A Nice Summer Lightning Display

11:30pm…

Well that was briefly fun.  At least 1/2 of the metro area saw lightning and heard a few rumbles in the distance…a few of you had an excellent show with lots of loud boomers.

From 9:30-11pm thunderstorms fired up in Washington County and then across the south metro down into Clackamas County.  It appears it is most likely over at this point.   This is the radar image from earlier:

The movement was interesting as they were stationary at first and then drifted SOUTH or at least propagated that direction.  It wasn’t the south to north we often see in these summer events.  It appears that was due to us being on the backside of the upper-level disturbance as it passes through Oregon.  I see a couple spots in West Linn & Oregon City picked up around .80″ rain, plus viewer Steve Huffman sent in this pic of 3/4″ size hail in the Farmington area south of Hillsboro

There were also a few strong storms around Stevenson/Carson and the Hood River Valley earlier.  This pic is from Gabor Gardonyi

Unless we get a surprise shower or thick drizzle late tonight or tomorrow morning, it appears this event will leave Portland dry.  It’s back to a major marine push tomorrow, then a thinner marine layer over the weekend.  Summer 2018 rolls on…

Chief Meteorologist Mark Nelsen

9:20pm: A Few Storms Popping Up in Valley/Metro Area

It’s been real quiet here in the valleys so far, but in just the last 20 minutes 2-3 thunderstorms have popped up in the West Linn/Oregon City, Molalla, & Scotts Mills area.  First lightning strike of the day in the metro area is around Rosemont Ridge area of West Linn.

The upper-level disturbance is doing it’s job.  Keep an eye on the sky the next couple of hours and enjoy any light show we get.

Marine air is pouring inland…check out those chilly valley temps!

Chief Meteorologist Mark Nelsen

4:15pm: Big Storms Over Cascades, Quiet in Valleys

As forecast, big thunderstorms have popped up over the Cascades this afternoon.   The current radar/lightning image:

Several have likely produced damaging hail…that possibly only deer, elk, or bears noticed.  Just about all of them have been over forested areas and not in towns.  Although at this moment I see one may be producing large hail very close to Lost Lake

These storms have unusually tall tops for our area, at one point I saw one reach 45,000′ as estimated from the radar.

The lack of cloud cover means today is a scorcher in the metro area.  Check out the 94 at PDX this hour!  By far the hottest day of 2018 so far

The message remains the same for this evening:

1. Between now and 2am storms may also develop out into the valleys.  Anyone from the Coast Range east could see a thunderstorm, but they will be scattered and not everyone will see one.
2. Storms will be slow-moving which means some of us could get a huge soaking, while 5 miles away it remains dry.
3. A strong push of cool marine air arrives west of the Cascades the next few hours (note it’s 20 degrees cooler in Eugene right now!).  Thursday will be mainly cloudy and in the lower 70s

Chief Meteorologist Mark Nelsen

Thunderstorms Possible For Some Wednesday PM & Evening

7pm Tuesday…

Today was a warm one, we hit 91 in Portland, our 3rd 90 degree day so far this season.  Let the annual 90 degree day count begin…

Tomorrow the atmosphere overhead warms slightly, plus we don’t get any cooling onshore flow until after 5pm.  That tells me we have a good chance of hitting 90, but it all depends on thunderstorm cloud cover.  If it arrives by 3-4pm we’ll stay in the 80s.

Speaking of thunder…the weather pattern tomorrow screams THUNDER ACTION to this weather geek.  We have a perfect setup for Cascade thunderstorms to spread down into portions of the western valleys of NW Oregon and SW Washington.  An upper-level “wave” moves overhead.  Note the southerly wind flow at 500 millibars over us Wednesday.  That’s around 18,000′ up.  The little kink in the lines in SW Oregon shows the disturbance moving up through Western Oregon.  There is plenty of lifting ahead of it.

Models are all in agreement showing Lifted Index well below zero (lots of instability). Lots of moisture will be available overhead with precipitable water up around 1″ or more.  That’s a juicy atmosphere.  Lots of CAPE available as well

The WRF-GFS is showing a nice blowup of storms between 1-8pm…here’s the simulated satellite pic at 8pm:

Storm Prediction Center has the central part of our state under a marginal risk for severe thunderstorms

To summarize:

1. Thunderstorms will develop over the Cascades early-mid afternoon tomorrow. Some could become quite strong.
2. Sometime after 3pm they may move out into the valleys, or just develop directly over the valleys.  Anyone from the Coast Range east could see a thunderstorm, but they will be scattered and not everyone will see one.
3. Storms will be slow-moving which means some of us could get a huge soaking, while 5 miles away it remains dry.
4. Storms should be ending after 10pm as a strong push of cool marine air arrives west of the Cascades.  Thursday will be mainly cloudy and up to 20 degrees cooler!

 

I’ll be here all afternoon/evening tomorrow and we’ll be on the air of course from 5pm onward.  A rare busy summer weather day in the Pacific Northwest!

Chief Meteorologist Mark Nelsen

 

Hottest Day This Year, Then Thunderstorms Roll In

7:30pm Sunday

This has been a nice little “welcome back to work” evening for me.  I’m sick (who gets sick in June?) after doing a cruise with my family through the western Caribbean the past 7 days.  We hardly saw any rain, then I think I found more lightning right over Portland once I get back!

First, we had our hottest day of the year so far…hitting 92 at PDX

 

Then, as models had hinted…thunderstorms developed over the Cascades and moved down into the eastern/central part of the Willamette Valley.  Note the UW WRF-GFS morning run showed the thunderstorms…this is a 24 hour rain total:

The UW-MM5 model showed the same thing but (this really hurts), King ECMWF did not bring showers over us.

But in addition to areas of heavy rain…

A strong surge of wind poured across the metro area as cool air rushed out of the bottom of those storms and spread westward.  Peak gusts were very impressive and the line of wind could be seen on the radar reflectivity as well.

At this hour almost 10,000 PGE customers are out of power…rare for thunderstorms in our area.  Quite a few broken limbs around the area.   30-40 mph gusts are pretty strong for June!

We remain in a very warm airmass the next 3 days, so high temperatures will still be around 90 (plus or minus a few degrees) through Wednesday.  The thunder action should remain over/east of the Cascades tomorrow.

Chief Meteorologist Mark Nelsen

 

 

Vacation Time

4pm Friday…

The kids are out of school, it’s June, and I’m off on vacation through Saturday the 16th.  No posts during that time.  Hopefully no hurricane, tornado, or blizzard…

Grand Floral Parade: Showers Likely

4pm Thursday…

A quick forecast for those of you headed into central Portland for the Grand Floral Parade Saturday.  A look back at the past few years plus a few climate stats for this time of year:

 

We’ll be in a classic “April” weather pattern this weekend as an upper-level disturbance swings through the region.   This means Saturday features the typical showers-sun-hail-thunder setup.  All of those could happen within a 20 minute period too!  We COULD get lucky and see most of the showers build during the afternoon; in this case the morning/midday showers wouldn’t be too intense.  Regardless, plan on a wet parade and be pleasantly surprised if the showers briefly bypass downtown Portland.

Chief Meteorologist Mark Nelsen