FAKE WEATHER: No, It’s Not Going To Snow In Portland Next Week

October 27, 2017

3pm Friday

I’m on a day off, but was just summoned by a coworker wondering whether it’s going to “snow next week in Portland”  due to something read in a local newspaper.  I immediately came running in out of the warmest temperature we’ve seen this late in October in 42 years to see what’s up.  I checked all the models.

Nothing says SNOW to sea level, or below 1,500′ elevation for that matter.

Here’s what happened:

  • There are maybe 4 longer-range models that we regularly look at run at least twice each day.
  • Each of those 4 models have 15-50 different “ensemble” members that run just slightly different.  That way we can get an idea which models are doing best.
  • We call that “ensemble forecasting”.  There are literally HUNDREDS of different computer model forecasts for a week from now.
  • From now until mid-March, there’s always a chance that SEVERAL (OR EVEN 50!) OF THOSE HUNDREDS OF DIFFERENT ENSEMBLE MEMBERS COULD SHOW A COLD/SNOWY PATTERN over us while most models/ensemble members don’t.

So if you use a weather app…it has to make a decision which model to use.  Then that automated forecast ends up on your app, without any human input!

I see the same app that focused on one cold overnight model (snow close to sea level), has now corrected itself and looks like this for next weekend, which is probably still colder than what we’ll actually see:


The National Weather Service sure hasn’t forecast snow to sea level (they only forecast 7 days out anyway), and neither has any TV station in Portland.  As of this afternoon no model shows a snowy pattern late next week, just the very cool pattern I mentioned in my previous blog posting.  For the foreseeable future, humans are still needed to interpret computer modeling of our atmosphere.

A far more disturbing issue is the rise of, yes, FAKE WEATHER across the Internet.    Sorry to use the term, but it’s true.  Weather dis-information spreads at the speed of SHARE, FOLLOW, & LIKE.  Scary for forecasters…it gets discussed quite a bit by meteorologists across the USA.

I ‘m disappointed that this time the weather “disinformation” came from what I would typically consider a very solid local source of information, the biggest newspaper in Oregon.  Not quite Clickbait…but close.  You better stick with FOX12; you know as a weather geek I sure won’t leave you wondering about snow the next few months!

Well, back to the sunshine!  Enjoy a few more days of fantastic weather.  73 in Portland at 3pm.   Wow, only twice in Portland airport weather record history have we made it to 73 on the 27th of October or later in the Fall.  Just once in 1975 we hit 73 and then a 75 in 1944.

By the way, this might be a good time to mention the yearly WINTER WEATHER FORECAST CONFERENCE is tomorrow at OMSI.  There will be a recap of last winter, plus a few outlooks for this winter.  It’s always fun if you are into weather…details:

Mark OMSI Forecast Meeting Promo


Chief Meteorologist Mark Nelsen



Unusually Warm Late October Weather; November Likely Starts Cool

October 24, 2017

7 pm Tuesday

I love it when I’m wrong…at least in this case.  A few weeks ago I figured we had seen our last 70 of the season since a week or two of chilly weather was on the way.  But today we just squeaked out a 70 degree temperature at PDX.  That was due to a very warm atmosphere overhead plus a mild offshore wind.

To show you how unusual today was…note we haven’t had a 70+ day in Portland this late in the season (October 24th or later) in 14 years!

We also saw the strongest Gorge wind so far this season…with gusts 50-60 mph in the Corbett area and Crown Point due to over 7 millibars easterly pressure gradient across the Cascades.  I think that Vista House sensor may still be damaged from last winter since it should have read a little higher (compared to Corbett).  That pressure gradient is dropping rapidly this evening and Gorge wind will turn breezy WESTERLY by midday Wednesday.  That’s due to an approaching cold front and lowering pressures east of the mountains.

This front will arrive somewhat dramatically tomorrow afternoon with a cloud deck turning our skies gray quickly the 2nd half of the day (after AM fog breaks out to sunshine).  I think we could get a shower or two but that should be about it with this system; it’s dying as it moves down over the Pacific Northwest.

Upper-level high pressure will rebuild three times over the next 10 days near the west coast of North America or in the NE Pacific.  Models are in generally good agreement on this, or at least their ensembles are.   First ridge is Thursday and Friday; right over the top of us.  Note the ECMWF ensemble 500 mb height anomaly.  This is a dry pattern for us with no wet Pacific weather systems able to make it to the West Coast

Then after a brief wave of energy gives us lots of cloud cover and onshore flow Sunday (but no significant rain), another ridge develops slightly farther west Monday:

This time it is slightly farther west, so we’ll turn cooler for Monday and Tuesday…but likely dry for Halloween.  By late next week, about 10 days out, ridging seems to want to develop even farther west.  That’s over/near Alaska.  The GEFS & Canadian ensembles have it closer to us.  Note the lower than normal heights in both of these charts out over the Easter Pacific west of California.  That implies some “undercutting” of the ridge by moisture and weak systems.

That’s a cool weather pattern for us in November, but still drier than normal.  This is also somewhat similar to what we saw last December/January (far warmer of course this time of year).  When wet systems would sometimes move into California while cool air came down from the north over much of the Pacific Northwest.  The combination of those two brought us numerous snow/ice events.  You can sure see the drop in temperatures after Halloween on the ECMWF ensemble meteogram:

and the GEFS anomaly chart.

“0” means average temperatures.  Note we go below average in early November as the ECMWF shows.

To summarize.  We have 3 more beautiful days Thursday through Saturday, although with another round of gusty east wind.  This will likely be the LAST of the mild/warm east wind patterns.  Next time that wind comes back it should be chilly…no warm east wind for you until at least the Ides of March!  Rainfall will likely be sparse for the next 7-10 days with little or nothing in the next 7.

Chief Meteorologist Mark Nelsen


Quick Storm Wrap

October 22, 2017

9:30pm Sunday

Now THAT was a soaker!  If models keep doing this well I’ll be out of a job in the next 5-10 years.  We ended up with around 2-3″ in just about all of the lowland elevations in the metro area from when the rain started Friday night to this morning when the rain stopped in most areas.

and those 8-10″ rainfall did end up panning out over the wettest parts of the Coast Range and Cascades

The usual extremely wet gauges didn’t disappoint.  Lees Camp along Highway 6 in the Coast Range along with North Fork SNOTEL south of Dodson saw over 10″.

Wind was a bit lighter than expected for much of the coastline…only a couple spots even made it over 60 mph at the lower elevations.  That was Gleneden Beach and Lincoln City

Here in the metro area almost all gusts remained at/below 40 mph (as expected), PDX officially hit 37 mph.  Not a windstorm by any means yet a loud reminder that stormy season is almost here.  Even those relatively weak gusts caused lots of trouble for power companies.   It appears there were LOTS of small outages and some of you are still out of juice after almost 24 hours.  That’s due to all the leaves still on trees which makes for plenty of wind resistance compared to the bare limbs of winter.

With the weekend rain, we’re now above normal for rainfall in Portland this month…that was easy to do.  3″ is the average and we’re well above 4″.  That makes 2017 our 4th consecutive wet October.  But that should be just about it as we go into another relatively long dry period.  I see very little rain from now to Halloween.

Weekend Flood Watch; Beautiful Fall Weather Follows

October 20, 2017

7pm Friday

We’ve made it to Friday and here we are sitting on the cusp of a soaker this weekend.

Nothing has changed from my thinking last night at this time (see previous post).  Steady rain associated with an atmospheric river arrives in western Oregon and SW Washington right after midnight.  That steady rain continues through tomorrow afternoon in the lowlands, then mainly shifts over/north of the Portland metro area tomorrow evening.  The cold front then slides back south during the morning hours Sunday.  So during the day Sunday rain will end first up around Kelso/Longview, then end by sunset down around Eugene.  Total rain?  1.5 to 3″ in the lowlands and 6-8″ additional in the wettest parts of the Cascades.  These totals will likely be enough (by Sunday morning) to bring localized ponding of water or flooded areas on roads.  This won’t be enough to give us any sort of widespread river flooding though; especially since we’re only looking at 24-30 hours of steady rain in the lowlands.

Wind is also an issue tomorrow; not a big windstorm but enough to bring us a few power outages.  That’s especially the case since leaves are still on the trees.  A high wind warning is up for the coastline…

and a wind advisory for the western valleys…

So to wrap things up…Saturday still looks to be a soaking wet day, with rain tapering off in the evening from Portland south.   Sunday starts wet, but then rain ends by midday, hopefully just in time for the 1pm Timbers match.

One would think this will be the beginning of the big wet season, but models say that isn’t the case.  Upper-level ridging wants to linger just to our west for the next 10+ days.  The result will be an extended period of mainly dry weather and beautiful fall weather.  Take a look at the ECMWF model ensemble forecast of 24 hour rainfall.  The big surge over the weekend and then just a few scattered showers here and there on the different ensemble members for the following 2 weeks.  Pretty good for the end of October and the first few days of November!

The blue line at the bottom is the ensemble average…quite dry.

Try to stay dry this weekend and hopefully we’ll avoid any big flooding issues.  But if you’re driving around tomorrow through midday Sunday, expect lots of water on the streets.

Chief Meteorologist Mark Nelsen

A Very Wet Weekend Ahead

October 19, 2017

7pm Thursday

It’s been a classic wet Pacific Northwest day.  It’s not like we’ve seen massive downpours, but it rained just about every hour of the day.  Expect the same tomorrow as waves of showers move inland behind today’s cold front.  One difference tomorrow is that we’ll see sunbreaks between the showers; it won’t be such a gloomy day.

But this weekend is a bit different.  All models forecast an “atmospheric river” (another name for a Pineapple Express) aimed somewhere near the Oregon/Washington border from Saturday through midday Sunday.

GFS Water Vapor

GFS Water Vapor2

I’m very confident it’ll be aimed somewhere within 100 miles north or south of that spot, but exact location of the deepest subtropical moisture is critical in determining how much rain any one part of our region gets.  As always the heaviest rain will be in the Coast Range and Cascades.  Models are in pretty good agreement that this is going to be a very wet event.  They have consistently been forecasting 8-10″ (or a little more) in the usual wettest mountain locations.  Here is the morning ECMWF rain forecast:

ECMWF Precipitation Accumulation

Once again (for maybe the 4th-5th day) it’s showing a maximum of 10″ or more in those usual extremely wet spots.  That would include a few of the western Coast Range slopes and SW Washington Cascades.

If we indeed do see 3″ of rain from Saturday morning through Sunday midday, I think we could get some urban & creek flooding.  Especially Saturday night and Sunday morning since precipitation intensity appears to be highest during that time.  So keep a close eye on the forecast this weekend!

By the way, I just noticed snow has begun sticking at 5,000′ on our Skibowl camera.  The snow level drops to Government Camp by morning and stays there through Saturday morning.  By the time the snow has changed to heavy rain late Saturday morning we will have seen another nice dumping on the mountain

Snow MtHood Outlook

Much of that will be washed away later Saturday and Sunday of course so this sure won’t mean an October start to the ski season.  But it’s always nice to see early snow.

Chief Meteorologist Mark Nelsen

Fire Season 2017; Was it Really “Near Normal”?

October 17, 2017

7pm Tuesday

Today, a drizzly & cool day might seem like a strange time to talk fire weather.  But for the past 3-4 weeks we’ve seen little to no fire activity across the Pacific Northwest.  That’s due to the very wet week back in mid-September putting an early end to most of the big fires.

So how “bad” was the fire season?  One would think that half of the Pacific Northwest woods burned up based on the amount of smoky days and issues with big fires near populated areas.  But Fire Season 2017 was near normal;  acreage burned in Oregon and Washington this year was quite close to the 10 year average.

Take a look at the last 8 years…

Fire NW Summer Stats

The 10 year average is somewhere around 700,000 acres per year so in theory this year would be considered somewhat “normal”.  I would argue it was not for several reasons:

  1. The huge acreage in 2012/2014/2015 came from quite a few very large range fire.  I remember one fire that chewed up 200,000 acres in just a few days in SE Oregon one of those years.
  2. The vast majority of big fires this year were in the Siskiyous & Cascades, not Eastern Oregon.  That includes NE & SE Oregon.  There were very few fires in the Blues & Wallowas.  Didn’t seem to be much fire action in the open range country south and east of Burns either.
  3. Those Cascade fires and their thick smoke came during the peak of the mountain lake recreation season.  Lots of us had to change our plans in August due to closed campgrounds, resorts, trails, & highways.  This was up and down the Cascade Range from Breitenbush all the way to the California border.  I remember one evening several Cascade passes were closed at once.  There was abundant news/weather coverage of these fires throughout the month of August and into the first week of September.  This was the first time in my career I’ve seen so many fires going at once over and west of the Cascade crest.
  4. Two huge fires got lots of media attention; for good reason.  The 190,000 acre Chetco Bar fire threatened southern Oregon coastal cities including Brookings at the end of August.  Then the fireworks-caused Eagle Creek fire in the Columbia River Gorge spread east/west along a 30 mile stretch during and after Labor Day Weekend.  Of course that fire dropped ash in the Portland metro area on Labor Day; for most of us that was the first time we’d seen ash fall (from a forest fire) in the metro area.

The net effect?

Burned acreage was near normal, but this fire season WAS far more disruptive for the highly populated areas west of the Cascades than in previous years.  In most years the majority of smoke/ash moves east of the Cascades and we don’t see big fires in the Gorge.  We also typically don’t see so many fires in the Cascades at once.

Once again, location is everything!

We did get lucky on two counts this year:

  • NOT MUCH LIGHTNING  We saw far less lightning than normal for a 2nd consecutive year.  For the weather geeks like me it was a boring summer waiting for thunderstorms.  Of course that’s good news for fire starts.
  • NO BIG “ECLIPSE FIRES”  Remember the huge concern leading up to the middle of August was the possibility of numerous human-caused fire starts due to the massive influx of outsiders into our woods & range lands.  It didn’t happen!

Chief Meteorologist Mark Nelsen


A Beautiful Weekend; Showers Return Tuesday

October 15, 2017

9:30pm Sunday

The weekend is pretty much over now but wasn’t that fantastic for October?  Both days were mostly sunny with a chilly start (more so Saturday) and nice afternoons.  By the way, the 36 at PDX Saturday morning was the coldest temperature we have seen in the first half of October in a generation!  October 15th 1992 we hit 33 degrees.  Today was obviously warmer…high temperatures peaked in the mid-upper 60s in the metro area.

High Temp Last 13 Days

It’s always funny how quickly things change from late September to late October.  Just 2-3 weeks ago we were thinking high temperatures in the 60s were chilly, yet I think most of us would agree today was a spectacular day.  We have one more beautiful day tomorrow and then we get into a mild & wetter pattern.  This October has been totally different from last year.  At this point last year we had received 5″ of rain and almost no sunshine.  This year we’re seeing piles more sunshine.  In fact if we were cloudy EVERY DAY after tomorrow the rest of the month, that would just give us our average number of cloudy days…

Mark Cloudy Days Summer


The jet stream is setting up to our north much of this week with Oregon on the mild side of that jet.  That means snow levels will remain high until Friday and we won’t see any heavy rain in most of our viewing area.  Check out RPM forecast of rain the next 2.5 days and you see very little falls south of the Columbia River in the interior of Oregon

RPM Precipitation Accumulation

Yet by the end of the week, a 2nd atmospheric river event will likely trigger some flooding across NW Washington and SW British Columbia just to our north:

ECMWF Precipitation Accumulation

With the warm airmass overhead, we can expect mainly rain in the Cascades until a cold front comes through Thursday night or Friday morning

ECMWF Snow Level From 850mb Temps

Most likely 5-8″ new snow will fall at Timberline and possibly as low as Government Camp Friday and/or early Saturday.  That’s after quite a bit of melting during the workweek.  I think it’s unlikely we’ll see a re-opening of that Pucci chairlift at Timberline again this weekend.  That was amazing to see 27″ snow on the ground down below 6,000′ the past few days.  A nice change from our warmer Octobers.

Enjoy the sunshine Monday!

Chief Meteorologist Mark Nelsen