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Friday, July 30th, 12:30 P.M. 

After a warm start to the day, temps will soar close to 100° in the Portland metro area this afternoon/early evening. We are keeping an eye on some clouds and showers over the Cascades this afternoon. I can't rule out the chance for a brief shower or thunderstorm in the metro area or central valley this afternoon and evening.

High pressure will slowly back off over the weekend, but we will still have a southerly wind overhead. Thin smoke and high elevation clouds will be possible at times, and isolated storms could fire up during the afternoons & evenings along the Cascades and east of the mountains. Highs should trend back into mid 90s to upper 80s Saturday and Sunday.

High pressure will continue to inch away from the Pacific Northwest next week, resulting in cooler temperatures. Afternoon highs will slowly trend back down into the 80s, with overnight lows in the upper 50s and low 60s. 

  • Posted

9:30pm Thursday...

It's been nice waking up to sunshine every one of the past five days. And we'll do it for at least another five, but now it's getting a bit...weird. It's been nice, but we don't live in Sacramento. Most of our viewers live in western Oregon and Washington.

Take a look at those temperatures the past few days. We've gone from a high of 53 Saturday to 76 today in Portland...the warmest day of the year.

VERY DRY SPRING

We've only seen .09" rain so far this month and now we've reached the midpoint of meteorological spring. March-April-May is spring in the northern hemisphere (officially defined by NOAA). Take a look at the numbers...in the past 7 weeks we've seen less than 2" rain in Portland.

Assuming it doesn't rain by Sunday (it won't), this will be the driest March 1st - April 18th on record at PDX. Those numbers go back to 1940. I checked Salem, Astoria, & Olympia. Similar extremely dry numbers.

Last year was a bit dry, our 5th driest April. Luckily last year we had a wetter May and very wet June to make up for it.

I remember the flooded sports fields back in 2017 & 2018. Each year is different, but this spring (so far) is exceptionally dry.

The NWS has a Red Flag Warning out for much of western Oregon, also quite rare for April

WHAT'S AHEAD?

A strong ridge of high pressure in the upper atmosphere is centered in British Columbia with a cool low just to our southeast. It's been a chilly mid-week from Boise over to western Colorado, snow in spots

That warm ridge slides down right over us by Saturday...warmer atmosphere overhead

Then it weakens a bit by Monday, but at the same time another pocket of cool air is sliding down just to our east

The result will be offshore (easterly) flow and warming temps tomorrow & Saturday. 850 millibar temps to around +12 to +13 imply we could get as high as 84, but we're going slightly conservative with a high of 82 Saturday. That would be enough to break a record for the day

Then onshore flow arrives on the coast Saturday afternoon and tries to push a bit inland Sunday. I don't think that will drop our temperature more than a degree or two Sunday. The result is a very summerlike 3 days ahead. Then as the cool air drops in to our east Monday, that's high pressure which renews the easterly flow across the region. A cooler airmass Monday, but offshore flow returns quite strong. Looks like more sunshine for Monday and Tuesday. This all adds up to five more days of sunshine.

When does the rain return? Each operational model is different, but they all suggest a pattern change later next week. The ECMWF ensemble forecast suggests not much rain Wednesday/Thursday, but by Friday and into that last full weekend of April we could be back to a more typical wet/showery weather pattern

We can't do anything about the lack of rain, so enjoy the sunshine while we have it. And there's no reason to panic thinking that we're going to have a "terrible fire season"...remember last June we had soaking rains the first part of the month.

Chief Meteorologist Mark Nelsen

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Weather is a bit slow this evening...

We've seen some weather action the past few days with three Pacific frontal systems moving across the region. That first one Friday night and Saturday morning was sure a soaker; up to an inch in parts of the metro area. Our October rain total is slowly starting to add up

Western slopes of the Cascades have picked up 7-9" of rain the past month...that has pretty much finished off the fires up there!

Last October was very dry, but we're tracking a bit wetter this year so far

After a very warm start (and warm September!), we've cooled back to normal

What's ahead? Typical October weather...lots of clouds and some showers at times.

A large upper-level ridge is building just west of us. It'll be the main factor in our weather over the next week. It looks about like this right now

By Friday...

The forecast is very tricky Saturday through the middle of next week. That's due to the ridge wanting to move just slightly farther west and "flatten" a bit. That leaves the door open to weak systems moving by to the north. Basically we may get clipped by several waves of clouds and light rain showers. You can see one moving by Sunday

The morning ECMWF model (pictured here) really flattened the ridge and carved out a cool upper-level trough. This would be a setup to bring light snow down below 5,000' in the Cascades. But other models and even some ensemble members of this model keep a stronger ridge closer to us. We'll see. I think the main point is that we're probably not headed into a warm and sunny 7-10 days, but also no sign of stormy weather either. Just a typical mix of clouds, showers, and occasional sunny days. The ECMWF ensembles show temps cooling a bit more the next 10+ days; that would be normal for late October

Speaking of cooler temps, La Nina is now into the MODERATE category in the equatorial Pacific. Forecasters are confident this will be the case for upcoming Winter 2020-21. I'm working on the general winter outlook and should have it finished up next week. I'm feeling very confident we should see quite a bit more action than last winter. Remember how boring it was? Almost no storms and no lowland snow until mid-March! To whet your appetite a bit...take a look at the past 20 winters in Portland.

And farther back in time...seems like we have leveled off the past three decades a bit. Last winter finished off the 2010s decade; a new weather decade starts this winter. Snow measurements were taken at the NW corner of PDX up until 1996, then moved to Parkrose (near Sandy Blvd) for the past 24 years.

Last winter was very mild, some of my annuals from the previous summer made it through.

My banana bushes/tree, which most winters die down to the ground, made it to the 2nd story roofline by late August!

In fact last winter EVERY SINGLE DAY made it to at least 40 degrees for a high. It's been 18 years since we've seen a winter without a 30-something degree day.

  • Posted

10pm Thursday...

Today was another fantastic day...as the most consistent/stable weather pattern of the entire warm season continues. Each of the past 8 days in Portland we've topped out between 78 and 84 degrees. Keep in mind a typical high temp this time of year is 80-81 degrees; this is about as normal as it gets folks!

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Humidity has been low, skies have been mainly sunny, & nights have cooled well down into the 50s. Many would say we are having a perfect summer weather pattern. That's because hot high pressure has stayed to the south, allowing just enough onshore flow to keep us comfortable

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Somehow my pool has remained in the mid-upper 70s, even with lows in 40s and highs only 75-80 out there. Must be the constant sunshine each day. We are living through another warmer-than-average August.

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Does it seems like late summers have been consistently warm lately? Sure enough, Portland hasn't seen a cool August since 2010! Although 2011/2013 were only a little above average. Of course the Portland/Vancouver metro area has an increasingly warm "urban heat island" at night which leads to ever-increasing nighttime temps under clear skies. But daytime highs (a more reliable indicator of a warming climate in a city) have been steadily marching uphill too. 1940-2020 August high temps at PDX, make sure you click on it for a MUCH better view.

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After a slightly warmer day tomorrow, in the 85-88 degree range, we'll cool off over the weekend with more onshore flow. Then a weak upper-level trough passes nearby Monday

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Models say we could get lots of clouds and even a few light showers out of this system late Sunday night and Monday morning. I have a feeling the last day of August will feel more like September. But then things heat up again the first week of September. All models agree a flat, but strong ridge of high pressure in the upper atmosphere parks over the Pacific Northwest. You can see the very warm ridge on Tuesday's 500mb chart...this is the pretty one we use for TV.

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The ECMWF ensembles say summer is coming back the first 7-10 days of September. Check out the rain outlook, little/no chance for rain through the 10th, after the showers this coming Monday

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And the surface temp forecast shows 10-15 degrees above average daytime highs. The Euro, GFS, & GEM all hint there could be some sort of heat event during this period. I mean several days at/above 90 degrees. At least hot weather in September is accompanied by much cooler nights than July and early August!

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To summarize

  1. Nice summer weather continues through Sunday
  2. Monday is THE ONE DAY in the next 10 we may see some showers
  3. Sunshine and much warmer weather returns the first week of September.
  4. There is no sign of an early start to fall rains and/or cool/wet September weather like we saw last year.

Chief Meteorologist Mark Nelsen

 

 
 

  • Posted

We are entering the final stretch of Summer 2020. Just a little over two weeks left in August. So far this summer has been near normal temperature-wise. Notice no real anomaly (much warmer or cooler than average) since mid-May

Of course the first half of June was very wet, but since that time it’s been VERY dry. PDX has only seen 0.26″ rain in the past 8 weeks! But that’s not unusual and I sure don’t see any sort of real rain in the next 10 days.

We do have at least a four day heat wave on tap.

Summary

  1. Expect hot weather Saturday through Tuesday. The first two days will feature high temperatures somewhere between 98-102 degrees in the western valleys of Oregon and extreme SW Washington
  2. Next week looks warm/hot even after we get a “cool down” Monday.
  3. Very warm temps make it to the ocean beaches Saturday and at least part of Sunday.
  4. There’s no sign of thunderstorms west of the Cascades through this stretch
  5. By early next week we will have reached our yearly “allotment” of 90 degree days. That’s 13 days, but about to become 14-15 when new climate normals come out next year. For the 2011-2020 period, we’ve averaged 17 per year! This year we’ve seen one in May, June, six in July, and one in August (so far)

Weather Geek Talk

A strong ridge of high pressure has begun developing over the Western USA. By Sunday/Monday it looks about like this around 18,000′

Models have been trending with a stronger ridge and hotter atmosphere overhead this weekend and beyond. Today there is excellent agreement that over Salem we’ll see 850mb (C) temps jump to +19 tomorrow, +25-26 Saturday PM, +22-24 Sunday PM, then down to +18-20 Monday/Tuesday. I just checked my “August Chart” for 850mb temps. In the 10 year period from 1999-2009, the highest afternoon temp in August was 24.5 degrees. Folks, this is a “top tier” heat event coming up!

Alright, so what about surface wind direction? That becomes very critical from mid-August into fall. No offshore flow and we’re not going to hit 100 degrees. Tomorrow the pressure gradient goes flat across the Cascades/Gorge. No windsurfing at Hood River and calm conditions for that fire out in Mosier. But a “thermal trough” develops along the coastline tomorrow night and Saturday. Here’s a classic sea level pressure map for a heat wave; click for a closer view. Saturday at 5pm

I see 3-4 millibars easterly flow through the Gorge Saturday. Add in the crazy hot atmosphere overhead + all sunshine = we’re headed to/above 100 degrees. In theory we could be as high as 104, but I decided to go with a 102 Saturday, assuming easterly flow won’t be TOO strong. That’s after checking the 2008 and 2016 heat waves that produced 100+ temps in mid-August. You can check out blog posts from each of those events (lower right side of this page). Maybe most interesting is that there’s no reason to panic if it’s only 80-82 at noon Saturday; we can easily jump 20 degrees after noon in this pattern.

Saturday night should be a VERY warm night; possibly only dropping to around 70 well after midnight in the city. Easterly flow goes away Sunday, but with such a warm start + hot atmosphere we should still hit 100 in the afternoon. Of course if we have any significant high cloud cover (some models show that), we won’t hit 100. Here’s 2pm Sunday as the thermal trough is about to push east of the Cascades

Finally, a strong push of marine air should drop us 5-10 degrees Monday; “only” a high around 90 or so. But notice this chart shows 850mb temps (from ECMWF model) remaining above average through most of the next two weeks. Green is the average temp (notice it goes downhill in late August), blue is average of all 51 ensemble members. Each thin line is one ensemble member

Enjoy the cool temps tonight, and try to stay cool this weekend. Here’s our ocean beaches forecast; the left side forecast temp for each day is the central Oregon coast. Right side is up on the north coastline, including Long Beach peninsula. In general it’ll be quite a bit warmer the next few days up around Cannon Beach and Seaside

I’ll be on vacation tomorrow through most of next week so probably no posts until Saturday the 22nd.

As US passes 150,000 coronavirus deaths, group warns of hundreds of thousands more without action

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The United States has surpassed 150,000 recorded Covid-19 deaths -- a milestone that comes as the country's rate of daily coronavirus deaths i…

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It finally happened, after a very cool start to July we’ve seen two consecutive hot days. We hit 90 in Portland yesterday and 93 today

This tied for the warmest/hottest temp so far this summer. At this point we’ve seen 4 days at/above 90 in Portland this summer. Keep in mind all the other numbers below refer to the entire summer. A typical summer will see around 13 days at/above 90 in Portland. Some crazy hot summers in there! (2014, 2015, 2017, 2018). Last year and this have been so much more reasonable.

June was wet (although not cool), and the first 10 days of July were very cool. That prompted the annual worry-fest about whether “this could be the year without a summer”. But the past 10 days have brought our temperature for the month close to normal. This definitely isn’t and will not be the year without a summer

Something really sticks out on this map…do you see it?

It’s Newport. Check out the HIGH of 52 today; similar to a January day out there! And it’s much cooler than other coastal stations in the 60s to lower 70s. What’s going on? It’s the very chilly Pacific Ocean sea surface close to the coastline. The latest sea surface temps here, along with some buoy water temps

Notice most of the Pacific offshore is in the 60s, or at least upper 50s and 60s. But a narrow ribbon of 48-55 degree water is right along the beaches. This is called “upwelling”. Gusty northerly and northwest wind blowing down the coastline causes a slight “rightward” movement in surface water (farther offshore). That allows cold subsurface water to replace it; I remember learning about it during a 5th grade school visit to the beach. I sure remember that field trip from Monitor Grade School. We all got into BIG trouble for wading into the ocean and had to write an essay about how bad we were…but I digress a bit. Scary to think about as a parent now!

Diagram credit: NOAA

You can read more about upwelling here and how critical it is for our fisheries along the PACNW coastline.

The downside is of strong upwelling? Colder than normal water temperature right long the coastline = chilly onshore wind. When we turn hot and the marine layer is thin, temperatures will vary dramatically depending on location. For example that Newport high of 52 is at the airport right at South Beach.

Looking at those other high temps, I would say the high at Newport was really more like 60 degrees. You get the idea…right on beaches = cold, slightly inland = just a little cool.

So what’s ahead? More of the same. We haven’t seen significant rain in a month and no model shows showers in the next 10 days either! Check out the ECMWF ensemble forecast for the next two weeks; this is 24 hour precipitation. Only 5 of the 51 ensemble members produce more than .10″ rain in Portland through Monday August 3rd

A weak push of marine air tonight should keep us below 90 tomorrow, then a major push tomorrow evening means highs around 80 for Wednesday-Friday. Models then develop upper-level ridging (warming) overhead Saturday through next Monday/Tuesday. Expect warming again. This is the typical seesaw west of the Cascades in midsummer. Very warm, cooling, then warm again

Looking at this you can pick out the days that are best for certain activities. Mow the lawn on cooler Thursday, hit the lake or your pool tomorrow and this weekend. Regardless, enjoy our fantastic Pacific Northwest summer weather free of high humidity and extreme heat!

Chief Meteorologist Mark Nelsen

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It has begun…complaints about cool summer weather. I often get complaints this time of year, some people expecting that we should have Sacramento style heat in Portland. To be fair, the past two days have been especially cloudy and cool. Today was the 2nd day in Portland without seeing a 70 degree temperature; our typical high this time of year is 78-79 degrees!

We’re now approaching two weeks of below average temps. The average high temperature for this first week of July is the coldest since 2000! My little butternut squash and cucumber plants are struggling…just a few inches high. Too little sun and most days only in the 60s up in the hills. At least we haven’t seen much rain the past 2+ weeks; it’s very clear our dry season has arrived.

So, the big question…

IS THIS IT?

WHAT WE ARE SEEING NOW…IS THIS OUR “SUMMER” THIS YEAR?

The short answer; it’s unlikely this same cool weather pattern continues the next 9 weeks to Labor Day. But there is no sign of hot weather in the next 7-10 days either.

First, we are overdue for an average or cool summer west of the Cascades. I’m not saying that’s about to happen, but the past six years have featured an unprecedented string of warm to hot summers in the Portland metro area. 2016 wasn’t crazy warm and neither was last year. In fact much of the warmth last year was due to excessively warm nights; a consequence of warmer than normal ocean water offshore.

My point in bringing this up is that, at some point, we should expect to get a cool summer.

The weather pattern the past two weeks has featured a setup like this in the upper-atmosphere; weak “troughing” or a dip in the westerly flow over the Pacific Northwest. High pressure (and warmer air) has been suppressed to the south and east regularly. Notice most of the country is very warm to hot! We are all alone in the cool weather out here

A warm/hot July weather setup looks more like this; the westerly flow pushed farther north into Canada. That takes much of the cloud cover and showers north as well = sunnier and warmer weather west of the Cascades

Looking ahead, that upper-level trough backs off a bit the rest of this week. The result is more sunshine and warmer days. By Saturday that hot upper-level ridge is much closer to us. At this point it appears this should finally be a setup for a sunny Saturday and temperatures in the 80s.

But by Monday another system is passing by to the north, once again bringing a surge of cool marine air inland Sunday and maybe even a shower. A continuing issue the past couple of weeks is models only catching onto these cold troughs about a week ahead of time. A week ago it appeared we’d be heading into a very warm summer pattern this coming weekend. Instead that is being delayed once again by this system Sunday/Monday

Looking farther ahead, we should warm again a week from now as high pressure builds just offshore. This is the GFS model for next Wednesday the 15th

The morning ECMWF model’s forecast for high temps in Portland shows this trend as well.

Warming through this Saturday, then cooler, then warming again a week from now. You can add about 5 degrees to most of these to get a Portland high temperature. In general this is a bit warmer than what we’ve seen the past two weeks. It would imply the next 10 days will be near average for mid-July.

No model shows a wet weather pattern ahead, just a few drips here and there. ECMWF says less than .20″ in the Willamette Valley through the next two weeks. As mentioned earlier, the dry season is here:

It’s summer and vacation time, so I’ll be off until Sunday. Enjoy the warmer late-week temps!

Chief Meteorologist Mark Nelsen

Amazon giving $500 million in one-time bonuses to front-line workers as a 'thank you'

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Amazon is giving out more than $500 million as a "Thank You bonus" to front-line workers who were with the company throughout the month of June.