Will 4 Days of Warm Rain End An Early Ski Season?

November 19, 2017

9pm Sunday

November has been near to slightly below normal temperature-wise across much of the West.

Compare that with the blowtorch November last year across the entire USA!

Along with near normal rainfall that has given us a very nice mountain snowpack already.  At the Mt. Hood Test Site at the lower part of Timberline Ski Area, 34 inches of snow sit on the ground, containing 7.80″ snow water equivalent.  That means if you could melt it with a snap of your fingers, it would be just like 7.80″ of rain fell suddenly.  See how this compares to the past 8 Novembers at that site.

Pretty nice eh?  Quite a change from the past 3 mid-Novembers with very little snow on the ground at this moment.

That was the good news.  The bad news?  We have 4 days of warm rain (Monday-Thanksgiving Day) headed for all elevations in the Cascades.

The result will be substantial snowmelt.

But I do NOT believe this is the end of our early ski season.   There is no reason to panic when you hear many inches of rain are coming to your favorite ski resort.

It’ll be a setback, but this was an early bonus anyway.  A good part of the current snowpack will survive, in fact in the past 20 years we haven’t made it to 30″+ snow depth at this location followed by a complete melt down.  Sometimes it has dropped quite a bit (like the week ahead), but then more snow fell within a week or two.  If you are a skier or ski resort manager there’s no reason to freak out.

The pattern for the next 4 days looks like this…

a big ridge of high pressure with very warm temperatures overhead.  Lots of subtropical moisture will be streaming north around this ridge, pushing sticking snow levels up around 8-10,000′ on Mt. Hood.  We’ll be breaking out of the usual November inversion when we get a southerly wind so we can also expect a very warm Thanksgiving Week in the lowlands.  A record high is possible in Portland either Tuesday or Wednesday (records are 62 & 59 for those dates).

I expect lots of rain, but this isn’t generally a flooding rain pattern with the flow coming steeply from the southwest (instead of west).  Plus no one system seems to sit right over us for an extended period of rain.

There is one huge bonus…THANKSGIVING TRAVEL THROUGHOUT THE PACIFIC NORTHWEST SHOULD BE EXCELLENT.  There will be no snow over mountain passes anywhere in Oregon or most of Washington from tomorrow morning through Thanksgiving Day.  Even after that time through Sunday sticking snow levels seem to remain mainly above the Cascade Passes.

So enjoy the week ahead…at least you’ll save on your heating bills!

Chief Meteorologist Mark Nelsen

Winter is Here, And Not Just In The Mountains

November 15, 2017

9:30pm Wednesday

Heavy snow is falling in the mountains tonight.  The nice folks at Skibowl installed a very bright yard light this fall, so now we can see what it looks like after dark (until night skiing starts in December).  It’s been like a big “snow-globe” on the big monitor overhead here in the weather center.  This is great news; two more local ski resorts will be opening this weekend:

The cool westerly flow of showers will continue through early Friday, dumping 1 to 2 feet of fresh powder

Of course that means rough driving over the Cascades tomorrow and Friday.  Things should improve over the weekend with Saturday sunshine and then a warmer system the 2nd half of Sunday.   But the message is clear:  WINTER HAS ARRIVED AND IS HERE TO STAY IN THE CASCADES.  I don’t expect to see the ground appear again up at our camera location until sometime in May…or beyond.  That’s a 6 month-long snow cover!  Meanwhile down in the valleys it was a gloomy, cool, & dark day.  Most areas west of the Cascades have seen around an inch or rain…give or take a few tenths.

Today we are at the halfway point through November, which has been slightly on the cool side.  Can you believe that right now we are actually entering winter in the lowlands west of the Cascades?  It may seem like a silly statement, but in reality now through mid-February is “prime-time” for our winter weather.

Almost all of our flooding, snow/ice storms, damaging arctic blasts and (to a lesser extent) windstorms show up from now through mid-February.  Yes, I know it can snow either before this date or after mid-February, but those times are the outliers.  We are entering the main “weather action season”.

In the short term, it’s obvious we have a mild 2nd half of November coming…seems like upper-level ridging wants to linger over the western USA for a good chunk of the next 10-14 days.  Here’s the ECMWF 500mb anomaly for next Wednesday, a mild southwest flow of air

Then Sunday AFTER Thanksgiving, wet with temps near normal

And finally the last day of the month…Thursday the 30th

The last few runs of the GFS are not quite as ridgy, so maybe it won’t end up as mild as these maps would imply.  Regardless, the 12 Day trend I show many nights around 10:45pm will look like this:

The big message is that travel conditions might be very good for Thanksgiving…maybe even reasonable in the Cascades too.  #FingersCrossed

Chief Meteorologist Mark Nelsen

Wet & Windy Monday, Then Mild November Weather Ahead

November 12, 2017

7pm Sunday

So far November has been cooler than normal in Portland and rainfall just slightly below normal…the temps:

It appears the middle & 2nd half of the month will likely be milder (compared to normal).  That’s because all models are advertising a typical onshore-flow pattern with wet weather systems frequently moving through the area the next 10 days.  None of these the next week appear to be a big storm by any means.  In fact I don’t see a setup for widespread flooding or damaging wind.  But we DO have one strong low pressure system moving by offshore overnight and the back side of it will swing onto the Washington coast by midday tomorrow (the poisonous tail of the bent-back occlusion!).  That’s some serious weather nerd lingo there.  That has prompted NWS to issue a High Wind Warning for the Coast and Wind Advisory for the valleys:

The 980-985mb low is a little farther offshore than we would typically “want to see” for a significant windstorm in our area.  And here in the valleys the isobars (lines of equal pressure) are not oriented right for a big south wind in the valley.  Still, gusts 30-40 mph can bring down a tree just about anywhere or cause some outages…so expect some of that tomorrow.  Strongest wind both areas will likely be around midday.  If you are right on a beach or exposed headland I suppose you could easily get a gust higher than 65 mph too, and somewhere north of the Columbia River on the beaches I could see gusts above 65 mph too as that occlusion comes onshore midday.  Those numbers are for 95% of the coastal population.

One other thing about tomorrow, it IS the type of day (based on several parameters) in which we have seen funnel clouds or worse out at the coastline in the past.  No, I’m not saying there is going to be a tornado on the beaches Monday, but SOME TORNADOES IN THE PAST AT THE COASTLINE HAVE OCCURRED WITH THE METEOROLOGICAL SETUP WE HAVE IN PLACE TOMORROW.  We’ll be keeping an eye out of course.

Beyond tomorrow we have a few colder systems coming through which means snow in the mountains!  Keep in mind there is still around 20″ on the ground at 6,000′ (Timberline Lodge).  ECMWF projects maybe 2-3 feet of fresh snow above 4,000′ through Friday.  We’ll see if the weekend precipitation either shows up or is cold enough for snow up there.

This should be enough to open more runs/lifts at Timberline and maybe enough to get Meadows open for the weekend before Thanksgiving too.  And there appears to be plenty more valley rain and mountain snow beyond as we head into Thanksgiving Week.  Take a look at the ensemble-average upper-level flow (lines) and departure from normal (colors) this Thursday.  These are the ECMWF ensembles.

Cool troughing over us later this week means near normal temps and plenty of mountain snow.  Then 4 days later…the Monday of Thanksgiving Week

Troughing is a bit farther offshore, this is a mild and generally wet pattern.  Then Thanksgiving itself…11 days away:

All models keep showing ridging over the Western USA, but we appear to be on the edge of that, and over the past few days they have been shoving it farther east.  Again, this is a wet pattern with near normal temps.  Maybe a bit above normal in the lowlands since we’ll have a lot of cloud cover (no cold nights).  Looks great for mountain snowpack building too.  When the weather pattern appears to be somewhat settled in the longer-range, I show this “12 DAY TREND” graphic in the 2nd half of the 10pm newscast.

Right now some of you may be wondering if there’s any chance for snow/ice at Thanksgiving (my wife just asked today!).   Or if there will be any sort of dry spell so you can finish up an outdoor project.  That’s why I created this graphic…to give you a “peek” farther ahead without any sort of detail.  No one can forecast exactly what’s going to happen in two weeks (or even 10 days), but in times like this we can sometimes give a general idea of the trend.

Chief Meteorologist Mark Nelsen

Lots of Wet Ahead! November Gray & Rain Here to Stay

November 7, 2017

6:30pm Tuesday

This fall has been a bright one with lots of sunny days but still plenty of rain in between those days.  But now it appears we’re headed into a long period of gray and rain.  Let’s hit the highlights first:

  1. After today I don’t see a single totally dry day in the next week and beyond.  In fact it’s possible we get some sort of measurable rain almost every day the next two weeks!
  2. Expect a lot of gray, but that is normal from November through February…get used to it, book tickets for the tropics, or drive about 16 hours south on I-5.
  3. Through Saturday the rain won’t be very heavy, but weather systems will likely be stronger NEXT week.
  4. There is no sign of valley snow/ice in the next 10+ days; this will be a mild and wet weather pattern, in fact a bit warmer than what we saw today

You want to see gray?  Take a look at the ECMWF cloud cover forecast from all of the ensembles.  Blue=cloudy, white=clear

Note that almost the entire two-week period the ensemble average is more than 80%.  Then see the total rainfall forecast for the next 10 days.  Lots of rain, yet no specific setup for flooding or a pineapple express.

In the short-term we’ve got a classic Gorge ice/snow storm setup for Wednesday and Thursday…except the atmosphere is just a bit too warm to get either one all the way down to freeway level.  If you live up above 500′ (more likely closer to 1,000′), expect your first snow to ice event starting Wednesday afternoon and continuing through at least Thursday midday.

Peak gusts tonight through Wednesday evening at the west end of the Gorge will likely reach 70 mph in the usual cold-season windy spots.  That’ll be accompanied by sideways rain and 35-40 degree temps…not real pleasant I think…

There is one big bit of good news though…this wet pattern for the lowlands will turn into a heavy snow in the Cascades.  Snow levels through Sunday generally remain above the passes, with a good foot or more accumulating at the ski resorts above 5,000′.  Then we get a HUGE dumping Monday through Friday next week.  ECMWF shows a solid 3-4 feet snow at/above pass elevations:

Even if we get half of that, there’s a good chance we’ll have some decent skiing starting up the weekend before Thanksgiving.  If so, that’ll be fantastic to get the ski season started in mid-November!

Chief Meteorologist Mark Nelsen


2 Dry Days, Then Classic Wet November Weather

November 5, 2017

7pm Sunday…

This was sure an interesting weekend weatherwise as an extremely early season “arctic front” (leading edge of cold and dry air) dropped south, west of the Cascades, to around the Twin Cities and then fell apart Friday evening as it passed farther south through Kelso.  That’s about what we expected.  That gave a dusting (or more) of snow to parts of Puget Sound.  Then an area of low pressure at the surface moved across southwest Washington last night and this morning, bringing a gusty southerly wind to all areas west of the Cascades in the KPTV viewing area.  On the north side of that low, snow fell all the way down to sea level in spots today.   So Puget Sound ended up with 2 little “snow events”.  One could argue that it’s now SEATTLE 2, PORTLAND Zero for this “winter” so far.

The ECMWF model was by far the best forecasting this event; you may remember the GFS and even the GEM models kept showing today’s low coming right down into NW Oregon to our south.  Well, we now know that COULD have brought snow all the way into the metro area (or for sure the Gorge) IF those models would have been correct.

Moving along…

A surge of cool air (and high pressure) will pour south into Eastern Washington tonight and give us a 2-3 day period of strong easterly wind through the Gorge and into the east side of the metro area.  That begins Monday afternoon and continues all the way through Wednesday.  This will be the first “cold” east wind of the season.  Highs will only be in the 40s, compared to low 60s with the wind last week.  Quite a change!  Keep in mind you can not go to Vista House to experience the wind through the foreseeable future.  Fire never made it to that location so I’m not sure what the reason is for keeping the road blocked 1/2 mile before that point.  Rumor says that MAY be the situation the entire winter.  We’ll see.  But the good news is the dry easterly wind will give us two dry days…Monday and Tuesday.  Enjoy, because we’re going into a rainy pattern starting Wednesday and continuing through the next 10+ days.  Take a look at the ECMWF ensemble 24hr precipitation forecast.  Each horizontal line across the top is one of the 51 ensemble members.  The lower blue part is the ensemble average, showing several peaks of precipitation forecast.

The only real obvious breaks in there are the next two days.  But it gets gloomier; check out the cloud cover forecast for the same period.

Wow…that’s a lot of gray!  The ensemble average for cloud cover is around 80% through the next two weeks.  Hmm, seems like November to me!  Total rain in the next 10 days or so doesn’t appear to be excessive since systems will be relatively weak

There IS some good news if you are a skier.  Snow levels will rise after tomorrow, and linger in the 4,000 to 5,000′ range through most of the next week.  The result is additional snow base-building at the top of Skibowl and a good part of Timberline and Mt. Hood Meadows ski areas.

I think there should be a solid 2 feet or more on the ground in those locations, not just fresh snow but a building base.  This is a good sign that we might have a good start to the ski season like last year.  #FingersCrossed.  Down at Government Camp it’ll be a mix many days during the next week so you folks will likely lose some of your 10-12″ on the ground right now.

So there’s no sign of a real stormy pattern (wind or flooding), and no sign of low elevation snow or freezing rain in the metro area.  Now depending on how cold the airmass is in the eastern Gorge Wednesday, it’s possible we get either snow or freezing rain out there, but we’ll see about that.  Might just be up in the higher valleys away from the towns.  More on that in the next two days.

Enjoy the dry weather!

Chief Meteorologist Mark Nelsen



Snow To Sea Level Up North, But A Chilly & Wet Weekend For Us

November 2, 2017

7pm Thursday

November is here but the weather pattern the next 5 days looks more like December.  That means cold rain showers in the valleys and lots of mountain snow, plus some snow (above freeway level) is likely in the Columbia River Gorge too before the weekend is out.

Today we actually have an “arctic front” sitting across the northern part of Washington State draped east and west from an area of low pressure over the Strait of Juan de Fuca.  I’ve colored it in red on this sea level pressure map.  You can see the cold air north of that line.

It’s a boundary line between chilly/moist Pacific air to the south and dry/cold modified arctic air to the north.  North of the line sticking snow is falling down to sea level (or very close).  A gusty northeast wind is blowing across NW Washington and snow fell today (on November 2nd!) at the border crossings you’ve likely used to get to Vancouver BC.  The arctic air has pushed south due to a northerly flow in the upper atmosphere from NW Canada all the way down to Washington

Overnight the low pressure will weaken and drift south.  But the cold burst of northeast wind won’t make it any closer to us then around Seattle west of the Cascades.  That leaves us with scattered showers and a snow level down to around 2,000′ or so the next two nights in our area.  Friday will feature a mix of showers, sunbreaks, and cooler temperatures.

A 2nd disturbance drags more of that arctic air over the Pacific Ocean and spins up a low pressure center Saturday evening.  That low moves inland across SW Washington Saturday night and Sunday.

This means another burst of snow in the Cascades and valley showers later Saturday through Sunday.  Luckily the low is passing by to the north which will minimize any cold air getting pulled westward through the Gorge.  One of the inferior models (GFS) was showing just this setup in the past few days, but it has now come around to the “warmer” models.  That said, in such a chilly airmass it’s always possible we’ll see snow at the eastern end of the Gorge.  If you live in the upper Hood River Valley or anywhere else near/above 1,000′ at the east end of the Gorge there’s a pretty good chance you’ll wake up several inches of snow Sunday morning.  If the low comes any farther south than forecast, snow could fall very close to river level too…if it does.  Here in the metro area our wind should be southerly, pushing snow levels up to around 3,000′.

To summarize:  The next few days will be cool and showery in the lowlands, with highs only in the 40s Saturday and Sunday.  Lots of snow will fall in the mountains, but snow won’t stick at any point below 2,000′. 

How much snow in the Cascades?  The ECMWF seems reasonable bringing a total of around 2 feet above 5,000′

Once the Sunday system exits, we’ll be left in a cool and mainly dry beginning of the week (Monday & Tuesday).  Models diverge quite a bit for the 2nd half of next week.

The more reliable ECMWF shows mild atmospheric river event the 2nd half of the week and into the following weekend.  This would of course bring more rain than snow to ski areas.

But other models keep us in a cooler pattern with several more surges of cool air coming in from the northwest the next two weeks.  Regardless, you can enjoy this early taste of a winter chill!

Chief Meteorologist Mark Nelsen

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