Back to Hot, Plus Humid This Week

August 6, 2017

10pm Sunday

Today was MUCH more pleasant with a relatively “chilly” start.  Many of us started way down in the 50s…ahh, nature’s air conditioning

PDX Observed Low Today

At the same time morning clouds covered much of the metro area.  At noon today it was only 74 degrees in Portland!  Yet we eventually made it up to 88 this afternoon.   So as you know we sure won’t break any hot streak here in Portland…this heat wave will go down as a somewhat typical heat wave, but with two VERY hot days right in the middle.  Down in Salem the 90 degree streak continues and the next two days should establish this hot spell as the longest in Salem’s history:

90 Degree Days Heat Salem

We sure did get a thicker marine layer today.  That kept temperatures down, but tomorrow that layer should be thinner under a building upper-level ridge.  There will be no offshore easterly flow this week, but the hot atmosphere overhead will remain with a weak onshore flow through Thursday.  That will keep those 100 degree temperatures away, but inject plenty of moisture for a more “humid experience” this week.  Dewpoints are in the lower 60s in the metro area this evening; unfortunately I think we’ll see lots of those 60-65 degree dewpoints through Thursday.  It won’t help that there will be lots of moisture coming in overhead as well.

Hot Headlines2

Looking farther ahead, it appears that for the first time in almost a month we have a chance for a cool/showery weather pattern.  Remember, I said CHANCE.  For days models have been telling us the ridging overhead will break down this weekend and beyond.  Note the big drop in 850mb temps on the ECMWF


The blue/red lines are temperature in celsius at 5,000′.  Check out the return to normal temperatures by next Monday.  And there’s good agreement among a majority of the ensemble members that we’re turning a corner to cooler weather.

What about rain?  Here’s an interesting graphic from the GFS showing total rain accumulation through the 2 week period from each of its 21 ensemble members.  Note 12 of 21 (over half) produce measurable rain in Portland before eclipse day (21st)


Before you panic and worry about that $500 you plunked down for one dusty campsite for one night in a field…keep in mind this is a “total” accumulation of rain through the two-week period.  A better view might be from the ECMWF 24-hr chart:


This one shows all 51 ensemble members from that model.  Each member is a horizontal line again, but in this chart you only see 24 hour periods that contain rainfall.  Any color means at least .10″ rain in a 24 hour period.  This is for Salem as well, not Portland.  Now things don’t look so bad do they?  Just a chance for showers here and there.  The main message here?  Models are telling us NEXT week will be much cooler and a few of us could actually get some rain showers.

It’s still too far away (15 days) to get a good idea what might happen for eclipse day itself.  More on that later this week or next weekend.

Chief Meteorologist Mark Nelsen 


August 3, 2017

7pm Thursday

Today was an insanely hot day in the Portland Metro area; all official stations were between 102 and 105 degrees.

PDX Observed High Today

Of course this broke a daily record, and came within 2 degrees of our all-time high temperature.

Mark PDX Record High Hot

Up through 3pm most metro locations were running a degree or two cooler than yesterday, leading me to believe we’d top out around 101 to 102 degrees.  Then from 4pm-5pm the hot and dry air overhead suddenly “mixed down” over the city.  No, we didn’t get a dry easterly wind, that had already disappeared in the Gorge.  Instead you can see it by checking the dewpoint.  At 3pm it was 57.  By 5pm it was down to 45.  That’s a very dry airmass poking down to the surface; the reason for the sudden jump in temperature.

Here are a few other temperatures west of the Cascades, notice slightly cooler highs in Salem and Eugene

Todays Observed Highs OrWa 2017

One other unexpected event was the overnight lows; many areas were cooler than I expected, in fact PDX ended up 4 degrees cooler than forecast.  Yet on many hills around town the breeze from the north or east kept blowing, keeping temperatures in the 70s.  The warmest I could find in the metro area was the Sunset Transit Station at 77.

PDX Observed Low Today

So after two blazing hot days we have some cooling coming up…about 10 degrees cooler tomorrow then another 5 degrees cooling Saturday.  That means we’ll spend most of Saturday in the 80s in the metro area…much better than today!

The bad news is that the upper-level ridge, although weaker, is going to linger along the West Coast for another 7 days.  Models have gradually been shifting to this solution over the past two days.  You see that in the 500mb anomaly map from the ECMWF ensembles for Sunday and again Wednesday (click for better view)


This means even though 100 isn’t likely again, temperatures will RISE again Sunday through the middle of next week.  IF we have a high of 90 or above Saturday, it’s likely we’ll see a stretch of 11 days at/above 90 degrees in Portland.  That would be our longest stretch, after 2009 & 2015


There is good agreement among the ECMWF (and GFS) ensembles for the sustained heat for one more week:


But the sudden change about 11-12 days from now is something to watch.  Ensembles from both models are trying to bring a trough much closer to us for much cooler weather about a week before the eclipse…but that’s still a ways off.  Try to stay cool the next 7 days!

Chief Meteorologist Mark Nelsen


August 2, 2017


Final numbers are in and they look like this:

and this:

Note the 107 in Salem and 108 in Roseburg…are we still west of the Cascades in Oregon???

They were both just one degree off the all-time high, but saw the same temperature two years ago during that late July heatwave in 2015.  But Medford has beat us all, those folks just endured their hottest day since I was 12 years old…that’s a long time!  But no stations in Oregon reached all-time highs…we knew a few would be close.


Record Breaking Wednesday & Warm Night Ahead

August 2, 2017

4:30pm Wednesday

It’s a scorcher out there at this moment.  Tons of smoke has been in the air all day too.  It feels like we’re in some sort of southern California weather hell don’t you think?

The official highs are not in yet, but Salem has hit 107 and PDX 103.  That’s only one degree off your all time high down there in Salem.

PDX Observed High Today

Believe it or not the fire smoke has probably kept us a degree or two COOLER than we could have been.  At 2pm I checked two different solar radiation sensors (Forest Grove & Corbett) and found they were seeing 5-8% less solar energy today compared to yesterday.

I’ll be on the air from 5-7pm with all the latest numbers and we’ll pull out the radar as well on a perfectly cloudless day…why?  Check out the Whitewater fire which appears to have really taken off this afternoon east of Detroit.  The plume is up to 30,000 ft.  If we didn’t have all the smoke from the Canadian fires we’d be able to see that plume from Portland.

KPTV 2017 Default Earth

It also shows up satellite quite well near Mt. Jefferson


The fire smoke will be with us again tomorrow, so I lowered the forecast high down to “only” 105 at PDX.   Between now and tomorrow of course we have to deal with tonight.  I think low temperatures will only get down to around 70 in the city, but 60s in most other areas.  Better than a hot night east of the Rockies, but still the warmest we’ve seen since the big 2015 heat wave.

2017 Forecast Tonight Metro

One last note…for the record it IS possible to fry an egg in your car in this weather.  The before and after pics (45 minutes apart) from Gary Kinney:

Chief Meteorologist Mark Nelsen

Tuesday Recap: Near 100 in Metro Area & Smoke Moving In

August 1, 2017

11pm Tuesday

Today was a scorcher as expected, although temperatures were a notch or two below the forecast high here in Portland

Other parts of the state were incredibly hot

That Medford high and forecast for tomorrow is just amazing.  114???  Wow.

So how will we end up 5-8 degrees warmer tomorrow here in the Willamette Valley?  It’s all about the wind direction.  Today we had weak onshore flow and light westerly flow through the Gorge.  Overnight and tomorrow the hot thermal trough of low pressure shifts west of the Cascades.  That produces light easterly flow through the Gorge and over the Cascades.  Add that to a slightly warmer airmass and it’s going to be a blazing hot day Wednesday…the hottest in 8 years for many of us.  We’re forecasting 105 in Portland, although there is one thing that could drop that temp a few degrees…smoke.

Take a look at the GOES-16 image of smoke surging south from British Columbia wildfires this evening

Soon after 7pm, air quality took a huge tumble in the metro area.  As of 11pm it’s considered UNHEALTHY in Portland.  IF that smoke thickens much more, that will cut down on energy coming from the sun and our temperatures won’t rise as much as expected tomorrow…we could end up at 101 or 102 instead of that 105.  Regardless, it’s going to be a hazy and hot day around here.

Chief Meteorologist Mark Nelsen

Forecast On Track; Warmest Night of Summer Ahead

August 1, 2017

3:30pm Tuesday

It’s a scorcher this afternoon, well into the 90s in the metro area at 3pm:

2017 Current Temps PDX Metro Area Earth Scene

At least the relative humidity is low, so it’s our usual “dry heat”.

We are on track to top out around 98-99 officially in Portland, and several spots in the metro area will likely make it to the century mark (Hillsboro, McMinnville, Aurora).

I expect a warmer night with temperatures remaining in the 80s, then 70s all the way through about 3am.  Eventually we’ll all get down into the 60s so that’s good news

2017 Forecast Tonight Metro

The warmest night so far this summer was 63 during the first heatwave in late June.  By Thursday & Friday mornings we’ll struggle to get below 70 in the urban areas…too warm!

It’s hard to believe, but we expect 6-8 degrees WARMING tomorrow.  Of course that gets us up close to or tying the all-time high of 107 degrees here in Portland.  It’ll be all about the big numbers the next two days as skies stay sunny.

One change tomorrow is the wind…it’ll be lighter and won’t help cool us off as much.  This might help…it’s a cool afternoon at Newport and you’d probably need a jacket out there!  Only 64 with a gusty north wind.

Live Cam Beaches

Tomorrow is the ONE day with hot temperatures on the north coast and the one day that will hit 80 along the central coastline.  A wind reversal (cool southwest wind) arrives early Thursday and that’s nature’s air conditioning.

Stay cool!

Chief Meteorologist Mark Nelsen

Heat Wave Update: Monday Evening

July 31, 2017

9pm Monday

Today was the beginning of our heat wave, but at least it was just a “regular” hot day.  Temperatures moved into the lower 90s in the Willamette Valley:

Todays Observed Highs OrWa 2017

Forecast-wise nothing has changed the past 24 hours.  In fact our 7 Day forecast looks just the same as it did 24 hours ago for the next 3 days.

7 Day Forecast Graphic 2017

One change is temperatures remaining near/above 90 degrees through the weekend.  Models are much slower weakening the upper-level ridge hanging along the coastline this week.  As a result the cooler marine air will only slowly leak into the western valleys of Oregon and Washington.  This means we are in a stretch of as many as 8 days at/above 90.

Hot Headlines2

Here is our current forecast vs. records for each of the next 3 days.  The record highs for the first few days of August are pretty low hanging fruit as they say.  Easy records to break!

Mark Hot 3 Day PDX Forecast

By the way, here is a list of Portland’s 5 hottest days, notice we’ll have to get to 106 to make it into that list.

Mark PDX Record Hottest Days Ever 100.png

So hang on, we’re in for a hot ride tomorrow.  Models are in good agreement giving us 5-9 degrees of warming, which should put us into the upper 90s by 5-6pm.

One other note; there is quite a bit of smoke to our south and north plus northeast from fires in the region.


At this moment I don’t expect enough smoke over NW Oregon to have an effect on high temperatures.  But even just a thin veil of smoke any of the next 3 days COULD be enough to keep temperatures 1-2 degrees lower than forecast.  We’ll be watching that closely.

Chief Meteorologist Mark Nelsen