fire

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

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