Much Needed Rain On The Way Next 4 Days

June 24, 2019

6pm Monday…

June has been very dry across the region.  Only .23″ in Portland so far this month, with just 6 days to go.

Month Climate Rain Calendar Saturday Start

This is our 5th consecutive drier-than-average June and most of the Pacific Northwest has been dry.

precipanomaly

But I see some hefty showers Wednesday-Friday, especially west of and over the Cascades.  What’s up?

A cool upper-level low is dropping down the Canadian coastline right now, and it arrives offshore by Wednesday morning.

wrf_500_wed

A couple points.  First, this isn’t quite as cold as the low that brought Timberline snow this past weekend.  The other is that as it approaches the upper-level flow turns southerly plus the airmass moistens up.  That begins tomorrow afternoon.  There are hints that some showers and/or thundershowers pop up across the region.  I think that’s most likely over the Cascades but can’t rule out a brief shower over the western valleys for your Tuesday afternoon.  Just keep an eye on the radar and sky tomorrow afternoon.

Far more likely is a three day period with widespread showers and embedded thunderstorms Wednesday through Friday.  By Thursday morning that upper-low is directly overhead = pretty good lifting.

wrf_500_thu_pm

This pattern in June is typically a very good rain producer.   By the time it leaves the area Saturday, the “new and improved” GFS (American) model gives us a nice soaking.  Maybe 1/2″ or more in the valleys and over an inch in the mountains.  Even a little in Eastern Oregon with thunderstorms.

gfs_totalprecip

The ECMWF is somewhat drier, sending less than 0.25″ into most western valleys of Oregon.

ecmwf_totalprecip

Both models shut off just about all the showers after Friday once the low moves to the north.  You can see it on the 24hr rainfall forecast from ECMWF ensembles.  Just about all the “rain action” is going to be Wednesday through early Saturday.

ecmwf-KPDX-indiv_qpf_24-1377600

To summarize

  1. Expect a cool, wet, & breezy period Wednesday through Friday
  2. Water sports won’t be pleasant Wednesday-Saturday…chilly!
  3. Thunderstorms are possible any of those days; could be a situation where you get 1/2″ of rain at your home and 5 miles away it’s sunny at the same time.  Think spring weather.
  4. At best we’ll see up to 1″ of rain in a few lowland locations by the time July rolls around a week from now.  At worst, just a quarter inch of rain to wet only the top of the soil.
  5. Regardless, this puts the beginning of fire season off for another week or two.  No major fire worries until the 1st or 2nd week of July.

Chief Meteorologist Mark Nelsen


Slow Start To Fire Season 2019

June 20, 2019

9pm Thursday…

Have you noticed one thing is missing so far this season?  Hardly any talk of fires or smoke in the air.  That’s because fire activity UP TO THIS POINT has been lower than any year since at least 2009 here in the USA.  Check out acreage burned so far across the entire country.

Fire USA Summer Stats

That’s only a quarter of the acreage burned compared to this date in the previous 3 seasons.  Most likely that’s due to a late/cold spring from the Rockies westward into California.  Temperature departure the past 30 days

cdas-west-t2m_f_anom_30day_back-1053600

and of course the very late wet conditions everywhere south and east of Oregon have put off the beginning of fire season

hrap-nw-30day_percent_anom-0038400

Only western Oregon and Washington have been drier than normal late spring and very early this summer.  You can see that in the “1,000 hr fuel moisture” for the western slopes of the northern Oregon Cascades.  The black line is this year, light gray is average, and red is record driest.  We’re tracking near to a little drier than average for those larger fuels in this part of the forest.

Capture.PNG

What we haven’t seen yet is any sort of warm/hot weather lined up with dry lightning.  That’s what gets the big fires going.  No sign of that through the rest of June as we are now in a cooler and wetter than normal pattern.  I would expect fuels to be wetter by the time we get to July 1st.

Now I remember many years where it’s all quiet through mid-July and then all hell breaks loose with one lightning outbreak in late July or early August.  So obviously a slow early season doesn’t mean much for later this summer.   We had another relatively light year for lightning, nothing like the crazy 2012-2016 summers!  Chart from USFS

Capture2

You probably remember the “perfect storm” for August & early September smoke the past two summers?  Big BC fires, big and persistent SW Oregon fires, and then of course the close-by Eagle Creek fire in 2017.  It’s unlikely we’ll see that convergence of fire smoke again this year unless we get another scorching hot summer plus a ramp-up of lightning action compared to last year.  We’ll see.

At this point it appears we’ll see some sort of warm up beginning somewhere around July 1st.  Models say the upper-level troughing goes away about that time.   So enjoy the cool late June weather (not my tomatoes) and cross those fingers for a slow fire season and not much smoke!

Chief Meteorologist Mark Nelsen

 

 


Warm & Dry June Turns Cooler Next 10 Days

June 18, 2019

7pm Tuesday…

Today our weather returned to normal temperature-wise.  That’s follows 9 days of  a mid-summer weather pattern; temps mainly in the 80s & 90s.

High Temp Last 13 Days

Of course this means June is tracking very warm…

Month Climate Temps Calendar

and quite dry.  Only two days with measurable rain through the 18th, that could continue all the way through the 22nd or 23rd I suppose.

Month Climate Rain Calendar Saturday Start

But the last 10-12 days of June sure look cooler.  Or maybe more accurate…

Typical June Weather is On The Way

What’s changing?  More cloud cover and cooler temps is the general story.  For now we have higher than normal upper-level heights over the Pacific Northwest

ecmwf-namer-z500_anom-0859200

But quite a change Thursday as a cold trough of low pressure drops in.

ecmwf-namer-z500_anom-1032000

That’s followed by a 2nd pool of chilly air sitting just offshore or right over us much of next week, starting Tuesday.  These charts are from the ECMWF model for Tuesday and Friday NEXT week.

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It’s not like we’re going to see endless days of rain and highs in the 60s, but expect noticeably cooler weather next week with some showers at times.

Two Big Questions

  1. Will it be dry this weekend?  YES, FOR MOST OF US.  We’ll be in-between that cold system Thursday and the one early next week.  FRIDAY AND SATURDAY WILL BE NICER THAN SUNDAY.
  2. How much rain could we see in the next 10 days?  Probably not enough for you to shut off irrigation for crops and lawns.  Maybe enough to back off on your garden veggie watering around the middle/end of next week.  Until that time (through this weekend), I don’t see any significant rain.

Here’s the 10 day total rain forecast from the operational runs of the ECMWF & GFS models.  Both imply 1/2″ or less in most lowland areas (where most of us live west of the Cascades).  Of course more in the mountains.

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Checking the ECMWF ensembles for Salem (middle of the Willamette Valley), the average is around 1/2″ as well.  That’s in green; bottom half of chart.  Notice a few members (top half of chart) are wetter, but some are drier…thus the “average”.

ecmwf-KSLE-indiv_qpf-0859200

To Summarize

  • The next 7-10 days will be near normal to cooler than normal for late June
  • Expect some showers at times, mainly AFTER next Monday
  • No sign of hot weather returning through the end of June

Chief Meteorologist Mark Nelsen

 


Midweek Scorcher Delivers

June 12, 2019

6pm Wednesday…

Whew!  What a scorcher.  98 at this hour in Portland ,which is also the high temp for the day so far.  Tomorrow will be so much nicer since we get a major marine push.  A good 15 degree drop.

I’m at a weather conference in California for a couple more days.  Try to stay cool tonight!

 


July Weather Next 10 Days; Includes A Midweek Scorcher

June 9, 2019

9pm Sunday…

Quite a change the last few days.  Most of us were in the 50s and lower 60s with showers/thunderstorms Friday.  Yesterday was a clouds to sunshine day; good news for for Grand Floral Parade day.  Temps rose 5-10 degrees. Then another 10 degrees warming today brought temps well above average once again:

High Temp Last 13 Days

The big picture says we’re going to be quite warm for the next 10 days or so.  From the ECMWF model you see upper-level heights (ridging in this case) above average through the next 15 days.  The three images represent Days 1-5, 6-11, and 11-15.  That takes us through the first three weeks of June.

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Looks to me like it’s going to be our 7th June with average to above average temps.  Those three cold Junes 2010-2012 seem like a long time ago now.

June Month In Review

What about rain?  Little or none in the next 10 days.  Each line on the top half of this chart shows one ensemble member.  Quite a few show less than .10″ in the next 15 days!  This may be the beginning of the dry season.  If so, it’s going to be a long one again…

ecmwf-KPDX-indiv_qpf_24-0081600

And well below average rain the next 15-16 days forecast by both ECMWF and GFS ensemble systems.  Wet weather continues across the saturated central/eastern USA.

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In the short term, tomorrow should be similar to today, but up a few degrees.  Then the big change is a switch to easterly wind Tuesday through Wednesday midday.   You can see it circled on the WRF-GFS cross-section over Portland.  The 11/12 along bottom axis = June 11th at 5am, and 12/12 = June 12th at 5am.

Capture

 

At the same time 850mb temps rise up to +21 or +22 over Salem.  According to my chart, based on past similar setups, we should see high temps both days between 95-100 degrees.  Cooling onshore flow doesn’t arrive until Wednesday evening after peak heating.  Whew!

Luckily a quick cooling overhead along with low-level onshore flow should drop us into the 80s Thursday and then down around 80 Friday.  This won’t be a many days-long heatwave.  Still, daily record highs will probably fall both Tuesday/Wednesday

Mark Hot 3 Day PDX Forecast2

Stay cool!  Chief Meteorologist Mark Nelsen


A Changing Climate: Spring 2019 Another Warm One

June 3, 2019

6pm Monday…

Spring 2019 is in the record books now that May has ended.   Meteorologists consider spring to be March through May in the Northern Hemisphere.  How was it?

In a sentence… WARMER & DRIER THAN AVERAGE IN THE PORTLAND METRO AREA

You may remember the first 10 days of March were very chilly due to leftover snow cover over much of the Pacific Northwest.  But then April and May were significantly warmer than average.  May 2019 and 2018 rank as #4 and #2 warmest on record!   The result = Spring 2019 was #15 warmest out of 80 springs.

This COULD be one effect of a changing global circulation here in the Pacific Northwest (higher upper-level heights); but could be partly cyclical as well.  While speaking with local meteorologists at a Portland Water Bureau meeting last Thursday this subject came up.   It seems we are seeing more up/down movement of the jet stream and fewer stormy periods with strong westerly flow.  This would account for the extra cold/snowy February weather recently with persistent ridging offshore.  Or the shift to ridging directly overhead at times (warm and dry).  This is all anecdotal of course. One local meteorologist feels this has occurred in the past, mentioning similar setups in the 1980s.  Interesting eh?  Regardless, 4 of the top 10 warmest springs have occurred recently; in 2014, 2015, 2016, & 2018.

What about rain?  Of course it’s easy to remember the unusually dry three weeks in late April and early May.  But March was quite dry, and even with a little rain later in May it still ended up below average.

Most interesting is that this is NOT a trend in our area.  Looking back 50+ years the trend is slightly wetter, not drier.

I think these are the three most memorable weather events this spring:

  1. Record cold temps (but sunshine!) in early March.  A rare early March snow-cover east of the Cascades along with easterly wind allowed cold/dry Canadian air farther south than normal.  PDX hit 24 in early March!
  2. Rare (or unprecedented?) April flooding in Willamette Basin.  First time I’ve seen flooding this late in the season.  Did this expand the “flood season” in our area?  Time will tell.
  3. 2nd consecutive year with a long dry spell mid spring.  Around 25 days with little/no rain in our area from 3rd week of April to mid-May.

Looking ahead…

We have seen a series of warm June months as well.  We haven’t seen a “chilly” June since 2014 and looking ahead I wouldn’t be surprised if this happens again in 2019.  The warm May pattern continues into early June on models, but with a brief downturn the mid-late part of this week.  A cool upper-level trough drops into the Pacific Northwest just in time for Friday/Saturday Rose Festival events.  See the ECMWF ensemble 500 millibar heights for tomorrow AM

Then by Friday a cold trough is overhead.  Expect some June snow down to at least Timberline Lodge, could even get a dusting down to Government Camp and those Cascade lakes!

Behind this trough the strongest/warmest (hottest?) ridging of the season develops early NEXT week.  It’s possible we’ll see 90 degrees or higher around Monday-Wednesday next week if this pattern shows up

Rain?  Not a whole lot, but we’ll wet things down a bit Thursday-Saturday.  Possibly as little as .10″ in the driest parts of western valleys to 1″+ in Cascades

And the timing is VERY clear on the ECMWF ensembles.  This is 24 hour rainfall from each of the 51 ensemble members, then the average (in blue) down below.

They all agree on rain Friday/Saturday, then totally dry for several days following.  Obviously late this week isn’t a good time to plan a deck-staining, mowing the lawn, or painting a shed outside.

Chief Meteorologist Mark Nelsen

 


The Vanport Flood: On This Date in 1948

May 30, 2019

MarkVanportFlood

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.
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 1/3 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