Worst Spring Ever In Portland? I’d Say So!

May 31, 2011

June is only 2 hours away…really hard to believe isn’t it?  What a strange and cold spring it has been.  As meteorologists, we generally consider the three spring months (if there are 4 seasons) to be March, April, and May.  This is the only spring I remember where we’ve seen no decent warm spell.  Yes, of course we had all of three days around 70 a week or so ago, but that’s it. 

So is it the WORST SPRING EVER?  I think so…here’s why:

1.  The March-May average temperature was 49.33 degrees, the 4th coldest in Portland’s history and the coldest in 44 years!.  The 3 colder were 1955, 1964, and 1967.

2.  The March-May total rainfall (with 2 hours to go) is 14.41″  That’s the 2nd wettest in Portland’s history.  And only .09″ below the wettest year of 1997. 

So how wet were those other cold years?  All three were near or well below average rainfall-wise.  Those springs were chilly, but not wet like this year.

And how cold was the wettest spring, 1997?  Not very cool…in fact during May 1997, there was a 10 day stretch in which 7 of those days made it into the 80s!  I remember that one clearly…that was a fantastic May. 

Put those two together and I say we haven’t seen such a combination of cold and wet during the three spring months in Portland’s history, at least back to 1940, which is when airport records began.

 

Current Weather:  Nice cluster of showers really giving a soaking to the extreme SE part of the metro area this evening.  It appears that a marine push coming in from the northwest through the rest of the metro area kept the convection just to the south.  You could see a swift movement of lower clouds coming in from the northwest on our Skyline camera around 6-7pm.

Looking ahead…models are still in line for the big, brief warmup this weekend!  Easterly flow commences overhead Friday afternoon and continues through early Sunday.  850 mb temps went a little crazy on the earlier GFS (+18 deg C!), so I based an 85 degree temperature forecast Saturday from our chart, which shows a possible high between 83-88 degrees based on a +15 deg 850mb temp and offshore flow.  Most important, models are not shifting the low any closer…a very good sign of model continuity.

Chief Meteorologist Mark Nelsen


Willamette River: Highest in 14 Years

May 31, 2011

Here’s a nice graph from the USGS showing the past 15 years of water level on the Willamette River.  That’s right at the Morrison Street gauge.  Today it peaked at slightly over 17′, just a foot below flood stage.  That’s the highest the lower Willamette has been since early June of 1997.  As a result the city of Portland closed the East Bank Esplanade for the first time since it’s construction in the late 1990s.

Is it a coincidence that at the same time the Columbia is seeing its highest level in 14 years as well???  No, because the Willamette River is not REALLY flooding, but the Columbia River is.  The two rivers are connected in the northwest part of Portland, so if one rises the other one does as well.  If there was a ton of water flowing down the Willamette River you’d expect high water in Salem and Albany, but that’s not the case.  Right now the river is 13-14′ below flood stage at those two gauges.

So how high CAN the Willamette get in Portland?  Here are the numbers…

The two highest crests both occurred in June; similar setup with water coming in from major Columbia River flood events.

33.0′  June 7, 1894
30.0′  June  1 & 14, 1948 (Vanport Flood)
29.8′  December 25, 1964 (Winter Flood)
28.7′ February 2, 1890 (Winter Flood)
28.55′ February 9, 1996 (Winter Flood)

During the first 3 floods above (maybe the 4th), water flowed into downtown Portland, up to 5′ in spots during the 1894 flood.  You can find pictures around the Portland area showing this flood.  Imagine paddling a canoe down 3rd avenue or SW Oak St. on a sunny day in June (the image below)!


Forecast Disaster Possible: Next Weekend

May 30, 2011

Will it really get to 85 degrees this upcoming weekend?  Is that possible, considering we haven’t even hit 75 yet?  Let me explain.

The very last thing a forecaster in the Pacific Northwest wants to do is predict the warmest and sunniest weekend of the year so far, especially after a cold and wet spring, and have it turn into a cloudy and cool weekend.  This ranks up there even higher than a busted snow forecast since we are all in a delicate emotional state about the 3 month long cold/wet spell.

So I walk in today and see the potential for 80+ degree temps Saturday and 75+ temps Friday and Sunday.  The reason isn’t quite what you would expect.  There is no big huge ridge of high pressure developing over the West Coast.  Instead, another upper-level low (with it’s cool weather and showers) dives south towards us.  That’s nothing new the last few weeks.  However, this time around, models are insisting it’ll stay off the coastline and park itself off the California coast Saturday.  You can see it on the 12z ECMWF, 12z GFS, and 12z GEM (Canadian) models here…all 3 upper-level maps are for 5am Saturday morning.   Click on each for a view you can actually read.  Note they are all extremely similar and all are from the same “initialization” time:

The key is the location of the upper-low.  Note the upper-level winds are then easterly over Washington and Oregon, causing pressures to fall west of the Cascades.  A nice setup for easterly flow and sunshine.  Combine that with 850mb temps up around +15 C and we could easily hit 84-87 degrees here in Portland on Saturday.  It only occurs for one day, but the easterly flow actually starts Friday afternoon and ends early Sunday, so upper 70s would be possible on each “side” of that day.

Here’s the problem…5 days ahead of time we have to assume models are correct with location of the upper-low and the pressure pattern. to get those temperatures.  If the low is a bit closer, right over us, or to our west, forget about real warm weather.  Thus, the high potential for a change in the forecast.  A real pain.  So we decided to keep highs in the 70s on our 7 Day forecast until models are more clear, or at least continue to show the exact same pattern over successive model runs.  Even that is better than we’ve seen so far this season.

In the short term, an active pattern the next two days with southerly or southeasterly flow bringing moisture up over us for showers.  Our RPM model shows a cluster of showers turning up into NW Oregon overnight, leaving us with a very wet start to Tuesday.

On a far happier note:  here are the wedding photos from Brian MacMillan and Sophie Soong.  They both got married Sunday (but to different people…just want to clear that up).  Those are some good looking people!

 

Chief Meteorologist Mark Nelsen


The Vanport Flood: This Weekend In Weather History

May 27, 2011

63 years ago this weekend, 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 2011.

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 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.
YOU WILL BE WARNED IF NECESSARY. YOU WILL HAVE TIME TO LEAVE. DON’T GET EXCITED.”

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 1/2 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.

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


Summer Arrives…In Alaska

May 26, 2011

A beautiful live view from Fairbanks, Alaska…current temp is 76 degrees.

For perspective, here is the forecast for Friday for several cities:

Fairbanks-83

Anchorage-72

Juneau-64

Moscow (Russia)-75

Portland, OR-58

Curling up into the fetal position and rocking right here in the weather center now…Mark


Podcast #6 Posted

May 25, 2011

Brian and I just finished up another 30 minute podcast.   The link is here:  http://www.kptv.com/northwest-weather-podcast/index.html

This episode, we welcome FOX 12 Weather Producer Pat Rosborough to the show.  We talk about the devastating tornado in Joplin, Missouri, flooding on the Columbia River, answer kids’ questions and much more.

We’re now on iTunes!  Check out this link to subscribe to the show.  Enjoy!

Chief Meteorologist Mark Nelsen


Almost a Funnel Cloud!

May 25, 2011

An impressive line of showers moved through the eastside metro area between 2:30-3:30pm.  One turned particularly strong over Parkrose and Government Island, passing directly over the NWS office.  Notice the image above shows the radar reflectivity, with 62 dbz showing up in the pink area.  But there’s more…definite rotation with this storm today.  Check out the “shear tracks” on our radar system, showing areas where there was directional shear in the atmosphere:

 37 mph is pretty impressive for us, in fact I only saw 22 mph shear when a funnel cloud showed up over Milwaukie about a month ago.  So there could easily have been a funnel cloud or weak tornado over the Columbia River or anywhere just east of I-205 today.  Of course 30 minutes later the storm is weaker and already in the Cascades.  Classic west side “here one minute, gone the next” funnel cloud producer.  But so far we’ve received no reports…

Chief Meteorologist Mark Nelsen


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