Stable and warm summertime weather pattern here to stay

9:30pm Sunday…

Our last weekend of June was just perfect, at least in my very humble opinion. Full sunshine, plus warm, but not hot, afternoon temperatures. Lows in the 40s & 50s. It’s like “old Portland” summer climate. No need for air conditioning in this weather. Keep those windows open. Quite a nice warmup after the chilly weather one week ago. Notice that we’re running just a bit above normal for the month in Portland

(kptv)

Temperatures will be a bit cooler the next two days with a marine push this evening bringing in that cooler ocean air. Expect spots of morning clouds but likely no drizzle inland. Some would also say 75-78 degrees with morning clouds is just perfect too.

A glance at the pattern overhead shows that weak upper level low still lingering over the region; that’s why we aren’t seeing any heat and thunderstorms have been firing up each afternoon over/east of the Cascades. That continues for another couple of days. This is the view at about 18,000′. Warm colors are “higher than average” heights for this date. Those are areas with ridging, cooler areas are troughs

(kptv)

By Friday, that upper-level trough has finally departed, and warming has resumed overhead. It’s getting warmer and the marine layer is thinning. We’ll be back in the 80s starting Wednesday, or Thursday at the latest.

(kptv)

By the first weekend of July, that ridging has strengthened quite a bit. These is the ensemble average from the Euro model. Heights up to around 588dm generally mean hot weather west of the Cascades. Although the ridging is a bit “flat” which leads me to believe we don’t get hot/dry east wind next weekend.

(kptv)

At this time, models are not implying that hot ridging will stick around long. Notice that 10-12 days from now, Thursday the 6th, the ridging has weakened and/or moved westward.

(kptv)

So the big question right now is whether we have our 2nd heat wave of the season (3 days at/above 90 degrees) on the way starting next weekend? Possibly

(kptv)

This afternoon’s GFS model was an excellent example showing why we heavily lean on ENSEMBLE model forecasts and not OPERATIONAL model forecasts. The 18z GFS produces highs 105-110 next Monday/Tuesday. Right…

(kptv)

The ensemble average is much more reasonable, showing highs around 90 Sunday through Tuesday the 2nd-4th

(kptv)

Other models are showing similar numbers with the warming this weekend and early next week, then cooling a bit. I checked the ECMWF ensemble runs and see 5-10 (out of 50) members have extreme heat during that same period. Something to keep an eye on, but a low risk as of this evening.

Summer Dry Spell Is Here

Portland will end up with a drier than normal June, after a dry May. Luckily we had that inch of rain a week ago because it’s clear there’s no sign of rain heading into the first week of July. Look at the GFS ensemble average rain forecast through the 4th of July…nothing. Just scattered thunderstorms east of the Cascades

GEFS Rain Forecast(kptv)

And the operational ECMWF is the same

ECMWF Rain Forecast(kptv)

In fact check out the Euro ensemble 24 hour rain chart for the next two weeks. Almost totally dry. We’re done with “spring rains”. Those of you that didn’t get much last week? In reality your summer dry spell DID start in mid-May. Let’s hope for a rare late August soaking…

(kptv)

https://a086c2725306bc9c842c1eb9336c0df6.safeframe.googlesyndication.com/safeframe/1-0-40/html/container.html

That’s it for this evening. We’ll keep a close eye on the heat possible heading toward the 4th, but at this point I don’t see any sort of significant heat wave.

To summarize…

1) Most likely no rain falls in the I-5 corridor between now and at least the 5th of July. Of course any sort of thick marine layer can produce drizzle, but I don’t see that for at least a week.

2) There is a POSSIBILITY of at least a minor heat wave (3 days at/above 90) in the next 10 days. If it happens, it’ll be around the 2nd-4th.

3) The chance for a significant heat wave looks minor at this point, but it IS a small possibility. Watching closely!

4) A stable summer weather pattern is in place…good for your tomatoes/veggies, and water play over the next 7-10 days.

A nice soaking includes waterspouts, tornado, hail, & thunderstorms. What’s ahead heading into late June

10pm Monday…

When we have “upper-level lows” overhead in spring, summer, or fall, we tend to get vigorous showers. And sometimes they include thunder, hail, and funnel clouds. And every once in awhile a tornado spins up as well. We’ve seen ALL of that Sunday and today as heavy showers mixed with sunbreaks both days.

First, the rain. Check out rain totals since it first showed up Saturday night. Notice central and east metro area picked up the most rain. And some western Willamette Valley locations (Banks and Forest Grove) picked up only a tenth of an inch or so.

(kptv)

That brings June up to normal rainfall-wise at PDX, but I don’t see much for at least a week. Then the waterspouts. One was seen over the Columbia River near Camas Sunday morning

Then a couple more seen off Cannon Beach this morning around 10:30am

Cannon Beach waterspouts; Monday 10:30am(Credit: Kane Degerstedt)

Portland NWS also says a spotter saw 5 different waterspouts during this time!

I’ve seen several pics of funnel clouds as well. This one near Pacific City (inland).

Pacific City funnel cloud(Credit: Kristen)

One of those funnel clouds did touch down and become our first tornado of 2023. Just an EF-0 event with no damage. It was about 5 miles east of Harrisburg in the Willamette Valley

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This is (sorta) tornado season in our area. It’s spring and fall. I just re-checked the stats for tornadoes from 1950 to 2022 in our area. That’s SW Washington and NW Oregon counties only. From Lewis Co. in Washington down through Lane Co. in Oregon.

(kptv)

Then the hail, quite a storm passed through outer SE Portland and then down into Happy Valley and Clackamas. That was yesterday. I didn’t see any reports of significant hail today.

What’s Ahead?

1. Summer is returning; remember that until these last 3 days we’ve had an amazingly warm/dry late spring. Expect that same weather to return beginning Wednesday
2. There’s no sign of rain after early afternoon Tuesday. Most likely we’ll be dry until at least next Monday/Tuesday
3. But I don’t see a heat wave either. Just a bit warmer than normal temps for late June

The big picture shows that chilly upper-level low right over us tonight. This is the 1 day average 500mb height

(kptv)

The trough splits apart and atmosphere warms overhead. By this weekend the trough is gone and a new one has developed off the California coast.

(kptv)

The warm colors represent higher than normal heights = warmer than normal typically. There are hints that trough may try to get closer about 8-10 days from now. Here’s the Euro ensemble forecast for Wednesday the 28th

(kptv)

And the 24 hour rainfall forecast shows many ensemble members producing some sort of showers during that time (circled)

(kptv)

So our forecast looks quite nice over the next week; plus this coming weekend will be MUCH warmer than the weekend we just experienced.

Portland’s 7 Day Forecast(kptv)

I’ll be headed to the 50th AMS Broadcaster’s Conference the rest of this week, although I’ll be back on-air this weekend. Jeff and I plan on a fun podcast from the conference this Thursday or Friday. Make sure you tune in for that one or look for it in your feed

Cool and showery weather pattern returns for first time since early May

8pm Tuesday

For the first time in many weeks we’ve got at least a few days of cool/showery weather ahead.

KEY POINTS

• Other than a spot of drizzle, the first real chance for showers shows up on Father’s Day. Most likely we’ll see the showery weather through Tuesday.
• At this point, it appears we’ll see 1″ or less rainfall during that time. Possibly only 1/4 to 1/2″. We’re not going to make up our 5 week long rain deficit during this time.
• There’s no sign of hot weather for the next 7-10 days. I don’t see a heatwave through at least the 22nd

WHAT’S AHEAD?

We’ve been very dry the past month. In Portland we’ve seen less than a tenth of an inch of rain since mid-May! By Thursday, it’ll be the driest mid-May to mid-June on record in the 80 year period of record at PDX.

(kptv)

Another way to look at it? Much of the metro area has seen less than 1″ rain in the last 7 weeks! That’s late April to mid-June. Your lawn needs about 1″ rain each week during the warm season.

We’ve had a long stretch of warm weather too. Only six days in the last month have remained below 70 degrees, quite a feat for May and early June in our climate.

The last month in Portland(kptv)

Not much changes the next 3 days, yes a bit cooler tomorrow after a dry cold front passed through today. But then weak upper-level ridging over us Thursday and Friday (the image below).

(kptv)

A cool “upper level low” drops down out of Canada and into the Pacific Northwest by Sunday. This is a classic cool and showery setup for us. Typically we see showers mixed with sunbreaks, maybe hail or thundershowers too. Unfortunately it starts on Father’s Day

(kptv)

By the middle of NEXT week, that upper-level trough has moved off to the east and another one is developing offshore. In this setup our weather improves quite a bit; high temperatures at least back into the 70s or even a bit warmer

(kptv)

We don’t know yet whether that next trough swings in over us for another round of cool showers around the 22nd-25th. There are hints on the Euro ensembles that could be the case. See the negative height anomaly just west of us the weekend of the 24th/25th.

(kptv)

But that’s just one model and way out there in time. Of more interest is how much rain could we see Sunday through Tuesday.

Looking at those ensemble forecasts again for Portland, there’s no 24 hour period (from the Euro) with more than 0.20″. That’s the average of all those ensemble members.

(kptv)

Another way to look at it is the “QPF Plume” product. It shows the total rainfall over Salem the next 15 days from those ensembles as it adds up over time. The green line is the average; maybe .30 to .40″ from those 3 days. Possibly a little more in the 10-15 day period. Maybe. By the way, each gray line is one of the ensemble members. Notice only 4 of the 51 members produce more than 1″ rain down there in the Willamette Valley the next two weeks. Keep watering for now…

(kptv)

To wrap it up, the timing is bad (holiday weekend), but it’ll be good to have at least some cool/showery weather to delay fire season a bit. Enjoy the cooldown because you know it WILL get hot again at some point.

Summer has arrived early in the PACNW; no end in sight to the unusually warm and dry weather

Remember when it seemed like the cool and wet weather just wouldn’t end back in April? What a change! May ended up the warmest on record in Portland and rain pretty much disappeared after the first week of the month. So now it’s been about a month of much warmer than normal temperatures and mainly dry.

(kptv)

Take a look at 80 degree days so far compared to previous years AT THIS POINT. Last year we had ONE 80 degree day by June 5th. This year’s = 16. That’s the 2nd highest number of 80 degree days. I think Salem was something like 3rd highest; so it’s not just about an extra warm urban heat island in Portland.

(kptv)

Portland hasn’t seen measurable rain in 22 days; pretty rare for late May to early June. It’s unlikely we get anything other than a few drops (at most) during the next week. IF we don’t get more than a tenth or so before the 15th, it’ll be the driest mid-May to mid-June we’ve seen

(kptv)

I’ve noticed just during this last week that grasses along the freeways are drying quickly, turning from green to brown. Often that doesn’t happen for another 3 weeks or more. That means the top layer of the soil is drying out quickly! I’ve begun watering everything at home as if it’s July and you should be doing so as well. Take a look at the “rain frequency” chart for Portland during the summer months

(kptv)

This graphic shows the chance of rain on ANY ONE DAY as we go from June through mid September. Locals know that late July to early August is the driest time of the year around here, that shows up nicely on the graphic. But also notice the drop off once we hit mid-June; seems about right doesn’t it? Soon after Rose Festival ends we often turning reliably warmer and drier. Each year is different, but it seems many years we get a first heat wave (3 days at/above 90) in that 2nd half of June as well. I’m hoping we get some sort of cool trough at some point in the 2nd half of this month to give us at least an inch of rain before the summer dry spell really kicks in.

Unfortunately my gut feeling is that the summer dry spell has already begun and the chance for significant rain (an inch or more) is slipping away quickly. Why? Take a look at what we’re seeing in the weather forecast models. First, the big picture shows higher than normal upper-level heights (stronger ridging that normal). The main (and weak) jet stream is well north of us. An upper-level low has been lingering over California for quite awhile; cooler than normal down there. This setup is keeping Pacific weather systems farther north than usual for late spring and early summer = little or no rain. This setup is allowing thunderstorms to pop up each afternoon over the southern half of Oregon, but these should remain south and east of NW Oregon and SW Washington

(kptv)

By Saturday that low over California has moved east, only to be replaced by another!

(kptv)

That leaves us dry, although thunderstorms are still possible east of the Cascades in that easterly flow north of the California low. Noticed the ANOMALY chart for the same time shows we are still seeing higher than normal heights overhead

(kptv)

Jumping ahead 5 days, the anomaly through the 16th shows those higher than normal heights continuing most of NEXT week. This is the ECMWF ensemble average, but other models are similar.

(kptv)

This tells me the dry or nearly dry weather continues for another 5-10 days. There are SLIGHT hints that the ridge might be slightly farther offshore in the 10-15 day period and allow a cooler trough/troughs to drop in…maybe. This is the 16th-21st 5 day average

(kptv)

Looking at ensemble 24 hour rain total through 15 days, there are hints the 3rd week of June (”2″ and “3″ in my writing means 2nd and 3rd weeks of June) could be showery. This is the Canadian model.

(kptv)

That said, a week or two ago there were hints this coming weekend could be wet too. That didn’t/won’t happen.

SUMMARY

• This unusually dry/warm pattern continues until further notice
• But there’s no sign of hot weather for at least a week after tomorrow
• Thunderstorms should remain over the Cascades and eastward the next few days, but one could slip west of the mountains Thursday or Friday. That’s most likely south of Portland.
• There’s a chance (but just a chance) we get some sort of showery pattern sometime after the 15th, but not before that time.
• Keep watering everything!