Rare August Storm On the Way Saturday Morning

August 28, 2015

4pm Friday…

A storm is developing as expected off the Northern California coastline and will sweep northward off the Oregon and Washington coast tomorrow morning.  This setup appears to be just about unprecedented in our area at this time of year.  I could only find one example back in 1972.  Mid-August that year a sudden windstorm arrived with very little warning along the Oregon/California border.  Southerly wind gusts in the 60+ mph range sunk many boats and 12 fishermen died.  Luckily nowadays we have much better satellite/radar and numerical modeling of storms.  Yet, this may be the one “out of season” storm we talk about for years to come.  We’ll see.

The Latest Highlights

High Wind Warning on the Oregon and southern Washington coast for Saturday morning:


Wind Advisory for the Willamette Valley and lowlands of SW Washington for Saturday morning”


Expect the wind to arrive in Salem/Portland sometime between 8am-10am.  Note those peak gusts…I’ve never seen/forecast gusts over 30mph at the beaches in August!  I can’t believe Hood-To-Coast relay has all those tents/tables set up along with a very high stage/backdrop too out in Seaside right now.  If our forecasts are correct, I can see quite a bit of damage tomorrow morning out there when gusts 50+ arrive.  I’m also concerned for the safety of runners moving through the North Coast Range after 8am.   Many of those roads have trees overhead and even just a breeze and rain combined can bring down an old alder tree.  We haven’t seen a gusty south wind since March.  Be careful out there!

Meteorological thoughts…

There is still a chance we don’t get gusts over 50 at the coast and over 30 in the valleys…models could still back off with the last runs this evening.  That said, satellite imagery sure looks impressive off the California coastline.

I did notice on this morning’s runs the ECMWF has the low tracking slightly farther offshore, which could help to reduce the wind in the valleys.  Yet this time of year the airmass is well mixed so stronger wind above will surface easily, counteracting weakness in pressure gradient or low location.

12z WRF/NAM/RPM all show a closed (or mainly closed) low coming right up against the Washington coastline by midday, around 990-993 millibars.  They all indicate gusts 60-75 mph at the coast.  Hard to believe that will happen in August, but we sure wouldn’t argue with that modeling in winter.

We’ll see what the 00z models show.

Chief Meteorologist Mark Nelsen

A Wind Storm In August? It May Happen Saturday!

August 27, 2015

Things are getting weird this evening…I came in to work today, looked at the maps and thought “that looks like late October or November!”.  Why?  Models were showing a relatively deep surface low pressure center scooting up the coastline quickly right after daybreak Saturday.  As a precaution, the NWS issued a High Wind Watch for the coastline.  Now evening models are quite similar.

Here are the highlights in case you don’t care about the meteorological info:

  • Unusually strong wind is POSSIBLE on the central/north coastline of Oregon early Saturday morning.  Gusts 50-70 mph are possible.  That’s not tent camping weather!
  • In the western valleys, including the I-5 corridor (Salem/Portland/Longview), we could see southerly wind gusts in the 35-50 mph range Saturday morning. (7-11am)  
  • With leaves on trees, this could cause some significant damage.  Wind gusts just 40 mph would bring us lots of power outages this time of year.
  • The highest wind gust ever observed at PDX in the month of August is just 39 mph.  That was a southerly wind gust too.
  • If the surface low ends up weaker or takes a different track, winds will be much lighter.  We have two more model runs (tomorrow morning and tomorrow evening) before the event.  That will give us a better handle on what’s going to happen.
  • Unrelated, but of interest to you…IT’S GOING TO BE WET IN OUR AREA TOMORROW.  I am working on a project outside and have a bunch of tools/nails etc…lying around.  Get things covered or inside by sunrise!

In my entire career (24 years in Portland), I’ve never seen the NWS issue a High Wind Watch for anywhere west of the Cascades in the summer.  That alone isn’t all that shocking, but it’s backed up with several models showing the same setup for Saturday morning.  Check out the 8am image from the WRF-GFS (UW model):


This model and others are showing 9-12 millibars southerly gradient from Eugene to Olympia.  That’s a big number even in winter.  And this time of year the warm weather allows good mixing of stronger winds above.  The WRF-GFS shows 70-75 kts at 850mb.  Unheard of in August!  Our RPM is quite strong with the wind as well:  Here’s a wind gust forecast:


Over the past few winters I’ve noticed these speeds tend to run a bit high vs. reality.  Still, this shows gusts 40+ mph in the valleys and 60-70 along the coast SOUTH OF THE LOW.  Note that if our RPM (or the WRF-GFS) is correct, areas up around Astoria would stay mainly calm.

More tomorrow on the wind…

As for tomorrow’s weather, we’ve made a dramatic change in the forecast since radar, HRRR model, RPM, & WRF-GFS all show the rain band about 50 miles farther east.  That puts measurable rain overhead for the first time in about two weeks.  Here’s the HRRR forecast through 11am:


and RPM through Sunday afternoon is looking more pathetic…that’s too bad:


The WRF-GFS is now only showing about .50″ in the valleys too.

Chief Meteorologist Mark Nelsen

Soaking Rains Likely: After An Incredibly Dry Summer

August 25, 2015

11pm Tuesday…

There’s good news…it’s looking more likely that we actually have a soaking coming this weekend.  Check out the latest numbers from several different models.


Looks wet doesn’t it?  We need it.  There is a very good chance this will be our wettest period since back in April & May. Check out the rain totals IN THE PAST 12 WEEKS!


Hard to believe we’ve seen less than 1/2 inch of rain in some parts of the metro area in the past 3 months!  May was unusually dry too of course and that’s why our trees/shrubs are suffering.

Confidence has gone up now with a good soaking late Friday through the weekend.  Very high precipitable water content, around 1.00-1.50″ will ensure plenty of moisture to work with as a cold front moves across the area Friday night.  Then several more waves of rain & showers continue through Sunday.  The WRF-GFS is especially wet, showing widespread 1.20″ and above over western Oregon with some areas getting more than 2.00″,


Seems unlikely, but history tells us it CAN happen in August.  Late August 1977, 1983, 2004, etc… those were all big soakers.

It’s nice to be able to leave things outside for weeks at a time and not worry about them getting wet, but that will end early Friday…showers may show up as early as commute time Friday evening.

Chief Meteorologist Mark Nelsen

Big Fires: Oregon Fire History

August 24, 2015

11pm Monday…

The Okanogan Complex in Washington is now the state’s largest fire in history.  256,000 acres and still growing.  You may remember that last year’s Carlton Complex was the largest in the state’s history since the Yacolt Burn in 1902.

So how big have they been in Oregon?

The Silverton Fire in 1865 is the largest on record at just shy of one million acres!


By the way, for those of you not inclined to acres…it takes 640 acres to make one square mile.  So that fire burned about a 40 by 40 mile square!  Wow.

That was during a time of extremely large fires…from 1850 to around 1900 there were repeated huge burns in the Coast Range.  I didn’t even bother to put two more huge fires in the Coast Range from the late 1800s on the chart.  I had forgotten about the huge fire in SE Oregon 3 years ago…of course that was mainly rangeland, but a lot of acreage in just a few days!   The first big Tillamook Burn charred just over a quarter million acres in 1933 too.

After a huge firestorm in Idaho and western Montana in 1910, the USFS went to a “put out all fires” mentality for a long time so massive fires mostly disappeared in the Coast Range and Cascades.  Whether that has increased fire problems nowadays is well beyond my area of expertise (weather).  Someone else can tackle that subject.

The cooler and hopefully wetter weather coming up this weekend and early next week MAY really dampen the current fires.  We’ll see.  I see a bit of a drier trend in models the past 18 hours.  We’ll see.

Chief Meteorologist Mark Nelsen

Open The Windows! Air Quality Good in Portland This Evening

August 23, 2015

10:40pm Sunday…

Whew…good news!  Things are changing quickly this evening in air quality news.  Just as models were showing, the onshore flow this evening is shoving the smoke to the east and air quality is rapidly returning to normal.  Take a look at the current values of Air Quality Index which have all been dropping through the evening.  In fact just as I was typing this up at 10:30pm, it suddenly went to GOOD category in Portland…very nice.


Note many locations are already back to normal but some spots are taking longer to clear out, mainly eastern sections of the western valleys and Cascade foothills.

Enjoy the fresh air, the sun should look a LOT brighter tomorrow!

Chief Meteorologist Mark Nelsen

Yuck! Thick Smoke Over Metro Area Today

August 22, 2015

I mentioned last night that smoke from Washington fires would move in on east wind today but this is the thickest I’ve ever seen in the metro area.  It’s nothing new this time of the year in other parts of the Northwest; but it just happened to be directed right at us today instead of east of the mountains.  This is normal at times in Bend and other eastside cities in late summer.  This is what it looked like at midday overhead:


Overnight and tomorrow the smoke will thin some, but it’ll still be hazy like we’ve seen a few times over the past several weeks.  Then a westerly wind will push just about all the smoke out of here starting about 24 hours from now.  By tomorrow evening skies should be much improved.

 Air quality was just about the worst I have seen in the metro area in summer too; you can see the sudden increase in pollutants after 11am:


This is the first time I’ve busted a forecast because of smoke…we didn’t get hot weather today because too much sunlight was blocked.  Only reaching the mid-upper 80s.  Less smoke tomorrow should mean warmer temps.

Chief Meteorologist Mark Nelsen

Hot & Smoky Weekend Ahead & Much Warmer 7 Day Forecast

August 21, 2015

6pm Friday…

The lack of fire smoke west of the Cascades has been nice the past two days, but it’ll be back this weekend.  Take a look at the latest U.S. Forest Service BlueSky smoke dispersion model:


A couple of still images show smoke from big fires in northern Washington and the Cougar Creek fire on Mt. Adams heading to the east-southeast right now:


Then as our wind switches to northeast and easterly the next 24 hours the smoke is carried right into Western Oregon and SW Washington during the day Saturday.


That smoke will be pushed back out of our area again late Sunday and Monday as the flow turns weakly onshore again so at that point haze should diminish again.

So how warm will it get this weekend?  It’s obvious we have a pretty decent easterly wind flow through the Gorge tomorrow…maybe 3 millibars.  You can see the solid offshore flow during the daylight hours Saturday on the 4km WRF-GFS cross-section.  Note time goes from right to left.  This morning is on the far right side, Monday afternoon on the far left side:


Winds will probably be gusting around 40-45 mph at the Vista House wind gauge tomorrow morning-midday.  Gusts 15-25 mph on the east side of the metro area midday as well.  850mb temps climb to around +18 or +19, which according to my chart means a high temp 90-95 degrees.  I figure we need to knock off a couple degrees for loss of sunlight due to the smoke, so I have gone with a high temp of 92 at PDX.  Sunday maybe just a notch or two cooler, but still we probably will add 1 or 2 more days to the 90+ count for this year when the weekend is finished.

The big change to the forecast is for next week.  Models are definitely struggling with what’s going on in the Pacific, and the Ridiculously Resilient Ridge.  They HAD been advertising a cool trough coming down and hanging around for an extended visit along the West Coast.  But in the past 24 hours they have steadily been pushing the low farther and farther offshore with each run.   The 18z GFS has now gone as far as suggesting we stay very warm with maybe another 90 or two returning the latter part of next week!  Take a look at NEXT Saturday, the 29th from last night’s GFS run vs. the latest.  See the difference?



The unprecedented dry weather will continue; we’ve only seen .12″ rain so far this month.  I am starting to see young trees dying (fir trees turning brown) on the sides of the freeways on my daily commute…water your trees!

Chief Meteorologist Mark Nelsen


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