Spring 2015 Wrap Up: Warmest and Driest in Years

June 18, 2015

Comparing this posting to the previous summer outlook these probably seem to be reversed, but I was out-of-town when the final spring temp/precip numbers were released by NCDC.

The highlights:

In Portland it was the warmest spring since 2004 (11 years) and the driest in 8 years.  That said, since April we have been on track for record dry.  The April through June rainfall is the driest we have seen in over 70 years (driest ever at PDX).  Airport records go back to around 1940 and rainfall stats were in a different location before that time so it’s an apples/oranges comparison.


What about the rest of the region?  Temperatures nationwide show Oregon saw its 3rd warmest spring on record.


And the Cascade climate zone of Washington was the warmest on record:


We’ve come a long ways from the cold and wet springs centered around 2011.  Take a look at just the Willamette Valley spring temps over the past 100+ years and you see the huge rebound the last 3 years:


Note that this HAS HAPPENED IN THE PAST.  Check out the mid-1920s and late 1950s…very cool and then a sudden swing upwards.  I’m not discounting any manmade effects, but the point is we tend to focus on small periods of time.  I was so wound up after those cold springs that I built a greenhouse.  Wow it’s been hot in there this past month!  Seems kind of silly now, but I’m sure cool springs will return again.

Precipitation?  The bad news is that a wet May east of the Cascades was not able to overcome the rainfall deficit except in the extreme SE part of Oregon.  The spring total was still a bit below normal due to dryness in March and April:


Looking ahead, I know there has been lots of chatter about a “record heatwave” showing up on the ECMWF and to a lesser extent the GFS.  Here’s the ECMWF ensemble chart showing the insane +30 degrees 9 days from now.


Note that not a single member of the 51 ensembles was that hot.  BUT, note the ensemble mean is around +21 and look how long it is way above average (green line).   That plus other models gives me pretty good confidence that we may see a heatwave the last week of June, starting right at the end of our 7 Day forecast.

Right now our June average temperature in Portland is just barely the warmest on record.  If models are correct, June 2015 will be our hottest on record.  We’ve seen 4-90 degree days and I could easily see another 3-6…what a scorcher.  It’s also unlikely we’ll see rain the rest of the month, unless we get sprinkles tomorrow morning.

Chief Meteorologist Mark Nelsen


2015 Summer Outlook: Probably Warm, Could Be a Scorcher!

June 16, 2015

Is it going to be a scorcher this summer?  Not sure about that but…


By “Summer” I am referring to June, July, August.


1. Very little has changed since last summer…warmer than normal atmospheric conditions have prevailed now for over a year

Take a look at the past 12 months…almost every single one has been above average with 5 of those exceeding the record in Portland:


The past 30 days have seen very warm temps across the northwest quarter of the USA


The past 120 days as well, note you can click on any of these images for a larger view.


That’s because an upper-level ridge has been over or to our west/northwest for much of the past year.  It has come and gone at times, but it keeps coming back.  Some have named it the Ridiculously Resilient Ridge.  Seems appropriate.

2. Sea surface temperatures in the northeast Pacific remain unusually warm…the “Blob” is still alive

Warmer than normal water off the coastline helped give us the warm temps last summer and boosted humidity levels at times.  Take a look at the current anomaly; that’s degrees above or below normal in celsius:


See the large area of “warm” water?  Compare it to last June:


The warm water doesn’t want to go away.  During most of the warm season our air flows in from the ocean, so if the water is warmer than normal temperatures will often be warmer than normal too.  Now you may notice one critical difference this year, take a look at below normal temps right along the coastline itself.  That’s due to “upwelling”.  With high pressure firmly established in the eastern Pacific much earlier this year (our nice but dry weather since early May), the gusty northerly winds along the coast allow a bit of a motion to the right as they travel down toward California due to the rotation of the earth (long story).  Cold water below “upwells” as a result.  Last June we didn’t have high pressure offshore as much so the ocean water was a bit warmer.

3. El Nino conditions are present in the equatorial Pacific

El Nino was just trying to develop last summer, it got going (just barely) through the winter, and now is firmly a “moderate” El Nino episode.  What have we seen in previous El Nino summers?  I looked at summers where the June-August ONI was 0.5 or greater (like we’ll see this year) for the past 25 years.


Then all the same type of years back to 1951


Interesting don’t you think?  Analog years suggest we will have a warmer than average summer.

4. All modeling that I’ve seen continues the unusually warm weather through summer & early fall.

This is a biggie.  Our numerical simulations of the next two weeks (through the end of June) are generally showing warmer than normal temperatures most of that time.  In fact there are strong indications that we may have a hot spell somewhere in the last 10 days of June.  Note the ECMWF ensemble chart shows 5,000′ temperatures well above normal through most of the period.  Normal is the green line.  There are two brief cool periods (near normal) this Friday and again early next week.


The weekly maps I posted yesterday from the same ECMWF (EURO) model showed the warm pattern continuing the next 30 days.  The CFS model forecasts above normal temps along the West Coast too…this is an average through the end of July:


I’ve found the CFS really likes to forecast above normal temps for our area, although I’ve only been watching it closely for about two years and most of that time it really has ended up warm!  So maybe it actually knows what it’s talking about more often than I think.

Going farther out in time, here is the latest CFS forecast for July surface temperature anomaly


and August


I’ve seen one other model…the JAMSTEC, and it forecasts above normal temps for us as well.

5.  Most forecasts I have seen are similar.

What are others saying?  The NWS agrees with a warm forecast.  The June-August forecast temps:


I’m not allowed to post it so I won’t, but WeatherBell is forecasting a very warm Northwest too…quite similar to the NWS.

A lot of you may remember Pete Parsons from his TV days at KGW & KOIN.  He’s a friend and forecasts for Oregon Department of Forestry/Agriculture.  He’s going the other way in his public forecast, expecting a cooler than average summer.  You can find the full forecast here:  http://www.oregon.gov/ODA/programs/NaturalResources/Pages/Weather.aspx


So there you have it…I have a gut feeling we could be in for a scorcher this year.  Although if the patterns set up right it IS possible to have a record warm summer, but not get extreme heat (100+).  Remember last year we didn’t hit 100 in Portland even though it was our warmest or 2nd warmest on record!  We didn’t have any strong thermal troughs to turn the wind easterly and push us up into the 102-106 range like in 2009.  Let’s hope we don’t see that again!

Chief Meteorologist Mark Nelsen

Warm Start To June

June 15, 2015

I notice we’ve seen more 90 degree days in June (4 so far) than any year since 2006


The June record is 6 days, which is easily beatable if we get another hot spell in the 2nd half of the month.  There is a reasonable chance that could occur since models are showing above average temperatures continuing.

This evening was real interesting with a strong marine push providing a huge temperature contrast across the northern Willamette Valley.  Check out the 6pm temps…


At the same time mid-upper 80s were widespread, areas west of the Willamette River south of Chehalem Mountain were dropping into the 60s!  That was a surge of cool marine air moving in through the low gap in the Coast Range west of Sheridan.  The same thing happened at Corvallis, gusts there reached 30 mph.

I noticed how dry it is outside today…feels like early-mid July in my yard.  We’ve only had 1.00″ of rain in the past 6 weeks and no rain is on the way.  Check out the 10 day rain forecast from the GFS




No sign of any significant weather to give us a soaking.  This is the driest late spring/early summer so far in my entire career here in Portland.  You have to go back to 1992 to find a similar start to summer.  That’s assuming we get little or no rain in the next 2 weeks.

Chief Meteorologist Mark Nelsen

ECMWF Monthly Run: Summer Is Early & Sticks Around

June 15, 2015

Back from vacation…here are the 4 weekly maps of average 500mb height and anomaly.  Wow, things sure haven’t changed much in the past year.  Upper-level heights remain above normal over us or just to our north and west.





It’s been an unusually warm and dry end to spring and start of summer and there’s no sign that’s going to change.  It’s going to be a rough summer for our native vegetation due to lack of water and for our forests (from fire).

On the flip side, my cucumbers, tomatoes, and squash are going to do great!

Chief Meteorologist Mark Nelsen

Vacation Update

June 10, 2015

As mentioned in the previous post, I’m on vacation this week.  Hot and sweaty in Florida, as it always is in June!  We’ve seen some nice thunderstorm action three different days and Tuesday evening was great after dark with lightning flashing around the theme parks but not too much rain.  After my daughter spent almost all of the last trip in the hospital, I thought she should get a chance to go back and see all the Harry Potter stuff at Universal Resort in Orlando.  We’ve been here 3 days, then we’ll do 1 at Disney and 1 at the beach (Melbourne) before heading home.

After yesterday evening’s thunderstorm the crowds cleared out and the sky looked like home (in winter).  That plus the “snowy” buildings made for a great picture that definitely doesn’t look like Central Florida!  Don’t let it fool you, it was warm and sweaty at the time.


Vacation Time

June 6, 2015

I’m off through Sunday the 14th, so probably no blog postings during that time

Chief Meteorologist Mark Nelsen

Hot Weekend Ahead; But Not Really A Heat Wave

June 4, 2015

5pm Thursday…

All signs point to our warmest weather (okay, hottest weather) of the season so far this weekend.  Just a couple of days ago models were a bit warmer, forecasting highs well into the 90s or even closer to 100 (the GFS)  in the Portland metro area.  But now they’ve settled on a more reasonable period of briefly hot temperatures Saturday and Sunday right around 90, plus or minus a couple of degrees.

I lowered our forecast high temps a bit today, and then noticed the NWS did as well…for two reasons:

1. This isn’t the heat wave pattern with easterly/offshore flow.  We never totally lose the west wind in the Gorge and there is no thermal low pressure area west of the Cascades.  As a result we continue weak onshore flow through the weekend and early next week.

2. 850mb temps peak out at +18 to +20 degrees over Salem.  Previous cases in this pattern have high temps right around 90.

IF this exact same atmosphere was overhead and we had good easterly flow, temperatures would soar into the 95-99 degree range.  But that’s not going to happen.

To consider it a real heat wave in our area I would expect 3 days 90 or above generally.  And no records will fall at PDX.  The record highs are 98, 93, 94 for Saturday, Sunday, Monday.

So enjoy the hot weather if you are one of those people.  River levels are lower than normal and they are running warmer than last year as well.  The Columbia River is already up to 64 degrees, pretty warm for the first week of June!


Looking ahead through next week and beyond, we have definitely entered a stable summer-like pattern for awhile.  Both the GFS and ECMWF have NO precipitation for the next 10 days…Continue watering!



By the way, May continued the trend of warm months in the Pacific Northwest.  Only 1 month out of the past 12 has been below average…that was November


Chief Meteorologist Mark Nelsen