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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

I've changed the format for today and Sunday...come back to this same link  regularly throughout the day for quick updates as we go through the rest of Saturday.  Newest information FIRST.  Remember you can follow me on Twitter: @marknelsenKPTV and Facebook @marknelsenweather

9pm Final Saturday Update

What a historic day! Portland (and probably Troutdale) broke all-time temperature records…reaching 108 and 109. The final numbers…

And for the region

What’s ahead? In general the forecast hasn’t changed at all. Two more scorching hot days (hotter than today), then a strong marine push Monday evening brings in 70 degree air by 8-10pm west of the Cascades…it’s going to feel glorious. But, of course we have more record-breaking heat first. Tomorrow will be the hottest day south of Portland, due to that marine air arriving Monday midday down there. I expect at least 5 degrees warming from Salem to Eugene tomorrow, setting some all-time records. And at the coastline there will likely be a period from Noon-3pm on the north coast when temperatures soar. Tomorrow will feature conditions I never thought I’d see west of the Cascades. Temperatures to 110 and higher, a dry easterly wind, and nary a cloud in the sky. And keep in mind we’re starting much warmer tomorrow! It’ll take most of the night to get down below 80 in the urban/suburban areas

This will probably break Portland’s all-time warm low temperature. These are bit trickier to do because the weather data is collected for the calendar day (midnight to midnight). If we have a hot spell that ends with a strong marine push in the evening (that will happen Monday)? The late day temperature (close to midnight) could end up being cooler than the warm morning low. I’ve seen it happen in the past. But tomorrow night will be even warmer than tonight so I’m confident we will set this record.

For tomorrow, all models continue to agree that we’ll jump another 3-6 degrees, so I’ve put our forecast high at 112. The new 00z WRF-GFS shows a classic thermal trough from about Medford to Astoria in the afternoon

Easterly wind, although not strong, should be more widespread, and it’ll be windy in the western Gorge tomorrow. I’ve been watering my plants/lawn furiously the past two days in anticipation of that.

Look at those 104 degree highs just about touching the northern coastline beaches…plus 112 or so in the northern Willamette Valley

Then assuming cooling southwest wind doesn’t arrive until 4pm or so Monday, maybe a notch or two warmer. The east and southeasterly flow is very strong through midday Monday overhead and 850mb temps are 31-32 over PDX!  But you see how close the cooler air is...just south of the metro

That’s it for now…I’ll be on TV at 10pm with lots more numbers.

 

7pm

Portland officially hit 108 today, hottest on record. More coming up by 9pm or so...dinnertime

5pm

It happened! PDX is reporting 107 degrees as the current temperature AND the high so far today.

That ties the all-time 107 degree record from 1981 and 1965. I’d say about 1/2 of the time when the high is also the current temp at PDX on a sunny summer day…we end up a degree warmer. Unless the NWS puts out a special statement (seems likely), we’ll know for sure around 7:20pm. It’s quite possible today will go down as the hottest day in Portland’s history. Remember the downtown station has not gone above 107 either and those records go back into the late 1800s.It’s possibly the 109 at Troutdale is an all-time record, looks like Vancouver is one degree short. A few thoughts

  1. Models nailed this, even better than we did. Even our “high” forecast of 106 has been exceeded. Models have been going more like 107-108 today. Sure enough, we’re doing a little better than Euro showed…which is disturbing for tomorrow.
  2. All models are forecasting between 3 and 6 degrees warming tomorrow as more of a widespread dry/hot easterly wind surfaces. That’s just unreal. Do the math and it’s obvious 110 is probably too low. Working on that now
  3. This has been an exceptional triumph of meteorological modeling. Models forecast all-time records being broken 5-7 days ahead of time.
  4. Power outages are beginning to pop up. About 3,500 PGE customers out

3pm

100 at PDX this hour, running 11 degrees above yesterday at 3pm. That puts us on track to hit our 106 degree forecast. Dewpoint is 67...very humid...yuck. Easterly (dry) wind beginning to surface in a few spots. Sure, it's drier, but hotter. Troutdale and Scappoose jumped to 105 at 3pm! 102 at Rhododendron just below Government Camp is amazing for 1,600' elevation. Heading toward max temps in the next 3 hours. Once drier air punches down into PDX, expect a temperature spike. Possibly the 107-108 models were forecasting was right. TODAY could be the day we set our all-time record. The drama...

Working on forecast right now and there's a problem on the north coastline. WRF-GFS pushes easterly flow all the way to beaches and slightly beyond from about Tillamook north tomorrow. 100+ temps may be a possibility just inland from the surf from Long Beach down to Pacific City tomorrow. Maybe Astoria WILL break the all time record you see in the previous post. More later...

 

 

 

Noon 

Looks like all is proceeding according to plan and no changes to forecast.  Rode my bike around 10-11 a.m.  Tolerable, but turning hot! 

Portland is 91 at noon; that's plus 10 from yesterday at the same time.

Does that mean we'll be 105?  Could be, but humidity is still high, dewpoint of 64...yuck.  That tells me the hot atmosphere overhead hasn't surfaced or "mixed out" yet.  At some point within the next five hours, some drier air from above should surface.  When that happens the temperature will spike, then relative humidity falls.  Notice Yacolt is already 95???  It won't matter by that time since we'll be above 100 degrees.  Some other temps around the region are about what I would expect.  

Portland only dropped to 70 last night!  A record for the day, 2nd warmest ever in June.  The other two warmest were during the 2015 heatwave.  Of course that means you just endured the warmest night in 6 years.  Even out here at home in a rural area I only had a low of 63...rare.

Right now pressure gradients around the region are light northerly, or very light easterly across the Cascades.  Wind is light east in the Gorge, but stronger easterlies are arriving on many ridges.  I see Middle Mountain in the Hood River Valley is blowing along with Larch Mtn. and Three Corner Rock Washington.  That's a sign the blistering hot easterly flow has begun overhead.

I haven't made the forecast yet, waiting to see what happens this afternoon with regard to raising tomorrow's all-time high temp forecast. Morning GRAF & ECMWF models are the same...forecasting well above 110 both tomorrow and Monday as that dry east wind surfaces both days

That's it for now.

  • Posted

9pm Thursday…

This is just a brief post because NOTHING has changed meteorologically with the weekend forecast. All the points from yesterday are still valid. Just a tweak here/there

HIGHLIGHTS

  • What will likely be the hottest heatwave on record in the Portland area (and much of northern OR/southern WA) arrives tomorrow and continues through Monday. And there’s a good chance we remain at/above 90 the rest of next work week.
  • Expect three 100+ days in Portland, and they may all be 105+
  • I’m very confident we’ll hit 106-108, and think 110 is quite possible for the first time here. Records go back to the late 1800s both at the airport and Downtown.
  • Humidity will be mostly reasonable…it sure won’t be “Bourbon Street Humid”, more like our typical heatwave humidity.
  • Overnight lows will likely end up warmest on record in Portland too. Low-mid 70s Sunday and Monday mornings. That means homes/apartments will remain dangerously warm with no chance to cool off. Typically we see reasonable overnight temps in our area.
  • The only place to cool off will be the coastline…more like 75-90 out there over the weekend. Most likely you won’t be alone if you want to play on the beaches. There’s a chance the far north coast makes it to 90 on Sunday…we’ll see.
  • I do not expect any sort of strong wind anywhere in the Northwest. BUT, some easterly wind will be felt over the metro area Sunday. Gusts 20-30 mph are possible. Enough to move an accidental fire along, but not enough to drop powerlines into trees.

I didn’t change any numbers for the weekend in today’s 7 Day Forecast, although we “overachieved” today with highs right around 90 in the metro area. I was thinking more like 86-87.

That boosts confidence in our extreme forecast numbers. Today’s forecast

850mb temperature forecasts remain the same (temp around 4,000′ overhead in Celsius). In fact, while making the forecast, I noticed both GFS & ECMWF ensemble averages matched through Sunday! +19 tomorrow, +25 Saturday, +29 Sunday (new record), +25-27 Monday PM. The only disagreement is over how quickly the upper-level low to our southwest Monday slides north offshore. Quicker movement Monday would lead to an earlier marine push = cooler high temps. Slower movement gives us another extreme day Monday. The most recent ECMWF ensemble average temps for Portland (near sea level) are just amazing.

We were a few degrees warmer than forecast today. As I mentioned last night, we see that with Euro surface forecast temps in the warm season. That’s why we’re going 96 for tomorrow. Since the numbers turn so extreme Saturday-Monday, I’ve stuck with these numbers instead of going higher. I couldn’t imagine forecasting 111-114 for Portland…so I didn’t.

Check out the fresh 00z IBM Graf model, which handles warm season temperatures well. 108 Saturday, then around 114-115 Sunday! Just like the other models.

I’ve haven’t noticed this model “over-forecasting” heat in the last two warm seasons. Part of the reason we’re seeing such extreme temps (other than sun, offshore flow, and hot airmass overhead) appears to be the surfacing of that very dry subsiding air below the upper ridge. Notice the dewpoint drop both weekend afternoons. Sunday that would be relative humidity in the teens. The icing on the cake is the easterly wind Sunday. The GRAF is forecasting east wind to surface throughout the metro area that day (but not so much Saturday). It’ll be a “dry” 110 degree heat as they say…

In case you are wondering, the coastline WILL be cooler through this event. This applies to the northern Oregon and southern Washington coast…take off 5-8 degrees for Lincoln City and Newport

A few more numbers for you this evening. Portland’s all-time warm low temps. These are from the airport. With such a hot airmass, plus a larger metro area, plus a warming climate, it’s fair to assume we’ll be warmer than this.

This is dangerous for medically fragile or elderly folks…if you know any, please check in on them regularly!

That’s it for now, I’ll be on-air and online through NEXT Friday, the 2nd. I was already scheduled to work this weekend which is convenient. Make sure you are following me on Facebook: @marknelsenweather and Twitter: @marknelsenKPTV. I will be updating those much more frequently than this blog. 

Chief Meteorologist Mark Nelsen

  • Posted

Can you believe that just over two days ago we were moving through a peaceful and sunny Labor Day Weekend? Things have changed…

Now, based on various reports/video/pics:

  • Firestorms have burned hundreds of western Cascade forests. Productive private timber lands have burned as well.
  • It is assumed hundreds of homes have burned. Large portions of several towns appear to have burned down. That would be Detroit, Mill City, Gates, Blue River, Talent, Phoenix, and possibly others. We know at least two people have died and it’s also assumed there are others that didn’t make it out of the firestorms late Monday night and Tuesday morning.
  • Medford and Diamond Lake Resort had close calls last night. Both appear to be safe for now. We will see about the Olallie Lake area.
  • Thousands have left their homes in many parts of western Oregon.

You may recall over the weekend we were warning a dangerous fire situation was on tap for late Monday through today. Check Sunday evening’s blog post. Sure, we get dry east wind and warm temperatures every fall, but this was forecast to be extra dry and extra windy. The wind wasn’t too extreme in the metro area as noted in yesterday’s post, but unusually strong gusts (for any time of year) hit the west slopes of the Coast and Cascade Ranges. Weather forecast models nailed that situation.

Satellite imagery today shows something I’ve never seen; almost all of western Oregon blanketed in thick smoke…not from California fires but our own. This is a GOES image that also includes fire detections (orange areas) as an “underlay”.

Fire crews have been totally overwhelmed in the region due to so many fire starts. Many fires have been relatively small (less than 100 acres), but the large fires continue to rage in the Cascades this evening. Here’s the 9pm fire detection, using the infrared channel. Black is a heat signature. Click on image for the current loop

The three big fires are quite close together now. Latest numbers are 112,000 acres for Riverside fire SE of Estacada/Colton. This one DID NOT EXIST 36 hours ago. The Santiam Fire (renamed from Beachie Creek Fire) is around 160,000 acres and has joined with the Lionshead fire as that one moved westward across the Cascade crest and down toward Detroit. Add in 90,000 acres there and you get a third of a million acres of timber burned…let that settle in.

I thought it was revealing what someone said this afternoon during a news conference. He was from from Detroit Fire District I think. He mentioned that late Monday night the high winds hit and suddenly fires were popping up everywhere due to power lines down. That tells me the extreme wind gusts really did surface in spots. Same thing with wind damage around Lincoln City where a gust to 62 mph was recorded…easterly of course. A 98 mph gust was recorded up at the top of Hoodoo Ski Area early Tuesday morning. Clearly this was an “off the charts” east wind event for September.

WHAT LED TO THESE MASSIVE FIRES? 3 SPECIFIC CAUSES

  1. Easterly wind was stronger than we typically see this early in the season = lots of powerlines down into dry trees/brush.
  2. It’s the driest airmass I’ve ever seen in September. Dewpoints in the 20s today and relative humidity below 10% at times west of the Cascades. That’s because it was an extra-early “arctic airmass”
  3. It was the worse possible timing for forests/grasslands. No fall rain yet, not even a weak frontal system. Fuels are the driest of the entire year. If the wind/dry air arrived in October with wet/moist forests the fires wouldn’t have blown up so much.

I’m sure there will be plenty of discussion about how much climate change (warmer/drier late summers), past forest practices (not enough harvesting), and power company maintenance (lines through forests instead of underground) played into this unprecedented event. It sure is interesting that the corridor where PGE cut the power has seen no fires (Sandy to Gov’t Camp). I’ll leave all that to others.

The good news is that onshore flow is about to return to the Oregon coastline, that should greatly reduce fire threat tomorrow for the coastline (only).

Inland, the easterly flow is weakening, although still about 5 millibars pressure difference across the Cascades. That easterly flow ends by late tomorrow. By Friday afternoon a normal (but weak) onshore flow arrives into the valleys and Cascade foothills. Humidity goes up, which slows fire growth a bit. So the explosive growth phase of these fires should end by Friday, but I don’t expect rain until early next week.

The massive plume of smoke stayed mainly south of the metro area yesterday and this morning. But you probably noticed it advanced overhead this afternoon & evening. At 6pm…

Smoke modeling shows the plumes will veer more northwest through tomorrow. There’s a good chance the metro area will be under a dense smoke layer tomorrow with temps around 80 instead of 95 we were thinking a few days ago (for tomorrow).

Thursday could be a real nasty day for air quality in Portland. Maybe as bad as early September 2017 when the Eagle Creek fire sent smoke/ash into the metro area.

That’s it for now, heading back to TV land for the 10/11pm newscasts. See you there.

Chief Meteorologist Mark Nelsen

  • Posted

9pm Sunday…

I’m on vacation this week (at home for now), but we’ve got some serious fire weather ahead. First, while I’m standing in my kitchen about two hours ago, my wife’s phone gets an emergency alert. It came in with a blaring tone like a civil emergency or Amber Alert.

Other than the crisis of her phone having less than 50% charge, what does this mean? Power may be shut off in 24 hours? My phone didn’t receive this alert, but hers is probably pulling from a cell tower closer to Mt. Hood.

This is a first, I’ve never seen a situation where PGE has considered de-energizing power lines to avoid forest fires. Indeed, they have the “Hoodland Corridor” (east of Sandy to Welches to Government Camp) under this possibility

They are taking the proactive step after seeing what can happen with high winds, low humidity, and extremely dry vegetation. We’ve seen it in California the past couple of years. We get gusty easterly wind sometimes in September, nothing unusual, but this time is different. MODELS ARE FORECASTING A “HISTORICALLY STRONG” EASTERLY WIND EVENT BEGINNING MONDAY EVENING AND CONTINUING THROUGH TUESDAY

WIND HIGHLIGHTS

  • Nothing unusual through late afternoon Monday over and west of the Cascades. It’ll be a hot afternoon though, into the lower 90s in Portland.
  • Sometime around 5pm or so, a strong easterly wind will start coming over the Cascades, through the Gorge, and down into the lower elevations. Wind will be around through Wednesday.
  • DAMAGING WIND (gusts over 45-50 mph) should be confined to ridges in the Coast and Cascade Ranges, plus down into the Cascade foothill communities. That’s eastern Clark, Multnomah, Clackamas, Marion, & Linn counties. Wind gusts 40-60 mph are not a damaging wind in the western Columbia River Gorge.
  • I DO NOT EXPECT A “WIND STORM” IN PORTLAND, but gusts 35-45 mph are unusually strong for early September and some limbs will probably fall. Expect a few power outages Monday night and Tuesday.

THE BIG FIRE WEATHER PROBLEM

I’ve never seen a high wind setup (for the foothills and Cascades) this early in the “Fall east wind season”. This is unusually strong even for November/December, but this hasn’t happened when forests are still totally dry and humidity will be extremely low. This could be a once-in-a-quarter century type of event. I haven’t seen it in my 29 years forecasting here! The Storm Prediction Center has our area under an “extremely critical” fire threat; I don’t think I’ve seen that either

The problem?

  1. TERRIBLE TIMING: Forests are at the driest of the season…ready to burn. In fact a bit drier than average for early September. If this was May, we might be okay.
  2. DRY AIR: Relative humidity will plunge into the single digits to teens all across Oregon as dry air arrives Monday night. Almost unheard of west of the Cascades in September.
  3. STRONG WIND: Wind gusts 30-60 mph (depending on location) could whip any spark into a massive fire in a few hours in these conditions. Imagine if a Douglas fir branch drops onto a power line, bringing it down & starting a fire. 30-40 mph gusts could spread a fire many miles with downwind spotting. The Eagle Creek Fire on this date in 2017 spread 15 miles through the Gorge in one night! That COULD happen somewhere along the west slopes of the Cascades tomorrow night or Tuesday.
  4. HISTORIC SEPTEMBER FIRE TIME: The largest fires west of the Cascades have blown up under these conditions; Tillamook Burn in 1933, Yacolt Burn in 1902, Eagle Creek Fire in 2017 etc…

WHAT YOU CAN DO THE NEXT 2 DAYS

  • Stay out of the woods and travel only on graveled/paved roads. Never drive over grass once your vehicle warms up.
  • If you live in a rural/forest area DO NOT MOW or do anything outside that can create a spark during this time
  • No cigarettes, fireworks, or shooting practice (Pit Fire near Estacada started this way)
  • If you live in the foothills of the Cascades or western Gorge, be prepared to leave home quickly if needed and stay alert. I still have my camping trailer hooked up since we just got home. I decided to leave it that way until Tuesday night…just in case. It happened 3 years ago…

I won’t spend too much time on the technical details. We have a hot ridge of high pressure over the West Coast right now. Temps are running about 10 degrees above average and more like +15 coming up tomorrow. A 597 dm high is VERY hot. With offshore flow that could put us close to 100 degrees. But we had onshore flow today

The upper-air pattern becomes highly amplified (briefly) Monday night and Tuesday. An early season cold airmass digs south into the Rockies, doing a “drive-by” of the Pacific Northwest. This is 8pm Monday. That’s quite a setup, hot airmass along coastline and cool fall weather coming down through Idaho. This general pattern is perfectly normal in September/October, but this is an extreme version of that pattern

By Wednesday the hot upper high is back over us…other than fire weather the big story is a continuing hot/warm pattern through NEXT weekend.

To show the contrast between the “cold” airmass coming in to our east vs. the hot to the west. Take a look at 850mb map for tomorrow evening

About 35 degrees BELOW NORMAL at 5,000′ over Montana, yet 12 or so ABOVE NORMAL over the Oregon coastline. That’s a tremendous thermal gradient. So a dry cold front will push south and west across the Pacific Northwest tomorrow afternoon-night. You see the arrival in the WRF-GFS cross-section over Portland. Right around 00z tomorrow (5pm). 60-70kt wind speed around 3,000′ over Portland. That’s amazing; I’ve never seen that in September/October, and it’s very rare anytime in the cold season. So we’re in a bit of uncharted territory here. For example, how much of that strong wind will “mix down” into the valleys?

The same model shows the benign wind conditions at 2pm tomorrow. Northeast wind is just arriving at The Dalles and northeast Oregon. This is what we would call the “arctic front” if it was winter; the sudden wind switch to easterly. Note these are calculated wind gusts, not steady speed.

By 2am Tuesday (tomorrow night), high wind has arrived in the Cascades and gusty wind in most of the metro area as well. There could be some crazy strong wind gusts in the Cascades and western foothills. 50-65 mph possible there. Notice more reasonable wind in the metro area…gusts 25-45 mph; still strong for September.

Also note (in red) the 8-9 millibar easterly gradient across the Cascades; I’ve never seen that in September either. Right now there are two large fires burning in NW Oregon. One north of Detroit (Beachie), and one large one (Lionshead) just east of Mt. Jefferson. Imagine what could happen with either of these fires the next 48 hours. Not good..here’s the Beachie fire this afternoon from folks at Willamette National Forest

So, meteorologically we’re about to see something very rare for this time of year. IF we don’t get any large fires, it won’t go down in history as something that interesting for regular folks. But of course if we get one or more large fires, we’ll all remember!

Chief Meteorologist Mark Nelsen