Ana’s Long Life

October 27, 2014

Ana lived about 17 days, from tropical storm to hurricane, then back to tropical storm, then hurricane.  Finally, Ana’s life ends tonight as a colder low pressure system fading into the British Columbia coastline.  Here’s a movie showing the entire path.  I only have satellite imagery for the last 7 days, thus the “fade on” partway through:


All Customers Back On!

October 27, 2014

PGE told us today that 140,000 of its customers lost power at one point or another during the Saturday storm.  The peak at any one point was 79,000.  Pretty impressive numbers considering the wind speeds were “low” for a windstorm.  That was likely due to the leaves on the trees and the wet ground.  That said, this was the strongest windstorm I’ve seen in October in my 23 year career here.  In fact in some winters we haven’t seen a stronger wind gust the rest of the winter.  Windgusts_30years

The chart above shows the peak gust at PDX each cool season (October-March).  Yellow numbers are years where the highest wind gust was from the east (Gorge wind).  The one red 55 mph gust wasn’t really a windstorm, but a quick squall that moved through the valley in mid-March 2011.  It lasted all of 15 minutes.  I should also point out that from 1995 to around 2006, the ASOS sensor used a 5-second gust, as opposed to a 3 second gust before and after that time.  That means that to get a 60 mph gust (for example), the speed has to hit 60 for 5 seconds.  So during that ~10 year period, peak gusts were reported lower than compared to before and after that time.  For example a 45 mph gust during that period would show up as a 51 mph gust with the 3 second requirement.  I just made up that number, but you get the idea.

As of 10pm this evening it appears there are only two small outages on the south side of Salem and those may not be from Saturday. Here is a chart comparing this storm to some others over the years.  Thanks to PGE for the info…

Mark_PGE_PowerOutages

Note that over the years the number of customers goes up…no surprise there.  In 1962 there were about 280,000 customers, but now there are around 850,000.  So the percentage is a better indicator of storm severity than the numbers when compared to 20+ years ago.

This time around it took less than 2.5 days to get EVERYONE back online…impressive I think.  In 2006 it was 4.5 days.   After that storm crews had to work in some areas that were frozen or a little snowy…no fun.  At least this time it was 55-60 most of the time.  In the massive 1995 windstorm, the last customers came back online in 8 days or so.

The granddaddy of them all, the Columbus Day Storm, took out just about everyone’s power…98% of PGE’s territory.  Wow…the last customers came back online 14 days later.

Chief Meteorologist Mark Nelsen


9pm…Storm Wrapup

October 25, 2014

It ended up being a decent windstorm for us.  Not a really big storm, but not just a windy day either.

  • 76,000 PGE customers out at the height of the storm.
  • Peak gust 49 mph at PDX, 51 mph at Salem
  • This was the strongest October windstorm in my career here in Portland (23 years)
  • My forecast windspeeds at 10pm last night were a little high.  I said 45-60 mph gusts and most spots were close to 45.  That said, at the time there were no watches/warnings/advisories up for wind and none showed up until 3am, so I don’t feel too bad.

Here are the peak gusts…

plot_wind_metro_peakgusts

A 60 mph gust didn’t make it onto the map in the SW hills of Portland and a 47 mph gust in the Felida area north of Vancouver.  There was a 70 mph gust reported down at sea level at the Port of Vancouver.  That doesn’t appear to reflect reality, so I’m calling cow dung on that one.  Especially with Vancouver Airport 43 mph just a mile or two away!

Spread out over the entire area, this storm was stronger than anything we saw last winter.  Yes I know in mid February there were gusts over 50 mph in a swath right through the middle of Portland, but most other locations had stronger wind today. Couple that with leaves on the trees and that’s probably how we got so many more lines down.

The low track and intensity was pretty good, although models were a bit too high on the central pressure, it ended up close to 980 millibars instead of the 985-990 models forecast.  Wind speeds were slightly too strong on the wind gust graphics from the WRF-GFS and ECMWF, although close enough!  Pressure gradients were forecast well (16.9mb EUG-OLM), although peak wind generally showed up well before the peak gradient from Eugene to Olympia.  The EUG-PDX gradient peaked at 9.9mb.

Hope you all had fun tracking/following it!  And of course I hope that you all get power back on soon too.  It’s going to take awhile…

What are YOUR thoughts on the storm?  Go ahead, my feelings aren’t easily hurt.

Chief Meteorologist Mark Nelsen


2pm Wind Gusts: Salem Gusts over 50 mph

October 25, 2014

Salem and Aurora have both gone above 50 mph now, although Aurora had that gust way back with the initial wind arrival between 11am-Noon.

Here are the peak gusts so far…

PLOT_Wind_Metro_PeakGusts


1:30pm Update: Strong Wind Arriving

October 25, 2014

Quite a burst of strong wind moved through the metro area the past hour, heralding the storm’s arrival.

Peak gust of 45 mph at Hillsboro, 46 at McMinnville, & 44 at Salem.  The Yaquina Bay Bridge had a gust to 71 mph and on Meares Hill (west of Tillamook), a gust to 87 mph.

Wind should increase the next hour or two, remain gusty through sunset, then die down quickly after that.

The low pressure center is moving north quickly, a nice circulation shown on radar west of the Columbia River mouth.

codnexlab.NEXRAD.LGX.N0Q.20141025.2013.024ani

As of 1:25pm there are around 7,000 PGE customers out of power and that number should climb into the tens of thousands this afternoon.  At least it’s mild outside and no one is going to get very cold!

Still thinking anywhere in the metro area we will see gusts between 45-60 mph.  That goes for the Willamette Valley and Kelso/Longview areas too.

Chief Meteorologist Mark Nelsen


Afternoon Wind Storm More Likely

October 25, 2014

All models and the NWS are now hopping on the Windstorm Express!

Here’s the latest at 8:40am…

  • Gusty south wind will arrive in the western valleys around Eugene by noon
  • It then spreads north to the Portland metro area sometime in the early afternoon
  • Southerly gusts 45-60 mph are likely.
  • National Weather Service has issued a High Wind Warning for the Portland Metro Area and valleys.
  • We haven’t seen widespread gusts in this range in quite a few years…especially if lots of us get over 50 mph.
  • Coastal gusts will be in the 70-80 mph range on the central coast, maybe a bit lighter on the north coast.  Same timing as valleys
  • Prepare for lots of power outages and some trees knocked down
  • As the wind starts to arrive around noon, temperatures may jump close to 70 briefly…enjoy that!
  • Wind will be much calmer after 7pm

12z models are in agreement, even our weak RPM shows wind gusts around 50 mph through the whole valley now.

rpm_3pm

The 12z NAM has stronger gusts than the 00z showed:

nam_2pm

The 12z WRF-GFS isn’t out yet.

I’m still a little concerned about the mature-looking low.  Totally wrapped up in itself which isn’t generally a good sign.  But it won’t be weakening much and its movement will be accelerating.

There are very few cases of a deep low moving so close to the coastline at such a steep angle (south to north).  Generally lows track more SW-NE.  I scanned a bunch of past storms and found just one that was similar in track and depth…March 1, 1974.  Here is a link to Wolf Read’s summary of that storm.  It produced a gust to 61 at PDX and 64 at SLE.  The center of this low will be a bit farther north though.

I’ll be at the OMSI What Will the Winter Be Like meeting until around noon, then probably post after that time.  By the way it’s free, from 10am to noon, and in the auditorium.

Chief Meteorologist Mark Nelsen

I


Tough Forecast: Will There Be A Wind Storm Saturday?

October 24, 2014

11pm Friday…

The chance of strong wind in the Willamette Valley and Metro area Saturday has dramatically increased this evening, but it’s definitely not a “done deal”.  Here’s the latest:

  • Models have come together with MOST of them showing a surface low tracking north along the coastline quickly tomorrow afternoon.
  • Air rushes in the south side of the low as it moves north quickly, thus a gusty south wind behind it.
  • My latest thinking is wind gusts 40-50 mph possible from Portland down to Eugene.
  • Two models imply the wind could be significantly stronger in the central valley….gusts 60+.  If so, that would be the strongest Willamette Valley windstorm in years.
  • Prepare for power outages and some downed trees if either scenario occurs.
  • Whatever happens will be done after just 2-4 hours, then back to the usual showers and breezes through Sunday.
  • As of 11pm, there are no watches/warnings/advisories from the NWS and no media freak out.  It’s a bit weird.  We’ll see if that changes in the next 12 hours.

So what has changed?

This evening’s model runs have mostly all (ECMWF comes out in 20 minutes) converged on a low center tracking in the perfect path…right along the coastline and then inland over SW Washington.  That’s the GFS, NAM, and GEM.

They also don’t show the surface low “filling”, or pressure rising within the low, like they did this morning and on earlier runs. Plus the pressure is lower on the earlier runs.  What caught my eye this evening is the very strong wind field over us as the isobars line up with the Willamette Valley.  Take a look at the WRF-GFS sounding over Portland…50kts just off the surface up to around 70kts at 850mb (~4,500′)

wrf_2pm_sounding

We don’t often see the wind field at all elevations aligned directly south to north at the same time the pressure gradient at the surface jumps up from Eugene to Portland.  The WRF-GFS goes nuts, showing 55kt wind gusts (around 65 mph) in the central valley.  Other than earlier this week, I’ve never seen this model show such strong wind in that area.

wrf_2pm_windgust

The NAM is not quite as strong, although it still shows gusts around 50 mph in the valley.  Models still don’t show the low deepening as it moves north; that would be a major windstorm.

Hmmm, a few other hints.  moswind  The 00z GFS MOS (model output statistics) shows an unusually high south wind averaging 24 mph at 2pm as well.  We don’t see it go that high very often.  The Salem value is 34!  That’s average speed.

I should point out this may be a last-minute screwup in modeling.  Our RPM (not always a stellar performer) still has just a baggy-looking low pressure trough with wind gusts maybe 30 mph…snooze.

ECMWF UPDATE 11:15 PM  Whoa!  The Euro just came in with the exact same track and strength. It’s even faster (good if you want strong wind) and forecasts 18 millibars pressure gradient late afternoon from Eugene to Olympia.  That’s significant windstorm material.  It also forecasts 50kt (around 60mph) wind gusts in the valley. ecmwf_windstorm  So all major models are showing the same thing right now…confidence is even higher.

I’ll be up early tomorrow morning before the OMSI meeting (at 10am sharp!) checking things out.

Chief Meteorologist Mark Nelsen


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