A Good Night To Migrate! Birds On Radar Tonight

April 9, 2018

10:30pm Monday

It happens each spring; the huge nocturnal (night) migration of ducks, geese, swallows and all those other birds from warmer regions on our planet to northern/cooler areas.  Think about this; there are probably birds flying right over your home tonight that will end up spending the warm season in the Yukon or even near the Arctic Ocean!  Oh, and they may have spent the winter in Mexico or Costa Rica too.  That part doesn’t sound too bad does it?


Because birds are large compared to precipitation (rain/hail/snow) they show up quite well on radar and it doesn’t take that many to trigger an “echo” on the radar screen.  Of course you might be wondering like me why we don’t see birds on the radar screen all through the warm season?  We usually don’t because those birds don’t have any reason to move high up into radar range (more than a thousand feet or so).  But when migrating they go high to avoid low-level wind fields, instability, and denser surface air.  Tonight is a great night for them since there is a solid south/southeast wind ahead of the approaching cold front.

They are quite visible on the “VAD” wind display.  That’s the wind profile the past couple of hours from the Portland radar.  The radar is located up around the 2,000′ elevation just west of Scappoose.


Time goes from left to right.  Look at how the targets rise quickly in elevation right after sunset.  Note it says 50 knots!  That’s likely the 20-30 kt southerly wind plus the motion of the birds.   It’s also fascinating that the highest echoes (birds) gradually increase in altitude…those guys are working hard to get up to their “cruising altitude”.  Ducks have been known to fly up around 30-50 mph even under calm conditions.  They can cover 800 miles in one night if they really want to.

This is what it looks like on the “regular” radar screen as the birds take off, from an earlier blog post.   Note they don’t like to fly over water.  The Ocean Shores radar on the Washington coastline shows almost all “bird action” tonight is over land.


One final note, the dual-pol radar is pretty good at detecting the type of “target” we are seeing in the sky.  Note the current display shows almost all “BI”.  That means BIOLOGICAL.  It could be insects, but not in this case.


By the way, there is a movie called WINGED MIGRATION (a documentary) produced about 10 years ago using hand-raised birds. They follow the birds (usually geese) while flying and migrating using some sort of very light aircraft. Or, actually I suppose the birds follow the aircraft since they imprinted on humans at hatching.  That means they think humans are part of their family. Now, believe me, this is no “party movie”, actually it’s REALLY slow, but great visuals for little kids to watch. Filming was done all over the planet. Here’s a clip for a little evening relaxation:


Chief Meteorologist Mark Nelsen


A Blustery April Day; Wind Dying Down

April 7, 2018

5pm Saturday

I was out and about for 4 hours this afternoon attending that groundbreaking and then doing errands.  The wind was a little…well…underwhelming.  Gusty wind at times, calm other times…seemed just a little winder than an average blustery April day.  I just saw a Twitter post from another media outlet saying a “strong wind storm” is on tap for tonight…but that’s definitely not the case.

The 35-50 mph gusts we forecast DID end up materializing, but it was another relatively weak wind event in our area and nothing like last year’s April storm.   Portland barely hit 40, and only a few thousand PGE customers lost power at one time from tree limbs or trees that fell here and there.  Not a “non-event”, but not a windstorm in the valleys either.

Peak gusts so far look like this, plus or minus 1 mph since the FAA is having some sort of rounding issue going from knots > mph recently:

Portland 40
Hillsboro 41
Troutdale 40
Scappoose 33
Vancouver 35
Aurora 45
McMinnville 47
Salem 45

Astoria 53
Pacific City 58
Newport Bridge 63
Cape Foulweather (very exposed) 72

Models show wind gradually decreasing this evening/overnight.  We’ll lose the warm daytime mixing too which means we just have a breezy night ahead.

Gusts will be mainly in the 25-35 mph range through the night, more like 20-35 mph by sunrise Sunday.

Expect lots more rain tonight…it’ll be a soaker!


Chief Meteorologist Mark Nelsen

Saturday Morning Update: Windy 24 Hours Ahead

April 7, 2018

8am Saturday

The gusty south wind has arrived across the region as a deep surface low is passing by to the west.  It was a beautiful satellite loop the past 12 hours as the storm wrapped up offshore; especially considering we’re a week into April!  Here’s the latest image:

The yellow spot is the location of the low pressure center.  Notice it’s just now making it across the important 130West longitude?  Unless the low is far deeper, here in the interior valleys we generally don’t get big windstorms with storms this far offshore.   With this image I’ve added the expected movement of the low (in blue) and then a more typical windstorm track for the inland valleys.

The low will gradually weaken and very slowly move toward the central/south part of Vancouver Island the next 24 hours.  This will give us a prolonged period of gusty south wind…all the way through the first half of Sunday!  See the current location from the NAM-MM5 model:

and at 5am Sunday…that’s still a “south wind gusts 30-45 mph” setup in the valleys there:

To summarize:

  1. Coastal wind (so far) appears to be significantly weaker than expected once again (it happened with last April’s storm).  I see a 72 at Cape Foulweather, but lots of 45-60 mph gusts otherwise.  Windy, but nothing too crazy out there.
  2. Inland wind gusts will ramp up with daytime mixing.  Pressure gradient will line up better with the north/south valleys the next 12 hours.
  3. Peak gusts still likely in the 35-50 mph for most of us in the valleys.  That could happen anytime between now and early Sunday morning.  Not a big windstorm by any means, but plenty of power outages and a few trees down.


If you have any outdoor activities, they can still go on since showers will come and go, but expect a blustery & wet spring day.  If you are an organizer of an outdoor event I sure wouldn’t cancel it.

I’ll be at the Crown Point Country Historical Society groundbreaking event in Corbett at 11am…looks windy.  At least the ground will be soft for plunging those shovels into the ground!

Chief Meteorologist Mark Nelsen


Stormy Saturday Update: Looks Slightly Weaker

April 6, 2018

Noon Friday

Just a quick update to let you know things still look about the same for tomorrow, although models have backed off SLIGHTLY on the amount of wind we get and position of the surface low.


  • Gusty south wind spreads onto the coastline late tonight, then it’ll be windy all day tomorrow out there.
  • Strongest wind at the coastline will be in the first half of the day…gusts 55-70 mph are likely.
  • Gusty south wind arrives in the Portland metro area and western valleys from Longview to Eugene right around sunrise.
  • I expect a wide variation in peak gusts since it’s springtime; strong wind overhead mixes down in “bursts” in this setup.  Wind will come and go all day long.  35-50 mph speeds likely for most of us.
  • A few very exposed spots (Chehalem Mtn, top of West Hills, top of Mt. Scott etc…) could see gusts over 50 mph.

This isn’t a big storm, but a pretty good “wind event” for April.  Some limbs/trees will fall of course and there will be plenty of power outages.


Take a look at the ECMWF & GFS model forecast of low pressure location at 11am tomorrow:

The storm is pretty far offshore, and just barely to the 130W longitude location we like to see lows travel to give us a windstorm.  Models have also trended SLIGHTLY farther offshore with it.    The 12z WRF-GFS is similar; here’s a closer view at 11am tomorrow:

For comparison, last year’s April storm was a little stronger and well inside that critical 130West line:

This is the main reason I’m not too wound up about a big windstorm like last April 7th.  The GEM (Canadian) model is still pushing a pretty strong wind field onshore though.  Check out midday tomorrow:


The NWS has upgraded the High Wind Watch to a High Wind Warning for the western valleys of NW Oregon and SW Washington.  Typically you need 58 mph gusts for a HWW to verify, but I think that’s unlikely for 90% of us.  They are concerned about a few pockets of strong overhead wind mixing down to sea level at some point during the day; we’ll see how that plays out.  My gut feeling is that the airports (official observation locations) will likely be in the 40-50 mph range tomorrow.  Those speeds are still the strongest we’ve seen this entire storm season…it’s been a quiet year!

Ahead of the storm, enjoy the warmer temps today, satellite imagery shows some pockets of clearing finally arriving.  It should be a warm afternoon with showers not returning until sunset or beyond.

Chief Meteorologist Mark Nelsen





A Stormy Saturday Ahead

April 5, 2018

5pm Thursday

One year ago, on April 7th, the strongest April windstorm since the 1950s hit the valleys of NW Oregon and SW Washington.   Peak gusts looked like this across the metro area:

It was PGE’s biggest power outage event since the December 2006 storm and it took over 3 days to get the last few customers back online.  That said, most customers were back within 24 hours due to those hard-working crews.

Mark PGE PowerOutages LengthOfTimeOut

So of course it’s VERY interesting that we have another wind “event” coming up exactly one year later…Saturday April 7th.  Luckily, this one does not appear as strong, but will likely cause some inconvenience for many of us during the daylight hours Saturday.

Just like all of our wind storms/events, a deep surface low pressure center will be tracking up the coastline Friday night and Saturday morning.  It ends up around 972-980 millibars depth somewhere around central/southern Vancouver Island Saturday afternoon.  Note the 2pm location from the WRF-GFS model.  Also see the tight packing of isobars, indicating large pressure change over relatively short distance.  The tightest packing is generally associated with the strongest wind as air rushes from high to low pressure.  Looks windy on the coast!

Each model is slightly different in the low location by midday/afternoon which makes for differing wind speed/gust forecasts.  Check the intense NAM-WRF 3km wind gust forecast showing 50-60 mph gusts inland

and the ECMWF, although it’s a bit weaker.

The WRF-GFS around 11am Saturday

Here’s our current forecast:



A few important points:

  1. The National Weather Service has issued a High Wind Watch for the western valleys, the only one of this entire “storm season”!  That’s due to an abundance of caution even though it’s unlikely we see widespread gusts above the 58 mph criteria required for a High Wind Warning.   Remember it’s a WATCH, not a WARNING.  The NWS may upgrade to a warning tomorrow or convert to a Wind Advisory…we’ll see.
  2. When comparing current models to last year’s storm, they are all a bit weaker, by maybe 10 mph.  That plus the low placement/depth leads me to believe that instead of 45-60 mph gusts in the valleys (last year) it’ll be more like 40-55mph for the vast majority of us.
  3. Coastal wind gusts were “weak” last year; the main action was inland.  We’ll see how that plays out this year.  In the springtime the strong upper-level winds mix down easily in the “warm” valleys so we can get as windy as the Coast.
  4. 42 mph is the peak southerly wind gust we’ve seen in the past 6 months.  Very weak.  That means it’ll be relatively easy to topple a few trees here and there.  Expect plenty of power outages, even if we only see gusts 40-45 mph.


To summarize…

We have a bunch of wind coming up this weekend, not a MAJOR storm, but pretty darn windy for April!

Chief Meteorologist Mark Nelsen




April Is Here; But Lots of Rain Ahead

April 2, 2018

7pm Monday

Spring Break is finished in Oregon, but now it’s Washington’s turn.  It appears both will turn out wet…not really a surprise if you grew up in this area.

I had a great time travelling through Idaho & Utah with my son (mountain biking), then met the rest of the family in Nevada.  Lots of red rocks and sunshine!  This is Gooney Bird rock along the “Mag 7” trail system near Moab, UT


We had one last run-in with snow in the higher elevations this morning.  I woke up to a little slush left over on the deck and greenhouse at home.  I had mentioned on-air last night that some areas in Northern Clark county up through SW Washington, under heavier showers, could see sticking snow down below 1,000′.  It happened in a few spots.


Lynn Hayes sent this pic from above La Center at 900′ elevation.

There is no sign of hilltop snow in the next 10 days.  In fact temperatures move uphill to more typical upper 50s and lower 60s for highs the next week…after tomorrow.  Here’s a confusing-looking chart from the ECMWF model.  But you can glean a few tidbits from it.  The lower section shows 6 hourly maximum temperatures for the next 10 days at Portland.  Time goes from left (right now) to 10 days from now on the right.  Note the uphill trend in general, with a peak around this Friday and next Monday.  The green is the average of all 51 “ensemble members” from that model.  The black is the actual operational model.  Ensembles are often safer because they even out any one member showing some sort of extreme high or low on its own.  On the upper half of the chart each thin horizontal line is one of the 51 members.  Note the areas of yellow/orange.  When you see a whole column of yellow, there’s pretty good confidence that day is going to make it into the 60s if the model is correct.  Note again that’s Friday afternoon and again Monday PM.  It’s a nice visual way to quickly isolate warmer days in the model run.


A wet westerly or southwesterly flow will be over us Thursday through Sunday and it looks unusually wet for early April.  Check out rain accumulation at PDX from the same model:

ECMWF 12z Rain Graph Next 10 Days

You see the heaviest rain on Thursday, and again Saturday plus Sunday.  Don’t make any big outdoor plans for this coming weekend.  But at least it’ll be a “warmer rain”!

Mt. Hood just had a 7-15″ dumping from a winter storm last night, but now April warmth is going to turn much of the coming precipitation into rain.

ECMWF Snow Level From 850mb Temps LONG TERM

See the snow level going above the passes from tomorrow through Saturday?  That’s a lot of rain falling on top of the snow.  Rivers will be running high over the weekend, but there is still LOTS of storage available in the Willamette Basin due to the lower than normal snowpack.


I see most of those reservoirs are a bit lower than normal for early April, so this coming weather pattern should top things off nicely.  Typically water managers aim to have the reservoirs at full summer levels by May 1st.

To summarize:  The first half of April looks like a soaker

Chief Meteorologist Mark Nelsen