The Vanport Flood: On This Date in 1948

May 30, 2019


71 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.

( This post is a repeat from May 2017 with just a few small updates)

I love weather AND history, so I find this flood fascinating, especially since it’s results echo through Portland even in 2017.

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 (Vancouver+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 14′ 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.  Note the triangular are of trees on the edge of the slough in both pictures: 

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.

Here are the results:

1. About 1/3 of the residents were of African-American descent; largely settling into north and northeast Portland following the flood.  Lots of  good information about this online which is way out of the scope of a weather blog, but really interesting, especially considering demographic changes in the area the past 20 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, golf course, and wetlands.

4. The Flood Control Act of 1950 spurred more dam building along the Columbia and it’s tributaries, due to the 1948 flood.

Chief Meteorologist Mark Nelsen

Warm & Dry Start For June

May 29, 2019

6pm Wednesday…

We’re quickly approaching the end of May; it’s been a warm month!  Today we got rid of the marine clouds early leading to a much warmer day

Todays Observed Highs OrWa 2017

Check out the May stats so far…

Month Climate Temps Calendar

Notice only two days were cooler than average, and of course that first full week of the month was like July weatherwise.  Memories of cool/wet springs have faded (for now) west of the Cascades; we haven’t seen a cool/wet May in 7 years!  Check out rainfall as a percent of normal across the West.  We are alone in western Oregon and Washington.  Most of the West has been quite wet.  Check out those spots in the Southwest with 4X the typical May rain!

anomimage (1)

The setup this spring hasn’t changed all that much since late winter (February).  Ridging to the west and northwest of us, and troughing (a dip in the jet stream) over the rest of the western USA.


By the way, this is also the reason for the persistent stormy pattern across Tornado Alley.  A southwesterly jet moving across the Great Plains and Mississippi Valley plus cool air pushing across the Plains from time to time.  Lots of moisture = flooding and big thunderstorms.

So what’s ahead for Portland and other areas west of the Cascades?

  1. Little or no rain through at least NEXT Wednesday.  Of course a thick marine layer can produce drizzle, but that’s all I see.
  2. Temperatures remain above average over the next week.  Marine layer depth will influence whether we have a high of 70 or as warm as lower 80s at times.
  3. All clear weatherwise for Starlight Parade and Timbers home opener Saturday.  Thorns game should be great as well Sunday.
  4. Time to plant the rest of your warm weather veggies if you haven’t yet.  It’s okay even in the foothills where it’s cooler/wetter than the cities.

The weather pattern evolves just a bit over the next week.  For now there is a strong upper-level ridge sitting just to our north.  That’s the reason we’re seeing early fires in British Columbia and Alberta; you’ve probably noticed the hazy skies?


By Saturday the ridge is a bit stronger and more directly overhead.


By next Tuesday (in this example using the GEM) the ridge is still there, but “flattened” a bit.   This is a classic early summer weather pattern; no hot weather but temps above average and dry.


I have high confidence with the dry spell, see the GFS ensemble rain outlook for the next 15 days.  Each horizontal line is one of the ensemble members.  The total at the bottom (in green) is the average of all those members.    Notice only a few produce showers late next week or weekend of 8th/9th.


The ECMWF is similar; no ensemble member produces rain until at least next Thursday.  This model is a bit wetter right around the Grand Floral Parade day (8th).


Enjoy the dry start to June, hopefully we can get one more (brief) soaking before we get to July.

Chief Meteorologist Mark Nelsen

Memorial Day Weekend Forecast

May 23, 2019

7pm Thursday…

The weekend is just about here, and it sure won’t start with the weather we saw today.  Portland hit 80 81 degrees this afternoon, that’s after cloudy skies through noon.  It was a quick warm-up once sunshine arrived!

Todays Observed Highs OrWa 2017

Strong high pressure remains in the eastern Pacific through the weekend.  But a slight shift farther away from us tomorrow and Saturday allows two weak weather systems to move south out of Canada.  Compared to 24 hours ago, that 2nd system Saturday is looking stronger and will give us lots of clouds and showers.  That system is quite cold for late May; sticking snow will fall down to Timberline Lodge at 6,000′ or even a bit lower tomorrow evening through Sunday morning.  Only hardcore tent campers will be having a good time in the mountains Friday & Saturday.



  1. The first two days (Friday & Saturday) will be cloudy, cool, and occasionally wet in Western Oregon and Washington.  That includes the western Gorge and Cascades
  2. Sunday and Monday turn warmer again, with just a chance of an afternoon/evening shower drifting off the Cascades and down into the lowlands.
  3. This means Sunday/Monday are your best outdoor days with warmest temps


Forecast for the ocean beaches (this works for central Oregon coastline as well)


It’ll be very chilly camping in the Cascades through Saturday.  Then much better (but not rain-free) Sunday-Monday.   Expect afternoon showers to build over the mountains each of those days.


Enjoy your weekend, it appears the mild/warm weather will continue into the last few days of May (next week).  That’ll wrap up another warm spring.

MarkSpring WrapUp

Chief Meteorologist Mark Nelsen




Memorial Day Weekend; Warm, But Shower Chance For Many Of Us

May 22, 2019

8:45pm Wednesday…

Can you believe it’s been 5 years since we’ve seen measurable rain for the holiday weekend?  A look ahead in a moment, but today was a very nice late spring day.  A mix of clouds and sunshine, but not excessively warm.  This evening, as expected, downpours have developed in the east metro area.  Showers and maybe a thunderstorm coming off the Cascades.  I see a few spots up around 1/2″ of rain!

Todays Observed Highs OrWa 2017

This month has been MUCH warmer than normal, mainly due to record warm temps in the first half of the month.   We’ve seen a “cool” period the last 8 days, but the below average daytime highs have been balanced by above average nighttime temps.  The result?  May is running 6th warmest on record at PDX!  Looks like those strawberries, blueberries, blackberries may show up at the farm stands early again this year.

Month Climate Temps Calendar

Memorial Day Weekend

I can see this weekend is going to be a real pain to forecast.  First, it’s been five years since we’ve had measurable rain on the holiday weekend.  But typically we get lots of cloud cover, a few showers, and a high temp around 70.  Clearly we’ve been overachieving the past few years.


This year we’ll be under the influence of strong high pressure in the Eastern Pacific.  It’s far enough offshore that Friday and Saturday we’ll see several weak disturbances set off showers as they move south out of Canada.

Jet Stream Forecast 2017

Yes, this is precisely the weather pattern we saw in February.  Of course it’s 30+ degrees warmer this time of year.  It’s not a real wet weather pattern, but the chance for showers is there.  This will be a risky weekend to camp outside in tents, whether it’s west of the Cascades, IN the mountains, or through the Gorge or Central Oregon.  Here’s what I’m thinking for the beaches:

Memorial Day Coast Cascades2

and the Cascades

Memorial Day Coast Cascades

There you go…not a dry weekend, but not constantly wet either.  At least temps will remain near/above average with sunshine as well.

Chief Meteorologist Mark Nelsen

A Wet Weekend, Warmer & Drier Ahead

May 19, 2019

9pm Sunday…

Yesterday was exciting with lots of lightning in the valley during the afternoon hours.  Then outflow wind from those storms plus a switch back to onshore flow gave us gusty evening wind in the metro area.  Overnight some hefty showers moved through too.  Here are the weekend rain totals:

Rain Totals Metro Area


I expect a little more rain west of the Cascades this week, but I think we’ll stay below a 1.50″ total going into the Memorial Day Weekend.  Maybe only an inch here in Portland.  This 10 day cool/wet period only has a few days left and we’ve been cheated a bit by lows going farther south into California than initially anticipated.  This is similar to a wintertime El Nino pattern.  Look how dry Seattle has been and then check out San Francisco and Santa Barbara!  May total so far…

Rain So Far This Month Or and Wa Earth Scene

Now those California numbers don’t look huge, but compared to normal they are “way out of whack” one could say.  Check how the numbers above compare to typical May rain through the 19th

Rain Totals West Coast Percent

So Sacramento has seen 6 times the average so far this month, that includes a record .83″ today with hail showers around too.

The general weather pattern is still on track this week; a chance for showers tomorrow and Tuesday, then warming/drying the 2nd half of the week.  Not TOTALLY dry, but west of the Cascades I don’t see many showers after Tuesday.  Models are hinting at thunderstorms developing over the Cascades Wednesday/Thursday; we’ll see if they head straight south along the mountains or come out over the valleys.  Regardless, temps will be warming the 2nd half of the week.  More on that tomorrow…

Chief Meteorologist Mark Nelsen



A Week of Showers Ahead and First Look at Memorial Day Weekend

May 16, 2019

6:45pm Thursday…

Yesterday we saw vigorous showers move through the east metro area around this time, dumping up to 3/4″ of rain.  Today the heavy showers are east of the Cascades with lighter showers west of the mountains.  Models are shoving lots of moisture into far eastern Oregon tonight and Friday; NWS Pendleton has a flood watch out for that area

Mark Flooding California

The reason for all that rain is an upper level low moving into Northern California this evening.  I expect two more of these disturbances to take a similar track over the next week.  They show up nicely on the ECMWF model’s ensemble forecast.  First, Sunday morning you see that cold low in the same position as tonight’s low


Then a second low on Tuesday as the first low spread severe thunderstorms and tornadoes into the Great Plains…


Both of these are forecast to drop a little farther south than what models were showing earlier in the week.  That means most of the rain the next seven days heads into California and we see lighter showers across NW Oregon and SW Washington.

This setup of lows moving by just to the south is a forecast nightmare as well.  Little waves of showers spin north; each model run is slightly different on placement and timing.  It’s safe to say we’ll see light showers at times, but there could be large windows of dry weather some days in the next week.  Right now it appears the first 3/4 of Saturday will be dry and much of Sunday could be as well.

Check out the ECMWF rain forecast for California…FAR more than anything they typically see in late May

ECMWF Precipitation Accumulation

Now the big question…

How long will this cool/wet pattern continue?

There are strong hints that we’ll return to a drier/warmer pattern as we head toward/into the Memorial Day Weekend.  No, I’m not saying we have a sunny/hot/warm/dry holiday weekend on the way (for now).  And yes, it’s 9 days away, but we can see general weather patterns that far out.

For several days most long range model solutions are showing the cool upper-level troughing sinking farther south into the Desert Southwest and high pressure (ridging) developing once again just to our west.  Similar to what happened in late April and early May.  Notice the ensemble forecasts from the GEM, GFS, & ECMWF for Saturday the 25th all look the same

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This would say mainly (or all) dry weather with average to above-average temps.  We’ll see how that plays out.

You can see the drastic change from week #1 to week #2 in last night’s 45 day ECMWF run.  This is surface temperature anomaly.  First from this coming Sunday to the Sunday of Memorial Day Weekend.   Look at that cold anomaly over Nevada/Utah, 15 degrees below average next week…Brrr!


Then the following week; cold moves farther east/south.  The west coast of North America from Oregon to Alaska would be very warm


So there you go.

Cool and showery this next week but not too much rain.

Enjoy your weekend!  Chief Meteorologist Mark Nelsen


Forget An Early Fire Season; Soaking Rains Ahead

May 13, 2019

5pm Monday…

The past 3+ weeks have been quite a ride.  We’ve only seen a few sprinkles in much of western Oregon and southwest Washington.  Soils are totally dry like what we’d typically see in late June or July.  All of us are watering (or should be) lawns, gardens, & crops well ahead of the usual time.  But the “outside living” has been spectacular with dependably dry weather as if we’re in mid-summer.

This is the 2nd consecutive year we’ve seen a prolonged dry spell in late spring.  In fact this year is record dry.


Maybe more interesting is the lack of wet weather in May recently.  We haven’t seen a wet May since 2013, although 2016 & 2017 were close to normal.


And of course we’ve seen quite a stretch of July weather in May.  The first 13 days this month have all been above average.  We didn’t quite hit 90, but were very close with one record high on the 10th.

High Temp Last 13 Days

There has been lots of concern (including from me) that we’re repeating the very early fire/dry season from last year and 2015.  But there is good news!

A pattern change means the next 10 days will be unusually wet across the region.  This is much different than the early dry seasons last year and 2015.

We’ve been very dry because upper-level high pressure has been just west of us in the Eastern Pacific or right over the Pacific Northwest since mid-April.  The 30 day anomaly shows those much-higher-than-average heights well


Now here’s the forecast from the ECMWF ensemble run this morning.  Both the GFS and Canadian models are similar.  In three days (Thursday), a cool upper-level trough will run right into northern California.  Heights are below normal all along the West Coast.


Then a 2nd, even deeper low moves inland early next week


This means a stretch of much cooler weather plus widespread rain from southwest Canada all the way down into Southern California.   The showers/rain will come in waves and at this point I don’t see any “atmospheric river” setting up over the Pacific Northwest.  Here’s the ECMWF rain forecast for Oregon through Thursday the 23rd, just ahead of Memorial Day Weekend


The GFS model is similar for the next 10 days


I think it’s safe to say at least 1.00″ is likely in the western valleys, possibly over 2.00″ in spots if we get convection (thunderstorms) at some point.  In the Coast and Cascade ranges a solid 2-4″ is likely in the next 10 days.  Excellent news!  We can forget about fire issues through late May if this comes to fruition.  Notice they both show some rain east of the Cascades as well; good news for “dryland” grain farmers in central & north-central Oregon.

Does this mean all the rest of May will be wet and cool, including Memorial Day Weekend?  There’s no reason to think that for now.  The ECMWF ensembles show at least weak ridging (or lack of cool/wet) arriving between 10-15 days from now.  That’s over the long holiday weekend…


To wrap it up:

  1. By sunrise tomorrow (Tuesday) light rain arrives for many of us.
  2. Finish all dry weather projects this evening; bring in everything that shouldn’t get wet.
  3. Waves of light rain/showers continue for the following 8-10 days.
  4. EVERY DAY WILL NOT BE A SOAKER.  At this point Friday and at least part of Saturday look dry.

Chief Meteorologist Mark Nelsen