Thunderstorms & July Ends 4th Hottest

August 1, 2014

8am Friday…

Many of us in the metro area woke up to lightning and thunder during the night as storms gradually formed to our south and then moved north.  Take a look at the lightning strikes across NW Oregon and SW Washington.  Interesting that there was nothing north of Mt. Jefferson or the Olallie Lake area but plenty of action in the lowlands.


and a closer view of just the Portland metro area


You can see the areas that really got nailed were from Hillsboro north to Scappoose and also the western side of the Willamette Valley.  I see the thunderstorm that woke me up at 2am was centered on the east side of Gresham.

What a warm summer night too with temps close to 70 through 3-5am for even the outlying areas.  At my home it was the warmest overnight temperature of the summer in the lower 60s.  At least relative humidity has been low.  The showers are ending this morning and we still have plenty of sunshine on the way by midday, quite a sharp back edge of the cloud cover working its way north through Marion county at 8am.  After that we’ll see some smoky skies overhead the rest of the day and another high temp around 90.



August is now here and the July stats are complete…in Portland the average high was 83.8 and the average low was 59.8.  So the average temperature for the month was 71.8.

  • Warmest month in 5 years, since July 2009
  • Warmest July in 5 years of course too
  • 4th Warmest July on record, after 1985, 2009, and 1996
  • 7 days at/above 90 degrees, 3 above average.  Record is 13 days in 2009
  • Hottest temp was 99 on the 1st.
  • No 100 degree days

I’ve mentioned this on-air a few times, but we’ve had just enough onshore flow to avoid extreme heat here.  We had the 99 on the first, but all other hot days have been closer to 90.

Consider how much hotter other spots have been…

90 degree days this month

Salem:  14 (twice as many as Portland…average high was 87.2)

Eugene: 16  (avg high = 87.5)

Roseburg: 20

Medford: 25 (13 days at/above 100!  Average high was 96.9!)  Hottest July Ever

I’ve been on vacation this week and will be most of next week too.  Enjoy the summer weather as it looks a bit cooler this weekend and beyond.


Chief Meteorologist Mark Nelsen

July Ends Very Warm…or Hot

July 25, 2014

It’s another Friday evening and the weather is about the slowest we get here.  Nearly constant sunshine above 2,000′ and south or east of the Portland metro area for the next 5-7 days.  Occasional low clouds will push onto the coastline and up the Columbia River from Longview to Portland.  That’ll be mainly tomorrow morning and then again later next week.  Here’s a nice view of the eastside low clouds this morning from our newly upgraded Skyline Camera.

We finally installed an HD camera up there a few weeks ago and the view is much better.  I would sure like a weather sensor up there before winter too…we’ll see.

The reason for the slow weather in the upcoming week is a return of the upper level ridge in the Western USA.  The center of the high will remain over Nevada or Southern Idaho, which means we won’t get a sharp thermal trough and offshore flow in the next week.  As a result, high temperatures along the Columbia River from Longview to the Portland metro area won’t get much above 90 degrees.  The warmest temperature we have on our 7 day forecast as of Friday evening is 92.    You can see the ECMWF model’s meteogram (over Portland) showing gradually rising temperatures through midweek then cooling late week.


But if you live in Salem or farther south in western Oregon, farther removed from the marine air, high temps will make it into the mid 90s.  Of course east of the Cascades will be HOT.  Sunday through the rest of next week will see high temps around 100-105 at the lowest elevations and 80s even high up in the mountains.  This will be the 2nd heat wave of the summer over there.

Enjoy the weekend and stay cool next week!

Chief Meteorologist Mark Nelsen


Yacolt Burn Drops to #2, After 112 Years!

July 22, 2014

The Yacolt Burn has been dethroned.

News just came in this evening that the Carlton Complex Fire has now surpassed the size of the great Yacolt Burn of 1902.  That was the fire that burned about 240,000 acres in just a day and a half during an east wind event.   It started near Carson (in the Gorge) and ended up quite close to Yacolt and Battle Ground just 36 hours later.


243,000 acres is the current acreage of the complex up in northern Washington.

Unusually Wet & “Stormy” July Day Ahead

July 22, 2014

The next 24 hours will see very active weather across the Pacific Northwest, unusual for what is typically the driest time of the year for our area.





Increasing instability in the atmosphere ahead of an approaching cold front means showers pick up, especially after midnight west of the Cascades.  There is even a chance of a thunderstorm or you could wake up to downpours.  Our RPM model goes crazy showing a cluster of heavy showers/thunderstorms developing along the east side of the Willamette Valley in the wee hours of the morning.


That may or may not happen, but the point is that we’re in moist southerly flow during the night.

Also, east of the Cascades a strong disturbance moving into northern California rides north this evening, setting off lots of thunderstorms.  Some of those could be strong to severe before midnight all the way up through north central Oregon and into southern Washington.  The Portland and Boise radars are going to have to work overtime…the Pendleton radar is out of service.  It is supposed to be working again tomorrow.  Ooops…


Think May…a cold front moves through in the mid morning hours with steady rain, possibly a thunderstorm embedded too.  There could be some downpours during the morning commute.  Then behind the front, from midday through evening, we’re in the cool and showery part of the system.  That means showers, sunbreaks, southwest wind gusts to 30 mph, and a decent chance for hail or thunder with some of those showers.  Of course this can also be the type of weather that can give us funnel clouds, so be on the lookout for rotation if you spot one.

Total rainfall the next 36 hours?


Somewhere between a quarter of an inch and one inch in the lowlands depending on where any heavy rain bands set up.  Once again note our RPM going crazy with heavy totals on the east side of the valley.  Probably misplaced, but the point is that someone is likely going to get a big soaking west of the Cascades.

Chief Meteorologist Mark Nelsen

Another Sign That Our Snowpack Isn’t Disappearing

July 21, 2014

You may remember I posted back in early July a graph showing that the snowpack at one location (on Mt. Hood) has definitely not shown a tendency to melt any earlier.  At least in the past 30+ years.

Today Cliff Mass up at the UW pointed out in his blog that Mt. Rainier melt out day has arrived at the Paradise measuring station.  Then Mark Albright, former state climatologist, and a friend from my days up there, sent me this graph:


It shows the average melt out date for 221 sites in the entire Pacific Northwest.  Same pattern here, no sign of an earlier melt out in the Cascades we would expect in a warming climate.  Interesting eh?  Cliff has some thoughts on why that might be on his blog.

Chief Meteorologist Mark Nelsen

Sprinkles/Shower Sunday Morning and Impressive Fire Stats

July 18, 2014

A dying cold front will push some light rain showers or maybe just sprinkles inland on Sunday morning.  I don’t expect much, and much of the westside of the metro area might not even see a sprinkle.  We’re talking really light stuff folks!  Take a look at our RPM rain forecast:


Then the WRF-GFS forecast from the UW showing no one in the lowlands will get more than .05″:


None of this will make it east of the Cascades of course which is bad news for the fires over there.  I have never seen such an outbreak of fires all at the same time.  Oregon Department of Forestry said this morning that there were at least 50 small fires on the Mt. Hood National Forest.  You could see several of those from Timberline Lodge yesterday and today.  Take a look at the USFS web cam up there this afternoon:


I even see one west of the Cascade crest too.

The fire stats are impressive, a third of a million acres have burned in the past week just here in Oregon!  A large percentage of that is from the fast-moving range fire east of Burns.


Put that on a map of the metro area and that would mean an area from Hillsboro to Gresham and Salmon Creek to Oregon City would be blackened!


Looking ahead, models seem to be converging on the idea of a cool trough giving us widespread showers the middle of next week, then ridging popping back up afterwards.  You can see the cooling then warming on the freshly minted 00z GFS ensemble chart this evening:


The ECMWF warms things up quicker later next week with the ridge:


Chief Meteorologist Mark Nelsen

Good News! Heat Wave Goes From Sizzle to Fizzle

July 13, 2014

10:30pm Sunday…

The big weather news this evening?  What was going to be a pretty impressive heat wave is now down to just a couple more  hot days.

  • Tomorrow’s high temps, after morning clouds, stay mainly in the 80s or just barely touch 90…nothing unusual for mid July.  Although it will be more humid than normal for mid July.
  • Tuesday will likely be our warmest day with temps into the lower 90s, still not exactly a scorcher by July standards.
  • Then a gradual cooldown the rest of the week.  So no record high temps and it even appears the humidity may drop a bit Tuesday and Wednesday.

Why the change from my post on Thursday?  The upper-level ridging is slightly weaker than shown a few days ago, plus the orientation is such that we don’t get offshore (really hot) flow at any point.  So basically the Pacific Ocean air conditioner is going to keep us from getting too hot.

And of course today’s thunderstorms, while not a surprise, happened to keep firing up right over NW Oregon and SW Washington.  The solid cloud cover, plus some onshore flow (low clouds) in some areas gave the forecasters a huge bust.  Sure, we said 90, but isn’t 74 close???  I’m just kidding, I would have screwed up the forecast too if I was working yesterday.  It did stop our streak of 80+ degree days at 9 here in Portland

Check out the Pacific Northwest lightning chart for today


and then just the metro area.


So stay cool this week, but the big picture is that this work week will only be a little warmer than last week; no big heatwave on the way.

Chief Meteorologist Mark Nelsen



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