The Vanport Flood: 74 years ago today

May 30, 2022

6pm Monday…

74 years ago today, what was once Oregon’s 2nd largest city was erased from the map in hours.  If you’ve never heard of the Vanport Flood, read on…it only happened 5 miles from downtown Portland.

I love weather AND history, so I find this flood fascinating, especially since it’s results echo through Portland even in 2022.

I’ll be brief, since it’s a long story.

During World War II (1940-45), huge numbers of workers were brought in to work in the shipyards here in Portland.  There was an urgent need for housing, so a city was quickly built and called VANPORT (a “portmanteau” of Vancouver and Portland) on the flats north of Portland.  That’s the low area west of I-5 around Delta Park where PIR, Heron Lakes, and Delta Park West is now. 

That city contained 40,000 at it’s peak, making it the 2nd largest city in the state!

After the war, lots of folks moved away, but there were still around 13,000+ residents there by the spring of 1948, three years after the war ended.  Even a college had opened in the city for the returning GI’s…the Vanport College.

The winter of 1947-48 brought massive snowfall to the mountains of the Pacific Northwest and Rockies, along with lots of rain.  At this time there were very few dams to hold back spring floods on the Columbia and Snake Rivers…although Grand Coulee and Bonneville Dam both were operational.  The Columbia River rose throughout May 1948 and by Memorial Day Weekend was approaching the 30′ level on the Vancouver gauge.  That’s within 4′ of the all-time high in 1894.  For comparison, that 1948 level is about 22′ higher than the river is right now!  I notice the Portland Housing Authority had put out a notice in the week before saying  “REMEMBER: DIKES ARE SAFE AT PRESENT.

That didn’t happen.  On Memorial Day, May 30th, (used to be on that date instead of the last Monday of May) the railroad dike on the west side of the city (where the railroad is now) burst around 4:20pm.  A 10 foot wall of water went surging into the city.  By sunset the city was inundated and remained so for over a month.  A few factors helped keep the death toll quite low (just 15):  it was the holiday weekend with lots of people out of town and mild temps plus bright daylight kept confusion to a minimum too I suppose.  Here’s the view two weeks later from just about the same vantage point as the earlier pic.  Note the triangular are of trees on the edge of the slough in both pictures: 

It’s interesting to note that the river kept rising, and peaked about the date this picture was taken…at exactly 31′ on the Vancouver gauge.  The flood was the 2nd highest on the Columbia River since record keeping began in the 1800s.

The result?

1. About 1/3 of the residents were African-American; largely settling into north and northeast Portland following the flood.  My grandparents on one side of the family were raised in and lived in that area from the 1910s to 1950s. I remember them talking about the changes after WWII. You can find lots of  good information about this online which is way beyond the scope of a weather blog. Interesting, especially considering demographic changes in the area (once again) the past 30 years.

2. Vanport College was called “the college that wouldn’t die”, restarted in downtown Portland, and became Portland State University.

3. The town wasn’t rebuilt, but became a raceway, a park, a golf course, and wetlands.

4. The Flood Control Act of 1950 spurred a massive program of dam building along the Columbia and its tributaries — due to the 1948 flood.

Chief Meteorologist Mark Nelsen

Cool Memorial Day Weekend ahead, but not all wet

May 24, 2022

7pm Tuesday…

The big holiday weekend is approaching quickly! Last year was the 2nd warmest Memorial Day Weekend on record in Portland. That sure isn’t happening this year!


We have seen some warmer weather lately which has been nice. I’ve been able to work in the yard and garden sans mud. But May is still running (so far) the coolest since 2011.


Those numbers are for Portland, but I checked Salem which has been influenced less by the urban heat island. This month was close to the average temperature from the early 1960s to early 1980s. That WAS a cool period, but the point is that this “chilly May” isn’t really all that bad and we’ve sure seen it before.

We’ve all had a chance to get outside and enjoy dry weather for several days now. No measurable rain the last 4 days at PDX is the first time we’ve seen 4 consecutive totally dry days since early February! A few passing showers have dropped a trace today, with some of you picking up measurable rain this evening. Definitely more than I expected. Of course we picked up our typical May rainfall in the first half of the month:


High pressure strengthens a bit tomorrow and Thursday for warmer temperatures. I expect low-mid 70s both days. But then things are going downhill once again. The warm upper level ridge overhead will be replaced by a wet westerly jet stream by late Friday. Even California will get some showers…unusual in late May


By Monday, a chilly upper-level trough is sitting over the western USA. We will be on the cool side of that jet stream Saturday, Sunday, and Monday.


Right now it appears we won’t see that many showers Friday, but an organized (& wet) system comes through the region Saturday. Showers may even show up in the driest parts of central & north-central Oregon Saturday. Then expect lots of leftover showers Sunday. The good news? Most of the cool/wet airmass has moved to the south and east by Memorial Day itself. That means the 3rd day of the weekend could be best.


Weather this long weekend might be better along the beaches…not so many “pop-up” showers Friday and Sunday near the chilly ocean water. This is what I’m thinking for the northern Oregon and southern Washington coastline


With a cold airmass over us through the weekend, higher elevations are NOT the place to be. Expect snow as low as 5,000′ during the overnight hours. Passes will be fine, but it’s a cold/wet camping experience at the Cascade lakes!


By the time May ends and June arrives (Wednesday), the cold trough is gone and that means much warmer and more typical weather.


Just 4 days later the Starlight Parade is on tap…it’s too far out to see if another trough will be dropping in for a visit. For now it seems safe to say that we’ve got a few days of showers from late Thursday through Sunday, then drying the middle/latter part of NEXT week. You can see the gap in the ECMWF ensemble chart



1) A cool and somewhat showery weekend is on tap across the ENTIRE Pacific Northwest. But not a soaker every day

2) Wettest should be Saturday and Sunday. Much more reasonable (or mainly dry?) Friday and Monday

3) Expect mountain snow down to 5,000′ at times


4) Even the driest parts of the region in the Cascade rain shadow (Central Oregon) will get at least a few showers

Chief Meteorologist Mark Nelsen

How can we be in a drought with so much rain, and why are forecasters talking about it?

May 16, 2022

7pm Monday…

It’s a totally fair question I’ve been getting on social media and even on email…


HOW CAN WE POSSIBLY BE IN DROUGHT? MORE “FAKE MEDIA” WEATHER NEWS? (someone actually suggested that 2nd one)

Two answers:

1) The Portland television market is much larger than you think. We broadcast to temperate rain forests and also to very dry deserts. Some areas ARE in severe drought right now, but others (everywhere west of the Cascades) have plenty of water for the next few months. No drought here!

2) East of the mountains, regular rain & mountain snow has improved conditions slightly over the past 6 weeks. But it takes a long time to erase a 2-3 year long drought!

First, the USDA Drought Monitor shows the current extent of drought. NO drought from Eugene north to the Canadian border. We have plenty of water this year west of the Cascades. Notice the Cascades themselves are just fine too.

Now take a look at the Portland TV market viewing area. These are counties where Portland television is the dominant local TV news source. There are about 200 TV markets around the USA.

Portland TV Market
Portland TV Market

Notice it ends at Albany west of the Cascades (Eugene is its own TV market), and does not include Bend/Deschutes county east of the mountains. Yet it extends to Baker and Harney counties! “Gerrymander” is the word of the year, and it applies to our viewing area. All Portland TV stations focus on these areas. You’ll notice our forecasts generally cover these areas. Sometimes I’ve had people ask why we don’t forecast for Medford or Klamath Falls. That’s because they have their own TV stations down there.

Now lay that over the Drought Monitor and you see maybe 50% of our geographic viewing area is in drought. That said, only about 10% of our viewers live east of the Cascades. Something like 85% of our viewers live just in the I-5 corridor counties from Longview to Albany, thus our focus here. But we sure don’t want to leave those of you east of the mountains out of either forecasts or drought talk…and THAT is why we cover it.

Of course April and May HAS been cooler/wetter than normal east of the Cascades in the drought areas. Notice the foothills of the Blue Mountains (Umatilla River drainage) is in good shape now after lots of mountain snow and some rain events. But back in Central Oregon things are still very bad. Redmond picked up less than 1″ of rain since April 1st! Wickiup Reservoir is already dropping since irrigation season started last month. Prineville Reservoir is below last year (a drought year) and WAY below normal.

(Credit: USBR)

To summarize (again)

IF YOU LIVE OVER OR WEST OF THE CASCADES NORTH OF EUGENE there will be plenty of water this summer and we are not in a drought

IF YOU LIVE IN MOST OF THE REST OF OREGON a third year of water shortages, low reservoirs, & irrigation cutoffs has begun

Chief Meteorologist Mark Nelsen

A wet & cool Pacific Northwest spring will continue

May 11, 2022

9:30pm Wednesday…

I’m hearing lots of complaining the past week or so as our chilly spring weather goes on. These last two days were quite reasonable with partly cloudy skies and dry conditions (for most of us). But even with the dry weather, we only made it within 5 degrees of normal today!


That’s because we’re still under the influence of a chilly upper-level low leaving to the south of us. Plus a brand new batch of cool air is swinging in tonight through Friday. You can see that 2nd upper low coming down the coastline


This has been the story for about 6 weeks now. Starting around April 9th, we’ve seen lower than normal upper-level heights over our region. In fact, the anomaly is just about the coldest in the entire Northern Hemisphere over the past month! Along with a cold anomaly over the Arctic Ocean.


So one could argue it doesn’t get much colder than this from early April to early May. I just checked the past 30 days at PDX. Coldest since 2011. For the locals, this is running quite similar to other cold springs like 2008, 2002, & 1996.


How about measuring our spring another way? Number of 70 degree days at this point in spring (at PDX)


Only 4 days at/above 70 degrees. That’s quite a change from the past few years. The average is around 9 days by May 10th. Again, this is similar to 2011, 2010, 2003, & 2002. In the last 10 springs, we’ve hit 80 degrees by May 10th, but not this year. We’ve only hit 75 twice. In a typical spring we see more up/down with chilly troughing followed by warm upper-level ridging.

I think the screaming message here is that WE WERE DUE FOR A CHILLY/WET SPRING AND NOW IT’S HERE. There’s nothing especially “unusual” about this spring. No, it’s not caused by climate change. And we’re not seeing any significant trends with temperature or precipitation in springtime west of the Cascades. Obviously summers are turning much warmer but that’s a different story. As mentioned in a previous post, in general springs have been just a little wetter compared to many decades back in time.


More of the same folks! A cold front moves inland Thursday with another .25-.50″ rain west of the Cascades, then a 2nd (weaker) system comes inland Friday night and Saturday morning. So we’ve got a soaker ahead Thursday morning, then much better by evening between those systems. Behind that 2nd system, a warmer southwesterly flow (no cold upper low!) pushes temperatures up around normal for the weekend. No, I don’t see a warm and sunny weekend, but at least the showers will be warmer and we COULD make it into the lower 70s Sunday IF the showers are widely scattered. So clearly Sunday is the better day of the weekend.

By the middle of next week models agree that another cool trough drops into the region, keeping us cooler than normal through all of next work week.


Many times I’d look a bit farther ahead (beyond 10 days), but the past month we’ve seen models regularly push us back into climatologically normal (warmer) pattern. And each time a cold upper-trough decides to crash the party. For now I think it’s safe to say:

  1. We’ll see below normal temps through at least the 20th of the month
  2. There’s no sign of a sustained dry spell for at least the next 10 days.

I won’t be staining my decks for quite awhile…

Are springs getting wetter? Not really, but lots more rain ahead!

May 3, 2022

10pm Tuesday…

It was dry today!

Morning clouds gradually broke up to afternoon sunshine west of the Cascades. Tomorrow (Wednesday) should be a spectacular spring day. Dry and about 10 degrees warmer. All of us in the I-5 corridor west of the Cascades should make it into the 70s. I expect little or no morning cloud cover and just thin high clouds drifting across at times.

Today on Twitter I had someone ask if the heavy rain was a sign of climate change (global warming). I promptly said NO, it’s just a return to wet spring conditions we haven’t seen for awhile. But I figured it’s time to take a closer look. Here’s what I found:

1. Total rainfall has not changed dramatically in the mid-late spring the past 100 years, there is very little change in the past century west of the Cascades. That’s at Salem, Portland, or even Redmond (Central Oregon)

2. There appears to be a very slight increase in rainfall during that time.

3. We have consecutive years with wet springs, then a few dry will follow. Or quite a few years wet with a really dry one sandwiched in. You get the idea, it appears to be somewhat random.

Get ready for a few graphs. Here’s the entire April+May rainfall record from Salem. This goes back to the late 1800s. Each bar is one April/May total rainfall. Click for a better view:


First, notice the wide variation from year to year. Some years very wet (1991, 1993, 1996), some quite dry (last year). The black line is the 10 year average. Not much change right? Maybe a minor peak in the late 1990s? The red line is the long term regression line. There has been a minor increase in rainfall during these 125+ years. What about Portland?


Similar wide yearly variation. Same up/down motion over the decades with that 10 year average. A bit of an increase in spring rain overall like Salem. We just went through 4 dry springs, so it was time for a wet one and here we are.

In case you’re wondering about east of the Cascades, in a severe drought right now, this is Redmond


Quite a change from year to year. We’re in a desert environment here, so a “wet” year is 2″ or more. 10 year average peaked around 2000 as well. Still, not a huge change over the past 80 years, but maybe a few more wet springs the past 20 years? It didn’t make it onto this image, but the regression line shows a minor increase across the entire period of record. It’s getting slightly wetter in spring in Redmond compared to many decades ago.


We’ve had some VERY dry May weather the last few years. In fact we haven’t had a wet May since 2013! I think it’s payback time…

May Rain
May Rain(kptv)

We have a LOT of wet weather scheduled for Thursday through Sunday, and possibly next Monday. After the break tomorrow, a strong westerly jet punches right in the PACNW Thursday & Friday. The view Thursday night up around 18,000′


Then Saturday the one upper-level trough is swinging through with a deeper trough developing way out to the west


By Sunday a cold upper-level trough dips farther south with rain/snow way down into Central California. We are in a cool/unstable/showery airmass that day


The ECMWF model is likely too wet, but I think somewhere between 1-2″ rain is likely in the western lowlands by Sunday night. Notice the 3″ of rain in the Cascades. Much of this WILL fall as rain Thursday/Friday since freezing levels will be high


With the cool/unstable airmass, we’ll probably get a round of thunder & hail showers once again over the weekend. And with the large upper-level low overhead, the possibility exists that significant rain COULD fall in parts of Central Oregon. Fingers crossed!

There are hints that we dry out a bit next week. But looking at the GFS ensembles, it’s clear that plenty of members bring more showers overhead later next week.


At this point I’m not sold that we’re entering a warm/dry period starting next week. Models have been putting off a warming/drying trend recently. I’m thinking in this La Nina spring that we’ll see more troughs dropping in from the northwest. We will see.

The main message here is that we have a very wet 4 days ahead…I have plans to clean the garage, maybe catch up on some streaming? I know I won’t be doing any gardening after tomorrow for quite a few days!

Chief Meteorologist Mark Nelsen