Get ready to endure a week-long heatwave as July wraps up

July 22, 2022

10pm Friday…

It’s midsummer; best weather of the year in the Pacific Northwest and vacation time. Forecasting is typically quite easy this time of year so I’ll be on vacation next week as well. Luckily the forecast IS quite straightforward.

1) It’ll be sunny EVERY DAY Sunday through late next week.

2) BUT…it’ll be HOT starting Sunday afternoon and that continues through the end of next week.

See, that’s an easy forecast. A few highlights…

(kptv)

Our 7 Day Forecast looks like this right now

(kptv)

That’s an especially long heatwave isn’t it? For comparison, the longest stretch we’ve seen at/above 95 degrees in Portland is 6 days…we may be close. Up until 2015 & 2021, that heatwave in 1981 was the all-time hot weather event in our area. The 1941 event was amazingly hot in early July. And of course 2015 (until last year) was one of our greatest/longest heatwaves

(kptv)

How about 90+ day hot streaks? Back in 2009 we had a 10 day stretch starting in late July. That was the heatwave that gave us back to back 106 degree days. I sure don’t see that happening next week. Notice 2015 pops up again.

(kptv)

The ECMWF model’s ensemble average has been very consistent the past 4-5 days. It looks like this right now; a bit hotter than our 7 day forecast since typically these run a bit cool (ECMWF #s) compared to reality in the summer. For example we should be in the lower 80s tomorrow, not 78. This would imply at least 8 days at/above 90 degrees…a scorcher!

(CREDIT: WeatherBELL Analytics)

This is a great chart that looks very confusing at first glance, but stay with me…

(CREDIT: WeatherBELL Analytics)

It shows the last 5 days of ECMWF (European model) runs; technically this is the average of all 51 members of each run. You are looking at maximum temperature forecast each 6 hours at PDX. The most recent run (today’s) is the last horizontal line (highlighted in yellow). I’ve put in S-M-T-W-TH-F-S-S to point out Sunday, Monday, Tuesday, etc… through next weekend. The beauty of this chart is that a forecaster can quickly look at any one day in the future and see what the model has been forecasting FOR THAT DAY over the past 10 runs. For example a few days ago (circled) this model was going extremely hot (102+) for Tuesday. But it backed off in later runs. The most important message here is that for day after day models have been forecasting the heat to begin Sunday, and continue through the end of next week.

There is a sliver of good news about next week. This will be a heatwave that features a shutdown of cooling onshore breezes, but no sign of a hot east wind coming down through the Gorge or off the Cascades. That’s good for fire weather. Much of next week will feature calm or just light wind conditions. With models generally forecasting 850mb temperatures at/below +25 (Celsius) and no easterly wind, it’ll be tough to get above 102 west of the Cascades. That’s good as well.

(kptv)

Without a dry east wind, the ocean beaches should be pretty comfortable during this upcoming week. I doubt 80s or 90s make it TO the beaches, but it’ll be hot just a few miles inland

(kptv)

And you can escape the heat (just barely) up around 4,000′ and above in the Cascades. These forecast numbers for Government Camp also work for all those mountain lakes (Lost, Timothy, Clear, Trillium, Laurance, etc…)

Hot weather ahead
Hot weather ahead(kptv)

We’ve enhanced and added content to our FOX12 WEATHER APP recently. Make sure you download it.

(kptv)

Plus we’ve got a fresh podcast out discussing the upcoming heat. You can find that on your regular Apple Podcasts feed or here: https://www.kptv.com/podcasts/weather/

That’s it for now, I probably won’t be posting again until the last day of July or August 1st. Enjoy your weekend! At least until it gets hot later Sunday afternoon.


A comfortable July so far, but heat wave #2 arrives early next week

July 20, 2022

9pm Wednesday…

Today was a bit hot…for the 2nd consecutive day we made it above 90 degrees in Portland. That’s the 7th day so far this summer

(kptv)

You see the typical cool beaches and very hot east of the Cascades in the daytime highs

(kptv)

(kptv)

Tomorrow should be cooler as the hot upper level ridge just to our east shifts farther away, plus a weak system passes by overhead. The combination of these two has started a “marine push” of cooler air through the Coast Range gaps and up the Columbia River. The result will be patches of low clouds tomorrow morning inland and temperatures remaining in the 80s. A stronger push tomorrow night makes for a refreshing day Friday; there’s a decent chance we don’t get above 80 degrees that day…quite nice! July has been near normal in our area, but very warm across a good chunk of the USA. Note that this graphic is a few days behind.

(kptv)

But we have a heatwave ahead folks! Next week will feature the hottest stretch we’ve seen so far this year, and I give it a 50/50 chance this could be the hottest of summer when we look back.

HIGHLIGHTS

  • Comfortable weather returns the next 3 days
  • Sunday turns hot, about like today
  • For at least 3 days (Monday-Wednesday) temperatures will be up around 100, plus or minus a couple of degrees
  • There’s a decent chance we make it to 100 in Portland/Salem/Eugene
  • There’s a much smaller chance we make it to 105 in one of these I-5 cities.
  • We don’t expect an extreme heat wave

Why so hot?

A strong upper-level ridge builds right over the West Coast AFTER a cool system passes nearby tomorrow through Saturday. Over the past few days models have been in some disagreement on the strength of the ridging. Would it be a huge “heat dome” with upper level heights over 594dm at 500 millibars with high temps well above 100 degrees (ECMWF/GEM)? OR, just high heights with general ridging…high temperatures 90-95 degrees (GFS), nothing too unusual. Luckily models have come together much better today. The Euro has cooled, and the GFS has warmed. 500mb heights on Sunday are rising, very warm, but no big ridge over us.

Then on Monday afternoon heights have risen a bit more. A ridge is building over the Gulf of Alaska, and most of the USA is covered by a hot/flat ridge

By Wednesday afternoon the two have linked up into a hot ridge right through the Pacific Northwest. Heights around 591dm

(kptv)

850mb temps (temperature in Celsius around 4,000′) look like this right now over Salem from the morning/midday runs:

MODELSUNMONTUEWED
GFS ENSEMBLE AVG+17+20+20+20
ECMWF ENSEMBLE AVG+20+22+23+24
GEM ENSEMBLE AVG+20+22+23+23

I based my forecast off +22 to +23 degree temps.

(kptv)

This tells me we’re not going to see a major/historic heatwave, but a more typical mid-summer event. 591dm heights oriented like this don’t produce a hot/gusty easterly wind across the Cascades and no models are showing that hot downsloping. Instead we’ll just experience a shutdown of the cooling onshore breezes for 2-3 days with the hot atmosphere overhead. That should push us up to right around 100 degrees Monday-Wednesday. Sometimes this setup (no dry east wind) can lead to relatively high humidity as small amounts of marine air seep into the I-5 corridor…we’ll see.

The heat next week will also ensure that July ends up as a warmer than normal month.

Enjoy the cooldown the next few days!


Pleasant July weather until further notice, plus slow fire season start…so far

July 14, 2022

10pm Thursday…

It seems quite far back now that many of us were complaining about the rainy weather. I was talking about slug bait, no staining of the deck, and waiting to plant some of my veggies. Now, looking back, it’s obvious our seasonal (and normal) summer dry spell began on June 19th this year. We’ve only seen one wet day since that time…July 6th. This is about as normal as it gets folks! The remarkably reliable switch from “regularly wet” to “unusually dry” happened right on time. That also means it’s the slowest time of the year for meteorologists. July through September is quite boring for the forecasts around here. A good time to take vacation (I just did) and you’ll notice very few weather blog posts during this time. My family and I camped at both Trillium and Paulina lakes last weekend and early this week. I made it about 3/4 of the way around the Newberry Crater rim bike trail. Quite the view!

Dry weather continues
Dry weather continues(kptv)

Temperatures are running just a bit above average for July, and June was near normal.

Dry weather continues

This summer is NOT turning into a repeat of those cool summers of 2010 and 2011. I was thinking it might happen after the excessively wet/cool April & May, but apparently not. This loop shows 500 millibar heights over the next 2 weeks.

Warming atmosphere in late July
Warming atmosphere in late July

Notice we have a weak upper-level trough (brings in cooler marine air) this weekend, then the hot upper level high over the Rockies pushes closer to us through the next 10 days or so. I see increasing orange/red that last week of the month. This is the ECMWF (European) model ensemble forecast; average of 51 ensemble members. The GFS and GEM models are similar through the next two weeks. This implies we have somewhat typical temperatures over the next week, then it MAY turn hotter as we head into the last week of July. Most important; there’s no sign of unusually cool upper-level troughing across the Pacific Northwest. And that means little or no rain. Notice the ensemble average total rain for the next 2 weeks is basically spots of marine drizzle. Less than .10″ for most models

Dry weather continues
Dry weather continues

To summarize: real summer weather (warm and dry) continues the next couple of weeks. But no sign of a heatwave for at least the next week.

This is good news for fire season 2022. The Pacific Northwest is at Level 1 Preparedness Level, a bit below average. Last year we went all the way to Level 5 by mid-July and stayed there for two months! You can check out all the previous years back to 2005 here: https://gacc.nifc.gov/nwcc/content/products/intelligence/NW%20PL%20YTD%20&%20Historical%20Charts.pdf

Dry weather continues

There has only been one large fire in Oregon so far this season. That was 40,000 acres way over southeast of Baker City…mainly on range land.

Dry weather continues

I don’t see a setup for widespread thunderstorms over the next week, that’s also good news. The result will be fuels continuing to dry as the month progresses. I have seen years where we have little or no fire activity in July and then August goes wild. It’s all about the temperatures and thunderstorms. We will see.

That’s it for now…enjoy your dry summer weather!