Where is Summer? A Look Ahead After Coolest July Start in 10 Years

July 7, 2020

8:30pm Tuesday…

It has begun…complaints about cool summer weather. I often get complaints this time of year, some people expecting that we should have Sacramento style heat in Portland. To be fair, the past two days have been especially cloudy and cool. Today was the 2nd day in Portland without seeing a 70 degree temperature; our typical high this time of year is 78-79 degrees!

We’re now approaching two weeks of below average temps.

The average high temperature for this first week of July is the coldest since 2000! My little butternut squash and cucumber plants are struggling…just a few inches high. Too little sun and most days only in the 60s up in the hills. At least we haven’t seen much rain the past 2+ weeks; it’s very clear our dry season has arrived.

So, the big question…

IS THIS IT?

WHAT WE ARE SEEING NOW…IS THIS OUR “SUMMER” THIS YEAR?

The short answer; it’s unlikely this same cool weather pattern continues the next 9 weeks to Labor Day. But there is no sign of hot weather in the next 7-10 days either.

First, we are overdue for an average or cool summer west of the Cascades. I’m not saying that’s about to happen, but the past six years have featured an unprecedented string of warm to hot summers in the Portland metro area. 2016 wasn’t crazy warm and neither was last year. In fact much of the warmth last year was due to excessively warm nights; a consequence of warmer than normal ocean water offshore.

My point in bringing this up is that, at some point, we should expect to get a cool summer.

The weather pattern the past two weeks has featured a setup like this in the upper-atmosphere; weak “troughing” or a dip in the westerly flow over the Pacific Northwest. High pressure (and warmer air) has been suppressed to the south and east regularly. Notice most of the country is very warm to hot! We are all alone in the cool weather out here

A warm/hot July weather setup looks more like this; the westerly flow pushed farther north into Canada. That takes much of the cloud cover and showers north as well = sunnier and warmer weather west of the Cascades

Looking ahead, that upper-level trough backs off a bit the rest of this week. The result is more sunshine and warmer days. By Saturday that hot upper-level ridge is much closer to us. At this point it appears this should finally be a setup for a sunny Saturday and temperatures in the 80s.

But by Monday another system is passing by to the north, once again bringing a surge of cool marine air inland Sunday and maybe even a shower. A continuing issue the past couple of weeks is models only catching onto these cold troughs about a week ahead of time. A week ago it appeared we’d be heading into a very warm summer pattern this coming weekend. Instead that is being delayed once again by this system Sunday/Monday

Looking farther ahead, we should warm again a week from now as high pressure builds just offshore. This is the GFS model for next Wednesday the 15th

The morning ECMWF model’s forecast for high temps in Portland shows this trend as well.

Warming through this Saturday, then cooler, then warming again a week from now. You can add about 5 degrees to most of these to get a Portland high temperature. In general this is a bit warmer than what we’ve seen the past two weeks. It would imply the next 10 days will be near average for mid-July.

No model shows a wet weather pattern ahead, just a few drips here and there. ECMWF says less than .20″ in the Willamette Valley through the next two weeks. As mentioned earlier, the dry season is here:

It’s summer and vacation time, so I’ll be off until Sunday. Enjoy the warmer late-week temps!

Chief Meteorologist Mark Nelsen


Nice Independence Day Weather Ahead; But July Starts Cool

June 29, 2020

9:45pm Monday…

We had quite a stretch of warm weather last week, topping out at 93 Tuesday. As models had forecast, a cold upper-level low dropped out of Canada over the weekend. Not much rain, but highs 15-20 degrees cooler

Today was a pleasant day but the constant onshore flow kept us in the lower 70s. A weak cold front passes overhead late tonight, thickening the marine layer and producing spots of drizzle/sprinkles the first half of Tuesday. The GRAF model shows this well for the morning commute; no significant showers but anyone west of the Cascades could wake up to wet.

What’s ahead?

  1. A relatively cool start to July; if our 7 day forecast holds, it would be the coolest first week of July in 10 years!
  2. There’s no sign of a wet spell and/or any unusually wet weather. Actually little to no rain falls in the next week. Just those sprinkles or light showers tomorrow and Wednesday morning.
  3. Not a single model produces any sort of summer heat in the next 7-10 days. No need for air-conditioning!

A deep and cool upper-level low is centered over Idaho right now. That brought us cool weekend showers. Rain totals the past 24 hours in the Wallowa Mountains have been amazing as the northeast flow coming around the low has been getting “scooped up” by the north-facing slopes. Enterprise and Joseph both picked up 1-2″ rain, with 2-5″ around Wallowa Lake! Above 7,000′ or so it was snow during the night with temps at freezing.

That low moves away from us the next 5 days, but it’s replaced by strong onshore flow at the surface tomorrow through early Thursday. Lots of clouds and sprinkles/drizzle are the outcome west of the Cascades. Upper-level troughing weakens by this weekend, but it’s still centered over the Pacific Northwest by fireworks time Saturday evening. This means weak onshore flow, comfortable temps, and plenty of sunshine after brief morning clouds for Independence Day.

But by next Monday (the 6th), the trough is deepening again

GEM (Canadian) model

and it’s still there 10 days from now (Thursday the 9th)

GEM (Canadian) model

This means the marine layer likely thickens again early-mid next week = cooler. The overnight run of the monthly ECMWF shows the pattern returning to a more typical summer setup just after 10 days out…we’ll see. Just for fun and to scramble your brain a bit…here’s the ensemble forecast for max temperature at Salem for the next 46 days.

Notice there is an uptick right around the 11th as the trough weakens. We’ll see how that plays out. But as of now there’s not reason to think this is going to be a cool and cloudy summer.

On the flip side, we are overdue for a cooler than average summer; we haven’t seen one of those in many years. Portland has seen 6 consecutive warm (or hot!) summers. Last summer was a bit warmer than normal, mainly due to unusually warm Pacific ocean water leading to warm nights. But no heat waves or 100 degree days, that was nice.

Chief Meteorologist Mark Nelsen


Much Cooler Weekend Ahead, But Not Much Rain

June 25, 2020

11:00pm Thursday…

We’ve had a nice spell of summer weather lately. Today was the 5th warm and dry day in Portland

We’ve only seen rain one day out of the past nine.

I finally hooked up my drip irrigation system in the garden the past two days; it’s pretty clear the summer dry spell has begun and we’re into a stable temperature regime. No long period of cold/wet weather is in sight.

THE BIG PICTURE

  1. There won’t be much rain the next 10 days or so. Showers are likely Sunday and MAYBE a shower the middle of next week, but that’s about it. You should now be watering everything in your yard and garden.
  2. Temperatures cool over the weekend, then bounce back to around normal through next week. There is NO SIGN of a hot spell or heat wave in the next 10+ days. If you want to hit the river or lake with your boat, you won’t find roasting hot temperatures to go with it.

In case you are headed to the northern Oregon or southern Washington coastline this weekend:

Take a look at the morning ECMWF ensemble model forecast of 24 hour rainfall. Each horizontal line on the upper half of the chart represents one “member”. Basically the model is run 50 times at a lower resolution with slightly different initial conditions.

Most ensemble members produce light showers overhead Sunday as an upper-level trough passes. But notice only about half of those give us .10″ or more. Not exactly a soaker! Then there are hints of a shower possibly Tuesday or Wednesday but that’s about it; mainly dry the next 15 days. The GFS model is similar

The cool weather coming for Saturday and Sunday is due to a cool upper-level trough dropping south out of Canada. If it was January we’d be talking about low elevation snow and modified arctic air moving south. The center of that low moves over Eastern Oregon and Idaho and that’s where the much heavier rain will fall. That low lingers through Monday and Tuesday over there. A very unusual late June soaker is on the way for northeast Oregon (which has been plenty wet this year). ECMWF thinks 1-2″ by Tuesday afternoon!

The Canadian model (GEM) brings an inch of rain all the down into the Ochoco mountains by this time.

This general pattern (without much rain) continues the rest of next week and likely beyond the 4th of July. Notice the below average heights across the West next week

Then just a bit below average heights for the 2nd week of July. This is from last night’s run of the ECMWF, but the GFS and GEM models are similar.

That’s it for this evening…I’ll be back at work Sunday.

Chief Meteorologist Mark Nelsen


Hot For A Day Tuesday, But Another Cool Weekend Ahead

June 22, 2020

9:30pm Monday…

As expected, after a bunch of rainy weather in June we’ve dried out quite a bit in the last week. PDX picked up a third of an inch on Saturday, but otherwise it’s been dry since last Tuesday. That’s good, since we’re now sitting on our fifth wettest June (of the last 80 years) at PDX.

A large ridge of high pressure is covering the entire Western USA right now. This is our midsummer weather pattern. Hot weather for all except coastal locations and areas near the Canadian border.

Today we hit 86 in Portland, 11 degrees above the average for this date. What changes tomorrow? Well, the 850mb temperature (temp in Celsius over Salem around 5,000′) on the afternoon sounding was +18. Models are forecasting about 4 degrees warming at that elevation tomorrow, and 3-6 degrees down here at sea level. That puts us somewhere between 89-92 for a high at PDX tomorrow. Seems reasonable so we are forecasting 91.

We get a moderate marine push tomorrow night and Wednesday as a weak system “dents” the upper-level ridge. High temps only 75-80 degrees with a cloud/sun mix is the result that day. Then the ridging pops up again Thursday-Friday for a return of 80 degree weather.

Then it gets a bit more interesting. A pattern that would possibly bring us snow or arctic air in winter sets up Saturday through Monday. A cold upper-level trough drops down out of Canada, centered over Eastern Oregon by Sunday. If it stays that far east, we won’t be very wet west of the Cascades. But the entire region will be unusually cool for the final days of June.

The ECMWF is forecasting an 850mb temp over Salem down around +2 to +3 on Sunday morning. It appears it has not been down to zero in late June in the past 60 years, so this is close to the coldest it can get this time of year overhead.

Will this ruin your outdoor event either Saturday or Sunday? Possibly, although right now models are dumping a ton of rain west of the Cascades in the I-5 corridor since the center of the real cold air is farther east. Areas without color on this map from the ECMWF model indicate less than .10″ rain. Most of it falls Sunday.

IF YOU HAVE AN EVENT OR PLAN ON CAMPING IN THE FOOTHILLS OF CASCADES OR IN THE MOUNTAINS, there’s a good chance for a soaking. Not so much in the middle of the Willamette Valley and west of I-5. Unfortunately once again it doesn’t look like great “lake weather” in the Cascades. This is total rain forecast by one model ending one week from now.

Sorry about the timing! A summer weather pattern weekdays and cooler temps weekends has been the theme lately. Be safe jumping in local lakes/rivers on these warm days, they are slow to warm up in June. The numbers today:

That’s it for now. I’m off tomorrow, but back on Wednesday-Thursday this week, I’ll try to update again before the weekend.

By the way, keep an eye to the sky the next couple of weeks when we have clear evenings. There have been lots of noctilucent cloud sightings recently around the northern hemisphere. They are typically seen between 10-11pm after the sun has set and you can’t see “regular” clouds well. Suddenly thin blue clouds may appear in the partially lit sky. We’ll see.

Chief Meteorologist Mark Nelsen


6th Wettest June In Portland, But Much Drier Weather Ahead

June 16, 2020

9pm Tuesday…

It’s been a wet month west of the Cascades, especially in the metro area. We saw another round of scattered showers and thunderstorms today. Of course in this weather setup some of us get soaked and others not so much. 24 hour rain totals (I’ve excluded anything under .50″) show some spots getting close to an inch!

Portland has picked up about .20″, bringing the monthly total to 3.16″. That’s our six wettest June

So we’re just at the halfway mark and we’ve already seen 11 days with measurable rain. That’s more “rainy days” this month than the last 5 Junes!

Of course we even saw a weak tornado Saturday evening in Damascus. One more in a series of EF-0 events the past three years

SATURDAY JUNE 13TH DAMASCUS TORNADO

What’s ahead? Some summer temperatures!

All models agree that upper-level ridging takes control for the next week (or longer). That does NOT mean we’ll be rain-free the next 7 days; it just means we’re done with the cold showers. The next three days will be great with warming temperatures and all dry weather; our first stretch of 3 dry days in a few weeks

It gets more interesting Saturday; an out-of season atmospheric river sends a lot of tropical moisture around the northern edge of the upper level ridge. You can see the high precipitable water values pushing north Friday

Even though the atmosphere will be warm, there’s a good chance we get at least a few showers Saturday through the first part of Sunday. Of course the farther south you go the better chance for dry weather. Right now the GFS is pushing about .10 to .20″ rain through the metro area during that time. The ECMWF ensembles are similar,

so we’ve made some adjustments to our weekend forecast. It’ll be a gray weekend, but not cool/chilly like the last two. More of a “humid/mild” weekend.

The screaming message for this upcoming weekend? If you want guaranteed dry weather, head south and/or east. It’s still possible the 2nd half of Sunday (Father’s Day) will be totally dry for an afternoon BBQ or outside dinner.

Beyond this weekend, the ridging is sticking around for at least the first part of next week, so I expect warming temps again Monday-Wednesday. The ECMWF high/low ensemble forecast keeps those temperatures well above average next week. You can typically add about 3-8 degrees to these numbers for a Portland high in the warm season.

Enjoy the warm & dry weather for a few days!

Chief Meteorologist Mark Nelsen


It’s Payback Time! June Rains Soak Portland After A Dry Spring

June 9, 2020

9pm Tuesday…

It’s been a soaker the past few days, especially central and east metro. These numbers are from PDX, the official observing site in Portland.

As of this evening we are sitting at 2.32″ for the month, a full half inch above our typical TOTAL June rain total.

One could easily argue, based on that image, that we’re overdue for a wet June. It’s payback time! We’ve seen quite a string of drier than normal Junes. By the way, how wet CAN it get in June? There have been three years with more than 4″ of rain in June at PDX: 1984, 2010, & 2012.

On my Twitter feed, a viewer asked me if this means anything for our upcoming summer? Does it mean we’ll have a cool/wet summer? I doubt a wet June means much for what follows. So many times I’ve seen the rain suddenly shut off later in the month and the summer dry spell begins. For fun, I checked the five wettest Junes in Portland (1954, 1981, 1984, 2010, 2012). What happened in July and August? The composite shows cooler than normal temps for July

August? Similar…cooler than average

Quite interesting. If we have a cooler than average summer it’ll be the first time in many years. Last summer may have been cloudier than recent years, but was still warmer than normal. This is last July/August combined…

Could we finally have a “cool” summer on the way? We’ll see. If so, NOAA doesn’t think so. They feel the odds tilt toward warm/hot for summer 2020

WeatherBELL’s summer outlook is similar

AccuWeather has hopped onto the “PACNW Summer Scorcher” train as well

The seasonal versions of the Euro and Canadian models also give us a warmer than normal summer.

Regardless, we have more rain on the way for the next week. I don’t see a decent chance for a 3 day dry spell through at least the middle of next week

How much more rain? Maybe another 1″ through next Wednesday or so as a cool upper-level trough moves overhead this weekend and then again the middle of next week. All models are hinting at a change about 9 days out. See the drop in 24 hour rainfall late next week? This is the ECMWF ensemble run from this morning. Each horizontal line shows 24 hour rainfall for each six hour period for the next two weeks. The bottom part of the chart is the average of all 51 ensemble members

So there’s your light at the end of the tunnel; we might see some real summer weather about 10 days from now…maybe. For now enjoy the rain, slugs, and comfortable temps!

Chief Meteorologist Mark Nelsen


A June Soaker This Weekend; Plus Funnel Cloud & Waterspout

June 7, 2020

11pm Sunday…

It’s been a real soaker this weekend. Showers started late Friday, then some downpours both yesterday and today. Of course when we get these hit/miss showers some neighborhoods get soaked but others remain dry. Can you believe that on June 10th we’ve pretty much received our typical June rain? Obviously with more rain on the way it’s going to be a wetter than normal month. It’s already the wettest June since 2014 in Portland.

Take a look at the numbers for PDX

PDX RAIN STATS

Today’s fun featured a funnel cloud over east Portland

Pic by Heather Waters

And a waterspout just offshore Tillamook County

Pic by Will (via Twitter)

And 3-5″ snow at Timberline Lodge; unusual, but not unheard of in early June at 6,000′

What’s ahead? It’s clear we’re going to see more rounds of showers the next 7-9 days. The ECMWF ensemble forecast for 24 hour rainfall shows a peak in rain Tuesday and then again Friday through NEXT Tuesday. My garden needs a lot of slug bait the next week or so…

Looking for more sunshine and/or dry weather? Either head to the eastern Columbia River Gorge or central/north-central Oregon tomorrow. Lots of sunshine out there Monday, and probably Wednesday/Thursday too. Those will be the nicest days west of the Cascades too. The ECMWF does keep hinting at some sort of upper-level ridging the 2nd half of June…we’ll see. If so that would mean summer weather could be 10-14 days away.

I’m out of time this evening so that’s it. Enjoy your mainly dry Monday… Chief Meteorologist Mark Nelsen