Messages

Warming and drying trend Monday and Tuesday

Minor to moderate heatrisk Tuesday with highs in the 90s.

Breezy winds Wednesday into Thursday with elevated fire weather conditions.

Synopsis

Isolated thunderstorms will move out of the area this evening and winds will subside. Temperatures warm Monday into Tuesday with afternoon highs in the 90s by Tuesday. The heat begins to break down Wednesday into Thursday with an increasing risk for breezy winds and mountain thunderstorms.

Discussion

This evening and tonight: Showers and thunderstorms impacting northeastern Washington and North Idaho will track to the east and come to an end before 6PM this evening. Gusty winds across the region will also subside with quiet weather conditions returning to the Inland NW overnight.

Monday-Tuesday: The next low pressure settles into the Eastern Pacific allowing downstream heights to amplify over the Inland NW. This will promote a warming and drying trend with temperatures rebounding into the 80s to lower 90s Monday then 90s Tuesday. Winds will be light with daily, terrain influence. The greatest impacts to ongoing fires will be the warm and dry conditions along with increasing instability Tuesday afternoon as mixing heights increase near 10K ft above ground or higher.

Wednesday-Thursday: The low pressure system off the coast will begin its slow journey inland. The latest consensus amongst the forecast models are for weaker impulses slinging out ahead of the main low to come through Tuesday night and again Wednesday. These impulses will help draw midlevel moisture northward toward the region though the moistening will be subtle and forcing weak leading to low confidence for high based showers and thunderstorms. The first wave arrives Tuesday with a glancing blow to far southeastern WA and the lower Idaho Panhandle. The second, slightly stronger impulse comes through Wednesday with a 5-20% chance for thunderstorms across the Idaho Panhandle and mountains along the International Border.

The upper-low will eventually swing inland across southwestern BC/NW MT Wednesday night into Thursday. Timing will be key to how the winds play out Wednesday afternoon. At this time, timing suggest the low will close enough by late afternoon and early evening for winds to increase slightly during peak heating then continue to ramp up through the evening and overnight hours as cooler air floods inland. This would suggest a short period of breezy conditions overlapping with the hot/dry conditions. However, as previously mentioned, if timing is sooner, we could be looking at another critical fire weather day. Thursday does look breezy to windy across the region similar to what is occurring today (Sunday) as temperatures cool back from the 90s Wednesday to 80s Thursday. Would not rule out additional showers and storms along the Canadian border Wednesday night into Thursday with coverage largely isolated.

Friday-Sunday: We see a lot more spread in the model guidance for late week into the weekend with the evolution of the next trough of low pressure. The general message is similar across the board that the Pac NW will continue to be influenced by another trough but how this comes through comes with many different flavors. Some are windy while others not so much. Same message for thunderstorm threats. The greatest confidence comes with temperatures being at or below normal for this time-frame and little to no signals widepsread precipitaiton events. /sb