Near 100 Today

July 15, 2018

8am Sunday

Just a quick note to let you know today looks to be a scorcher again, possibly the hottest day of the year in Portland.  For the first time in 3 days light easterly “offshore” wind flow has developed this morning through the Gorge.  That plus a very warm/hot atmosphere overhead and full sunshine means warmer temps than the low 90s from Saturday.  PDX officially hit 93 yesterday.


Today should be around 5 degrees warmer, possibly 7.  Of course that opens up the possibility that we hit 100 degrees for the first time this season.  Here is our morning forecast


850mb temps are not as hot as I’d like to see for PDX hitting 100, currently around +20 to +21 over Salem.  It’s a stretch to get that hot down here at the surface with those temps up above.  But considering the sudden surge of heat Thursday with the offshore wind (97 at PDX and 99 at Troutdale), temps around 100 seem reasonable again today.  It sure seems easier to get hot in the Willamette Valley & Metro nowadays doesn’t it?

As I mentioned the last day I worked (Tuesday) we are in this very warm/hot stretch for quite awhile.  By the time we get a major marine push Tuesday night, we will have gone through a 7 day stretch with highs 89 or higher.  All models are in very good agreement we get a nice cool down Thursday/Friday, then warming again (back to hot) for next weekend.  Note both the GFS and ECMWF meteograms from last night’s ensemble runs.  This is for Salem, but Portland is similar:




It’s going to end up as another blazing hot July; Portland, Salem, & Redmond are all running 3 degrees or more above average for the month at the halfway point today.  Note the 850mb ensemble chart from the ECMWF shows upper-air temps above average the rest of the month.


I’m on vacation this week, looking for a cool place…stay cool!

Chief Meteorologist Mark Nelsen

Hottest Weather of Summer Ahead

July 10, 2018

8pm Tuesday

Today was a fantastic day in my opinion…clouds to sunshine and temperatures right near seasonal averages.  The Willamette Valley ended up right around 80 degrees.

If you don’t like our mid-summer hot weather, find a cool place; it’s about to get hot west of the Cascades.  A sprawling upper-level ridge is already building this evening over the Pacific Northwest and more or less remains over us the next 7-10 days.


A long period of very warm to occasionally hot weather is likely Wednesday through the middle to end of NEXT week.

  1. Every day is likely to exceed 85 degrees, with temps as high as 95 either Thursday or Sunday/Monday.
  2. I think temps up to 100 or higher are unlikely at this point
  3. Overnight lows will be moving into the low-mid 60s at times…getting uncomfortable in the urban areas if you don’t have air conditioning
  4. Record highs are unlikely…all records through the 21st are at/above 101 degrees.

This one is interesting because it’s not a sharp ridge which gives us extremely hot weather and/or easterly downslope wind.  Instead it’s quite flat, indicating a large area of much warmer than normal temps.  Here’s the 500mb forecast from the ECMWF model ensembles (actual heights are the lines, anomaly is the color) for Thursday, Sunday, next Wednesday, and Saturday the 22nd.  No big, hot ridge, but abnormally high heights…seems like a lot of red across a good chunk of North America.

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850mb temps peak out around +22 Thursday and 19-21 on ECMWF ensembles Sunday-Monday.  Without decent offshore flow it’ll be very tough to get above 95 degrees (good!).

Note the surface temp forecast for Portland from this model


These numbers are a good 8-15 degrees above average for our area.  If you are into water sports this is excellent news.  If you work for a paving company…well…October will eventually get here.  We can forget about precipitation because in this pattern even thunderstorms are hard to come by as high heights squash the convective stuff.  Not a single GEFS ensemble member produces even .10″ rain in the next two weeks.  The ECMWF is similar.


Of course if we’re going to get an extended very warm to hot stretch this IS the time to do it.  Notice that here in Portland the hottest time of the year is typically the 3rd week of July to the middle of August.


How about the coastline?  Can you escape the heat there?  Yes!  In this pattern we shouldn’t see easterly flow make it to the beaches so 65-80 is a good guess for the next week, depending on location and day

7 Day Coast Plus Cascades Summer

And the Cascade lakes will be an excellent place to be as well as anywhere else at/above 4,000′

7 Day Coast Plus Cascades Summer2

I would suggest Ape Cave or any other lava tube near Trout Lake or Bend…it’s in the 40s year-round in most of those cave since they follow the ground, not air, temperature.

On a “big-picture” note…unless something changes drastically in August, this is going to be our FIFTH warm/hot summer in Western Oregon and SW Washington.  I can’t find any other period in at least the last 100 years where we’ve seen such a stretch of abnormally warm weather.  2015 was the hottest summer on record here in Portland.


As mentioned in the past, this is one season in which we are seeing dramatic warming in our area…not so much in winter but in summer.  That doesn’t mean we can’t have a round of cool summers right around the corner, but the trend is definitely up.  That cool summer of 2011 seems a long way back now doesn’t it?

MarkSummer RecentYears

Chief Meteorologist Mark Nelsen


Hot Summer Weather Later This Week

July 8, 2018

9pm Sunday

Today was warmer with highs well into the 80s west of the Cascades.  Meanwhile scorching hot weather continues east of the Cascades.  Everyone east side was in the 90s.

We have a relatively strong marine push in progress this evening.  Check out the visible satellite image showing clouds already moving over the Coast Range:


So tomorrow and Tuesday will be cooler with highs right around the average for mid-July…80 or so.

What changes the 2nd half of the week?  A huge/sprawling upper-level ridge will be covering about 3/4 of the USA by Thursday…


notice the 588dm heights covering a huge chunk of the USA at that time?  Notice also that much of North America is seeming higher than normal heights.  That’s something I notice continues well beyond the 7 day period in all the models.  A sustained period of unusually high atmospheric heights instead of a big sharp ridge of high pressure with a downstream trough.  What does that mean?  Models for the next two weeks seem to show a continuously warm/hot period as opposed to a huge heat wave followed by cooling, then more heat.

So how hot could it get over the next week?  Record highs are all 101 or higher beginning Wednesday.  Plus I don’t see a thermal trough west of the Cascades with its easterly wind, so I doubt we get to 100 degrees.  That said, both Wednesday and Thursday the GFS & ECMWF show no onshore flow with gradients flat through the Columbia River Gorge.  850mb temps reach +18 Wednesday (over Salem) and +21-23 Thursday.  That 23 is the ECMWF and its ensembles support the number.  So I forecast 90/98 for Portland Wednesday/Thursday; not record-breaking but the 98 would be the hottest we’ve seen so far this year.  A very weak marine push and 850mb temps down around +19 to +20 Thursday through Sunday means highs retreat to around 90 or just above.

With such a strong/flat upper-level ridge over us, thunderstorm moisture seems to be pretty well suppressed to the south much of the next two weeks.  This is the driest ECMWF precip meteogram I’ve ever seen:


Enjoy the next two days and then try to stay cool later in the week…

Chief Meteorologist Mark Nelsen

A Very Warm 4th of July On The Way

July 3, 2018

6pm Tuesday

The weather shouldn’t affect your 4th of July plans Wednesday, but it’ll be one of the warmer Independence Days of the past 20 years.  High temperatures will reach well into the 80s.  Gusty east wind during the morning/midday in the Gorge, Cascades, & east metro means extreme fire danger so be careful with those fireworks!

Today was just about a perfect day with a few patchy low clouds breaking up to sunshine across NW Oregon and SW Washington.  It’s about as normal as it gets this time of year with a high temperature around 77-78 in the metro area.

Of course tomorrow is the 4th of July so let’s take a look at the numbers:

Mark IndependenceDayHistory2

Notice that we average a wet fourth once every 4 years.  Yet we’ve seen only one with measurable rain since 1999!  1998 & 1999 featured cool/showery days, but since that time only 2008 saw just .01″ of rain.  My kids, in high school, have never seen a wet Independence Day!  The past few years…

Mark IndependenceDayHistory3

We’ve seen a very cool airmass drop through the northern Rockies and eastern side of OR/WA the past 36 hours.  Timberline only had a high of 39…on July 2nd!  That cool airmass plus mainly clear skies last night led to a chilly morning.  I saw lots of 40s around the metro area and Eugene’s low of 38 was the coldest on record for the month of July.  I see a few spots had a light frost in Central Oregon too.  That includes Sisters & Prineville with Madras, Bend, & Redmond quite close to that 32 degree mark.

The airmass is warming right now and that peaks tomorrow afternoon before a weak upper-level low approaches the region at the end of the week.  One interesting twist tomorrow is a brief surge of easterly wind over the Cascades and through the Gorge from later tonight through about midday.  In fact gusts at Vista House will likely reach at least 40 mph during the morning hours.  By the way, if you’re headed out there the old highway closes in Corbett area from around 10am-Noon for a parade.  Obviously the combo of dry east wind + very warm temps means even higher fire danger through the early afternoon hours.  Easterly offshore wind plus 850mb temps around +17 by afternoon typically means a high in the lower 90s this time of year.  But tomorrow we’ll see lots of high clouds during the daytime, and that should keep highs in the 80s.  Regardless, it’s going to be a toasty 4th.  But the benefit is that temperatures will be comfortable for fireworks after sunset

Independence Day Fireworks Forecast

Beyond tomorrow, a summer weather pattern continues as we head deeper into July.  The hot ridge establishing itself across the Rockies and 4 Corners region the next few days seems to stay just far enough east to keep real hot stuff away from Western Oregon and Washington.  But temperatures will generally remain above normal for the next 7-10 days.  Note the ECMWF ensemble forecast for highs in Portland the next two weeks:


Some ups and downs, but the trend is for summer heat to set in next week.  Rain?  Forget about it, unless we get marine drizzle of some sort (like yesterday).  The 2 week ensemble forecast from the ECMWF:


Only 4 ensemble members show .10″ rain ANYTIME in the next two weeks…that’s mid-summer dry weather.

Have a safe Independence Day!

Chief Meteorologist Mark Nelsen



Nice Start To July

July 1, 2018

10pm Sunday…

It’s REALLY slow weatherwise so I’ve been having some weather blog writer’s block.  Or possibly just a bit lazy as summer rolls on…

Take a look back at June, which nationwide was much warmer than average, including about half of the Pacific Northwest.


Portland looked like this


We saw 4 days at/above 90…most in that warm period mid-month.  Most interesting to me is that it’s the 4th consecutive warm June.  I’ve ALMOST forgotten about those terrible cold/wet June months when my garden just didn’t want to grow (2010, 2011, 2012).

It was another dry month of course, unless you happened to be right under one of those thundershowers late-month.


We’ve see less than 1.5″ since the middle of April!


Only one other time in Portland history has it been even close to this dry.  That was late spring-early summer 2015.  Of course that turned into a terrible fire season with the Canyon Creek fire around John Day and numerous massive fires up in Washington.  We’ll hope for some cool spells with a few showers at times over the next 8 weeks to keep things under control this year.

The weather pattern is interesting over the next 7 days with upper-level ridging developing over the central USA.  That’s where the extreme heat will be.  This is the 500mb map for Thursday:


We’ll be on the far western periphery of that ridge, which allows weak systems to bring occasional onshore flow at times.  Over the past 5 days I’ve noticed a trend of models trying to push that ridge right over the West Coast and then backing off and keeping it farther east.   We’ll see if that continues.

For now, it looks like we have a great weather pattern in general for this first week of July.  No real heat, thunderstorms, or cool/wet weather.  Enjoy!

Chief Meteorologist Mark Nelsen


90+ Today, Much Cooler Tomorrow

June 24, 2018

7pm Sunday…

We’re in the slowest season of the year weather-wise; under a relatively stable summertime weather regime.  So the frequency of blog posts slows down too.

Today was another example showing what just a little bit of offshore flow can do.  Models have advertised for several days that 850mb temps would rise up above +15 and we’d get a light easterly drift through the Gorge in the morning.  Combine that with the highest sun angle of the year and temps skyrocketed.  We hit at least 91 in Portland with solid 90s up/down the Willamette Valley

Todays Observed Highs OrWa 2017

That means we’ve already seen 5 days at/above 90 degrees and we haven’t made it to July yet!

90 Degree Days In June

I’m confident we don’t have any 90 degree weather in the next week or so, in fact we should linger near normal temperature-wise over the next week.

90 Degree Days Summer Heat

By the way, there was just a little bit of fire smoke (nothing like last year!) that drifted in on light east/southeast flow the first half of today.  I noticed it on the east side of the metro area.  GOES16 imagery showed the smoke movement from the fires in north-central Oregon, I’ve highlighted the smoky area in yellow.



A sharp upper-level trough quickly swings through tomorrow morning, dropping a few light showers or drizzle in spots.  But then I expect some decent clearing in the afternoon.  So we might at .01″ or so to the PDX rain gauge for June.  It’s been our 2nd dry month; interesting that most measurable rain has fallen around weekends.  Of course the thunderstorms on Friday missed east & north metro, and part of south too, including PDX.

Mark Monthly Climate Rain Calendar

We are more or less tied for driest “late spring/early summer” in Portland.  Just taking the mid-April to late June rainfall, only 2015 is similarly dry.  Do you realize we’ve had only 1.27″ since the middle of April???  Amazing.  No wonder it looks like late July with everything browning up quickly now.  And it’s too late to get a cool/wet spring pattern now, so fire season and drought development is totally dependent on what happens over the next 3 months.  If we remain warmer than normal with no significant cool spells things are going to get rough by the time we get into August!

There does appear to be some sort of upper-level troughing attempting to come into the Western USA around this Thursday/Friday.  Note the 500mb height anomaly from the ECMWF ensembles


That ridge offshore tries to move in over us those first few days of July, but then it’s interesting that all 3 models I generally look at through the 10 day period show another trough right overhead on the 4th of July.

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That said, it’s 10 days away.  It’s also interesting that my 17/16 year old kids haven’t seen it rain on the 4th of July in their lifetime.  We are overdue for a showery 4th, but that doesn’t mean it’s going to happen this time.  I think the main message here is that we have pretty typical late June/early July weather coming up in the next week or so.  No extremely warm or chilly weather, and just a threat of drizzle or a shower over a few different days.

Keep watering your lawns and gardens…it’s going to be a long summer!

Chief Meteorologist Mark Nelsen

A Nice Summer Lightning Display

June 20, 2018


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:

KPTV 2017 Default Earth

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