PORTLAND, Ore. (KOIN) — Stop me if you’ve heard this before, but this weekend is going to feel amazing…without rain for most of the Pacific Northwest. But – there’s always a but. A few rumblers will try to enter the weather picture for portions of the PNW. I’m talking about thunderstorms.

Thunderboomers

Hikers, campers, bikers: There’s a pretty good chance we’ll have thunderstorms over the Cascades in Washington and Oregon, including eastern mountain slopes Saturday afternoon and possibly Sunday afternoon. Forecast models are trying to bring isolated Cb (cumulonimbus) over the northern Willamette Valley briefly Saturday after 4pm. The trough responsible for this should remain lined up over the Cascades this weekend. Although, just like the smoking sections of the 20th century, these thunderstorms or showers could permeate beyond their boundaries too.

Saturday morning weather

Clouds started clearing out Friday leaving us with no rain on a Friday for the first time since April 1st. As a results of keeping dewpoints in the low 40’s and possibly encountering a shallow temperature/dewpoint spread, plus calm winds, we may get an hour or two of patchy fog around sunrise. I do not expect anything widespread. Then sunshine quickly takes center stage.

Weekend weather

Temperatures are warming up this weekend to the low 70s. Sunday may be a few degrees warmer with thin high clouds entering the picture. Remember to pay attention to our weather right here at koin.com/weather, as we closely watch the development of mountain thunderstorms in the afternoon hours.

Oregon International Air Show Forecast

During the flying hours 12:30p to 4:15p Saturday and Sunday, the weather is looking just about as good as it could be for this volatile month of May. Any fog that develops in the morning should quickly dissipate before the gates open at Hillsboro Airport. Northwesterly wind increases in the afternoon to 10-15mph. The sky over KHIO should remain mostly clear during flying hours. Slight chance for an evening (after 4pm) shower to pass by associated with a trough of low pressure situated over the mountains.

Weather Alerts issued by NWS

FROST ADVISORY IN EFFECT FROM 3 AM TO 9 AM PDT SATURDAY.

* WHAT…Low temperatures of 33 to 36 will result in frost formation. Isolated pockets of temperatures below freezing are possible.

* WHERE…In California, Western Siskiyou County and Central Siskiyou County. This includes the Shasta, Scott valleys, and portions of the Klamath valley. In Oregon, Josephine County and Jackson County. This includes the Rogue, Illinois, and Applegate valleys.

* WHEN…From 3 AM to 9 AM PDT Saturday.

* IMPACTS…Frost could kill sensitive outdoor vegetation if left uncovered.

https://forecast.weather.gov/wwamap/wwatxtget.php?cwa=MFR&wwa=frost%20advisory

Flying to Denver Saturday morning?

LATE SPRING STORM TO BRING HEAVY SNOW TO THE MOUNTAINS, FOOTHILLS, AND FRONT RANGE URBAN CORRIDOR.

Heavy snow is decreasing from north to south across the region early this morning. The heaviest snow at this time is over the Palmer Divide. Snow accumulation on trees will cause some tree limbs to break and produce scattered power outages. Do not park under trees and avoid walking under snow laden trees.

Boulder And Jefferson Counties Below 6000 Feet/West Broomfield County-North Douglas County Below 6000 Feet/Denver/West Adams and Arapahoe Counties/East Broomfield County- Including the cities of Boulder, Golden, Highlands Ranch, City of Denver, Lakewood, Aurora, Arvada, Littleton, Parker, Longmont, Denver International Airport, and Brighton

WINTER STORM WARNING REMAINS IN EFFECT UNTIL NOON MDT TODAY…

* WHAT…Snow ongoing. Additional snow accumulations up to two inches.

* WHERE…Boulder and the western suburbs of Denver, and Denver.

* WHEN…Until Noon MDT today.

* IMPACTS…Snow will accumulate on tree branches and powerlines, possibly causing them to break and lead to power outages. Travel may become very difficult due to snowfall on roadways.

https://forecast.weather.gov/showsigwx.php?warnzone=COZ040&warncounty=COC031&firewxzone=COZ240&local_place1=4%20Miles%20SSE%20Edgewater%20CO&product1=Winter+Storm+Warning&lat=39.6999&lon=-105.0459#.YoiTpajMKUk