Two Potent Storms This Weekend

November 30, 2012

A very active cold front offshore should move onto the coastline by midnight at the latest, then cross in the Willamette Valley with solid moderate-heavy rainfall.  We’ve seen a ton of lightning off the coastline with the approaching front.  In fact the lightning strikes are all that show up since we have such horrible radar coverage (worst on the US coastline) on the central/southern Oregon coast.  So plenty of flashing the next few hours on the coast and the strong wind gusts should subside right after it passes.  Inland we MIGHT see a flash of lightning, but usually the cooler land kills the most active cells as we move into December.

We get a break tomorrow with just showers and sunbreaks.


Models have come into better agreement (somewhat) tonight regarding the stronger system for tomorrow night.

Several thoughts:

1. Timing has speeded up quite a bit with the surface low or open wave crossing the Cascades well before sunrise.

2. No model develops a strong or deep low.

3. Several have a very weak amorphous blob of low pressure, others have a more defined low.

4. The WRF-GFS and our RPM both have a low tracking from the southern Oregon coast to about Spokane.  Remember strong wind is to the south of the low pressure center, so no model right now shows any threat for strong wind (40+ mph) from Salem northward.  Of course it’s possible  a surface low spins up a bit stronger than what models show (check out February 2002), but there’s no specific reason to believe that.  Hopefully 12z runs tomorrow morning all come together a little more.

It will be very windy with possible damaging wind behind the low in Central Oregon, SE Oregon, and possibly the Columbia Basin & Eastern Gorge early Sunday morning.  High Wind Watches are out for a good portion of that area.

On the positive side, a lot of snow coming up in the Cascades…possible 12-18″ between tonight and Sunday midday on Mt. Hood!

Chief Meteorologist Mark Nelsen


Record Warm Day; Warmest in 3+ Weeks!

November 30, 2012


The south wind finally punched through to ALL of the metro area the past few hours and it feels like we stepped off the plane on a tropical island…or something along those lines.  Look at the 1pm temps…60 in Portland, breaking the record of 58 for the last day of November. 

61 in Troutdale; you folks haven’t been above 48 in about a week!  Very nice warm southerly wind.

Enjoy it since we’ll go back to normal this evening as rain moves in.

Still tracking the possible strong wind for Sunday morning for someone, but need to look at more maps; I’ll blog about that this evening.

Chief Meteorologist Mark Nelsen

Strong System For Sunday and Long Range Thoughts

November 29, 2012

Some interesting twists and turns on models and maps the past 24 hours, probably the first time this season we’ve seen the possibility of strong wind here in the Valleys show up.  The key word is POSSIBILITY in that sentence.

The area of interest is later Saturday night or early Sunday morning.  Various runs of various models show some sort of surface low deepening and moving very quickly SW to NE somewhere across the Pacific Northwest.  If you want a good windstorm west of the Cascades, you want something like what showed up on the 00z GEM (Canadian) model LAST NIGHT:

A deep low making landfall around Astoria and tracking quickly east or northeast.  When that happens we get a great rush of wind from the south and southwest behind it; a classic windstorm.  And you want the isobars perpendicular to the valley so the wind can rush straight south to north.

In the past 24 hours other models have had the low much weaker, or farther south, or moving through as an open wave (weaker than a closed low), and now a couple don’t even show a consolidated low, but more of a double structure.   This evening the GFS, WRF-GFS, and GEM are showing the open wave or double-type structure.  That would imply nothing too exciting.


There is no good model consensus as of this evening what’s going to happen; but those 3 models might be a trend developing for a weaker wave that just gives us more rain and breezy conditions only.   We may get a strong surge of wind later Saturday night or very early Sunday morning OR just normal breezy conditions and no one will even notice.  As we say in this business; we’ll see what the next run of models holds.


Some chatter today about possible colder weather showing up on the maps.  I have several thoughts on that, especially for the newbies out there:

  • #1  You shouldn’t get excited about anything beyond 6-8 days unless it consistently shows up on most or all models.  That means run after run of similar results.  That did happen just before the 2008 cold spell; day after day of models showing a major change.  Otherwise you’re getting yourself worked up over nothing; and it sure isn’t worth arguing about
  • #2  We have 4 runs per day of the GFS that go out to 16 days, 2 runs of the ECMWF that go to 10 days, 1 run of the GEM that goes out to 10 days.  Plus a few other models.  There will be something “coldish”,  “near snowy/snowy”, or even an “arctic blast”  on ONE of those models almost every day between now and February.  Another reason to not get too excited unless #1 (above) occurs.
  • #3  Ignore the surface temps on the IGES output after about Day 3.  They’ll lead you astray; often extremely cold for the pattern.  Just keep an eye on 850mb temps, surface wind (Southerly or Westerly = Bad for Cold/Snow), and actually look at the maps instead of just reading text output.

That said, I don’t see anything too interesting in the next 7-10 days.  Cool troughs Sunday/Monday and again next Wednesday/Thursday will keep highs in the 40s then and maybe snow down around 2,000′ with that 2nd trough.  If so, that’ll be just about the lowest so far this season.  Here’s the 850mb ensemble chart from the 12z ECMWF:

Note the cold trough later next week with pretty good agreement on 850 mb temps down around -4 to -5.  Then most members seem to get a little milder but a WIDE variation (thus the “spaghetti plot” name).  Note a few members of the 51 members show -6 to -9 850mb temps in the 10-15 day range.

A few of you may have noticed my blogging frequency is down a bit the past couple of weeks.  I’m doing all 5 evening shows while Stephanie is gone (she’ll be back in two weeks).  Not much room in the workday for anything other than getting graphics put together, emails etc…  Luckily for me (but not for you) most of this Fall the weather has been relatively slow.

Chief Meteorologist Mark Nelsen

Strongest Gorge Wind Since January 2009

November 28, 2012

It’s been a crazy 24 hours at the western end of the Columbia River Gorge and far eastern suburbs of the Portland Metro area.  Take a look at the peak wind gusts:

Troutdale Airport: 44
SE Troutdale (near MHCC): 59 (highest since Jan 2009)
Washougal: 56
Corbett School: 75 (highest since Jan 2009)
Corbett:  85 (private anemometer very exposed)
Vista House: 89 (higher than last winter)
Biddle Butte: 69 (higher than last winter if memory is correct)

The anemometer on the Corbett school has been there for over 12 years, and only one other time has gone above 74 mph.  That was during the big east wind storm in early January 2009.  No, not the “Keely Chalmers Incident” in January 2010, that one was a bit weaker with only a gust around 65 mph in Corbett.  The big 2009 event saw gusts 50-60 mph spread well into Gresham, Orient, and east Portland.  Definitely not as strong this time around in those areas, but the strongest we’ve seen in several years.

I don’t think it gusted above 82 mph last winter on the Vista House sensor (correct me if I’m wrong!).  Due to it being such a historic and photographed structure, the anemometer only sticks out about 1 foot from the building, thus the lower than expected windspeeds.  From last winter, we know 75-80 mph on that sensor is about 100 mph on the steps, so I bet we were up in the 110-115 category up there late last night and this morning.  That area remains off-limits until construction ends in about a month.

Speaking of construction, I drove down there to get the sensor working this morning, and look what showed up in the 10 minutes between the drive down and back!  Luckily the construction guys pushed it out of the way with a backhoe.

As I mentioned on Facebook, when your time is up, it’s up.  Apparently it wasn’t quite time for me.  But I don’t think my little car would’ve handled a 2 foot diameter maple tree very well.  The large deer was bad enough.

Anyway, models have handled this east wind episode very badly, consistently showing the easterly gradient dropping way off YESTERDAY and very little wind today.  It will slowly drop off the next few days, but not fast enough for those of you already tired of the wind!

Chief Meteorologist Mark Nelsen

Brief Freezing Rain In Spots Eastside & Western Gorge

November 28, 2012


Our midday band of rain is moving in, and it’s cold enough in the Upper Hood River Valley, and above 2,000′ in north Central Oregon for spots of freezing rain.  It would be freezing rain instead of snow because of the warm air above; the 4am freezing level at Salem was 9,000 ft!  So watch out in Parkdale, Pine Grove, Madras, higher parts of the Warm Springs Reservation, Condon, and possibly down to Tygh Valley.  It won’t be much, and the temperature needs to be down around 29-30 to get ice on roads during the daytime, but there may be a few slick spots.  In the western Gorge there could be a spot or two on the trees; between 1,500′ & 2,000′ the next couple of hours.  I have 35 and steady rain here at 1,000′.

Models have been a total failure on handling the cold pool east of the Cascades; I had a feeling that would happen when I blogged Monday night.  This is a similar pattern to the big ice/snow storm in 2004 when lows approach from the SW with high pressure east of the mountains.  When those surface lows move towards the coast and then veer farther offshore (as it will today), it prolongs the strong east wind in the Gorge and keeps the pressure gradient high.  Two days ago models (including all the mesoscale ones) showed just a few millibars by late Tuesday and this morning.  In fact last night was the strongest so far with a gust of 59 mph near MHCC in Troutdale and the gradient INCREASED yesterday afternoon and evening to around 10-11 mb. between The Dalles and Troutdale.  

I’ll be hopefully fixing the Vista House sensor before noon (if it didn’t get damaged by water) and same with Corbett; we’ll see what the peak gusts were (maybe).  Biddle Butte at 1,400′ gusted to 69 mph early this morning; I think that was stronger than any gust there last winter.  It’s quite safe to say it gusted over 100 mph at Vista House on the “Keely Chalmers Memorial Railing” more than once in the past 24 hours.

Chief Meteorologist Mark Nelsen

East Wind Really Raging Now; Power Outages

November 27, 2012

The strongest gusts of this east wind episode have been the past couple of hours.   43 mph at Troutdale Airport, 53 mph up the hill near Mt. Hood CC, and somewhere above 64 in Corbett.  The Corbett area appears to be out of power since the sensor stopped reporting around 4pm. 

This is a purely “gap” wind event with the high winds confined quite close to the west end of the Columbia River Gorge; the vast majority of the metro area has light or calm wind right now.

PGE says about 2,300 customers out of power in central/eastern Multnomah County right now.

I’ll be headed down to Vista House tomorrow to hopefully get the computer & wind sensor working again; they had a watery mess in the office in October and it’s been offline since that time.

Chief Meteorologist Mark Nelsen

Raging East Wind In The Gorge Tonight

November 26, 2012

Peak gust of 61 mph out in Corbett within the last couple hours as the wind starts to really ramp up this evening.  Gusts to 70 mph are possible through tomorrow morning out there as the air is squeezed down by the warming atmosphere overhead tonight; an inversion.  Then it’ll gradually back off, but still remain very windy, through Wednesday.  Adding to the wintry feel, this is the coldest airmass of the season coming through the Gorge so far with temps in the 30s along with the wind right now.

Chief Meteorologist Mark Nelsen