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Monday, August 2nd, 3:45 P.M. 

Good afternoon!

Most of the metro area is experiencing a borderline hot afternoon with temperatures in the upper 80s and low 90s. We’ll end the day around 90-91 degrees at PDX. You may have also noticed the haziness out there. Wildfire smoke is drifting out of northern California, and will continue to do so for the next 24-48 hours. Air quality shouldn’t diminish a whole lot, as smoke is mostly confined to the mid to upper levels of the atmosphere.

High pressure will remain parked to the east of us through Wednesday, keeping afternoons hot and a southerly flow in place. Hazy sunshine is anticipated Tuesday, and at least for part of Wednesday. Between Wednesday and Thursday, our upper level wind will turn more out of the southwest, pushing smoke to the northeast. This is around when conditions will start to cool down. Expect highs to trend from the 90s back to the low to mid 80s by Thursday afternoon.

Between Thursday and Friday, a cooler trough of low pressure will make its approach out of the northwest. This system will push clouds back into the picture, as well as showery conditions. The best chance for measurable rain will be across northwest Oregon and western Washington. Points to the south and east of the metro area have less of a chance at seeing a soaking rain. That same system will drop our highs into the 70s Friday-Sunday.

Stay cool out there. Changes aren’t far away!

  • Posted

I’ve changed the format for the weekend…come back to this same link regularly throughout each day for quick updates as we go through the rest of this incredible heat wave.  Newest information FIRST. Remember you can follow me on Twitter: @marknelsenKPTV and Facebook @marknelsenweather

9pm

SLIGHTLY HOTTER MONDAY, THEN A DRAMATIC & WINDY EVENING COOLDOWN

Alright folks, we’ve got Portland’s warmest (hottest) night on record ahead, then slightly hotter tomorrow. Take a look at the all-time records set today. Pretty much every spot west of the Cascades in SW Washington and NW Oregon saw the hottest temp on record. Longview and Hood River numbers come in at a later time

Portland’s downtown observing location recorded a 110, which is also an all-time record. Those go back to 1874!

What’s ahead?

  1. Calm areas drop into the mid-upper 70s tonight. Windy spots only drop to 80-85 degree range…as if we’re in Arizona
  2. All model data tells us that tomorrow should be hotter than today, which is hard to believe. But it’s going to happen
  3. 850mb temps right now are around +28 to +29, and they go up to a record-breaking +31 to +32. This has never been seen in our area. Easterly flow INCREASES through mid afternoon Monday overhead, skies stay sunny. This all says several degrees of warming. I’ll stick with 114 for a high. That’ll be astounding if someone in the metro area gets within 2-3 degrees of Oregon’s all-time high (119 – Pendleton).
  4. Onshore flow sweeps up the coastline overnight = heatwave over. Then that cool air surges into the central/south Willamette Valley after noon. This should make for a cooler day south of the metro area. “Only” 95-105 south of Wilsonville-McMinnville line. Longview will also see a cooler day due to the onshore flow after about 1pm.
  5. The onshore flow will be some of the strongest we’ve seen in our area. A very shallow layer of chilly marine air surging inland trapped under a strong inversion (hot air overhead). Gusts 30-40 mph are possible 3-6pm from Sheridan to West Salem and north to Dayton. Yes, there could be a 40 degree drop from early afternoon to sunset for many of us! The cooler air arrives after 6pm in the Portland metro area, dropping us from 110+ to mid-70s by 11pm. It’s going to feel amazing…

Take a look at the WRF-GFS 5pm temperatures…112+ over a good chunk of the metro area Monday afternoon

Notice at 3pm we’ve got westerly wind beginning to pour into the central Willamette Valley. Salem is beginning to cool. Hot east/southeast wind from Longview down into the metro area

Then at 6pm things have turned VERY windy. Forecasting 8 millibars pressure difference between Lincoln City and Wilsonville! West wind gusting over 40 mph from Sheridan to Amity. Hot east wind still just barely going in the metro area. This is more of a “southwest push”; we’re not getting the real strong northwest wind coming up the Columbia River

Then at 9pm the southwesterly push has arrived in the metro area and hot east wind is gone. Gusts 20-30 mph will be ringing chimes in the southern half of the metro.

It will be a very shallow push, which means warm air overhead will mix down again Tuesday, just no extreme heat. We’ll like bounce back into the low-mid 90s Tuesday afternoon. Much better…

 

5pm:

112 in Portland today plus lots more all-time records

High temperatures come in every six hours from the regular official reporting stations and here they are

 

Lots of 112s, but that's also the current temperature at PDX. It's possible we go a degree higher...we'll see. Obviously that's a new all-time record for Portland, well above the previous 108 record (yesterday) and long-standing 107 degree record. But look at the valley! Salem just blew past the 120+ year old record, by 5 degrees!

 

Astoria tied the 101 degree record, plus Eugene & Vancouver set an all-time records. I'll have more with a detailed post about tomorrow and beyond by 8-9pm. The big message: 24 HOURS OF EXTREME HEAT STILL TO GO

 

3pm:

All-Time Record Heat Records Falling, But No Big Power Issues Yet

It's 111 at PDX, the hottest temperature many of us have ever felt, including me. The same temperature as Phoenix at this hour...though at least relative humidity has fallen to 16%...it's a dry heat. 3pm observations, notice all official stations are 108 to 111

All-time records have now fallen at PDX (again), Troutdale (again), Vancouver, Salem, and possibly Astoria where it hit at least 100. Eugene is only a couple degrees away. The Dalles at 114 is the highest I've seen at the airport sensor. The official record, I think it's downtown, is 115 degrees there.

Huge temperature variations continue along the coastline. Just a couple miles inland it can be 105 degrees, yet around 70-75 right ON the beaches. Live view from our Shilo Inns Seaside camera shows a westerly breeze on the sand, that tells me it's likely under 80 degrees in this spot. A lot of people. We've got two more hours of heating...typically. East wind has been blowing a few hours at PDX, and when that happens the temperature rise levels of a bit. That said, there's no reason it couldn't go up another 3-4 degrees. Hang on folks, we've still got 20-28 hours to go...depending on your location. I see just a thousand or so PGE customers out, that's no worse than yesterday. Fingers crossed...

 

Noon

Hot...PDX is just passing over the 100 degree mark this hour. Troutdale, where east wind has surfaced, jumped to 105...at noon.

 

Check out Astoria...97 with a light northeast wind. Hoquiam at 100 is an all-time high temperature record.

 

Farther south along the Oregon coast, the extreme heat is either on the beaches or just a couple of miles inland. Example: Pacific City...67 on the beach but 97 over in the estuary area

 

Easterly pressure gradients continue to rise through the Gorge and across the Cascades. That easterly flow continues through Monday morning. As easterly wind surfaces in more spots, expect temperature spikes, but humidity drops. It doesn't matter; either 102 and humid or 110 and very dry. It's blazing hot everywhere except the beaches. Even Government Camp has gone over 90 degrees this hour.

 

I see PDX officially dropped to 73 degrees last night, the 2nd warmest night on record and the warmest ever in June. 

 

 

10am

The heat is on big time this morning, as expected we are starting warmer and heating up much more quickly. Current temps

And regional temps

What grabs my attention right now:

  1. 850mb temp (about 4,000') over Salem was measured at +26.4 degrees (C) this morning. About 2 degrees below all-time record. Expected to rise to a record +30 by afternoon
  2. Overnight low was bad, but we did not set an all-time record in Portland. Down into the lower 70s
  3. Easterly gradient and breezes have developed as expected. Gusts 25-35 mph at Vista House, and wherever that wind surfaces temperatures are skyrocketing
  4. It's 100 (at two separate wx stations) in Yacolt...at 10:18am. Astounding...east wind has surfaced there.  I've got 95 at my home in the woods east of Corbett.  Easterly breeze here too.
  5. It's 92 already on the Long Beach Peninsula (Ocean Park). Blazing hot for some of you on the coastline the next 6 hours. Mainly north of Pacific City.
  6. PDX is 88 at 10am, already 6 degrees hotter than 10am Saturday

Hang on...it's going to be a rough day...

  • Posted

9pm Monday...

Quite a change today eh? Temperatures soared from near/below freezing yesterday evening into the upper 40s or even lower 50s today. The southwest wind did the trick; even Troutdale made it to 48. I think the McMinnville sensor may be about 5-6 degrees off, more likely 50 there.

A westerly surge of "warm" air is working through the Gorge. Cascade Locks has jumped into the lower 40s and Hood River should see it soon. By sunrise a 40-45 degree breeze should have made it all the way to Maryhill & beyond. The pressure gradient is now WESTERLY for the first time since last Wednesday in the Gorge. This cold event has ended.

The damage to the power grid is the biggest I've seen since the 1995 windstorm. Looks like around 300,000 PGE customers have been out at one time in two different "waves of ice". The first Friday night in the northern/central Willamette Valley, then the 2nd yesterday evening/last night in south and east metro areas. There was some overlap in those south metro spots. Here are some preliminary ice accumulation numbers. It's amazing how well models did showing the thick ice glazing in the southern half of metro area. I've colored the areas where we generally saw 1/2" or more.

The rest of this week features "normal" weather. Drier conditions tomorrow with just a few scattered showers, but heavy Cascade snowfall. Then ONE dry day Wednesday before rains resume Thursday & beyond.

A few notes:

  1. We don't see a February 1996 setup with flooding following the melt. There's no heavy rain on the way to bring us a flood.
  2. I don't expect re-freezing of wet roads tonight. Too mild with cloud cover for just about all areas west of the Cascades
  3. There's no sign of low elevation cold/snow in the next 10 days, but we'll remain on the cool side with lots of rain

Chief Meteorologist Mark Nelsen

  • Posted

4pm Thursday...

I've been off work the last three days and will be through Saturday. But I want to update you on two important changes ahead. Tonight looks especially interesting.

First, I see almost nothing has changed with regard to smoke. We are in an unprecedented (at least for the past 40 years or so) smoke event over the region. This is the 8th consecutive day with VERY UNHEALTHY to HAZARDOUS air quality in the Portland metro area. I never saw that growing up here and sure haven't in my career that started in 1991. We've been receiving a "double-whammy" of: light wind at sea level keeping surface conditions smoky, plus tons of high level smoke streaming north from Oregon and California. They have conspired to keep temperatures well below what they should be in the current weather pattern. The effect is that this fire/smoke event brought our "summer to an end" on the 10th this year, when under normal circumstances it would have continued through today. We don't have any sort of spell of "summer weather" in sight. Fall is here weather-wise starting tomorrow.

My wife is tired of me saying "if it wasn't for the smoke we'd be sunny and in the low 80s again today". That would be the case today of course. If we didn't have fires burning, this could have been a record warm first half of September. But you see starting a week ago the dense smoke kept us a solid 10-20 degrees cooler than we would have been otherwise.

Air quality numbers at 3pm:

Yesterday evening was interesting down in the south Willamette Valley. That's because a weak westerly push of marine air briefly dropped Eugene and Albany down into the GOOD to MODERATE category. But then a light northerly wind today has allowed the pollution to slosh back into the southern valley.

THUNDERSTORMS TONIGHT

This is the biggie. We haven't seen this setup since the end of May; a nice nocturnal lightning event is on the way.

  • Anytime after 8pm then on through sunrise tomorrow, ANY of us west of and in the Cascades (including coastline) could see quite a light show.
  • In fact the Portland NWS has the recently burned areas under a Flash Flood Watch since any heavy rain on dry/burned soil will cause all sorts of trouble. Landslides, rock fall, trees drop, etc...

The Storm Prediction Center even has us under a MARGINAL to SLIGHT risk of severe thunderstorms. A severe thunderstorm in this case would be a damaging wind gust over 58mph or large hail. Yes, that could happen during the night. Rare, but I have seen it happen here. And no, no one knows why SPC still uses those categories. Does any normal person know the difference between MARGINAL, SLIGHT, & ENHANCED??? No.

What's the reason? It's the large upper-level low offshore that's been spinning in circles all week. Tonight it makes the big move. Right now, notice the southerly flow in the atmosphere. Imagine how many fires are upwind this afternoon, thus the continuing dense smoke overcast:

Then tomorrow midday, it's about to move right over Portland...

By Saturday midday it has moved to the east, and we have a west-northwest flow overhead. By this point all upper-level air will be coming in clean off the eastern Pacific!

There is a lot of moisture as this system moves in. HRRR says about 1.50" precipitable water west of the Cascades...that's juicy!

The way the low is moving in leads to tremendous lifting in the atmosphere the next 12 hours. Especially 8pm-2am. This IS the classic setup for thunderstorms west of the Cascades. Each model is slightly different with location and timing, but I think the NAM-NEST represents reality well. At 8pm storms are starting to pop just to our south.

But by 1am they are spreading north quickly

And by 6am it's obvious SOME of us will have seen downpours, others relatively light rain

It's important to not focus on specific spots; the point is that over and west of the Cascades we'll see some heavy rain from thunderstorms during the overnight hours. Some areas could see up to an inch of rain, others just a brief wetting.

Beyond sunrise tomorrow, we'll be into a more typical spring/fall showers & sunbreaks pattern. That continues the rest of Friday.

AIR QUALITY

  1. A westerly breeze and thunderstorms should clear out the densest fire smoke by sunrise and we'll just have a smoky smell/view instead of this hazardous stuff. That's an improvement.
  2. Then much cooler air overhead with the upper-level low will finally break the inversion we've been under for 8 days; that should help quite a bit. Lots of the surface smoke should easily mix out after sunrise.
  3. Continuing westerly flow in the upper atmosphere starting late tomorrow through next week should keep California and Oregon fire smoke moving east and away from us.

BY TOMORROW MORNING AIR QUALITY SHOULD BE NOTICEABLY BETTER, THEN BY SATURDAY AFTERNOON WE SHOULD BE BACK IN "FRESH AIR" AGAIN!

Enjoy the weather "show" tonight and hopefully we avoid any significant flooding issues in those burned areas. This will be our first measurable rain in about a month; which means roads will be slick at first too. Stay safe!

Chief Meteorologist Mark Nelsen

  • Posted

3pm Saturday…

Nothing is more relaxing than a day off work, sitting by the fire, perusing the latest maps/models and meteorological info.  What could be better???  Isn’t that what everyone does?

I’ll be back at work tomorrow, but nowadays everything we need to make forecasts is available online (free or behind a paywall) and can be done from home.  It wasn’t like that 29 years ago when I first began forecasting in Portland.

Today has been a great day for skiing in the mountains.  I see 15-21″ new snow has fallen since Friday morning on Mt. Hood, most of that since sunset Friday.  The problem is high winds.  At 1pm Mt. Hood Meadows closed down after putting lifts on standby for an hour or so.  It’s just too exposed up there in the middle of a storm.  This is a four day long storm folks.  Tomorrow’s wind could be similar as another wave of heavy snow arrives.  By the time the snow tapers off Tuesday morning, we can expect another 3 to 5 feet!  Here’s one snow forecast from a weather forecast model (WRF-GFS) through 4am Monday

wrf_snowthroughMondayAM

We’ve got very large waves on the coastline and some occasional downpours in the lower elevations, but neither is too noteworthy since we’re in the middle of the storm season.

What you really want to know about is lowland snow for next week right?  Now that we’re within 2-5 days of this lowland “snow chance episode”, we’re getting a clearer picture of what’s ahead.

I see two specific periods in which there is a decent chance at least parts of the lowlands west of the Cascades will see sticking snow.  

  1. Monday evening/night
  2. Wednesday (or possibly Wednesday into Thursday)

Notice I didn’t mention tomorrow, tomorrow night, Monday daytime, or Tuesday?  That’s because it’s too warm tomorrow (40s), slightly too warm with strong southwesterly wind Sunday night (snow unlikely to stick much below 1,000′ along I-5 corridor), and a bit too warm Monday (36-40 degree day).  Then Tuesday will likely be dry, or mainly dry and 35-40 degrees too.  That’s why I’m thinking your lives should continue as normal during those times.

MONDAY EVENING/NIGHT

Increasing rain/snow mix Monday afternoon may change to all snow from the metro area south to Eugene around sunset and beyond.  If temps drop down to 32-33 degrees that evening and moisture keeps coming down, this could be a setup for a sloppy 1-3″ snow somewhere between Portland and Eugene.  Everything has to work out just right for this to happen.  So it’s just a chance for now.  But you should be thinking there’s a possibility at least part of this area (including Portland/Salem/Albany) could get sloppy/snowy roads Monday evening/night.  It’s still over two days away so tomorrow we should have a much better idea.  If something fun/snowy is going to happen in the lowlands, this is the first chance.

WEDNESDAY NEXT WEEK

This is our classic setup for a real snow or snow/ice storm.  If enough cold air pours out of the Gorge and into the metro area (and north), we could be left with a snowy/windy/frozen day in Portland.  Of course that extends east into the Gorge as well.  One of those days where most/all schools shutdown and it’s tough to get around.  A real snow day is a possibility.   Models are forecasting a dusting to 6″ (at the high end).  This is why I don’t show snow forecast maps from models many days ahead of time; totally irresponsible and then they get passed around on social media.  Three days ago they were throwing around numbers like 10-20″.  There are strong hints that the cold air may not extend south of the metro area.  It’s quite possible Salem/Albany get little or no snow out of this second event.  And nothing at the coastline.

BEYOND WEDNESDAY

It’s very clear that this week’s flirtation with snow/ice/cold is a one shot deal.  All models swing us back into the mild “split jet stream” setup we’ve seen all winter by next weekend and beyond.   Two of our models have a mild south wind and end of freezing conditions by Thursday morning.

SUMMARY FOR WESTERN LOWLANDS: LONGVIEW TO SALEM INCLUDING PORTLAND

  • SUNDAY EVENING & NIGHT:  Rain showers change to rain/snow showers mixed overnight into Monday morning.  Little or no sticking at lowest elevations and no freezing.  Trace-1″ up around 1,000′.  Maybe a few inches up around 1,500′  Monday morning commute should be perfectly normal, except some snowy roads up around 1,000′ and above.
  • MONDAY DAYTIME: Scattered light rain showers turning to steady afternoon rain.  Mixing w/snow by sunset and possibly changing to all snow and sticking later…beyond 7pm.  Yes, I’ll keep a close eye on this so we can avoid a 2pm, 4pm, 6pm etc… jammed freeway surprise.   Zero to 3″ late Monday evening through the night.  Best chance south of Portland.  Yes, I also realize zero to 3″ sounds ridiculous.  I’ll narrow it down tomorrow afternoon.  Some models keeping all the snow from Salem south at this point.
  • TUESDAY:  Partly cloudy, a flurry or two.  Areas that have snow-covered roads from Monday night would be icy.  But where it doesn’t snow Monday night, both commutes Tuesday will be fine.

METEOROLOGY BEHIND THE FORECAST

This weather pattern is a lot of work, but for a weather geek like me it’s nice to have something interesting ahead.  That’s after 2.5 months of “meteorological melancholy” since Halloween.  I took one day away from the weather maps/models yesterday then jumped back online this morning.  One message sticks out:  The GFS has been terrible leading up to this event, constantly pushing in cold arctic air too fast plus too intense.  I had a feeling that was the case but looking back at maps 2-3 days ago that’s very clear.  Other models have turned a little milder but they were never crazy with the arctic air to start with.  In fact it’s now clear no arctic air moves into the Portland metro area until it gets pulled in through the Gorge Wednesday.  For the geeks this has gone from what could have been an epic event to a typical (somewhat) brief midwinter snow/ice episode with no arctic blast.

That surface low moving by to the north Sunday night gives us far too much onshore flow for lowland sticking snow, even with 850mb temps down around -7/-8, especially since showers appear to dwindle to almost nothing by Monday morning.  I think Monday morning will be a non-event for 95% of us; some grass on some lawns/barkdust here and there but any real snow (1/2″ or more) up around 1,000′ and above. Tuesday’s forecast is easy because the surface low passing through Oregon Monday night is gone.  We’re left with -8/-9 at 850mb and flat gradient.  That should allow us to climb up around 36-40 degrees (assuming ground is bare).  But about that Monday low…

The ECMWF came in this morning going gangbusters with precipitation Monday evening.  It sends the surface low from Florence to La Grande, throwing up around .60″ precipitation over south/east metro!  A light northerly breeze at the same time = possible sticking snow.  The 18z RPM gives us maybe an inch of snow.

RPM_72_SNOW_18z

ECMWF (snowiest) says 2-4″ at least.  This is 12 hour precipitation from 4pm Monday to 4pm Tuesday.  I guarantee this will shift north or south on future runs.

ecm_precipmonday4pm-tuesday4am

Reliable WRF-GFS says band of precip stays mainly south; hosing metro area with little or no snow, but 2-3″ Salem to Eugene.

wrfsnowmonday4pm-Tuesday4pm

As for the 2nd event, both GFS and ECMWF are bringing a very deep low close to the coast, far enough north to put Salem/Albany pretty much out of the running for snow/ice.  Check out the WRF-GFS pressure pattern midday Wednesday…a tad windy in the Gorge maybe?  Strong south wind on the central/south coastline the same time.

wrf_wednesdaypmpressure

That 2nd event is far out in time so I’m sure this will be changing as we get closer.

So remember, the first real chance of lowland snow (for some of us, not all) is Monday evening/night, other than that you’re in the clear.  That’s it for now.

Chief Meteorologist Mark Nelsen