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  • Updated

Friday, July 30th, 12:30 P.M. 

After a warm start to the day, temps will soar close to 100° in the Portland metro area this afternoon/early evening. We are keeping an eye on some clouds and showers over the Cascades this afternoon. I can't rule out the chance for a brief shower or thunderstorm in the metro area or central valley this afternoon and evening.

High pressure will slowly back off over the weekend, but we will still have a southerly wind overhead. Thin smoke and high elevation clouds will be possible at times, and isolated storms could fire up during the afternoons & evenings along the Cascades and east of the mountains. Highs should trend back into mid 90s to upper 80s Saturday and Sunday.

High pressure will continue to inch away from the Pacific Northwest next week, resulting in cooler temperatures. Afternoon highs will slowly trend back down into the 80s, with overnight lows in the upper 50s and low 60s. 

  • Posted

11pm Monday...

A very brief post to let you know the weather has S-L-O-W-E-D down across the Pacific Northwest. Temperatures in Portland have hit 86 or 87 for the last 4 days! Not a lot of variation there.

We are in our summer dry spell with no significant rain in sight. There could be spots of drizzle west of the Cascades when the marine layer thickens Wednesday morning. Other than that, the ECMWF (GFS looks the same) ensembles show almost no chance of measurable rain the next two weeks. That's through the 20th

Just as unlikely through at least the middle of next week; a heatwave. No sign of that in the 15 day ensemble average

That's it for now. There's no need to worry about the lack of rain, there's nothing you or I can do about it. So enjoy the reliable sunshine while it's here. I'll be off the rest of the week.

Chief Meteorologist Mark Nelsen

  • Posted

8pm Sunday…

Quite a soaker eh? A warm and humid southerly flow has given the metro area somewhere around an inch of rain since it started yesterday evening. PDX has officially picked up .86″ as of 7pm with more approaching. I’m guessing that by the end of today (as early as 9pm?) WE WILL SEE MORE RAIN OUT OF THIS THAN ALL OF APRIL + MAY COMBINED! In a typical spring we’d get something like this maybe every few weeks. Not this drought year. The numbers so far…

By the way, in Portland we’ve haven’t seen this much precipitation in two days since…wait for it…the big snowstorm day! That’s Friday, February 12th (and into Saturday the 13th). Of course, it was all frozen precipitation (mainly snow) that day for much of the metro area.

A few areas have picked up over 1.50″…notice all (so far) over/west of I-5. Models have done very well sending the heaviest rain over there. This map isn’t real pretty, but it shows any location that has picked up about 1.50″ or more as of 7pm. That’s a huge soaking around Salem and Corvallis.

Of course in a warm and humid airmass with southerly flow one can expect thunderstorms in the Pacific Northwest. We’ve seen quite a few fire up over north-central Oregon, even as far west as the eastern edges of the metro area. In fact at 7:30pm this soaker was right over the Hood River Valley. Luckily it’s moving fast so the heavy rain won’t last long. You don’t want a 3.50″ hourly rain rate to sit still…

Ahead of today’s system, it’s been HOT in Eastern Oregon. Check out the afternoon numbers…close to 100 in a few spots!

What’s ahead?

More humid and warm weather tonight as the main upper-level low continues to spin offshore.

But good lifting that would produce significant rain tonight and tomorrow seems to go away. So showers continue tonight, but then we get a break again tomorrow. Other than leftover morning showers (mainly east metro), it should be a MUCH brighter day and mainly dry. Sure, maybe a shower here and there, but widely scattered stuff. Lots of fresh rain-cleaned air too.

As the cool upper-level finally “kicks out” to the northeast and over us Tuesday, we get a round of showers. Maybe a thundershower midday too…maybe.

By midweek the hot upper-level ridge to our east has been pushed south & east. But then a new ridge is developing in this spring’s favored position; in the Gulf of Alaska. That leads to weak and warm westerly flow to our north.

This is a warmer than normal pattern for mid-June, but not hot. 850mb temps on our models are generally well under 20 degrees with no sign of significant offshore flow. So our forecast highs remain in the 80s for now. Weather systems will stay away Wednesday through at least next weekend.

Looking farther ahead (this map shows anomaly), the pattern remains the same through early NEXT week. This is NEXT Tuesday. We don’t have a hot ridge of high pressure overhead, but it’s close enough to cut off any rain chance. That’s what we’ve seen much of this past spring.

The ECMWF ensemble forecast for 24-hour rain is the driest I’ve seen in weeks. Very few members produce even light showers over the next two weeks (after Tuesday). So…this was a one-shot deal rain-wise.

Enjoy the rest of the rain this evening, and you can look forward to some warm sunshine later this week as a July-like weather pattern arrives.

Chief Meteorologist Mark Nelsen

  • Posted

A very quick update this evening, I’m busy on-air until 11:30pm, you can find me there!

Everything is still on track for a gusty south wind tonight west of the Cascades as I posted about last night. Notice graphics are about the same

Several of today’s models continued to show strong wind gusts spreading onto the coastline. I think the 00z HRRR surface pattern shows what’s going on. As a strong cold front moves inland, a “wave” or open low pressure area tracks northeast, making landfall around Astoria in the early morning hours. You can see the small circle in the isobars (equal pressure lines) over the mouth of the Columbia River around 3am.

This tightens the southerly pressure gradient nicely during the wee hours of the morning.

Others were a bit weaker (GFS), but now they have come into line with the stronger solutions. The ECMWF and IBM’s GRAF model have been most aggressive, sending gusts up to 70 mph along the coastline and 50 mph in the valleys

Once the front passes and that wave moves north we go to a much more reasonable southwesterly breeze.

We’ll see how it goes…again, not a big windstorm, but many of you will wake up to rain pelting your south-facing windows. We recorded a podcast discussing the overnight setup early this evening as well. You can find it already dropped into your Apple Podcasts

Or listen at this link:

Chief Meteorologist Mark Nelsen

  • Posted

I took a full week off right when the heat wave began last week. 6 days of camping in the Cascades included Diamond & Paulina lakes (excellent!). One night at Still Creek campground too (not as excellent). Of course we ended up right around 100 degrees the first day of that heat wave, then cloud cover from the south kept us in the 90s the 2nd day. Then a third day in the 90s this past Monday before cooler marine air made an appearance. That first day all official observing stations in the metro area hit 100 except Portland & Vancouver. Troutdale was offline; inconvenient timing. Aurora and Eugene both hit 101.

The result is that we’ve just about hit our yearly “allotment” of 90 degree days. One more than last year…so far.

Porltand DOES get more 90 degree weather than in the past. Check out the average for each decade. The 1950s and 60s saw far fewer hot days than the last 20 years.

DECADE# of 90 Degree DaysAvg per year


Today I came into work and realized it was going to be the most boring forecast of the entire summer! This is GREAT news for all of us though; we are in a very stable late summer weather pattern through the foreseeable future. Many of us will consider these last 8 days of the month just about perfect:

  1. ABUNDANT SUNSHINE Models aren’t showing much marine layer west of the Cascades = very little morning cloud cover, if at all
  2. NO HOT WEATHER Just enough onshore flow to keep us in the 78-88 degree range
  3. COOLER NIGHTS Longer late August nights + dry airmass = overnight lows well down into the 50s, hardly a need for air conditioning.
  4. NO FIRE SMOKE All that smoke from California and central/eastern Oregon wildfires remains south of Medford and east of the Cascades

We are seeing a pleasant weather pattern because upper level heights are a bit above normal. Here’s the ECMWF ensemble forecast of 500mb heights for later this week (Friday), note the above average heights (warm colors). Click for a larger view

Next weekend a cool upper-level disturbance drops down just to our east, bringing early Fall temps to the Rockies, but leaving us dry. This is Sunday the 30th.

Notice that new ridge developing just to our west; models show that ridge becoming the dominant feature overhead in the week leading up to Labor Day. Here’s Wednesday the 2nd

Looking WAY out there, to Labor Day Weekend, models show that ridging sticking around; we may yet see additional 90 degree weather in the next 2-3 weeks. Here’s the ECMWF & GEM models for Labor Day, the 7th of September. Depending on your browser, this may or may not show with a “slider” to move between the two.


The main point?

There’s no sign of an early rainy spell as we head into the first few days of September. Warm and dry late summer weather continues until further notice.

We are now regularly producing a weather podcast here at KPTV. The 3rd episode this month was just posted online. This week while I was on vacation, Brian/Anne/Jeff got together. Hear about the “firenado”, record heat, and Anne’s chicken fears… Make sure you subscribe and rate/review if you get a chance.

Chief Meteorologist Mark Nelsen