10:00am: Wind Arriving Coast, 55 mph Gust McMinnville

March 13, 2016

Now that’s a beautiful area of deep low pressure!  9:15am visible satellite pic

vis_915am

The low appears to be just west of Astoria with the trailing cold front just onto the coastline now.  When that passes over the valley in the next 90 minutes we can expect the wind to arrive in full force; a classic setup where the wind comes in the the sun/clouds/showers mixed.  At least it’ll be a “bright” windstorm.  McMinnville just had a gust to 55 mph.

Pressure observations from Buoy #46089 about 80 miles west of Tillamook show at 9am a pressure of 980.1 millibars.  That’s a bit deeper than forecast and the low appears to still be in the intensification phase.  Due to that, the McMinnville gust, and the HRRR model now calling for stronger gusts, I’m thinking gusts 50-60 mph are possible between now and 2pm.  We MAY have underforecast the storm a bit.  Here’s the HRRR showing gusts 40-50 kts within the next 2 hours:

hrrr_gust_15zrunfornoon

Exact speeds don’t matter…45, 50, 55, 60…If you live near large trees hunker down.  Definitely not the time to be driving through deep woods with the trees swaying overhead.  Be safe out there and enjoy the storm from inside.

Chief Meteorologist Mark Nelsen


High Wind Watch Cancelled; More Typical “Windstorm” Instead

March 12, 2016

10pm Saturday

I’m not working today or tomorrow, but after that dramatic post yesterday I figure I should provide some sort of update.

All evening models are in  and all (except NAM) agree on a landfalling surface low on the Olympic Peninsula tomorrow afternoon.  They are a LITTLE bit weaker than 24 hours ago.  As a result of no “huge wind” solutions on models (closer or deeper low), the NWS cancelled the High Wind Warning and went with a Wind Advisory instead here in the valleys.  A Wind Advisory covers gusts 39-58 mph, which means just about every wind event we get that gives us outages and tree damage.  It takes a lot to get widespread gusts above 58 mph in our climate.

HIGHLIGHTS

  • Gusty wind arrives on the coast mid/late Sunday morning.  Gusts 65-75 mph are likely, especially north coastline
  • The western valleys should experience wind ON AVERAGE similar to what we saw about 10 days ago or possibly a little stronger.  A minor windstorm with a bunch of power outages (maybe 15,000 PGE customers?) and some trees down. Gusts 35-45 mph with a few spots to 50 mph for us.  If I were a betting man, I’d say a gust 45-50 mph at PDX midday or early afternoon.
  • We do not expect a big historic windstorm Sunday.  That’s one where 80-150,000 customers lose power, but you’ll definitely hear it blowing and see some effects.
  • Gusty south wind blows hardest in the valleys 11am-3pm.  It may arrive suddenly in that time just before lunch as well.

What has changed in 24 hours?…not too much, but a subtle shift towards slightly weaker low pressure and now consistent landfall location.  As a result gradients appear weaker inland.  For Eugene to Olympia, this is what models are showing with 00z runs:

RGEM=12, WRF-GFS=10, ECMWF=14, NAM-MM5=20!

That’s quite a range of solutions isn’t it?  Assuming models are handling the depth of the low correctly, we should escape a big windstorm here.  Stronger wind to the north and west of us closer to the surface low.

Here is the WRF-GFS at 1pm:

wrf_1pm

Notice the gradient “stacking” is not too tight in the Willamette Valley.  Compare that with the gradients last March 15th’s storm that gave us gusts 45-55 mph…not as tight.

The NAM-MM5 has continued to be stronger and farther south…3pm tomorrow:

nam_3pm

That’s a huge windstorm up in SW Washington!

Note the GFS ensemble low locations (21 of them!) all keeping the low farther north, not down south like the NAM when it makes landfall, part of the reason I’m not real excited about following that NAM solution:

gefs_slp_lows_conus_7

Happy low pressure tracking tomorrow morning!

Chief Meteorologist Mark Nelsen

 


Evening Model Runs…More Interesting

March 11, 2016

10pm Friday…

An interesting evening in the weather center hitting REFRESH numerous times to get the latest maps/models.  Here is the latest:

MarkWarnings_High Wind

HIGHLIGHTS

  • High Wind Watch is up for all of Western Oregon north of Eugene
  • Damaging wind is POSSIBLE Sunday, but not a “done deal” as of this evening
  • The setup is quite “good” if you want the strongest southerly windstorm of the season.  Bad if you don’t like power outages and downed trees
  • Big question still:  Is this a regular “gusts 35-45 mph” storm or “gusts 45-65 mph” (storm of the season) storm for the lowlands.  Right now I’m thinking the first is just about guaranteed, but it might be higher.
  • Confidence on timing = HIGH  Sometime midday/PM Sunday
  • Confidence on damaging wind event in metro area = MODERATE for now

 

MODEL THOUGHTS

All 00z models are in except ECMWF.  That’s the one model that was farthest west (offshore) this morning.  If it makes a significant move closer to the coastline Sunday my confidence on a damaging wind event will go up. (Edit at 10:15pm)  Well, it did move farther east, so now models are much closer together.  The 00z ECMWF has the low reaching the western mouth of Juan de Fuca strait at 980mb.  I see a 12 mb pressure gradient from Eugene to Olympia, which isn’t a big windstorm, but plenty windy!

ecmwf_mslp_m_nw_9

All these models have at least some sort of wind event for the metro area and valleys.  WRF-GFS was a little weaker for us and farther offshore, giving us 13 millibars EUG-OLM. That’s like the ECMWF

slp.45.0000

That’s not major storm material, but widespread gusts 40-50 mph.  Of course in that case the abnormally high PDX readings the past two years mean a 55-58 could be seen there I suppose.  Check out the track I plotted over Wolf Read’s analysis of past “classic” windstorm tracks.  The WRF track is the thick yellow highlighter:

Tracks_plusWRFGFS

The NAM-MM5 was very strong (image below)…that’s a windstorm for us with the low much closer, making landfall around Long Beach instead of up around Forks like the other models.  21 millibars from Eugene to Olympia with the real damaging wind up in SW Washington.

wgsfc.45.0000

RGEM (Canadian) looked almost exactly the same as the WRF-GFS, in fact the lowest central pressure was around 980 mb. as well.

00zRGEM

It is interesting (and helpful if you want a powerful storm) the low is deepening on all models as it passes by.  That’s very important for strong wind.

These storms are always so tough to forecast and each one is slightly different.  For example the Inauguration Day Storm in January 1993 took a similar path and was of similar strength to what the WRF forecasts yet left gusts only in the 40-50 mph range in the metro area.

More updates the next 36 hours if this impending storm holds together!

Chief Meteorologist Mark Nelsen

 

 


High Wind Watch For All of NW Oregon/SW Washington

March 11, 2016

4pm Friday…

The Portland and Seattle NWS offices just decided to issue a High Wind Watch for ALL of NW Oregon and Western Washington.  That includes all the cities in the I-5 corridor from Eugene to Bellingham.  That’s around 5 million people under that watch!  We haven’t seen one of those since mid-December.

MarkPromo_HD_HighWind_Coast

A High Wind WATCH means conditions MAY be right for damaging southerly wind on Sunday in our area.  That’s a HUGE (or is it UGE?) question mark right now.  Thus a “Watch” instead of a “Warning”.  High Wind Watch/Warning criteria means gusts to 58 mph or higher…that is a real windstorm as opposed to these weaker storms we’ve seen much of this cool season that have involved Wind Advisories.  That’s the 35-55 mph stuff.

I’ll reserve any deep thoughts until after the evening model runs tonight for two reasons:

  1.  It’s way early…we’re talking about something almost 48 hours away
  2. Several models (including the reliable ECMWF and latest GFS) show no such windstorm
  3. Yet the NAM, GEM, and earlier GFS run looked real stormy.

 

So, there you have it:  We may or may not see strong wind Sunday.  It’s too early to know whether a real windstorm is on the way…we’ll be WATCHING the maps/models closely this evening and again tomorrow morning & evening.  We have plenty of time to see if models come together on a common solution.

Chief Meteorologist Mark Nelsen


Quick Look: Windstorm or No Windstorm Sunday?

March 11, 2016

Have to get to work early today for something else, but my eye is sure drawn to this…

Both the WRF-GFS & NAM-MM5 forecast a significant windstorm in the valleys Sunday midday/afternoon.   Deepening surface low moves inland over Washington, isobars are perfectly aligned, and 15-20 millibar pressure difference Eugene to Olympia.  Wow, that’s like what we saw in December 2014 or stronger.  50kt gusts forecast over metro area at the surface.

slp.58.0000

Yet…ECMWF says WHOA!,  the low is headed into Vancouver Island instead and it’s just regular breezy here.  In fact none of its ensemble members from last night, or the operational run this morning have the low close by.

eps_slp_lows_nw_12

It’s an epic model fight but one we’ll be watching VERY closely…more later today.

Chief Meteorologist Mark Nelsen


Peak Gusts Last Night: A “Non-Event” In Valleys

March 10, 2016

4pm Thursday…

Well, I should have stuck with 30-40 mph gust forecast from Tuesday night.  We ended up forecasting gusts 35-45 mph in the metro area.  Instead it was more like 25-35 mph.  Just a breezy night as the cold front went through around midnight to 1am.  PDX and Troutdale were two of the higher windspeeds recorded in the lowest elevations:

PLOT_Wind_Metro_PeakGusts_MANUAL

Of course on the North Coast the wind was huge; strongest of the winter at Astoria!

MarkCoast_PeakWindGusts

Unfortunately one person was killed in that part of Hwy 26  where we see trees fall during the big storms; those first 10 miles east of Hwy 101.  So again, the biggest storm of the season out there.

Why was the wind weaker than expected in the valleys?  For one, as mentioned in a previous posting, you want isobars (lines of equal pressure on a surface pressure map) lined up east/west.  Then the southerly wind is forced to ride straight “down the gradient” through the north/south aligned Willamette/Puget lowlands.  Yesterday’s event was a terrible one for that; only 8-9 millbars pressure gradient from Eugene to Olympia.  With a typical (average) wind field higher up in the atmosphere, one would expect about these speeds.  But yesterday there was a much stronger than normal south/southeast wind overhead.  A good 70-80 mph at 5,000′!  The assumption (by all of the human forecasters including me) was that more of that would surface around the cold frontal passage time.  Not much of that did and as a result models did better than humans this time.  They generally had not shown a significant event.  On the other hand, around 9:30pm I did notice the 00z WRF-GFS forecast a spot of 45+ kt wind gusts over the north Willamette Valley around 1am…one of the reasons I didn’t call off the whole thing just before the 10pm newscast.

wgsfc.09.0000

But, with almost nothing happening at 10/11pm here in the valleys, my “forecast-mood” went downhill quickly in both those newscasts.  Anyone watching got the impression that I wasn’t very excited about any strong wind on the way…especially at 11pm.  Ahh, the good times doing TV!  Note I had tweaked the wording to POSSIBLE in this graphic I used both hours…

LIANA_HEADLINES

On to the next weather event…a cool and rainy weekend…great.

Actually it does look like tons of snow on the way to the Cascades Sunday through Tuesday…good news for spring break skiers!

Chief Meteorologist Mark Nelsen

 


Strong Wind Moving Onto Coastline

March 9, 2016

3:30pm…

Everything appears to be working out well so far…lots of gusts 55-65 mph at the usual coastal spots and of course the real exposed (higher) locations are stronger. I see an 81 mph gust at Meares Hill (1,400′) and 90 mph gust on top of Mt. Hebo (3,000′).

As mentioned yesterday, the storm is so far offshore that we won’t get damaging wind in the valleys. Maybe a few thousand power outages and a tree or two down somewhere, but that should be it. But the big story is at the coast.

COAST: High Wind Warning
Wind has arrived at the coast with lots of 55-65 mph gusts so far. Wind will ramp up another 10-20 mph for the next 4-8 hours. Gusts 65-75 mph are likely with a few exposed spots likely up in the 80-90 mph range.

VALLEY: Wind Advisory
Light wind so far (as expected). Breezy southerly wind picks up, mainly after 7pm. Gustiest wind in the middle of the night, like 10pm-1am. Gusts 35-45 mph. It SHOULD be a bit lighter than what we saw last week.

All wind backs off later tonight.

HURRICANE FORCE WIND WARNING: You have have heard about this. THIS WARNING IS NOT FOR ANYONE ON LAND. It’s a marine warning for the coastal waters, strongest wind out there since the storm is so far offshore.

Latest HRRR model run seems reasonable, showing strongest gusts at the coastline in the 6-9pm period:

hrrr_gust_portland_7

and inland around 10pm-midnight (note yellow spots showing gusts 35-40 mph):

hrrr_gust_portland_10

Hold on if you live at the Coast!  And enjoy a showery/breezy night here in the valleys.

Chief Meteorologist Mark Nelsen