A Nice Labor Day Weekend Ahead

August 30, 2019

7pm Friday…

Just a quick note to let you know we’ve got some very nice Labor Day weather on tap.  A very weak cold front moves onto the Oregon/Washington coastline Saturday morning and dissipates as it moves inland.  So other than coastal and Coast Range showers, the weekend should be dry.  Actually I suppose the overnight/morning clouds Saturday night and Sunday morning could produce a sprinkle/shower, but that’s it.

Expect mainly sunny conditions in the eastern Columbia River Gorge, the Cascades, & all of central/eastern Oregon.

High temperatures rise a few degrees tomorrow, fall a little Sunday, then go back up above average Monday.

Labor Day Grilling Fcst

Coastal weather looks reasonable except for those light showers at times tomorrow…


and camping (or cabin-ing) in the Cascades looks fine as well.  No thunderstorms in the mountains this weekend


Meteorological summer ends tomorrow night and I’ll be working.  I’ll work on a recap of Summer 2019 and hopefully get that posted by Sunday.

Enjoy your weekend!

Chief Meteorologist Mark Nelsen

Thunderstorms This Morning; A Soaking For Some

August 29, 2019

10:30am Thursday…

Apparently I was tired and in the wrong place last night!  Parts of the metro area saw a great lightning display and lots of loud thunder.  Others saw lightning in the distance but no thunder.  I had my windows open and heard nothing.  Disappointing…I know.  Gabor Gardonyi caught this shot along the Willamette River


Last night on each of our newscasts I was talking about the weak disturbance moving north across the region during the night and today.  It had put out just a few lightning strikes at that time and I figured we would get at least a little lightning by morning.  But there was lots more than “a little”!  I do remember telling you it might be wet by sunrise, hopefully you weren’t surprised.

Luckily the storms were high enough to be detected by radars in Washington and Pendleton.  Portland’s radar is down for a two week maintenance period.

GOES-17’s Global Lightning Mapper shows where the action was.  First a burst of lightning right over Salem around 2am and then again about 3am over Portland

Then a second round right over North Portland starting at 5am.  That line of strong thunderstorms slowly progressed north over Clark County from around 5-6am.  Looks like that was the best spot to be in for the weather action.  I see some spots from Brush Prairie to Battle Ground to Amboy saw up to 1/2″ of rain…that’s a huge soaker.

Here’s a link to a loop showing all lightning action from 2am-6am over the region:  https://col.st/axcTz

Make sure you hit the LOOP button if it doesn’t start moving.

The big story today otherwise is MUCH COOLER.  We’ll only top out around 80 degrees with a few more showers at times through early afternoon.  By 4pm or so showers should shift north and die out.

Chief Meteorologist Mark Nelsen

Hot Weather Ends, After a 2nd 98 Degree Day in Portland

August 28, 2019

10pm Wednesday…

It was another scorcher today all across Oregon and Washington, the only comfortable temps were at the coastline

Portland once again tied it’s warmest day of summer at 98 degrees.  That makes it our 11th day hitting 90.  In case you wonder, the 30 year average is between 13-14 days per season.

90 Degree Days Summer Heat

Some marine air is pouring into the western valleys this evening.  I see Kelso, Eugene, & Corvallis are dropping into the 60s already, even under thick cloud cover.  Speaking of…

Models have done very well showing an upper-level disturbance moving north over the Pacific Northwest tonight and Thursday.  That’s why clouds suddenly showed up around sunset.  That gives us a very warm night, but also a chance for a shower.  You may wake up to wet streets and/or showers Thursday morning.  There is even a slight thunder chance, although at this moment the GOES-17 lightning mapper is showing nothing west of the Cascades.  There was ONE strike west of Corvallis a couple hours ago and one more east of Lincoln city around 9:45pm.  You can find that here:  https://rammb-slider.cira.colostate.edu/?sat=goes-17&z=4&im=12&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=0&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=0&slider=-1&hide_controls=0&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&sec=conus&p%5B0%5D=cira_glm_l2_group_energy&x=7265&y=2864


Once we get beyond tomorrow morning I see a typical late summer weather pattern through the early part of next week, including Labor Day Weekend.  That’s varying amounts of morning clouds and afternoon sunshine each day.  At this point it appears a dying system moving onshore Saturday will bring showers out there and maybe a shower makes it into the valleys in the afternoon too.  Maybe.

Next week should feel a bit more like fall as temperatures only reach into the 70s or 80 each day along with the decreasing sun angle.  Thick morning clouds at times will add to that feeling as well.  The ECMWF ensembles hint an upper-level trough could bring showers either Tuesday or Wednesday.  No hot weather in sight!


Chief Meteorologist Mark Nelsen

100 Degree Heat In Willamette Valley Today; One More Hot Day to Go!

August 27, 2019

9pm Tuesday…

Whew…today was a scorcher, especially for so late in the summer season.  Let’s go over the numbers…

Several spots in the Willamette Valley hit 100 degrees, the hottest temps of Summer 2019.  Salem, Eugene, Aurora, and down in Roseburg too.

Todays Observed Highs OrWa 2017

Check out those coastal numbers!  Upper 80s to upper 90s throughout the FOX12 viewing area from Yachats to Long Beach.  When wind remains offshore through 1-2pm those temperatures can soar all the way down to the ocean beaches.

You can see we hit 98 in Portland, a new record for August 27th.  This also tied the highest temperature of Summer 2019 set in early June.

Hottest Days This Year

I had mentioned over the past 5-6 days this would be a classic late summer/early fall east wind event; it sure did deliver!  In one hour from 9:15 to 10:15 am Tillamook’s temperaure jumped 23 degrees! (63 to 86).  At PDX it jumped from 81 to 91 in one hour between 11am and Noon.

Easterly wind gusts made it to 52 mph at Vista House.  That’s pretty strong for late summer.

For the geeks, the 850 millibar temperature made it to 24.4 degrees on this afternoon’s sounding.  That’s right up with the big late summer heatwaves.  In fact during a ten-year period 1999 to 2009, only one P.M. sounding (out of 300+) had a higher temperature!  That day it jumped to 102 at PDX; likely earlier in the month.

What’s ahead?  Temperatures should just barely drop to 60 in the city by sunrise, and into the 50s outlying areas.   That’s thanks to nights two hours longer than a June or early July heatwave.  Areas that continue to see the easterly breeze (near Gorge and higher hills) may stay in the lower 70s.

Mark Forecast Night City Temps

Tomorrow the hot thermal trough (area of lowest pressure) shifts east of the Cascades late in the day.  That cools the coastline, but we’ll still get up to between 95-99 degrees in the metro area.  Another scorcher, but without the hot wind.

A weak upper-level disturbance passes overhead tomorrow night and early Thursday.  The ECMWF and WRF-GFS (UW) continue to insist showers pop up with this during that time.  The 18z ECMWF brings a swath of showers across NW Oregon and SW Washington through the first half of Thursday.


A bit wetter than other models though.  We’ll see.  Regardless, don’t leave anything outside tomorrow night just in case.  Of course temperatures will drop at least 15 degrees (or even 20) Thursday due to morning clouds/showers and a push of marine air.  Should be refreshing.

Beyond tomorrow we settle into a typical late-summer pattern of morning clouds and afternoon sunshine.  Labor Day Weekend will likely see highs between 75-82 degrees in Portland with varying amounts of cloud cover.

Chief Meteorologist Mark Nelsen

Two Hot Days Ahead, Plus Some 90s on North Coast Tuesday

August 26, 2019

7pm Monday…

In early June we had two very hot days, 97 & 98 degrees in Portland, the hottest of summer so far.

Hottest Days This Year

We have a repeat coming up tomorrow & Wednesday.   I get the feeling these two hot spells will be the “book ends” of Summer 2019.

The weather pattern is the same; a strong upper-level ridge overhead brings us a hot airmass.  But the “icing on the cake” is the switch to an offshore wind flow.  Today we lost all cooling coming in from the Pacific Ocean; light easterly flow has developed overhead.

Tonight a much stronger easterly flow develops with gusts to 40 mph in the western Gorge and exposed ridges along the west slopes of the Cascades.  Expect a that breezy easterly wind to push across most of the metro area by noon, and all the way to the coastline too.  Historically this is our hottest weather pattern.  Take a look at the surface weather map tomorrow at 5pm from the UW-WRFGFS model.  I’ve drawn in the “thermal low” which is the area of lowest pressure.  Wind moves toward that low


This is a classic hot weather setup west of the Cascades.  By Wednesday at 5pm the thermal trough is shifting over/east of the Cascades.  Weak onshore maybe arriving in the central/southern Willamette Valley at that time.  That said, often models are a few hours too fast moving that trough east so we’ve kept the high temperature forecast the same for both days.


A big push of ocean air pours inland Wednesday evening and that ends our mini-heatwave.  We’ll be somewhere down in the 80s on Thursday and that continues through at least the first part of Labor Day Weekend.

Data Driven Forecast Highs Next 7 Day Meteogram

Do you want to experience hot weather at the coastal beaches? That thermal trough position through mid-afternoon Tuesday is perfect for one hot day out there.  If easterly flow makes it all the way to the beaches, then it can be just as hot as inland spots. But I suspect the northeast morning wind turns north-northwest mid to late afternoon which should cap off the central coastline around 80 degrees and keep temps below 95 on the north coastline.

Mark Astoria Coast Record High

Let’s talk clouds and showers.  Our typical onshore flow returns Thursday and beyond and we’ll get clouds at times out of that.  But what about rain showers?  Models are hinting a weak disturbance could bring a few showers overhead during the daytime Thursday.  We now have access to the hourly runs of the ECMWF model 4 times a day which is helpful.  The 18z run, just like the 12z, showed a few light showers popping up Thursday.  So just keep in mind we might see sprinkles here/there on that day.

Chief Meteorologist Mark Nelsen


Feels Like September, But Last Week of August Will Bring Some Hot Temps!

August 23, 2019

7pm Friday…

Today has been a real nice late summer day.  We made it up to 84 in Portland (as of 6pm), above the average high of 80 for this date

Todays Observed Highs OrWa 2017

Yet it feels a bit different outside the past couple of days doesn’t it?  I think that’s due to several changes we see every late August.  First, the sun angle is getting lower, the midday sun just doesn’t feel as intense as it did in June and July.  Second, days are getting shorter.  In late August the loss of daylight begins to accelerate.  In fact we’ve lost two hours of daylight since the summer solstice in late June.

Mark Daylight Decreasing 1

Of course the longer nights mean we’re starting cooler in the mornings.  We’ve dropped into the mid 50s the past two nights in Portland, and have seen 40s for a few nights in outlying areas as well.  Fall is getting closer!

PDX Observed Low Today

Saturday will be a cooler day with more cloud cover, definitely a September feel for one more day.  That’s due to a very weak weather system dying over the Coast Range as it moves onshore right around sunrise.  Sunday turns sunnier and warmer as we onshore flow weakens.  It will be the sunniest day of the weekend.

But the main story the next week will be a hot spell (heat wave might be too strong wording, depending on how long/intense the hot weather will be).  Models have been doing a good job showing upper-level ridging (high pressure) developing right over the Pacific Northwest beginning Monday.  Right now we’re in weak westerly flow, very warm to the south and cooler than average in southern Canada.


By Monday the ridge has popped up right over us


It’s still there, although a bit weaker, next Thursday


Models are warming 850mb temps to the mid teens Monday, then lower 20s both Tuesday and Wednesday afternoons.  That’s the warmest forecast we’ve seen since the early June heat.  And it appears for the first time since June we’ll get a breezy offshore flow to go with it.  Check out the surface map for Monday afternoon


Surface high pressure is centered to our north, a gusty north wind is blowing down the coastline and Willamette Valley.  And it appears a very light east wind is trying to develop in the Cascades and Gorge.  A “thermal trough” is beginning to develop west of the Cascades.  That’s an area of low pressure that develops due to easterly wind going over the Cascades; lower pressure develops on the “backside” of the mountains (west side) in this setup.  By Tuesday afternoon, surface map shows we are in a classic east wind hot weather pattern, which we haven’t seen since that early June heat.  Look at the thermal trough stretching north from Redding all the way to Puget Sound.  In fact it appears to briefly get out to the coastline at some point earlier Tuesday.  This means that may be the day the northern Oregon coast reaches into the lower 90s as well. Everything has to work out perfect for that to happen.



Regardless, this would be a very gusty east wind day in the western Gorge, Cascades, and metro area since the easterly flow extends up to around 4,000′ or a bit higher.  Temperatures in the lowlands should soar that day.  My chart says August patterns with this setup have pushed us as high as 98 or 99.  More likely 94-98 degrees.  By Wednesday the trough is weakening and onshore flow is about to arrive in the western valleys of Oregon and Washington.   The 95+ temps will probably be for only Tuesday/Wednesday, then back to 90 or a few degrees by Thursday


Sure, it looks hot next week, but two factors make this one a bit different:

  1. Relative humidity will be very low with the easterly wind. This won’t be a humid setup, at least through Wednesday
  2. Long nights at the end of August mean we still drop down to 60 in the city, and well down into 50s outlying areas even after a 95 degree day.  Much better than June through early August.

By the way, there’s no rain in sight through at least the early part of Labor Day Weekend.  The ECMWF model ensembles only show a few members trying to bring in showers at some point during that weekend.


I have tomorrow off and then will be back on all next week Sunday through Saturday.  I’ll keep you updated as we go through the week.

Chief Meteorologist Mark Nelsen

A Soaking For Some Wednesday

August 19, 2019

10pm Monday…

Today was a nice day; brief morning clouds then afternoon sunshine.  A perfectly normal late August day with a high of 81 degrees.  It appears we’ll likely have more than our typical yearly allotment of 80 degree days.  In a normal year we get 56 days at/above 80 degrees in Portland.  Today was day #48.

80 Degree Days SO FAR

The weather pattern over the next 7-10 days continues to look somewhat on the boring side for meteorologists.  That’s except for Wednesday.  An surface low pressure system is developing well offshore.  It showed up very nicely on GOES-17 imagery just before sunset


The bulk of that system’s rain heads just north of us.  But there is an unusually high amount of moisture with this system.  Plus some of the highest sea surface temperatures I can remember are in place across the eastern Pacific offshore.  Buoy 89, about 100 miles west of Tillamook, is reading a water temperature of 67-68 degrees!


Here’s a forecast from the ECMWF, giving us around 1/2″ rain Wednesday, with up to 1″ or so on the northern Oregon coastline.


Some models are slightly wetter, some a bit drier.  The effect is the same

  1. ) Our very weak fire season will get beaten back once again.  As of this moment there is only one large fire actively burning in Washington and Oregon!  And that isn’t being actively put out since it’s in the Wallowa Mountains.  These occasional shots of light showers and higher humidity are helping out this summer.
  2. ) Everyone west of the Cascades gets at least a dust-settling rain.
  3. ) Southwest Washington, especially north of Longview, could see well over 1/2″ of rain, a nice late-summer soaking.

It’s quite clear that this is a one-shot deal.  Take a look at 50 members of the ECMWF ensemble run this morning.  Each horizontal line represents 24 hour precipitation from one of the ensemble members.  Then at the bottom you see the ensemble average.  It looks very dry Thursday through much/all of the last full week of August.


All of the global models say the last full week of meteorological summer (next week) could be hot as well.  That said, MANY times this summer they have tried to shove a hot ridge of high pressure right up over the West Coast.  They were only right way back in early June.  This morning’s run of the ECMWF showed a hot pattern developing by next Monday


And still there next Thursday, 10 days away


Both maps are hot, even for late August.  We will see…

Chief Meteorologist Mark Nelsen