June 12, 2021

Forecast: June 12th, 2021

By Preston Donion

Hello and Happy Graduation Day, Huskies!

On this Saturday full of celebration, we’ve been given one slight consolation prize for our seniors whose final year at UW was far from what anyone expected, and that’s the fact that the rain held off to start the day! It’s only a brief delay, as the system rolls in around sunset tonight, but we’ll take what we can get in “Juneuary”! 

If you have any outdoor plans to celebrate today, you should be in luck in terms of rain, but prepare for a bit more mugginess than usual! The atmospheric river that is stretching all the way from Hawaii to the Puget Sound carries tropical air with it, and that’s why we’ll see unusually mild temperatures throughout the storm and potentially record-setting dew points (a strong indicator of humidity). As local meteorologist Joe Boomgard-Zagrodnik (@joejoezz on Twitter) has highlighted, we’ll be flirting with a dew point of 65° or higher tomorrow afternoon, something never seen in June at Sea-Tac before. There is obviously a range of possibilities for just how high the dew point will climb tomorrow, but one thing is pretty likely: it’ll feel pretty soupy out there! For a closer look at the humidity forecast, check out Joe’s blog (theconvergencezone.com). 

Humidity is definitely a big part of this weather event, but it also packs a punch in terms of precipitation! In these images, you can see the river as it makes its approach this afternoon, and then as it hits our area early tomorrow. The measured variable here is precipitable water, which isn’t a reflection of how much precipitation will actually fall but rather a measure of how much potential precipitation the atmosphere is carrying at a given time. With values at or above 1″, this is definitely a potent rainmaker!

Below is a map of the UW model’s expected rainfall from 5PM today through 5PM Tuesday, and the verdict is a wet one. If this run verifies, we’ll have approximately 1.4 inches and that would put us at the 38th rainiest June at Sea-Tac…only halfway through the month! What’s more, if we get just over a half an inch (a very real possibility), we’ll have more rain in three days than seven entire Junes from years past!

As for the week ahead, it appears to be a tale of two halves, with the first few days offering plenty of moisture and below-normal temperatures and the end of the week showing a steady climb back to the temperatures we saw around the beginning of the month. Our overnight lows will remain mild thanks to the insulating layer of clouds through Tuesday morning before clear skies open the door to bigger diurnal swings.

With all that in mind, I hope you can enjoy a muggy commencement day, and maybe find some nice indoor plans for the rainy streak ahead. Perhaps if we’re lucky, summer will finally reappear by Thursday! 

Congratulations Class of 2021!

Reach forecaster Preston Donion at theuwdawgcast@uw.edu and on Twitter @PrestonDonion

ATMOSPHERIC RIVER (8 AM SUNDAY)	72-HOUR PRECIPITATION