Rain arrives on schedule; the numbers so far and how much more you can expect

9pm Monday…

I woke up today, looked out the window, and saw just about what I expected. It was a gray, wet, and cool late September day. For at least this week it IS nice to see all our vegetation getting a soaking. And local stinky/stagnant ponds and creeks are freshening up too.

So far we’ve seen quite a soaking west/south metro, not so much eastside. Look at the difference from west to east. This is opposite of what we typically see (heavier rain up against Cascades). That’s because a cold front lingered over the westside much longer

Metro rain so far today(kptv)

Going back to Saturday midday when the rain started, the numbers look like this

(kptv)

So now Portland has seen it’s first soaking of the season. Usually it happens in mid-late September, so the timing is pretty darn normal. There won’t be any October 2022 repeat this year. Remember numerous fires burning in the mountains through mid-month?

(kptv)

Most interesting is that one of the heaviest totals I can find in western OR/WA is right AT the most active fire. The Anvil Fire has burned about 22,000 acres just east of Port Orford. In the past few days 3-4″ rain has fallen in that spot; nice timing.

(kptv)

We will be in a showers/sunbreaks pattern the next 3 days. That should produce another 1.00″ of rain

(kptv)

Tomorrow night an organized cold front moves onto the coastline for a few hours of steady rain. There will be surface low pressure center that slides up the coastline, producing southerly gusts 40-55 mph on the beaches. Maybe even a few power outages out there. Here in the valleys the gusts should remain below 35 mph

https://ebfce610c47522d2aa5ba225dc5573bd.safeframe.googlesyndication.com/safeframe/1-0-40/html/container.html

(kptv)

When is the next break from the rain? Most likely (if not Friday) Saturday and Sunday will be dry. Possibly next Monday as well. If we get lucky we’ll see 4 dry days Friday through Monday.

That’s it for this evening. Enjoy the wet fall weather!

Rainy week ahead, bomb cyclone offshore, and surprising fire season numbers

9pm Friday…

Hopefully you took care of everything you wanted to get done before the first round of fall rain hits this weekend? The good news is that the first half of Saturday should be dry in the I-5 corridor, and even later Saturday won’t be too wet. But that changes as we head into early next week.

HIGHLIGHTS

• Rain this weekend will be quite light, and mainly confined to Saturday PM and midday/PM Sunday. I expect maybe just .10″ rain by sunset Sunday for many of us
• A huge storm develops in the Eastern Pacific tomorrow night through Sunday night, but it’ll be 500+ miles offshore. So no high winds from this first “bomb cyclone” of the season.
• Rain totals by the end of next week should be in the 1″ to 2″ range in the western valleys; enough to give the top few inches of the ground a soaking.
• We have avoided a dry/dangerous east wind episode early this fall. Whew! Once several inches of rain falls in the mountains in late September and early October, the soil/fuels won’t be drying out like we see in summer.
• Early-mid next week may feature one or more days with scattered thunderstorms and downpours. Someone may pick up a lot of rain in a short period of time

Today was AMAZING, considering the cool/showery weather ahead. PDX hit 79 under totally sunny skies. That’s not happening for at least 8-10 days. Forecast is on track for the next week. A quick animation here shows the next 10 days up around 18,000′. Lines represent upper level flow, colors are “height anomaly”. Basically warm colors are higher than average heights on this 500mb chart, cool colors lower than average. Notice a big upper level trough develops just offshore this weekend, sticks around all of next week in one form or another, then disappears the first few days of October. Then it’s replaced by weak ridging. This is an “ensemble average” from the Canadian model.

(kptv)

As the trough suddenly deepens this weekend, at the surface a “bomb cyclone” forms Saturday evening through Sunday evening. The criteria for that is a pressure drop of at least 24 millibars in 24 hours. In this case that’s around 992mb to 964mb on the Euro model. The lines are surface pressure contours

(kptv)

Bomb cyclone sounds dramatic, but they develop regularly in the North Pacific during the cooler part of the year. Luckily this one is so far offshore that most of our coastline sees gusts no higher than 30-40 mph on Sunday and Sunday night. The flow is a little bit too much out of the southeast which doesn’t help (if you want strong wind). Notable is some easterly wind coming down off the Cascades in spots.

(kptv)

Following the cold front this system, an unstable atmosphere moves overhead Monday. That should be the first of possibly 3 days featuring scattered thunderstorms. Keep in mind we can get some big downpours in early fall since a warm-ish atmosphere can hold quite a bit of water! Also remember that funnel clouds can appear in spring/fall with these convective showers. If you even have video/pics to share, you can submit them through our app OR go here: https://www.kptv.com/page/submit-weather-photos/

Have you wondered if Septembers are getting wetter or drier? I can’t find a clear trend over the last 100 years. Each year on the chart below is a blue bar, and the 15 year average is the line. Some Septembers are very dry (last year), and some turn quite wet. Often the really wet stuff is in the 2nd half of the month like this year

(kptv)

I doubt we’ll get into the top 10 wettest Septembers since we’re starting near zero right now

(kptv)

By the way, this fire season’s acreage count is far below normal. Quite impressive for a hot summer and an early/dry start to the summer. I don’t expect any major acreage increase heading into early October as this upcoming rain moistens even the large fuels in the forest

(kptv)

The weather team had a great discussion about the upcoming pattern during our weather podcast today. If you subscribe, it should have already dropped into your feed

(kptv)

We are now adding graphics to our podcasts, so it’s probably better to watch the video version nowadays. You can always find it on our weather page at KPTV.COM right here: First Alert Weather Podcast The first player on the top has the audio version, 2nd one (bottom) is the video version.

That’s it for this evening. Enjoy the dry parts of the weekend and…make some soup for a showery Sunday afternoon

What follows four months of dry weather? A much needed soaking on the way next week!

You’ve likely forgotten, but late spring was very dry in the Pacific Northwest. Almost no rain fell after the first week of May, then just under 1″ total in June. The dry season started early this year so all our native vegetation (trees/shrubs etc…) NEED a good soaking. I believe part of the color change we are seeing on some local trees is due to drought stress. Last year we didn’t get a soaking until the 2nd half of October; luckily this year we’ll get it 3 weeks earlier.

KEY POINTS

• This is NOT the beginning of the wet season, but a much-needed soaking on the way starting later Sunday
• Assume most (or all) days next week will be wet. A total of 1″ to 2″ rain is likely by the time September ends in the I-5 corridor from Longview to Eugene.
• Expect a lot of clouds and highs in the 60s/70s next week
• This weekend? A few light showers Saturday evening, then possibly much wetter later Sunday through Sunday evening. Timing of significant rain Sunday is still up in the air. Hopefully it’ll be late in day
• It appears we will probably get through this fire season without a dangerous east wind episode. A Public Safety Power Shutoff is far less likely in October after we get soaking rains in the forest
• Fire season itself will be dwindling away, on life support after next week. Good news! We have avoided another big fire season even during a very hot/dry summer. It’s all about timing of cooldowns, lightning, and hot spells

This graphic shows estimated rainfall just through Tuesday afternoon at PDX

(kptv)

Make sure you enjoy the next few days, Thursday and Friday look like amazing early fall days as the jet stream remains up north

Wx Blog(kptv)

But then quite a change by Tuesday as a large trough is moving onshore

Wx Blog(kptv)

Ahead of this trough a moist/warm southwesterly flow sets up Sunday and Monday. Precipitable water values go WAY up as an atmospheric river snuggles up against the coastline. This isn’t a “real” atmospheric river we typically see that lingers for 1-3 days and brings flooding; just a passing cold front that’s “juiced up” a bit. Last cool season we had something like 60 atmospheric rivers impact the PACNW…the definition is a bit loose!

(kptv)

A 2nd upper level trough likely drops in later next week. The operational Euro thinks that happens next Thursday/Friday. This looks wet…

(kptv)

The 24 hour precipitation forecast from the Euro ensembles is very nice nowadays after the upgrade to 9km resolution. Here’s the chart; each row represents ONE of 51 ensemble members. Hard to find a dry 24 hour period for at least a week starting Sunday.

(kptv)

Another way to look at it? Use the 4 day rainfall total (ensemble average) through next Wednesday afternoon. In previous cool seasons these numbers have tended to be too high at times. We’ll see if higher-resolution modeling and terrain help this time around

(kptv)

If we get 1-2″ (or more) rain in the last week of September, that won’t be unusual. Check out the 10 wettest “final days” of September. I remember that soaker in 2013!

(kptv)

To wrap things up, we almost always get a soaking around this time of year, but it USUALLY doesn’t mean we’re into wet weather for the long haul. Of the top 5 years above, only two (1940/1951) featured a wet October. Most Octobers see significant dry spells. So hopefully we get a good soaking and then some nice sunny weather to follow

Summer recap, plus hints of a wetter pattern ahead

9pm Thursday…

Meteorological summer ended on August 31st, but it takes a week or so for all the data to arrive. I’ve collected all the highlights for you here. Plus a look at rain possibilities follows

SUMMER HIGHLIGHTS

• The unprecedented stretch of warm/hot summers continues. We haven’t seen a cool summer in 12 years. Global Warming/Climate Change is making itself felt around here!
• It was the 3rd, 4th, 5th, or 6th hottest/warmest summer on record for most of us, depending on location
• We are in the middle of another unusually long dry period, less than 2″ rain in 4 months!
• The warm/dry season started very early this year, in mid-May
• Fire season has been reasonable considering the hot/dry. Luckily showers/cool followed a couple of lightning outbreaks

Every summer I think “maybe this will be the one summer that’s cooler than normal”. It hasn’t happened since 2011 and sure didn’t happen this year. This chart shows the average of western valleys climate stations over the past 100 years. The swing upward started around the mid 1980s, but really ramped up around 2013.

(kptv)

The numbers for Portland look like this, note the warmest August and month since records began at PDX in 1940

(kptv)

It was our 3rd warmest summer on record. Of course some of that was propelled by another summer of ridiculously warm nights. We are only two warm nights away from the all-time 60 degree night record.

(kptv)

And as of this evening we’ve seen 25 days at/above 90 degrees

(kptv)

I sometimes get comments such as “well, Portland is a huge urban heat island and it’s not representative of other areas”. That’s partially true, but the heat this last decade-plus has been widespread, including rural and coastal locations

(kptv)

Most notable to me is Corvallis. It has often been held up as a good climate location; removed from urban areas and a long history back into the late 1800s. 2023 has been the 3rd warmest summer there. You see #1 and #2 were both in the past 10 years. Even these long-term sites can have errors. According to the record books, Summer 1915 was warmer than this summer in Corvallis; but I noticed there was quite a temperature spike that summer that doesn’t exist at other Willamette Valley stations. Our state climatologist Larry O’Neill shared the observer form from August 1915 at that station. Yeah…no. Was the observer on vacation and his/her friend filled in, just adding in the 11am temperature as the low for the day? Who knows. But I’m quite confident there weren’t 3 nights with lows in the 80s! The result? I’m ignoring 1915 in Corvallis

(kptv)

Something did change back around 2012-2013 that’s giving us hot summers, but what? Notice the 75 year change in summer temps is strongly upward in the western USA; that’s not the case in the central USA. Summers haven’t changed much there. A climatologist from Alaska shared this on X (Twitter) today

(kptv)

As of today we’ve hit 90 or higher 25 times this year in Portland

(kptv)

Alright, that’s it for summer talk

HINTS OF A WETTER PATTERN

Most years we get some sort of soaking (more than 1/2″ rain) at some point in September. Last year was unusual in that the dry spell extended into mid-October.

https://87aa9bf09ebe2d016656b02b2ee6cc67.safeframe.googlesyndication.com/safeframe/1-0-40/html/container.html

(kptv)

A weak upper-level trough swings through the region next Wednesday and that should provide at least a few showers. But it’s passing through quickly which limits rainfall. More likely something is up about 10 days from now.

Here’s an interesting product that shows 24 hour precipitation forecasts from 51 different ensemble members of the ECMWF model. It’s showing the average of those ensembles. It also shows the model trend over the past 5 days, or 10 model runs. Time goes from left to right. Thick black line is right now. This morning’s run is the lowest row. The run from 5 days ago is the top row. This graphic is a great tool because you can see how the model is bringing in or taking away precipitation as time goes on. For example, at one point (for 3 model runs), it was hinting at a few showers Monday, but then over the last 3 runs that has gone away. What HASN’T changed is around the 23rd/24th (NEXT weekend). Notice a wetter period continues to be forecast starting at that time. When we see a model (other models too) consistently forecasting a change like this…we notice.

(kptv)

That’s it for this evening. Tomorrow will be hot again and then we’ve got a comfortable weekend on tap. Enjoy it because that following weekend MIGHT be much different with rain/clouds. We will see.

Perfect early fall weather ahead; plus fire season update and hot summer stats

7pm Tuesday…

September is here and the weather looks amazing most of the time over the next week or so. I was out of town most of Labor Day weekend so I missed the great lightning show across the south and southwest metro area. This was just one amazing shot from Annie Snyder in West Salem. Setting sun was behind her, rain to the east with the (double) rainbow, then lightning thrown in as well. What a catch!

Thunderstorm in Salem 9/2/2023(Annie Snyder – West Salem)

These were very wet storms that brought up to 1″ of rain in some of southern/west metro spots. Nothing fell in the city of Portland

(kptv)

But the big rain was along the Marion/Clackamas county line from Scotts Mills up Butte Creek. Some spots picked up 1.50″ or more. Large hail (up to 1″ size) accompanied those storms

(kptv)

WHAT DO WE SEE THROUGH MID-MONTH?

1. Comfortable, warm days and cool nights are likely through the 15th. Expect lots of days in the 75-80 degree range
2. Most days will feature mainly sunny or partly cloudy skies; no sign of long gray periods ahead
3. Little or no rain falls through the 15th
4. No sign of a hot spell OR dry/dangerous easterly wind for at least the next 8 days.

Basically we have a dependably warm/dry period for at least the next 10 days. Enjoy!

BRIEF SUMMER RECAP

I’ll publish another post later this week or early next when all the summer data comes in. But I think we all know it was another hot one. Meteorological summer ended August 31st. August 2023 was the warmest month on record in Portland, just barely edging out LAST August. Notice the theme…most of them have occurred in the last decade (in yellow)

(kptv)

Some other stats:

PDX: 3rd hottest summer. All 5 hottest summers have been since 2018

SALEM: 4th hottest summer, 2021 and 2022 were #1 and #2

REDMOND: 4th hottest summer

ASTORIA: 6th warmest summer, 2015 and 2016 were #1 and #2

We’ve picked up 24 days at/above 90 in Portland, the third consecutive summer to do so

(kptv)

WHAT’S AHEAD

Upper level troughing the past few days has given us cooler temperatures, cloud cover, and light showers. That changes heading into the 2nd half of the week. Here’s the 500 millibar (18,000′) pattern right now…

(kptv)

Notice the troughing goes away by Saturday and is replaced by a stronger system sitting in the Gulf of Alaska; we’ve got a nice 2nd weekend of September on the way!

(kptv)

A weak disturbance swings by later Sunday and Monday. It’ll only give us more clouds, cooler temps, and a shower chance

(kptv)

But it’s right back to upper-level ridging along the West Coast much of the rest of next week. Here’s the view from the ECMWF model NEXT Thursday

(kptv)

The result is that we’ll see very little rain through mid-month. Only a few scattered ECMWF ensemble forecast members produce .10″ rain in the next 2 weeks.

(kptv)

This is the time of year when the rain chance starts to pick up. Here’s one way of showing the increase

(kptv)

Or…how about the first time we pick up at least 1/2″ rain in September or October? Often it’s by the 2nd/3rd week of September. Except last year we waited until the 3rd week of October; that’s very rare

(kptv)

FIRE WEATHER

The first round of thunderstorms that last week of August started numerous forest fires over/west of the Cascades. We are VERY fortunate that temperatures cooled right after that time. Some showers have fallen in the mountains, and there’s no sign of a dangerous hot/dry easterly wind for at least another week. Take a look at the nearly smoke-free skies across Oregon this afternoon

(NOAA)

16 large fires are burning in Oregon, during most of August there were only 4. Yet less than 100 acres burned in the past 24 hours; most of them are just smoldering or burning slowly. With dry weather ahead, it’s fair to assume fire activity will pick up a big more in the next week. I don’t see any additional lightning outbreaks = good news!

(kptv)

MOST Septembers/Octobers we don’t see much fire smoke in the metro area; but we all remember when it DOES happen! Each horizontal line here shows maximum PM 2.5 concentration for the past 24 years in September/October. Notice we’ve had 3 “events” during that time: Eagle Creek Fire (Gorge) in 2017, Cascade Mega-Fires in 2020, and last year’s October fires in the Cascades. Notice the general decrease in air quality each October; that’s the beginning of fall inversions = more pollutants trapped in the lowest atmosphere.

(kptv)

That’s it for this evening…enjoy the sunshine!