We're going from hot and muggy to a round of possibly intense thunderstorms before the pattern settles back into something a bit more Emerald City-ish.
First up is the heat Monday, courtesy of an intense ridge of high pressure and a nearby thermal trough bring highs into the 90s. Seattle's record high is 95 and we could get close, if not reach it.
Attention turns from heat to thunderstorms as we head into Monday night and Tuesday as an upper level trough brings unstable air and prime conditions for thunderstorm development. Thunderstorms already in Oregon will drift north late Monday and the increasingly unstable air will be favorable for additional storms to form over Western Washington Monday night.
Thus, thunderstorm chances across Seattle and Western Washington increase Monday night and linger through the day Tuesday. Aside from the usual dangers presented by lightning, with the recent dry weather, there is an increased risk of wildfires, even in Western Washington.
The National Weather Service has issued a red flag warning for wildfire danger to most of Western Washington, including the Seattle area, where such warnings are rare. Forecasters are watching for an abundance of lightning strikes across our region and worry they could spark wildfires. In addition, the state Department of Natural Resources has taken the step of banning statewide all outdoor burning on DNR-protected lands, with no exceptions.
Aside from frequent lightning, any of the thunderstorms may also contain hail and heavy rain. Those with outdoor plans and sporting events/practices for Tuesday need to keep a sharp eye on the skies and should have someone monitor radars and forecasts on a smartphone for any approaching storms. As the National Weather Service likes to say: "When thunder roars, head indoors."
As the thunderstorms form in the upper levels, a cooling marine breeze will develop along the surface Monday night so Tuesday will be somewhat cooler and cloudier, with highs dropping to about 80. Forecast models are also indicating we could now see a period of steady moderate-to-heavy rains Tuesday night into early Wednesday as part of that trough moves through with showers decreasing during the day Wednesday but a shower chance lingering into Thursday as highs drop back ionto the 70s. By the end of the week, we finally get back to some semblance of Seattle summer normal with morning clouds and afternoon sun with highs in the upper 70s to low 80s. It will be well deserved.
Wildfire danger extends to Eastern Washington
The wildfire danger extends to Eastern Washington as well with thunderstorms likely there starting late Monday night with thunderstorm chances lingering through early Friday. Some of the storms there could be quite strong with gusty winds and hail and Red Flag Warnings are in effect for much of Central Washington as well, including the recent areas in north-central Washington that suffered massive wildfires. It's hot and dry there Monday, with the increasing thunderstorm threat through the week.
And to top it off, the winds will kick up mid-week as Western Washington cools off and those marine breezes shoot through the Cascade gaps into Central Washington. As we saw in mid-July when Seattle's last heat event broke, Central Washington was buffeted with several hours of 35-45 mph wind gusts. Firefighters could really have their hands full if new wildfires develop this week.
Scott will be providing frequent updates on Twitter as thunderstorms form and move across the region Monday night and Tuesday. You can follow him @ScottSKOMO.