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.

Mark…


Wind Storm…Strongest of Season at Salem

March 15, 2015

2pm…

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.

THE RAIN

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.

PORTLAND: 2.25″
VANCOUVER:  2.11″
HILLSBORO:  2.34″
TROUTDALE:  2.11″
SCAPPOOSE:  2.52″
McMINNVILLE:  2.40″
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.

WIND

  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:

nam

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.

eps_slp_lows_nw_5

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.

MOUNTAIN SNOW

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.

base

floodtop

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:

deto3_hg

Chief Meteorologist Mark Nelsen