Spring Break: Vacation Time

March 18, 2015

Wednesday, March 18th…


I will be posting very little (or not at all) during the next 10 days.  It’s Spring Break time in Oregon and I’m taking a vacation with the family through Saturday the 28th.

I’ll be back at work on Sunday the 29th.

Chief Meteorologist Mark Nelsen

Sunday’s Windstorm Wrap Up

March 16, 2015

When I visit schools and other organizations I often talk about how good our forecasting is getting nowadays compared to 25 years ago when I started.  I have sometimes said “we’ll probably never be surprised by a major windstorm again“.  We came close both in October and yesterday.  Not a whole lot of warning.

We sure didn’t see a major regionwide windstorm this year, like 1962, 1981, & 1995.  But we have seen 3 very impressive windstorms in the Portland metro area.  Each of those put at least 70,000 PGE customers out of power at one time.

It’s very interesting to note that all 3 low pressure center paths were similar; steeply south-southwest to north-northeast.  That’s different from more of a westerly angle like WSW to ENE. That is excellent for getting a major windstorm here.  This one bottomed out only just below 1000 millibars!  Hard to believe we saw widespread gusts 45-60mph with that isn’t it? The low pressure center made landfall right around Hoquiam. The December storm bottomed out around 973mb, and the October storm was around 980 mb.

Models had trouble with all 3 storms this year, and two of those storms occurred with only about 24 hours of warning (this one and October).

Here are the final peak gust numbers in our area:




For Salem, Hillsboro, & Battle Ground this was the strongest storm of the season…stronger than December.  The strong wind gusts were more evenly spread around the region.   Look how the Oregon Coast saw strong wind this time as well.



In December Portland saw higher gusts than many coastal locations, which was strange.

The problem this time around with the forecast was that models were having real trouble deciding where a wave along our very wet frontal boundary would track.  Look at the surface map for Sunday 5pm from the NAM-MM5 and WRF-GFS initialization.  Looks like a low pressure center around 996-1000mb just moved inland and is centered near Olympia.  This is what actually occurred.

nam_Sun5pm_initialization wrf_Sunday5pm_initialization

Now take a look at the forecast for this time from FRIDAY MORNING:

nam_Sun5pm_48hrfcst wrf_Sunday5pm_48hrfcst

At 48 hours away neither is close to reality.  NAM has a low along the frontal boundary in eastern Oregon and the WRF-GFS is spinning something around off the southern Oregon Coast.  These are the last maps I saw Friday evening before the 10pm show.

Let’s move to 36 hours out.  Forecast for the same time from SATURDAY MORNING’S RUNS:

nam_Sun5pm_36hrfcst wrf_Sunday5pm_36hrfcst

Now it’s very interesting and both models agree…some sort of gusty wind event is on tap for late Sunday evening.  The low is supposed to still be off Newport at this time.

Jump ahead to SATURDAY EVENING’S FORECAST…just 24 hours away from our storm:

nam_Sun5pm_24hrfcst wrf_Sunday5pm_24hrfcst

Both are faster, the GFS is getting quite close to reality.  At this point it’s looking like a minor windstorm is on the way

Jump to SUNDAY MORNING’S FORECAST, the last before the event:

nam_Sun5pm_12hrfcst wrf_Sunday5pm_12hrfcst

Timing has speeded up again!  NAM is very strong and just about right on for placement.  The GFS ended up being too fast.  They both show a perfect setup for strong wind.

So I’d say models latched on around 24-36 hours out and once they did the surface low pressure intensity forecast was close to reality from that point onward.  The larger scale models (GFS/ECMWF/NAM etc…) were similar to these.

Chief Meteorologist Mark Nelsen

ECMWF Weekly Charts

March 16, 2015

I’ll do a summary of the storm late this evening between shows, but for now I’ve got the 4 weekly maps from last night’s run of the ECMWF.  Still ridgy along the West Coast or just offshore through the period.  That sure doesn’t mean DRY through mid-April, but it means most likely we’ll AVERAGE warmer and drier than normal.

Week 1


Week 2


Week 3


Week 4, this goes through April 12th.


So no change right?  Well the 12z ECMWF today looks a little different to me.  On the last image (Day 15, March 30th), lower than normal heights would imply cool and showery over the West Coast:


Hard to tell if it’s a transient pattern for just a few days or if the model is changing the big picture.

Chief Meteorologist Mark Nelsen

3pm: Gust to 58 at Portland Airport

March 15, 2015

Quite a decent windstorm, especially considering the surface low pressure center isn’t very deep.  Definitely the windiest March day we’ve seen in at least 16 years.

Peak gusts as of 3pm:

It appears the storm has peaked south metro area and Salem.  The strongest gust at Salem was 2 hours ago…

Portland Airport: 58

Vancouver: 46

Hillsboro: 54

Troutdale: 48

McMinnville: 51

Salem and Aurora have seen winds decrease slightly from their peak in the previous post.


Wind Storm…Strongest of Season at Salem

March 15, 2015


Power going in/out here at home so I’ll be brief.

Wind has arrived a couple hours early as pressures jump to our south and the southerly wind races up the valley.  Peak gust of 58 mph at Salem at 1:20pm is stronger than either of the previous storms this season.  I see lots of power outages down there.  About 20,000 so far in PGE’s territory.

Other peak gusts as of 2pm (mph)

Portland Airport: 48

Hillsboro: 44

Vancouver: 43

Troutdale: 37

Aurora: 59  (that’s just about as strong as the December storm in that spot)

McMinnville: 46

Very warm temps with the air mixing down well from above…into the 60s.  That almost always happens in windstorms in our area.

Wind will continue for a few more hours and then die down quite a bit around sunset or a bit before.

Chief Meteorologist Mark Nelsen

Strong Wind This Evening & Heavy Rain Update

March 15, 2015

8:30am Sunday…

What a soaker!  And possibly our strongest south wind since December on the way late this afternoon.  Suddenly we have some exciting weather after 2 months of nothing.


Over 2″ has fallen all across the metro area so far and some spots will easily get 3″ right here in the lowlands.  Models did pretty well showing a lot of rain.  I just did some good old-fashioned number crunching adding total rainfall since the rain began up to 8am today.

AURORA:  2.48″
SALEM:  2.20″

Looks like only minor “urban” flooding.  That means mainly small creeks, intersections etc…  In this case the soaking is excellent since we’ve been so dry since late January.  The ground probably soaked up the first inch.  As the narrow band of heavy rain lifts north, rain will taper off a bit in the metro area and points south the next few hours.  Then more rain, although not as heavy, returns this afternoon as the cold front moves through west to east.


  1. Gusty wind arrives late this afternoon from the south.  Gusts 35-45 mph are likely in the metro area, similar to what we saw on February 9th.  That was the rainy Monday.
  2. There is a chance the storm is stronger and produces widespread gusts to 50 mph, if so that’ll give us lots of outages and more trees down since the ground is suddenly very wet.
  3. Timing is 3-8pm regardless of the intensity.

Since yesterday’s runs, models have been showing a surface low tracking northeast along the coastline late this afternoon, making landfall just north of Astoria.  It’s not very deep, but there’s quite a southerly pressure gradient on the south side of the low.  The NAM-MM5 has been most aggressive showing a deepening low almost up to landfall.  Here’s 5pm today:


That is “minor windstorm” category, probably gusts 45-50 mph in the northern Willamette Valley; strongest we’ve seen since the December storm.  Other models are not as strong.  Take a look at a product from the trusty ECMWF model, showing all 51 low pressure locations at 5pm from its different ensembles.


All generally have the same track but you can see wide differences on the depth of the low.  A lot of these would only produce gusts maybe 30-35 mph.  But some would be strong like the NAM-MM5 shown above.

The atmosphere is very warm and it’ll be easy for the strong wind a few thousand feet up to surface, that happens in March, just like in October.  No inversion this time of year.


Pretty bad as expected.  Here are two pics from Mt. Hood Meadows and Timberline (it looks the same elsewhere at the same elevation) where the snowpack is falling apart at the lower elevations.  Several inches of rain aren’t good on a thin snowpack.  A few fresh inches VERY high on the mountain today (6,500’+) but otherwise nothing new until next weekend.



One last bit of good news.  The rain is helping to fill reservoirs.  Check out the 10 foot rise forecast in Detroit Lake over the next day or so.  At least heavy spring rain can be captured:


Chief Meteorologist Mark Nelsen

Is This Weekend The End of The Ski Season?

March 13, 2015

The short answer is…possibly.  At the least I am confident skiing terrain on Mt. Hood will become much more limited after this weekend’s rain.

This has been a brutal ski season, Mt. Hood Skibowl says it is the worst they have seen since the 1950s!  And as I detailed in a blog posting 8 days ago, we are now entering uncharted territory.  We’ve never seen snow conditions this bad on March 15th and beyond.  And there is no sign of a cool and wet pattern.


  • 3 of the 6 main ski areas in the central/northern Oregon Cascades have been closed since early January.  That’s Hoodoo, Willamette Pass, & Mt. Hood Ski Bowl.
  • I don’t see those ski areas reopening this year, they are likely done.  There is no weather pattern in the next two weeks that would produce the 3 feet of snow needed.  Plus on average in late March there is more melting than accumulation at 4,000-5,000′.
  • Timberline has 3 of their main lifts shutdown: Pucci, Jeff Flood Express, & Molly’s.
  • Meadows isn’t operating Heather Canyon & Hood River Express.
  • The lower parts of both of these ski areas have large bare sections.  Grooming crews have done a spectacular job moving snow around this season, but there isn’t any more to move in to cover those lower areas.  We’ve seen more and more grass/soil appear on the webcams.
  • There is plenty of snow up around 6,000′ and above, but how to you get skiers back down from those spots if you can’t ski back down?



  • Heavy rain…1-3″ will fall on Mt. Hood with temperatures above freezing almost the entire time.  A warm and thin snowpack, that’s been exposed to two weeks of warm sunshine and temps in the 40s/50s won’t handle that very well.
  • Possibly some fresh snow (a few inches) Sunday above 6,000’…MAYBE


  • More warmer than normal weather…melting will continue up on the mountain, especially the later half of the week
  • No new snow, although NEXT weekend there are hints of some cooler weather and snow showers up there.

As a result…

THERE WILL BE SIGNIFICANTLY LESS SNOW ON THE GROUND A WEEK FROM NOW WHEN OREGON’S SPRING BREAK BEGINS.  Combine that with the already bare areas mentioned above and that’s a big problem.  There is a very real possibility that for the first time on record (that I know of) there will be very limited skiing on Mt. Hood for the start of spring break.

Chief Meteorologist Mark Nelsen


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