Thanksgiving Week Outlook; Partly Wet

November 22, 2020

8pm Sunday…

We had our first taste of the cold season “fog inversion” this weekend. That means cool air remained in the valleys while the atmosphere overhead warmed. Yesterday Portland only made it up to 41 degrees…quite a taste of a typical winter day around here

Which brings up a good point…from a meteorological point of view we’ve pretty much entered “winter” west of the Cascades. I suppose it seems like a ridiculous thing to say, with a week left to go in November? Nope, once we hit mid/late November, we’ve entered the busy three months of the year in our area. “Winter” tends to come early and melt away a bit quicker than in colder continental climates. No, I don’t mean just snowfall. I’m referring to what we tend to see in winter here

It’s EXTREMELY rare to see a real arctic blast outside of this window. And if we’re going to have an “all-day” snow event in the lowlands, the type where roads stay frozen, it happens during this time. Remember the past few years? When we’ve seen snow from mid-February onward, the effects on lowland roadways are minimal mid-late day. That’s because of increasing sun angle. If we get significant flooding this year, most likely it’ll be within the next three months.

What’s Ahead?

I took a few extra days off this past week; still have a few leftovers from our summer furlough days. When I came back in to the station today I noticed three specific items while perusing all the models/maps:

  1. I don’t see a stormy weather pattern in the next 10 days
  2. After a wet Tuesday/Wednesday, we’re headed into a drier weather pattern through at least the first few days of December
  3. There’s no sign of lowland snow/ice or an arctic blast in the next two weeks. That means most likely we won’t be seeing an early freeze this year (November or early December).

Basically the weather looks a bit on the slow side over the next 1-2 weeks. In the short term I see a couple weak systems moving inland tonight, then a stronger cold front and chilly airmass Tuesday/Wednesday. We should see another 1/2″ rain early this week out of these systems.

Beyond Wednesday, upper-level ridging wants to be the dominant weather feature over the western USA for awhile. Take a look at 500mb height map from Canadian ensembles for this Friday

and then 10 days from now…Wednesday the 2nd

I think the ridging may be overdone on this model. Other models show above average heights but not so extreme.

Weak (and wet) systems will probably still be coming through the ridge during this time; I don’t think it’ll be one of those “completely dry for 10 days” setups. But this eliminates the chance for any significant cold spell and/or snow in the lowlands for the next 10+ days.

Ski Area Weather

We’ve got a fantastic early season snowpack on the ground in the Cascades above about 3,500′. These numbers a bit deceiving since the average snowpack is very low this time of year; anything significant is way above the average. But you get the idea…

Both Timberline and Mt. Hood Meadows have about a 3 foot (or more) settled snow pack on the ground now. Even Government Camp has somewhere between 4-10″. In other years those first two ski areas would already be open, but of course COVID is throwing things off. Regardless, the slopes are just about ready! Timberline is opening this Wednesday the 25th and Meadows is opening for the season Monday the 30th! I don’t see anything that would stop either from happening. Another foot or so should fall above Government Camp by Thanksgiving morning. At least according to the ECMWF model

The only possible rainy weather at the ski resorts would be Friday night or early Saturday as a weak system moves through the warm upper-ridge. So we should remain in good shape for an early start to the ski season through at least early next week. We’ll see what happens beyond.

Enjoy the showers early this week; I’m focused on the dry weather later in the week. After Thanksgiving Day it’s the Christmas season…good weather for hanging some lights Friday-Sunday!

Chief Meteorologist Mark Nelsen


Cascade Snow Season Starts Early!

November 13, 2020

7pm Friday…

Last night was fun…strong wind arrived right on schedule. The first wind storm of the season produced widespread 50-65 mph gusts along the coastline. Of course the usual high wind spots recorded much higher speeds.

In the inland areas peak speeds were a bit lighter than models were forecasting, although close enough to our 35-50 mph forecast. PDX hit 37 mph. Around 7,000 PGE customers lost power in the northern Willamette Valley.

We picked up a LOT of rain, you probably noticed!

If there were any doubts this would be a dry November…that’s disappearing quickly.

We have November snowstorm #2 in progress in the Cascades. The live view from our Upper Bowl camera at Mt. Hood Skibowl shows at least 20″ on the ground up there. Last year we had trouble getting that much all the way through late December!

About a foot and a half of new snow has fallen above 5,000′!

Both Timberline and Meadows now have a base around 30″…ON NOVEMBER 13TH. This is way ahead of last year when ski areas had less snow on the ground the third week of December! Excellent news.

So what’s ahead? Lots more rain in the valleys, and snow in the mountains. Another system moves inland tomorrow afternoon/evening; snow sticks above about the 3,500′ elevation. That snow level does go as high as 4,500′ early Sunday, then drops by midday. The result should be another 8-12″ in the Cascades by Sunday evening when things dry out. I do expect a “warm” system in the mountains Monday and early Tuesday, but then we’re back to cooler systems the 2nd half of next week.

To summarize:

  1. Cascade ski resorts appear to be in excellent shape for early openings this year. In the past few years ski areas have opened with limited operations with only 20″ on the ground.
  2. There WILL be a 2 day spell of rain/warm conditions, but not really a pineapple express. I expect the snowpack to consolidate a bit and we’ll lose quite a few inches. But more snow fill follow the 2nd half of next week.
  3. There’s no sign of a warm spell or series of warm storms that would melt most of the snowpack. Good news!

This is quite a change from the past two years. Check out snow depth at the bottom of Pucci Lift. This is for November 19th (next Thursday). Last year there was nothing on the ground at this point…big improvement.

By the way, we’ll see at least another inch of rain in the lowlands this weekend. Keep in mind this is precipitation; much of that falls in the form of snow in the Cascades.

Expect a soaker the 2nd half of tomorrow, plus gusty southerly wind. Then it’s back to a showers/sunbreaks mix Sunday…like what we’ve seen today.

Enjoy your weekend!


A Wet & Windy Night Ahead

November 12, 2020

9:15pm Thursday…

A very quick update this evening, I’m busy on-air until 11:30pm, you can find me there!

Everything is still on track for a gusty south wind tonight west of the Cascades as I posted about last night. Notice graphics are about the same

Several of today’s models continued to show strong wind gusts spreading onto the coastline. I think the 00z HRRR surface pattern shows what’s going on. As a strong cold front moves inland, a “wave” or open low pressure area tracks northeast, making landfall around Astoria in the early morning hours. You can see the small circle in the isobars (equal pressure lines) over the mouth of the Columbia River around 3am.

This tightens the southerly pressure gradient nicely during the wee hours of the morning.

Others were a bit weaker (GFS), but now they have come into line with the stronger solutions. The ECMWF and IBM’s GRAF model have been most aggressive, sending gusts up to 70 mph along the coastline and 50 mph in the valleys

Once the front passes and that wave moves north we go to a much more reasonable southwesterly breeze.

We’ll see how it goes…again, not a big windstorm, but many of you will wake up to rain pelting your south-facing windows. We recorded a podcast discussing the overnight setup early this evening as well. You can find it already dropped into your Apple Podcasts

Or listen at this link: https://www.kptv.com/podcasts/weather/

We’ll see how it goes!

Chief Meteorologist Mark Nelsen


Lots of Rain & Wind Ahead Plus Another Winter Storm In Cascades

November 11, 2020

8pm Wednesday…

I’ve got a quick update this evening on our incoming weather the next two days, I’ll be on-air on FOX12 Plus 8-10pm and then on FOX12 10-11:30pm

HIGHLIGHTS FOR PORTLAND/VANCOUVER METRO AREA

  1. All quiet tonight and tomorrow morning, then light picks up tomorrow afternoon. Expect breezy southerly wind west of the Cascades. Maybe 25-35 mph gusts in the evening. A typical mid-November day.
  2. Tomorrow night and Friday morning rain turns heavy at times. We should pick up at least an inch of rain. Southerly wind gusts could reach 35-45 mph during this time. Not a big storm, but enough to drop a few limbs onto powerlines = a few power outages.
  3. Lots of showers & sun mix Friday afternoon through Saturday. Typical breezy southerly wind at 10-20 mph

A High Wind Watch is up for the Oregon and southern Washington coastline. In the Coast Range too. This is tomorrow night and early Friday.

Remember a WATCH means a weather event MIGHT be on the way, a WARNING says that event is imminent.

There are no watches/warnings/advisories for now in the interior valleys where about 85% of KPTV’s viewers live. At this point I’m thinking 35-45 mph gusts tomorrow night and early Friday is the best forecast.

A strong westerly jet stream is punching across the northern Pacific ocean right now. By tomorrow evening it’ll be at our doorstep. Check out the 220 mph windspeed!

All models agree that an area of low pressure (or two) will “spin up” underneath the “exit region” of this jet stream. That’s the northern edge where the wind slows down. But each model has it’s own idea where/when that happens and how deep the low pressure will be. Of course a deeper low is associated with stronger wind. Movement of the low is important too. Over the past three days SOME models were showing a very deep low pressure center traveling west to east just north of Portland, or up across Puget Sound. That could possibly give us a windstorm. But the screaming message this evening is that almost no models are giving us a significant wind storm. Take a look at the 30 ensemble member low pressure locations for 10am Friday. You get the idea. Some stronger, some weaker, some have the low going in SOUTH of Portland. In that case we wouldn’t get any sort of strong wind.

The latest operational ECMWF model gives us gusts 35-50 mph late tomorrow night, then Friday it’s back to showers/sunbreaks/breezy

In general what I’m seeing is not the setup for a windstorm, but lots of rain and some wind in spots. Maybe just a warmup for the storm season ahead.

The Cascades picked up around a foot of snow in the first storm of the season. Now we expect another 5-10″ at pass elevations and 20-30″ up above 5,000′. That’s tomorrow afternoon through Saturday afternoon. Maybe some pre-Thanksgiving skiing? We’ll see

That’s it for now, time for dinner. See you on TV!

Chief Meteorologist Mark Nelsen


Cool November Weather Is Here To Stay; Valley Rain & Mountain Snow

November 8, 2020

10pm Sunday…

Well, that’s been an exciting 5 days since the election started eh? Since I love numbers and politics I’ve watched everything closely. Now that things are settling down I figure we should talk about weather. And what a change we’ve seen!

For the first time this season we’ve seen sticking snow down below 3,000′. I took a run today, midday, with a temp in the upper 30s. It felt like December under a gray sky (east side of metro). Portland saw it’s coldest day of the fall, just 47 degrees

You know winter is close when at 8pm we’ve already got parts of the metro area below freezing.

Expect widespread mid-upper 20s tonight for another hard freeze. Whatever survived frosts a couple weeks ago probably won’t make it through tonight. We’ve seen a few inches of snow at Government Camp, maybe 4-5″ higher up at the ski resorts. Here’s the 8:45pm view from the top of Upper Bowl at SkiBowl

The rainy season has arrived; that’s the screaming message on maps/models this evening. In fact if you’re looking for a 3 day period of dry weather? Extremely unlikely…

Summary of What’s Ahead

  1. Expect steady rain or showers just about every day for at least the next week to 10 days west of the Cascades. IF we somehow squeeze in a mostly dry day, consider that a bonus! Somewhere between 2-4″ rain could fall in the next 10 days…
  2. Temperatures will remain between 40-50 degrees most of the next week too. A mild Pacific airmass will be in control of our weather most of that time.
  3. I don’t see a setup for low elevation snow OR ice/snow in the Gorge for at least a week, probably much longer. There’s no sign of cold Canadian air surging south in the next 7-10 days either
  4. Snowpack will be building in the Cascades over the next week. IF we don’t get a set of warmer systems NEXT week, I could see ski areas trying to open up at least a few runs!

Details

As expected we’ve seen a surge of cool/dry air drop south into the Pacific Northwest, thus the cold temps tonight. But starting tomorrow afternoon our weather will be dominated by a succession of cool-ish weather systems coming in off the Pacific. For at least the next week, none of these are forecast to be “warm” or related to atmospheric rivers. For example check out the ECMWF 850mb ensemble chart. Each thin line represents one of the 51 ensemble members. That’s for the next two weeks. It’s temperature (C) at around 4,000′. So the “zero” line means freezing around Government Camp.

Notice there is general agreement that there won’t be any extra-warm ridging or cold spells. In fact there’s only one or two of those members showing anything really “cold”, at the end of the run. Otherwise it’s generally just a little below average (green line) for this time of year; excellent for mountain snowpack.

Then check out precipitation from the GFS ensembles. Tomorrow through a couple of days before Thanksgiving (2 weeks out). Wet!

It shows six hourly rain totals for each of the 31 ensemble members. Each horizontal line (upper part of chart) is one member. You don’t see many gaps do you? This says it’ll be hard to find much dry weather the next two weeks. Other models are similar. The reason? A typical November Pacific jet stream aimed at the West Coast. Six days out, this coming Saturday

Models are telling us somewhere between 2-4″ rain could fall in the next 10 days west of the Cascades. Very wet, but…it IS November. And precipitation in Cascades maybe around 8-12″. Get ready for an overdue soaking, it’s time.

Snow levels linger between 3-5,000′ over the next week.

Snow at 4,000′ will come and go, but it’ll be ALL snow up above 5,000′. The ECMWF model shown here would imply 2-3 feet may fall at the top of Skibowl, and the upper parts of Mt. Hood Meadows and Timberline ski areas too. Ignore the Gorge, that’s a contouring issue with the terrain.

This COULD be enough to jump-start the ski season a bit early! What we don’t want to see this early is a warm/wet storm following next week to melt the snow. That’s not unusual in November. Last year there was some very basic skiing for Thanksgiving, but then things lagged until we got to mid-January. But this upcoming pattern looks great!

Again, there’s absolutely no sign of lower elevation snow. This is a mild westerly-flow setup, just a bit cooler than normal. Take a look at the stable temperature regime from the ECMWF, actually that’s weirdly stable.

Maybe this will be a 2007-2008 type La Nina winter? That’s when it hardly snowed in Portland, but multiple systems came down in WNW flow pummeling the Cascades AND the foothills with feet of snow. We will see. It’s still very early…kind of like looking at those first few hours of election results and making an assumption of how things were going to play out.

So remember, you’ve got a mainly dry day tomorrow to get outdoor projects done (I have a few), and then it’s on to wet, wet, wet…

Chief Meteorologist Mark Nelsen


Warm November Start; But Cooler Weather Ahead

November 4, 2020

9:30pm Wednesday…

What a warm day! Temperatures clipped the 70 degree mark in the metro area today; on November 4th. Portland was just one degree shy of the 69 degree record, and Troutdale broke it at 69 degrees. Even warmer temps to our south and east. It was the warmest day in the past three weeks in Portland

I see The Dalles, Meacham, and Yakima all broke record highs for the date. Of course it was just two days ago that Redmond broke their all-time November high temperature record of 76…reaching 80 degrees!

In fact it’s a bit strange that our temperatures have gone uphill in the time of year they typically go down. Remember that 48 degree sunny day with a gusty east wind? That was the coldest so far this season

I’ve been negligent in posting the past week or so. Slow weather, working on new weather graphics, and election drama has distracted me. But as we move deeper into November the weather action usually picks up. Although this year things are looking quite benign through mid-month.

Right now a very warm upper-level ridge is fading away, weak systems are pushing into the PACNW

A Pacific frontal system is getting organized offshore as cold air drops into the Gulf of Alaska under a developing upper-level low. Look at the change by Friday! That cold low has dropped down the central California coastline.

This gives us the “big rain event” of the week. Now through Friday afternoon, the GRAF model is showing up to an inch of rain in western valleys of OR/SW WA. Thursday is definitely an “indoor” day.

A secondary upper trough drops straight south out of Canada Saturday; it helps carve out a huge trough over the western USA. Las Vegas was in the mid 80s today, but only 50s by Sunday…

There won’t be much rain with that secondary system so this weekend will be mainly dry; most likely some afternoon showers popping up Saturday though. In the Portland area, temperatures cool off from 60s today to upper 40s Saturday/Sunday. Back to normal and then below. The pattern remains cooler than normal through the middle of next week, here comes another upper-level trough dropping down along the BC coastline Tuesday. This typically isn’t an especially wet setup, but cool

I expect at least a bit of snow in the Cascades the next few days as temps cool, but not a huge dump around Mt. Hood since snow levels will be relatively high through most of the precipitation.

At least it’ll be a start, but I sure don’t see skiing by November 10th.

So enjoy the rain tomorrow and refreshing/chilly weather over the weekend. Those leaves should be turning crunchy again by later Sunday/Monday as we dry out.

Don’t forget to subscribe to our FOX12 WEATHER podcast. Lots of weather geek talk every week or so. We’re on episode #9 and another should drop next week. Subscribe on Apple Podcasts or just go directly to the weather page on www.kptv.com

Chief Meteorologist Mark Nelsen


Early Cold Snap Delivers; But Back to Mild & Dry

October 26, 2020

8pm Monday…

It’s a beautiful October evening! A nice view of sunset from several of our weather cameras

Everything turned out just about as expected late last week through this morning. A chilly Canadian airmass dropped down into the Western USA right on schedule. Gusty northeast wind arrived in the metro area Saturday afternoon, clearing out the cloud cover and leftover morning sprinkles. Spokane ended up with the snowiest October on record. Around a half foot in that area. Temperatures hardly rose Saturday as the colder air moved in.

Then Sunday (yesterday) we saw a very chilly and windy day. Peak wind gust at PDX was 39 mph yesterday. Highs stayed in the upper 40s in Portland; one of the colder October days we’ve seen in the last few decades

Skies remained clear last night, dewpoints were down in the teens, and east wind backed off. That gave us just perfect “radiational cooling” conditions. Portland (airport) officially dropped to 29 degrees this morning. That was the earliest 29 in many years, although we’ve hit 30 earlier in the month in some years. Check out the rest of the metro area…

Some records were set too, the coldest October 26th in Portland, Hillsboro, & Eugene.

You might be wondering how cold it can get in October? The all-time October records…

I’ve hardly mentioned the eastern half of the state…brrrr!

Ignore Hermiston, there are a bunch of missing observations during the night. A warming airmass today, along with low relative humidity, allowed afternoon temps to climb rapidly. Redmond went from 9 this morning to 57 this afternoon!

What’s ahead?

Mild and mainly dry weather. Notice the ECMWF monthly run last night shows upper-level heights well above average this week

Then next week looks similar, possibly slightly wetter. That’s a warm pattern across much of the USA for the first week of November

A mild westerly flow, aided by a continuing “warm” eastern Pacific tells me we’re headed back into warmer than normal conditions for at least the next 10 days

With the main jet stream shunted north of us we can expect drier than normal conditions to continue. Just one weak system Friday afternoon/evening and that should be it for October rain. Another very dry month

Looking farther ahead, the ECMWF ensemble average paints drier than normal weather through the first week of November.

The monthly run of the GEFS is similar…very dry well into November. The new/improved GFS ensembles (in September) are now run 5 weeks into the future, once per day. But remember accuracy goes downhill after 10-14 days. You get the idea…dry. We’ll see.

To summarize:

  1. There’s no sign of a rainy/wet pattern in the next 7-10 days. We’ll be much drier than average.
  2. Significant snow at the Cascade ski resorts is unlikely over the next week or so.
  3. Have some outdoor projects you STILL haven’t finished? You’ve been given a reprieve! Lots of good/dry outdoor weather ahead in what is typically the beginning of the rainy season

Chief Meteorologist Mark Nelsen