fire off but general storm motion will be towards the southeast and east. Temperatures will drop a bit on Tuesday then rebound back on Wednesday close to temperatures we saw on Monday.

LONG TERM (WEDNESDAY NIGHT THROUGH MONDAY): 

     What is typically a rather wet month of May across the Northern Rockies is still really not showing any signs of this throughout this portion of the extended forecast period. We will remain under a more progressive west to northwest flow aloft that will allow almost daily weak shortwaves to migrate through the region helping to kick off a few diurnal showers and thunderstorms each day but without a lot of forcing or lift, instability will remain somewhat limited across the region. Most areas will more than likely stay dry rather than wet but keep in mind that there is at least the outside chance of a stray shower or thunderstorm each day through the extended forecast period.  Winds will also pick up a bit more each afternoon from the west and southwest as a thermal trough begins to develop along and east of the Continental Divide each day which is typical for springtime in the Northern Rockies. Winds won't be too strong but could gust up to 20 mph or so each day. Apart from a slight cool down likely on Saturday the region can expect high temperatures to remain well above early to mid May seasonal averages. Don't really see much of a pattern change until perhaps around the 15th or 16th of May when the amplification of the ridge flattens and we become more dominated by the still active North Pacific jet stream. This could result in a cooler, wetter pattern more typical of May than what we are currently experiencing. Stay tuned.   

Issued 04/28/2026 7:35 p.m. MDT / 6:35 p.m. PDT

SHORT TERM (TUESDAY NIGHT THROUGH THURSDAY):

     Cool upper level trough continues to be centered to our east across Central and Eastern Montana with a fairly strong upper level ridge to our west. Shortwaves continue to drop south and southeast across our region and with the cool upper level airmass in place along with decent instability and forcing with daytime heating has helped kick off daily rounds of diurnal showers and isolated thunderstorms. This has NOTHING to due with moisture as several of my meteorological coworkers have been trying to blame a source for the showers. Moisture is NOT an ingredient by rather a byproduct of airmass modification. Without anything to flush out the atmosphere, continued airmass modification will cause the atmosphere to continue to moisten and thus heavier and more widespread showers and isolated thunderstorms will continue to develop each day. Factor in passing shortwave disturbances and areas of locally heavy rainfall will also be possible. These instability showers and thunderstorms will fade away overnight with the loss of daytime heating and the exiting of shortwave disturbances. A "rinse and repeat" performance can be expected again on Wednesday afternoon and with surface temperatures warming a bit faster than the upper level temperatures it's likely that vertical cloud development will be a bit deeper so likely to see any showers and thunderstorms that develop to be a bit heavier as well. Wednesday will likely be the last day of this forecast cycle to see heavier showers and thunderstorms as the atmosphere will likely stabilize too much on Thursday although an isolated mountain shower will be possible Thursday afternoon. Temperatures will warm a bit more each day and by Wednesday will climb back above seasonal averages for late April and look to remain above average through the remainder to the month into the start of May.

LONG TERM (THURSDAY NIGHT THROUGH TUESDAY): 

     A rex-block pattern looks to set up throughout much of this period as an upper level trough drops south along the West Coast and cuts off into an upper level low by late Friday and slowly move inland towards the start of next week. On Saturday this upper level low will be close enough to the Northern Rockies to place our region in the favorable northeast quadrant of the upper level low. The added forcing and instability in this region could kick off some decent showers and thunderstorms across our entire area although the more favored region will remain across Sanders County in Northwest Montana along with much of North Idaho. This will likely be a one day affair as the upper level low will pull further south and the upper level ridge portion of the rex-block will have more influence. This will bring a stable atmosphere along with warming temperatures. It's possible we could see temperatures getting close to record highs for early May if the warmer airmass occurs. Will also need watch how the upper level low does track along with airmass modification along the development of a thermal trough and where that sets up. These features could all cause some instability along with a return of showers and thunderstorms. Something to watch.