Great early summer weather pattern, but cooler with shower chance for holiday weekend

8pm Thursday…

June is just about to wrap up this evening and we’re headed into July. Temperatures this month ended up a little WARMER than average, not cooler. The heat wave really balanced out the cool weekend temps. Actually that was the main feature…4 weekends of cool/wet weather with some pretty nice weather on many weekdays.

Of course we haven’t seen rain now in 11 days, the longest dry stretch since early last September.

Yes, it’s time to start watering your lawns even though it’s hard to believe that’s the case after one of the wettest springs on record. The “faucet” has suddenly just shut off. We ended up with about double our typical June rain, and 7th wettest June in Portland.

The heatwave last weekend turned out almost exactly as expected with mid-upper 90s for 3 consecutive days. We just barely squeaked in under 100 degrees last Sunday

WHAT’S AHEAD?

The holiday weekend is just about here. Do you realize we haven’t seen measurable rain in 14 years on the 4th of July? In fact my kids (20 and 21) haven’t experienced a “wet Independence Day” yet! The last cool/showery holiday was back in 1999

This week has been nice with temperatures running near normal; a steady onshore flow of cool marine air is keeping the weather from turning hot. But now an upper-level low pressure area (a disturbed area of weather high overhead) is heading down into the Pacific Northwest. It’ll be directly overhead late Sunday into early Monday.

When that happens, temperatures cool and the chance for rain goes up. But this system seems a bit different; a bit more “moisture-starved” compared to recent setups. So I don’t think we’re talking a bit soaker west of the Cascades. In fact check out the rain forecast from the ECMWF and GEM models from now through Tuesday.

The main effect over the holiday weekend will be a very strong onshore flow. Lots of clouds west of the Cascades with below normal temps, but not much rain. Maybe just sprinkles or a light shower here and there.

Are you are headed to the Cascades, Gorge, or Central/Eastern Oregon this weekend? Watch out for thunderstorms starting Saturday afternoon. An upper-level low offshore means southerly or southwesterly flow overhead. Straight southerly flow should bring showers and thunderstorms up along the Cascade crest Saturday night through Sunday morning. Of course those storms/showers would cruise right over the the top of the central/eastern Gorge during that time too. I think any thunder west of the Cascades is unlikely and we’ll be sitting under a thick marine layer during that time too. If you’re camping in the Cascades, I’m thinking a cooldown over the weekend too

The coastline looks quite mellow this weekend, but with the thick marine layer it’ll be tough to find lots of sunshine.

Later next week will be a battle between the very hot “4 Corners High” and cool weather offshore.

We may end up in the perfect spot; enough onshore flow to keep the heat away, but not too much that would keep us mainly cloudy. We will see…enjoy the weekend!

Chief Meteorologist Mark Nelsen

First heatwave of 2022 will likely feature a 100 degree day in Portland

9pm Friday…

Today was nice with a high temperature of 84 in Portland, but now the heat sets in this weekend.

Our weather forecast models are in agreement that a 100 degree day is becoming more likely in the Portland/Vancouver metro area Sunday. All the factors that can push us to that century mark appear to be in place for just that one day.

For those just wanting the details:

• Hot weather arrives tomorrow and sticks around through Monday along the I-5 corridor in western Washington and Oregon
• Expect low 90s tomorrow and Monday, but between 98 and 102 on Sunday. Skies will be sunny all three days
• Breezy and dry east wind keeps humidity low both tomorrow and Sunday, although it might get a bit more humid (briefly) Monday
• A breezy west/southwest wind arrives Monday evening along with a major push of cool Pacific air. Tuesday we’ll be in the 70s most of the day!

Our 3 day forecast for Portland looks like this:

Along the northern Oregon coastline, the forecast (as always) is a bit more tricky

That warm/hot easterly wind touches the beaches tomorrow, but then really pushes in Sunday. When that happens, it CAN be just about as hot at Astoria, Cannon Beach, & Tillamook as it would be here in the valleys. Thus the 90 degree possibility.

Here’s the plan for the next 3 days…

A “thermal trough” of low pressure is developing west of the Cascades right now. That’s because low pressure forms on the “lee” (downwind) side of mountain barriers as wind crosses it. Easterly wind has developed over the Cascades and now air is moving toward that blue line west of the Cascades down here at sea level. Easterly wind is blowing at Vista House in the Gorge. This is the classic signature of an approaching heat wave west of the mountains. Notice wind is still weakly onshore at the coastline.

By tomorrow afternoon, a strong thermal trough is in place west of the Cascades, centered over the Coast Range. Temperatures warm a bit at the beaches, but really skyrocket inland. 4 millibars worth of pressure difference between The Dalles and Portland means a gusty easterly wind in the western Gorge. High fire danger…BUT…all the vegetation is very green out there…for now.

Then check out midday Sunday. The thermal trough has broadened and is right over the northern Oregon coastline. Hot east wind is making it to the beaches in that area. 4-5 millibar pressure gradient remains over the Cascade for a continuing easterly wind. But also notice the cooling southwest wind has arrived on the central coastline. It WON’T be a hot day from Lincoln City southward Sunday.

Finally, by late Monday afternoon (5pm) things have really changed. The thermal trough has shifted east of the Cascades with a strong west-southwest push of marine air in progress everywhere west of the mountains. A westerly gradient of 5-6 millibars means a very strong west wind has returned to the eastern Gorge. Big afternoon for kiteboarders out there! It’s possible that from Salem south temperatures remain below 90 on Monday.

These images are all from the high quality WRF-GFS model from the UW. The cross-section product is excellent for showing us the deep easterly flow tomorrow and Sunday (area shown in yellow), then the switch to onshore flow Sunday night. Easterly wind is blowing almost 50 mph over Portland (overhead) tonight and tomorrow night. Note that time goes backward on this graphic

That does keep our humidity low through most of this event. Dewpoints may briefly come up to “normal” for summertime Saturday night, but that’s about it. Dry stuff = good.

Models are now pushing 850 millibar temperatures (temperature in Celsius ~5,000′) to +23 or +24 over Salem Sunday afternoon. There have been two previous events just like this one in late June. Temperatures were similar overhead in June 2006 and June 2017. Both produced 100 degree days in Portland. And the setup Sunday afternoon is “perfect”. Easterly wind dies down to almost calm at peak heating time in the metro area, but cooler southwest wind hasn’t arrived yet. Totally sunny skies uninhibited by high clouds too. This all adds up to a 100 degree day.

That’s it for now, find a place to stay cool this weekend, and be careful on our local lakes and rivers.

Chief Meteorologist Mark Nelsen

Summer 2022 dry spell arrives, plus a brief heat wave this weekend

10pm Tuesday…

What a change today! On the summer solstice we popped up to 83 degrees this afternoon in Portland. That’s the warmest day of the year so far.

It’s so hard to believe we had only seen ONE 80 degree day this season, back on June 2nd

Now it appears the threat for significant rain is mainly gone for the next 10+ days. Just a quick glance at the next 15 days from both the ECMWF and GFS model ensembles shows less than .20″ rain from both

This is because the endless string of cool upper-level lows dipping down into the Pacific Northwest seems to have “dried up”. These are the disturbances that bring us showers, clouds, and cooler than normal temperatures. It isn’t too unusual to see the “rain faucet” suddenly turn off. I can think of many years in which we’ve gone from regular showers to totally dry. Some years it happens in early-mid June, other years not until early July. I’d say the timing is just about average this year. Soon the complaints about a cool/wet spring will be forgotten…until next spring. 

To summarize:

• There is no sign of a soaking rain the next 10+ days
• Unless we get a sprinkle out of the low clouds tomorrow morning, the next chance for measurable rain isn’t until next Tuesday or Wednesday
• Get ready to start watering those yards and gardens…for the first time this year.
• We have entered the warmest/driest time of the year in the Pacific Northwest.  It’s time to hit the rivers, mountain lakes, Gorge, & Coast. Time for hiking, camping, bicycling and anything else you wait all fall/winter/spring for…

A weak system IS passing by to our north in Canada tomorrow.

But it only pushes in morning clouds the next two days, plus cooler temps. After that we expect a strong upper-level ridge to build over the western USA. This is THE FIRST TIME we’ve seen this setup all spring and early summer!

Did you notice that we’ve had very few totally sunny days? That’s due to the lack of strong ridging; we’ve only seen brief breaks between organized weather systems and those breaks don’t tend to give us totally sunny days.

WEEKEND HEAT WAVE

It’s been well-advertised (as all heat waves are around here) that we’ve got some hot weather coming this weekend. A combination of that warm ridge overhead, sunshine, and easterly (offshore) wind flow should make temperatures skyrocket. Temperatures up around 5,000′ (850 millibar level) are forecast up in the +21 to +23 range Saturday afternoon through Monday. Each model is slightly different, but their ensemble averages are generally +20 Saturday, +21 Sunday, and +18-19 Monday. That puts high temperatures between 90 and 100 degrees all three days. Heat waves are FAR easier to forecast than any other extreme weather in our area.  In fact I can’t remember screwing up a heat wave forecast in the past 25 years.  Sure maybe a 100 degree day became a 90 degree day because of high clouds. The easy forecasting is because we’re talking sunny skies. and it’s just a matter of HOW HOT IS IT GOING TO GET? And when all models agree, it’s pretty simple. Notice we don’t expect any records to be set this weekend because we saw a similar heat wave back in June 2017, then of course that all-time record heat last year

I don’t see a very humid heat wave this time around, and that should allow overnight temperatures to drop down to at least 65 degrees at night in the urban areas, cooler elsewhere.

That’s it for now…get your air conditioners ready!

Challenging Rose Festival weather this year; a look at the numbers

9pm Wednesday…

Cue the “it always rains on the Rose Festival” jokes right? I’ve been in Portland for 30 of the last 31 Rose Festivals, and lived within two hours of here most of my younger years. I know it’s not true that it’s “always wet” in early June in Portland. But this year that WAS pretty much the case. The stats below are from a brief report I sent to the folks over at the Rose Festival, all based on PDX weather station records.

The Portland Rose Festival normally encounters changeable weather since it occurs during the seasonal transition from spring to summer in the Pacific Northwest. Typical high temperatures during Rose Festival are in the lower 70s. Some years are showery, some almost all dry; but most years it’s an agreeable mix of the two. This year was much different.  Frequent showers, steady rain, or even downpours fell at the worst possible times.  This included: opening night and ribbon cutting, during the Starlight Parade, and record rainfall in the 12 hours leading up to the Grand Floral Parade. One bright spot was the Junior Parade; skies were partly cloudy with comfortable temperatures and no rain.

Starlight Parade was soaked this year!

HIGHLIGHTS

• This was the 3rd wettest Rose Festival since at least 1940, only exceeded by 2010 & 1997. 3.67″ rain fell from May 26th-June 12th (this year’s dates)
• 12 of those 18 days saw measurable rain
• The 1.42″ rain on Friday, June 10th, was the 4th wettest day recorded during a Portland Rose Festival.
• Temperatures were the coolest in several years, but not “record setting cool”
• Most notable was that coolest temperatures occurred on weekends with warmer midweek days; poor timing for those weekend events Take a look at high temperatures since Memorial Day weekend

Chilly weekends, but warm weekdays

EVENT DAYS

During the 11 main “event days”, rain was recorded on ALL of those except one. That was Junior Parade day. These 11 days include: Thursday-Monday opening weekend (Memorial Day Weekend), Friday-Sunday 1st main weekend, then Wednesday-Saturday ending parades/weekend.

Opening weekend:  A downpour for the ribbon cutting was followed by a well-advertised cool and wet Memorial Day weekend.  High temperatures struggled to get above 60 degrees Friday, Saturday, & Sunday, well below normal for late May.

Starlight Parade and weekend:  A steady and/or heavy rain was forecast for Saturday evening and it arrived.  It was a very wet evening.  That was followed by frequent showers on Sunday.  On the parade block KPTV was set up on this year, attendance appeared to be 1/3 to 1/2 of previous years.

Junior Parade:  A great day!  Partly cloudy skies with temperatures in the 70s

Grand Floral Parade:  This weekend was forecast to be a “cool and showery” weekend, but not excessively wet.  Parade forecasts called for just a few light showers or even mainly dry.  Little or no rain fell on the parade.  But extremely heavy rain fell all day Friday and into Friday night leading up to the parade.  As mentioned, that rainfall was some of the heaviest observed in the month of June in the Portland area. In fact it was the 4th wettest day in June history. This may have led to the perception of a “washout weekend” ahead for many Portlanders as they slogged through a Friday evening commute.

Heavy rain soaks the PACNW as “Juneuary” rolls on

7pm Monday…

This weekend I was camping (in an RV) in Northeast Oregon. I’ve never seen it so green in June over there and throughout the eastern Gorge and Columbia Basin. So much water in the rivers and creeks in one of the drier parts of the region. Meanwhile, a massive June soaking nailed the Portland metro area Friday and Friday night. I’ve don’t think I’ve seen so much rain in June over such a large area; typically it would be more isolated thunderstorm events with a soaking in one neighborhood, but much drier elsewhere. Regardless, I’ve always liked the term JUNEUARY, a portmanteau of JUNE + JANUARY. It’s a bit dramatic (it’s not really like January), but it works.

Portland picked up .37″ Thursday evening as the rain began, then 1.42″ Friday, .12″ Saturday, and .05″ today. That makes for 1.96″ at PDX out of this system, VERY wet for June and more than we typically see in the entire month. But wait, there was more…a LOT more in some of the surrounding east metro areas. Strong westerly flow in the middle atmosphere pushed subtropical air up into the Cascades. That squeezes out far more rain in the eastern suburbs than west metro. There were spots that picked up 4″ of rain in just 24 hours! Just a few totals here:

This is why, averaged out over time, that hilly areas and east metro picks up far more rain that west metro. I can’t tell you how many times I’ve left home and it’s soaking wet. I get to work (west metro) and it’s been dry all day. The driest parts of the metro area average less than 38″ rain per year, the wettest close to 60″!

(kptv)

(kptv)

Portland NWS put out a statement today that included many other locations: https://www.wrh.noaa.gov/forecasts/display_special_product_versions.php?sid=pqr&pil=pns

The result is mainly full flood control reservoirs throughout the Willamette Basin. A great video of water overtopping Cottage Grove Dam (it’s supposed to do that) for the first time in many years: https://www.facebook.com/watch/?v=3678519672375179

The Columbia River is also experiencing minor flooding in the metro area due to snowmelt upstream and plentiful rain. We saw it near this level in May 2018 and a bit higher in May/June 2011. That year (2011), it stayed near/above flood stage from late May to late June! Before the dams, the Columbia would rise very high (or flood) almost every late spring and early summer

What’s Ahead?

We get a bit of a break this week, more typical mid-June weather. Although temperatures remain mainly below average over the next 7 days. You’ve probably heard about the scorching heat across the middle of America? It’s because we are locked into a pattern with a large area of hot high pressure (a heat dome) over the continent, but a cool upper-level disturbance (low pressure) over the Pacific Northwest.

We haven’t had a single instance of a strong ridge of high pressure lingering for more than a day or so since way back in March. That will continue this week. At midweek (late tomorrow), that upper-level low is gone…we warm up a bit Tuesday-Thursday (like previous weeks)

But then check out this coming Friday. Another deep dip in the jet stream pushes cooler air inland again; that southerly flow along the West Coast can be wet.

Check out that extreme heat across the USA! Yes the rain is annoying here, but I’ll (for now) take the cooler/cloudier weather instead. It’s too early to know how much rain we might see next weekend. I’ve seen this pattern produce areas of heavy rain both west and east of the Cascades, but often it’s not obvious where the heavier stuff ends up until we’re within just a few days. The big message is…

FOR A 4TH CONSECUTIVE WEEKEND, PACIFIC NORTHWEST WEATHER WILL BE UNSETTLED

A weekend soaking in the Pacific Northwest, but dry in some unexpected places

9pm Thursday

It’s raining again…

After 3 mainly (or all) dry days, the rain is back this evening. I had just transplanted a bunch of veggies and flowers today hoping for some gentle evening rains. Now I see I’ve picked up over .75″ in less than two hours at home! That’s a big excessive… PDX has already seen another 1/3″.

Somehow we still can’t get 4 consecutive dry days. In fact only once since early April have we seen 4 of those days. Yet in January & February we had some nice week-plus stretches!

(kptv)

Since April 1st, Portland has seen 48 days with some sort of measurable rain, that’s about 2/3 of the days, only topped by the very wet spring of 2010

(kptv)

WHAT’S AHEAD?

We’ve got a relatively strong (for June) atmospheric river aimed right at Oregon and SW Washington this evening. An atmospheric river just means a “river of moisture” that flows along in the low-mid atmosphere. It’s not a “storm” or “event”. In general it means significant rain is more likely than elsewhere. If everything works out just right (or wrong?) heavy or flooding rain can be squeezed out of that atmosphere. That can include the “river of moisture” running into mountains. That will be the case the next 2-3 days in our region. One way to measure the strength of the moisture transport is IVT or Integrated Vapor Transport. You can see we are right under the bullseye this evening

(University of Washington)

It’s weaker, but still aimed at Oregon tomorrow at 8pm.

(University of Washington)

Then notice it really falls apart Saturday afternoon for more typical showers across northern Oregon and southern Washington. More solid rain is likely across the central/southern half of Oregon

(University of Washington)

How much rain might we see between now and Sunday afternoon? The past two weekends models have generally overproduced rainfall for the valleys, but were okay in the mountains. Our fresh GRAF model shows 1-2″ in the valleys and 3-5″ in the Cascades. Seems like around 1″ would be most likely in the valleys based on recent experience.

(kptv)

You may notice two other items. The northern Oregon Coast will likely be the driest spot this weekend! Same with SW Washington and up toward Seattle. The other is a very wet northeast Oregon again! Pendleton, La Grande, Joseph, and John Day will all see plenty of rain through Sunday. So wet…

GRAND FLORAL PARADE

It’s not looking so bad Saturday morning/midday in Portland. Just a few scattered showers here and there, definitely not a soaking.

(kptv)

ANY SIGN OF A CHANGE?

Here’s the biggie: There’s no sign of a change into “normal” warm & dry summer weather through at least the 20th. It’s obvious this wet late spring is morphing into a wet early summer. Temperatures have been about normal so far this month which has been nice. But we’ll turn cooler Sunday through Tuesday. Why does this continue? Because we’re not seeing a typical area of high pressure push the (weak) June jet stream north into Canada and SE Alaska. That’s what often happens in June; fewer weather systems moving through = drier and warmer. What we’re seeing right now is more like April or early May, although warmer since it’s June. A great animation here shows the “dip” in the upper-level flow through the next 15 days. This is from the ECMWF (Euro) model. Note the anomaly does weaken a bit in the 2nd week…we’ll see.

(WeatherBELL)

Until I see a warm anomaly over us, it’s fair to say the occasionally wet weather will continue. Temperatures will likely turn a bit cooler than normal as this pattern continues. That’s because “normal” temperatures rise quite a bit the 2nd half of June. Add about 5 degrees to all the numbers below. That gives you lots of days between 68-78 degrees, just like what we’ve been seeing lately.

(WeatherBELL)

That’s it for now. I’m headed off camping this weekend, in one of those very wet areas. Poor choice, but at least I have a roof and an awning…

Spring wrap-up plus a very wet June start

10pm Friday…

June is here and it is STILL wet.

That said, the last 3 days were quite nice with temperatures peaking around 80 each day and dry for most of us. Portland made it to 81 degrees Thursday, one of the latest “first 80 degree days” we’ve seen

Meteorological spring has ended and we are now officially in summer in the northern hemisphere. June, July, & August are the warmest months so that’s summer. The big question: was it the wettest and coolest spring on record? Not at all. Yes, a bit cool, and wetter than normal, but not a “record-setter”. Take a look at the temperatures in Portland

March-May was only a bit below average because March was so mild. If you take JUST April plus May, it was in the top 1/3 coolest springs, but not near the record. In both Portland and Salem, it was the coolest spring since 2012 or 2011. What’s most interesting is that temperatures this spring were more/less considered “normal” during the cool decades of the 1950s through 1970s. We were warmer before and of course after that time. For someone between my age and 80 years old, this spring was a bit of a “meh, I’ve seen it before” sort of thing. How about precipitation?

It was Portland’s 8th wettest spring and wettest since 2017. Once again, not THAT bad because a drier than normal March is brought into the average. If we once again take just April plus May? Wettest since 1996 in Portland and wettest since 1993 in Salem. Both cities picked up around 9.50″ rain in those two months. For fun, I added up some REALLY big numbers. Astoria saw 13″ rain in those two months. Detroit Lake 28.04″! That’s over two feet of rain in two months. That’s why there are so many large & green trees on the west slopes of the Cascades. Log Creek, a weather station in Portland’s Bull Run Watershed (across the ridge from Lost Lake) was similar; 25.40″ precipitation since April 1st. It’s been an amazing two months of recovery over much of the region.

The reason we’ve been so wet and cool is that we haven’t seen any sort of persistent upper-level ridging in the atmosphere overhead. So a (weak) May and now early June jet stream can still send weather systems our way.

IT APPEARS THIS PATTERN WILL CONTINUE THROUGH AT LEAST THE NEXT 7-9 DAYS. There’s no sign of a sustained warm/dry period through the first 10+ days of June.

This evening we’ve got a relatively strong jet stream aimed at the West Coast. Look at the “Integrated Vapor Transport” showing all the moisture headed our way.

By tomorrow evening, a 150mph jet stream is sending moisture directly into the region. That’s up around 30,000′…strong for June.

So we’ve got a strong jet stream, plenty of moisture, and it’s warm-ish. That means the potential is there for significant rainfall this weekend. Latest models are sending several surges of rain inland tonight through Sunday evening. The heaviest should be Saturday evening and overnight into early Sunday morning. Evening GFS model gives all areas west of the Cascades 0.50″ to 1.50″ rain by Sunday evening!

Other models are a little heavier, or have the heaviest rain in different areas.

Regardless. ALL parts of the region will get at least some rain this weekend, just like last weekend. Our latest GRAF model shows 1/4″ to 1/2″ rain in even the driest parts of Central and North-Central Oregon by Monday morning…excellent news for you folks!

So…hunker down for the weekend, put out some more slug bait around your favorite flowers, and get ready for at least a few nicer weather days once again next week. At least no worries about fire weather!

I’ll be down at the Starlight Parade on Saturday evening and I’m expecting a soaker. Remember our coverage (on TV) starts at 8pm, probably the best place to enjoy the floats and bands!

Chief Meteorologist Mark Nelsen