Weather action is picking up! Stormy tonight, snow in Gorge, & lowland snow possibilities

November 29, 2022

NOTE: Nowadays I post to our station website, then when I have time I copy the post to this site. It will have formatting errors and images you can’t enlarge. Unfortunately there is no way to get a notification when I post over there, but for the “full experience” check out posts there.

8pm Tuesday…

We had 2 weeks of high pressure and dry weather in mid-November, but now it’s payback time. I’ve got 3 weather items to cover this evening: stormy night tonight, heavy snow in Cascades/Gorge, & could we see snow in the lowlands later this week.

(kptv)

First, we’ve got a soaker headed into the PACNW right now. It’s a cold front and that’s the leading edge of another “maritime polar” or “maritime arctic” airmass. That means cold/dry arctic air has dumped out over the ocean and is moving toward us. That cold front has a lot of rain associated with it. I expect about an inch of rain (or a bit more) overnight in the western valleys of Oregon and SW Washington. Then the wind; southerly gusts will likely reach the 35-45 mph range around 11pm-2am just ahead of the cold front. Expect a few scattered power outages during the night

(kptv)

Tomorrow will be uneventful in the lower elevations with light wind and scattered showers

GORGE SNOW

For the first time this season we’ve got a (very shallow) cold airmass streaming westward through this sea-level gap in the Cascades. Add in abundant moisture moving in overhead and it’s the perfect recipe for a snow or ice storm. It appears this time it’ll be mainly snow, with a little freezing rain mixed in toward sunrise when the cold airmass thins out. Almost all the action will be east of Multnomah Falls. The cold air is so thin at the west end of the Gorge that it’s barely streaming over the top of Crown Point! Up around 1,500′ nearby it’s well above freezing. The cold air is thick enough on the Washington side to support snow a few more hours of snow NORTH of the Columbia River.

Weather Blog Images
Weather Blog Images(kptv)

Temperatures will warm tomorrow midday/afternoon and I-84 should be fine the rest of tomorrow.

CASCADE SNOW

There is plenty of snow on the ground in the Cascades and we’ll add 1-2′ additional tonight through Thursday morning. This will be the best December 1st snowpack in about 15 years!

(kptv)

Worst travel conditions in the Cascades will be tomorrow morning with lighter snow in the afternoon.

LOWLAND SNOW POSSIBILITIES

This is probably what many of you want to know…Will we get snow in the I-5 corridor between Longview and Eugene? Possibly, but I still don’t see a setup for widespread snow in the cities. The first two “close calls” this week have ended with nothing. That was Monday morning’s snow in the hills, then a brief “flurry storm” in a few spots this morning before the airmass warmed up. Models handled both well, although precipitation arrived a bit early today.

For the next 2 days, I think our commutes are clear except for Thursday morning. On that day we’ll be in a chilly airmass with scattered showers roaming about including during that morning commute. Typically this isn’t a significant snow producer west of the Cascades in the lowlands. BUT, if it snows a Trace to 1″ Thursday morning where YOU live, it’s a big deal to YOU!

The cold airmass behind tonight’s cold front will bring sticking snow down to around 2,000′ late tomorrow and around 1,000′ Thursday morning. Considering it’s just scattered showers, that usually means a few spots in the hills get a dusting and we don’t see anything other than a rain/snow mix in the valleys. BUT, if we get any sort of steady/heavy showers, that sticking snow can come right down into the lowest elevations. For the geeks, we’re bottoming out around 520dm thickness and 850mb temps -6 to -7 Thursday and Friday…that’s cold, but not “guaranteed” category for snow in the lowlands. Some models have been hinting an organized band of showers could develop tomorrow night or Thursday morning. The Canadian HDRPS model, HRRR, & NAM-3km imply this could happen and all 3 are producing measurable snow across at least part of the Portland metro area during that time. So…we will see what the evening GRAF model shows in an hour or so. Right now it thinks a few spots could get “stickage” early Thursday morning…stay tuned!

(kptv)

A repeat is possible Thursday night into Friday morning, but in general I’m thinking the vast majority of us in the I-5 corridor from Longview to Eugene will not see “sleddable” snow through Friday.

It could be a different story after that time…

Another cold upper trough drops down offshore Friday and spins up another wet frontal system. Models are all over the place on this one. The normally cold GFS thinks we’ve got a snow and then ice storm Friday night into Saturday morning. The ECMWF is much drier and has the system farther offshore. But it IS cold enough with a strong easterly Gorge wind that moisture would be in the form of snow/ice. So Friday evening/night is another possible “event” I’m watching closely. There is also plenty of cold/dry arctic air lingering just north of us through early next week. That means at any time some of that could get pulled south and interact with Pacific moisture as we’re seeing this evening. Winter is here for the forecasters and it’s busy!

That’s it for now…enjoy the stormy night.


Chilly week ahead, but tough to get REAL snow to lowlands this week

November 27, 2022

3pm Sunday…

Thanksgiving weekend is wrapping up and now it’s on to the last few days of November and then December. Right on cue, a colder airmass is arriving today with cold showers. I’ve seen a mix of hail/rain at home.

Snow hasn’t been too heavy in the Cascades so far, but intensity picks up a lot tonight through midday Monday. Cascades are the easy part of the forecast. Expect another 10-15″ at pass elevations (a bit more higher up) tonight through Monday. Add in a colder airmass and that means tomorrow morning you cold have 20+ miles of snow to drive through. That’s much tougher than just a few miles over the summits. Snow will stick down to around 1,000′ in the Cascade foothills tonight; I’m putting out my “snow board” for the season, anticipating a brief dusting here at home…maybe. This plus another 12-24″ Tuesday night through Thursday means ski areas should all be able to open this coming weekend with many feet on the ground!

Highlights for the lowlands

If you have a short attention span, or in a hurry, this is what I’m thinking over the next week or so…

1) Get used to lows/highs in the 30s/40s the next 7-10 days. Not really that cold, but these are mid-winter temps; a bit cooler than average for this time of year

2) There’s NO SIGN of an “arctic blast” west of the Cascades for at least the next week. No “pipe-busting” cold or anything colder than what we’ve seen so far this season. There’s also no sign of any significant cold east wind through the Gorge this week; typically that would help us get something frozen (snow or freezing rain). Not this week.

3) But, we have a few “close calls” with low elevation snow over the next week. Mainly late tonight, Tuesday evening/night (for some), and Wednesday night/Thursday AM. There’s a good chance that none of these produce measurable snow in the vast majority of the I-5 corridor from Clark county down to Eugene

4) The issue is that when it IS just barely cold enough for snow to stick to sea level this week, the precipitation is mainly gone. The heavier precipitation periods will be a bit “warmer”.

4) That also means that at this point I don’t see snow impacting your life Monday, Tuesday daytime, Wednesday, or Friday through Sunday in the lowest elevations. That could change, but it’s what I’m seeing right now

The Details

We are under the influence of a chilly northwest flow in the upper-atmosphere. A cold upper trough is passing through tonight, with 850mb temps down around -5 to -6 and 1000-500mb thicknesses around 520-521dm.

(KPTV)

Typically, to get snow in the lowest elevations, with onshore flow, we want to see -7 to -8 at 850mb and 520 or lower thickness. So at best the lower elevations with see snow mixed with rain overnight like we saw a few weeks ago…weak sauce. By the time it get’s quite cold (tomorrow evening and tomorrow night), the precipitation is all gone and we stay dry. I notice the freezing level bottoms out around 1,800′ tomorrow midday, so with relatively light showers early tomorrow, I wouldn’t expect sticking snow in the metro area below 1,000′…if it even gets that low.

Then Tuesday night and Wednesday another cold upper-level trough digs down from the north, but this one is headed farther west of us at first…Tuesday here:

(KPTV)

That means the really cold (arctic) air is dumping out over the Gulf of Alaska. It does spin up a nice bomb cyclone near the northern tip of Vancouver Island. Looks like a drop from 1012 to 978mb out there from Tuesday AM to Wednesday AM. But a surface low in that position pulls up a southerly wind over us = snow-killer in the lowlands. That said, as the precipitation starts Tuesday evening, it could easily start as snow but not stick out in Columbia county in Oregon and Cowlitz county in Washington. I’ll be watching that closely, but rarely has that pattern produced anything very interesting snow-wise in the metro area. So expect plenty of rain and big mountain snow during this time. Here’s the GRAF model’s snow forecast through Tuesday night. This sure doesn’t say “I’ll be sledding early this week in Portland”.

Blog images

One more way to look at it is the cross-section from the UW-WRF model. The zero line (32 degrees) is blue. Above that line it’s at/below freezing. I didn’t draw correctly on Tuesday, obviously we are above freezing most of that day. You can see the southerly wind (barb-looking things) pushing freezing level up to around 3,000′ later Tuesday night

By Thursday, that trough is STILL just barely moving onshore.

A lot of the energy has gone south us and into California. That delays the arrival of cooler air again and modifies the cold airmass offshore a bit further. At the surface an elongated band of rain/snow has become almost stationary over the West Coast Thursday

Another gray day with possibly a rain/snow mix in the lowlands, or just rain. Some models HAVE been implying we could get into a situation with heavy precipitation within the frontal boundary changes somewhere in Oregon over to all snow. I’ll be watching for that possibility closely; this model run says that may happen in SW Oregon; notice all the snow down there.

By Saturday, that trough is gone and another is swinging south; offshore like the Tuesday/Wednesday trough

You get the idea…much of the action is happening well west of us over the ocean. This spins up another wet frontal system for a solid period of cold rain sometime Friday through early Saturday, with showers to follow Sunday. 3-4 days ago models were keeping these troughs much closer to the coastline and bringing cold air down directly over us. Another way to see how they adjusted, a chat showing 6 hourly minimum temperatures out in time. Each horizontal line is one run of the ECMWF model. Notice the Thanksgiving morning run (12z 24 Nov) was showing very cold weather later this week with modified arctic air coming in from the north (upper part of circled area). Then in the 6 model runs since that time, ending with the latest, you see we’re back much closer to normal with a forecast for later this week. No arctic air moves south, but maybe some close calls with snow in the hills and mixed in the lowlands.

Maybe a better real world translation is: “3-4 days ago I was worried my wife would have issues getting to work in the early mornings this week. Now I’m not worried at all. Maybe an inch or so sometime in the next few days at 1,000′, but that’s about it”.

That’s it for now, I’ll be at work all week long!


Gusty east wind returns for most of us Thursday

November 16, 2022

10pm Wednesday…

Just about ALL of the metro area will be much windier tomorrow…watch out for flying garbage cans! You can expect a few scattered power outages too…just a few.

Strong high pressure east of the Cascades plus a sharp temperature inversion (warmer air over cooler air in lowlands) led to a very strong easterly wind through the Gorge today. Peak gusts exceeded 90 mph at both Crown Point and Rooster Rock. Gusts over 70 mph rocked the town of Corbett too, at the high end up what is typically experienced at both locations in the cold season. A person standing “at the rail” on those south-facing steps at Vista House certainly would have recorded gusts in the 100-120 mph range today.

Most interesting is that the cross-Cascade pressure gradient (difference in pressure between Portland and The Dalles), only peaked around 9 millibars. I would have expected lower gusts with that gradient. The key is that we have a strong inversion overhead. It was 53 today at 7,000′ at the top of Magic Mile chairlift on Mt. Hood. In a perfectly mixed atmosphere (warm season), high temperatures should have been around 80 down here at sea level! But it’s not perfectly mixed because days are so short and the sun is in its very weak winter position in the sky. Cool air gets stuck in valleys and warm air moves in overhead. In this case that “squishes down” the fast flowing air moving through the Gorge. Think of it as a certain amount of fluid being forced through a small hose. Velocity increases. But that fast moving air spreads out quickly and slows down under a strong inversion once it leaves the Gorge. Much of the metro area just saw light breezes today

What changes tomorrow?

Wind in the Gorge should be LIGHTER tomorrow, but much stronger wind (than today) should spread across the entire metro area at the same time.

A surge of colder/drier air is moving down into the northern Rockies tonight. The edge of that airmass should arrive over northern Oregon by sunrise. This loop shows 850mb temps…the temperature in Celsius around the 5,000′ elevation. From right now to tomorrow at 7pm. Notice at that elevation temperatures drop 20-30 degrees in just 24 hours around Mt. Hood; a drastic change. Timberline should stay in the 20s, instead of around 50 today. The change isn’t as dramatic westside, but significantly cooler air arrives several thousand feet up over NW Oregon too.

That will do two things…increase the pressure gradient a bit across the Cascades (more wind), but the cooling overhead weakens the inversion. The combination of wind surging right over the Cascades (instead of just through the Gorge) and weaker inversion means that wind will spread out into many areas west of the Cascades. That “small hose” of air will be a “much larger hose”. Less wind IN the Gorge, but a lot more elsewhere. This is common…I’ve always noticed that when we get easterly wind everywhere in the metro area, it tends to be weaker than expected at Vista House. The highest resolution model available (WRF 1.33km) shows quite the drop in wind gusts from 10am today to 10am tomorrow around Crown Point. Notice the blue area (gusts 45+ kts) on today’s chart is gone tomorrow, replaced by widespread gusts 25-40 mph in the West Hills and east metro.

We will see how this works out, but it’s just something I’ve noticed over the years. Another way to look at it is the cross-section around the Crown Pt. area. Light wind overhead today, but strong easterly by midday tomorrow (around 2,000′). And weaker surface windspeed tomorrow compared to today

It’ll be interesting to see if we get a tighter gradient (10-11 millibars) tomorrow but weaker wind out there. We’ll see. Regardless, plan on a few power outages in the metro area, but another sunny day!


Long & rare November dry spell plus gusty east wind

November 14, 2022

10pm Monday…

You have to admit, the bright sunshine was spectacular today! As I was driving into work, the parkway was line with bright yellow/orange maple trees, finally donning their fall outfits 2-3 weeks later than normal. We should see 5 more days like today…that’s Tuesday through Saturday. Then the normal November rain returns

November started with a soaker, but now we’ve gone 7 days without rain, and 5 more are likely. That means we’ll end up with at least 12 consecutive dry days, the November record is just 13. So this long dry spell in November is quite rare. It’s interesting that happened in the 3rd year of a La Nina…November 2000.

The reason for the unusually dry weather is the return of that pesky upper-level ridge along the West Coast. Here’s tomorrow’s forecast of 500 millibar heights, about 18,000′ overhead. The flow is going well around us, north into Alaska and Yukon, then heading south into the Midwest…brrr!

By Friday, the pattern isn’t much different

But a well-advertised change occurs Sunday through Tuesday. Wet westerly flow punches through the ridge…the view on Tuesday

I think it’s safe to say the first half of Thanksgiving Week will be wet, but it’s too early to know if that will continue through the holiday weekend. The ECMWF ensemble 24hr rainfall chart shows the change very well. Each horizontal line is one of the 51 ensemble members…but they are all wet aren’t they?

So we’re headed into mild/wet weather NEXT week, but this week we’ve got the sunshine, plus a gusty east wind.

November through February IS the “east wind season” in our area. What does that mean and why? In the cool season the sun angle is very low and we don’t get much energy from that sun. So when weather systems with clouds/rain are blocked from moving overhead, long nights lead to cold air pooling in the lowest elevations. There happens to be a bit of a “bowl” in Eastern Washington and north-central Oregon. This is the Columbia Basin. That “bowl” tends to fill with cold air and then the weak sun is not able to warm it up due to short days. That cool airmass can grow quite deep, often up around 3,000-4,000′ deep. The dense/heavy air means an area of high pressure develops. This is a pretty good depiction of that cool/heavy airmass.

Of course it’s trapped by the Cascades, like a dam holding back water (except that it’s heavy air). BUT there is just one gap below 3,000′ through the Cascades between Canada and California. That’s the Columbia River Gorge. So that heavy air surges west through that narrow gap and then spills out into the flatlands west of the Gorge. There’s an additional item, remember the cold airmass in the central Gorge is typically 3-4,000′ thick, but it’s usually less than 2,000′ once it reaches the east metro area. So it’s a bit of a “waterfall of air” too. Wind accelerates and peaks just inside the west entrance to the Gorge. Peak gusts reach 50-70 mph many times in this area during the cool season and can peak up around 100 mph during very cold easterly flow when a low pressure area approaches from the southwest. The strongest wind I have ever seen in that area was the day before the big February 1996 flooding rains arrived. Temperatures around 10-15 degrees were accompanied by a 101 mph gust in Corbett on a high-quality wind sensor. Strongest wind is always a combination of large pressure gradients plus a strong inversion and unusually warm temperatures overhead. The 2nd highest wind event I’ve seen was in January 2009. Peak gusts reached 50-60 mph even into Gresham.

As you can see, the eastern metro area gets the brunt of the cool season easterly wind. Strongest gusts are concentrated east of I-205 near an south of the Columbia river in a typical setup. The wind goes away in spring when the stronger sunshine starts heating land effectively east of the Cascades; that’s in mid-late March.

Tonight the satellite picture shows the “cold pool” has developed nicely east of the Cascades (clouds in white). The X marks Portland.

That’s another feature of the cold season…low clouds and fog (depends on your elevation) stuck in the cold air eastside. Places like Hood River, The Dalles, Maupin, and Madras can sit under gray low clouds for a week at a time. Yet Timberline and Mt. Hood Meadows will be in warm sunshine. During these inversion events you want to head UP to find warmer temperatures.

By the way, there’s no sign of a cold spell or lowland snow in the next two weeks. I think we are clear for Thanksgiving Weekend. Notice almost no ECMWF (Euro) model members produce any snow in Portland through the end of the month.

That’s it for now…enjoy the sunshine and try to stay out of the wind!


Weather Blog Note

November 7, 2022

This is the “legacy” FOX12 weather blog site.

Nowadays I post to our station website, then when I have time I copy the post to this site.

Since this is a simple copy/paste, you’ll notice occasional formatting errors, or extra large/small text. You also can’t click on most images to take a closer look since it’s a simple copy/paste.

The reason for this is that with a company change we’ve moved to new blog composer. I like the new one much better so I write over there and then copy here for future use/research. I strongly encourage you to bookmark/use this site: https://www.kptv.com/weather/blog/ And I thank you for reading all these posts for the past 17 years!


About that Sunday snow…plus lunar eclipse tonight and drier weather ahead

November 7, 2022

2pm Monday

Yesterday was a strange weather day, nestled in a chilly & wet weekend. I have been sick since late Friday, so I was actually in bed much of Sunday. Nothing serious, and I’m on the rebound so I’ll be back at work this evening. But I want to recap the surprise snow to some lower elevation spots during the daytime Sunday. To get snow to the valley floor on November 6th? Everything has to be exactly right for that to happen.

You may recall we had the atmospheric river and initial cold front pass through Friday and Friday night, models just nailed that one with about 2″ rain in the center of the metro area and 8-10″ in the wettest parts of the Coast & Cascade ranges. Then we were in the scattered showers behind the front Saturday; an uneventful weather day.

A cold front was forecast to move onshore Sunday morning and this would be the leading edge of cooler air. Snow levels would come down to around 2,000′ at times Sunday (the forecast), and 5-10″ would fall in the Cascades. That DID happen. Models were also forecasting very heavy rain to fall south of the Portland area down into SW Oregon with yesterday’s system. Note the rainfall forecast with very heavy rain south of Salem and down to about Roseburg. This is from the WRF-GFS model. That DID happen

Then notice the snowfall forecast for 4am Sunday to 4am Monday…almost all of this was expected before sunset Sunday when precipitation changed to showers.

A closer view shows that there would likely be spots with snow below 2,000′. This forecast would imply anyone could see snowflakes mixed in and it could stick down to 1,000′ in the Cascade foothills around Silverton, Mill City, & Sweet Home. That DID happen.

So there were hints that snow could fall down to at least 1,000′ as the cold front slowly moved south. But it’s very tough to get snow down to the valley floor anytime, and really tough so early in the cold season.

What Happened?

This was another case of extremely heavy precipitation dragging the snow level all the way down to sea level (or the valley floor) under calm conditions. In 3 hours, Corvallis and Eugene both picked up about 3/4″ inch of rain, and Salem saw 1.13″! Portland’s rainfall was less intense, at .55″ in 3 hours ending at 10am, although temperature did drop to 40. The heavy precipitation caused the sticking snow level to drop 1,000′+ lower than it “should have been”. This happened during the April 11th snow event, and our first snow event back on December 18th last year when 0.5″ fell in Portland on a soaking wet Saturday night. Except models caught the change to snow ahead of time during those two events. This time they did not. Sometimes it’s called an “anafront” as well, when most precipitation occurs on the back side of a cold front. Looking back at maps, I don’t even see an obvious signature this could happen. The wind WAS forecast to go mainly calm in the valley. One other complication yesterday was that the Portland radar seemed to be having some issues which made diagnosing what was going on difficult. You can see the WRF-GFS did imply wind wind go calm at Corvallis (circled area around 10am-4pm lowest part of atmosphere). Then southerlies would resume during the night and lift the snow level again. That DID happen. Most of us warmed during the night at the lowest elevations

This isn’t a perfect map, but at least those that reported snow to the COCORAHS network. You can see the snow reports in the southern valley, mainly up against Coast and Cascade range foothills

To summarize…1-5 degrees can make all the difference under heavy precipitation, calm wind, and a relatively low snow level. Magical things can happen, but most times nowadays the highest resolution weather models will catch that “magic” ahead of time. This time they didn’t.

What’s Ahead?

Much drier weather is ahead! How quickly the mood has changed; 4 months of dry weather followed by 2 weeks of wet and I’m already excited by a dry spell. At home in the western Gorge I’ve picked up over 10″ of rain since the dry spell ended. Portland has seen 6″; things are soaked nicely…

The cold upper level trough overhead…

Will slide east of us and be replaced by an upper-level ridge and a sort of “split-flow” later in the week.

This means if any systems make it through the ridge, they will be weak with respect to rain/wind/snow. This is generally a very “boring” weather pattern for meteorologists, but good for regular folks that don’t want weather to mess up their life.

https://889c5c4a6f57e35c7fe84ff00b8b34d0.safeframe.googlesyndication.com/safeframe/1-0-39/html/container.html

A fun/neat chart below shows the dry spell the rest of this week (after this evening’s showers) and mainly dry for at least part of next week.

It’s 6 hourly precipitation for the next two weeks based on the 51-member ensemble ECMWF model. Each horizontal line is one model run (each 12 hours) and the latest is at the bottom. Taking a look at that bottom line, I’ve boxed in this work week and next (1 & 2). Little/no chance for rain the rest of this week, and just light amounts for next week. Remember these numbers are averages of many ensemble members, so if just 5 of 51 members show rain on a certain day, for example Monday of next week, it’ll just show light amounts. You can go back 3 days worth of model runs (boxed weeks up above) and see how the model has gradually dried out this week’s forecast as we get closer.

Temperatures will be a bit cooler at night as drier easterly flow develops this week. Not any sort of arctic chill, but long overdue frost for outlying areas. Mid-20s wouldn’t surprise me in the colder suburbs within the next week and finally some sub-freezing temps in the city either Wednesday or Thursday morning. East wind does not look especially strong for this week, just the usual areas near/in the western Gorge turn windy. But that’s normal…it’s November.

Total Lunar Eclipse Tonight

It’s nothing like a total SOLAR eclipse, but we get to experience another total lunar eclipse in the middle of the night. We typically get 1-2 a year. I’ll be asleep, but if you are awake, the moon will be fully eclipsed in earth’s shadow from around 2:15am to 3:45am Tuesday morning. It may be visible since clouds will be breaking up a bit during the night. Cloud cover forecast says all hope is not lost…partly cloudy across much of the region

Cloud cover forecast for 1am Tuesday
Cloud cover forecast for 1am Tuesday(KPTV)

I borrowed this graphic from a sister station. SUBTRACT TWO HOURS since this is showing central time.

Eclipse timeline for SWLA
Eclipse timeline for SWLA(NASA)

First rainy/windy system of the season will be followed by unusually chilly November temps

November 3, 2022

8pm Thursday…

It’s about time for a blog post! I’ve been very busy the past few weeks; meetings, school visits, new weather branding (more on that below), and working on graphics. Plus we’ve added some time to our evening broadcasts, so…real busy. I strongly recommend you follow me on Facebook @marknelsenweather and Twitter @marknelsenKPTV because I regularly post on those platforms. Plenty of maps, models, and thoughts when I’m working on those sites. Blogging takes quite a bit longer, I need a good chunk of quiet time to do this…my kids would say that’s “because I’m a boomer”. Whatever.

QUICK RECAP OF RECENT WEEKS

October DID end up as Portland’s warmest on record, as did September, and August. All 3 were Portland’s warmest. Of course August was also the hottest of ANY month. We ended up with 12 days at/above 80 degrees (yellow outlines below) and even with the sharp change to cooler/wet the last 10 days of the month we STILL ended up about 6 degrees above average!

I had some people ask me either on social media or email if “the rain will ever come back this winter”. Most likely new transplants; the rain ALWAYS COMES BACK. And that happened in late October. That’s why I somewhat ignored those that were complaining about the 4 months of mainly dry weather. Yes, fires were starting to pick up again after the showers in late September, but we avoided a big east wind episode that could have led to lots of trouble. We ended up with close to normal rain by Halloween evening. And sorry about that Halloween soaker; those have been rare lately

WHAT’S AHEAD

The cooler weather and lots of rain hasn’t surprised me at all. But now it appears we’re headed toward much cooler than normal weather next week. If models are correct, this will end up being the most dramatic change I’ve seen in the fall; from 80s to highs in the 40s (or colder?) in just a few weeks.

Tonight we’ve got an atmospheric river setting up across the region. That’s due to a strong westerly jet stream approaching the coastline. This is the view from jetliner altitude tomorrow…about 30,000′ or so

Then Saturday…a 200 mph jet stream right over us!

Then by Monday a deep upper-level trough has dipped south out of Canada and is just offshore. That’s cold. So we get lots of rain through tomorrow night, then showers Saturday, a colder/wet system Sunday, then back to scattered (even colder!) showers Monday.

THE RAIN

How much rain? Models have backed off just slightly the past 24 hours. This will be mainly a “nuisance” rainfall in the lowlands, especially south and west of Portland. A collection of model forecasts

And the highest resolution model available to local meteorologists; the UW 1.33 km WRF-GFS (from the Huskies of course!). You can clearly see a very sharp rain shadow in the lee of the Coast Range. Less than 1″ around Hillsboro tomorrow, but up to 2.50″ central/east metro areas. I could see some water over a few roads if we do get 2.00″ or more in spots. Heaviest rain will be in the evening.

(kptv)

Another view of the heavier rain in the aptly named “Waterfall Corridor” in the Gorge.

THE WIND

A gusty southerly wind will accompany the atmospheric river/pineapple express tomorrow. That’s normal for these events and in this case it won’t be TOO strong. I think gusts 30-40 mph are likely in a few spots anytime tomorrow. Wind will come and go all day, but should be strongest in the evening just before the cold front passes through between 8-11pm. Normally that would just give us some isolated outages, but there’s a complication this time. You’ve probably noticed leaves have been very slow to change or drop off this year, due to the record warm 1st half of fall. So we’ve got a bunch of extra “wind-catchers” on the trees and I can see that adding to the outage count tomorrow. Regardless, especially if you are in a rural area, keep in mind the power COULD go off in your neighborhood tomorrow.

FOX12 FIRST ALERT WEATHER

For over 15 years at FOX12 we’ve used the branding “First Live Local” for our weather forecasts. It’s been time for a change for quite awhile, plus we are now part of the Gray Corporation. It’s nice working for a company that owns lots of TV stations and knows what it’s doing. So, we’ve taken on the First Alert Weather branding that most other Gray stations use. And I think it’s a good change. I’ll admit that sometimes I get a bit lost in the “meteorological weeds” during a weathercast and this will help focus things a bit more with most important information right up front. Apparently you can teach an old dog new tricks…

When a specific day shows up that really sticks out weatherwise (tomorrow?) we’ll draw your attention to it by marking it as a “First Alert Weather Day”. If we do it right, these should be days in which weather will significantly disrupt your plans or day. Tomorrow is a bit marginal for that; we’ll see how many outages we get and whether local flooding shows up in spots. We have specifically avoided using the terms WATCH, WARNING, or ADVISORY because those are used by the National Weather Service. This is NOT a replacement for those official watches/warnings/advisories! You can learn a bit more from this 2 minute video: https://www.kptv.com/2022/11/02/first-alert-weather-new-way-stay-ahead-weather/

COLDER WEATHER AHEAD

That cool upper-level trough I mentioned earlier drops down along the West Coast and sits there Monday through Wednesday. 850mb temps bottom out around -4 to -6 C during that time; unusually cold for early November. Typically that’s around 1,500′ to 2,000′ snow levels. That’s with onshore flow. But during that time next week, we get a cool north or northeast wind as a cold arctic high pressure area will be sitting over SW Canada.

The low level airmass will also be unusually cold, including north of us. Here’s a Wednesday morning forecast temperature map; keep in mind anything under about -17 (C) on this map is 0 (F). Very unusual to have temps around zero degrees in early November just north of the U.S. border.

With that chilly air filtering south, snow levels COULD dip all the way to sea level. But at the same time it appears we’ll likely be dry from late Monday through at least Wednesday next week. So I’m thinking sticking snow down to sea level is unlikely Monday through Wednesday. It’s a bit too warm still Monday morning, but then when it WILL be cold enough Tuesday/Wednesday we’ll probably dry out. Now later next week, we could see moisture return. Each model is different with timing so we’ll see what happens. Remember that it IS possible to get snow or freezing rain as we head into mid-November. In 2014 freezing rain made it all the way into the central part of the metro area on the 13th!

That’s it for now. Our forecast looks like this…with high temperatures 10-15 degrees below normal Monday-Thursday next week. Stay Tuned!