An inversion is when temperatures increase with height.
Today a super-inversion exists, with extraordinary warmth aloft.
At 6 AM this morning, temperatures are in the lower 50s in the south Sound and upper 50s to around 60F in central Puget Sound (see map). But looking to the western Cascade slopes, you see some warmer temperatures with some in the low 70s.
It was so chilly at local river valleys that fog and low clouds formed in some of them:
But now, let me shock you. Right above Puget Sound, just a little over a thousand feet up, the temperatures are in the 80s!
You heard that right. In a few hours, that warm air will mix to the surface and high temperatures will climb into the the upper 80s to near 90F over the western lowlands.
The warmest day for the remainder of 2024 will occur today
Below is the temperature structure at 6 AM from aircraft data at SeaTac Airport. Around 63F at the surface (452 ft ASL) and 80F at around 1600 ft. AN INCREASE OF 17F in around 1000 ft.
Mama Mia...that is an inversion!
The sun will warm the surface today causing increasing vertical mixing. Rapidly, the warm air aloft will be mixed down to the surface and lowland temperatures will surge.
The UW high-resolution ensemble of many forecasts (below), suggests a high around 90F at SeaTac, with cooling over the next several days.
And there is one other thing. Smoke.
The wind pattern aloft will move some of the smoke from fires in central Oregon into western Washington. In fact, you can see the smoke on a visible satellite image earlier this morning:
As the atmosphere mixes vertically today, some of that smoky air will be mixed down, mainly over SW Washington.
Finally, let me give you some good news. The National Weather Service has a red flag warning out for the western slopes of the Cascades (see below).
Fortunately, this is little chance of western slope wildfires today and particularly spreading wildfire. Why? Because strong easterly winds are not forecast today. Major wildfire events require wind and western Washington wildfires require strong easterly winds.
Fascinating forecast! We'll see :)
ReplyDeleteWe need to have a gigantic thermometer -like 600 feet or so, attached to the Space Needle, to show the difference in temperature at the base, compared to the temperature at the top!
DeleteRegarding the red flag warning for the west Cascade slopes, you say there is little chance for fire starts today, and maybe you are insinuating that there should not be a warning. It is warm and dry enough on the west side now for a fire to start if there is an ignition source, and also some local areas of moderate east wind, which could spread the fire rather quickly if it started in those windier areas. I think a red flag warning is appropriate, especially for the windier areas.
ReplyDeleteThe way you can tell whether a forecast is good is how it verifies. Not a single fire was started on the western slopes of the Cascades today (as viewed by high-resolution satellite thermal emissions). Need I say more?
DeleteI have to disagree with you on this. A red flag warning does not need a fire start to verify. It only indicates that conditions of weather and fuel are such that if there is an ignition source, a serious fire could occur. You probably noticed that the Williams Mine fire near Mt. Adams and the Ruby fire in the north Cascades (where the recent rains were supposed to end the fire situation there), plus a fire down in the Willapa Hills, increased in intensity today indicating the warm, dry conditions that exist, not to mention several large fires putting out lots of smoke in Oregon.
DeletePerhaps people were just more careful due to the fact there was a Red Flag Warning? Seems logical to me.
Deletewxman: the definition of a red flag warning is
DeletePrimary Red Flag Criteria: 1) Relative humidity of 15% or less combined with sustained surface winds, or frequent gusts, of 25 mph or greater. Both conditions must occur simultaneously for at least 3 hours in a 12 hour period.
Such conditions did not exist over most of the area in which the NWS had the warning. Therefore the warning was incorrect.
I think that the criteria for issuing a Red Flag can vary by past weather conditions, the nature of the fuels and other factors and is not just rigidly determined by the conditions you mentioned above. The Seattle fire weather office must have believed that the meteorological conditions you listed could occur and possibly took into consideration other factors so issued the Red Flag warning. Maybe they were wrong in their forecast, but your statement that a fire must occur in order to verify a Red Flag warning is also not correct.
DeleteToday was a nothing burger for East Wind on the Columbia River. Lot's of stranded down wind foilers hitch hiking back to their vehicles on HWY 14.
ReplyDeleteSweltering late summer day with dew point temperatures, underheard of at this time of year (and unheard of at any time of year prior to the late aughts-early teens), of 70F - or very near to it, all along the Western Washington interior lowlands.
ReplyDeleteVery glad this event will be mercifully brief!
This is not true. Similar temperatures and dewpoints have happened this time of the year.
DeleteC'mon, prof! It doesn't have to be a dissertation. Just a single mention of an occurrence, prior to around 2007, of dew point temperatures at or above 70F during the first week of September at any station anywhere in the lowlands of Western Washington. KBVS is currently sitting at a downright subtropical dew point of 72F!
DeleteJust back up your assertion with even one iota of actual data/measurement to show that I've got it wrong. This should be something a person in your position ought to be able to do in their sleep and with one hand tied behind their back! Take 2-minutes to slap up a response and let's do some learning!
I went to the wonderful Iowa site checked out Bellingham (where you live, right?) The highest dewpoint there yesterday was 66F and the record is 69F. If you don't believe me, go to the source
Deletehttps://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=213&network=WA_ASOS&zstation=BLI&date=2024%2F09%2F06&v=dwpf&opt=month&cmap=hsv&_r=t&dpi=100&_fmt=png
This was a humid period, but to say it was unprecedented is not correct.
Thank you for sharing! I'm having a little trouble understanding what I'm seeing though. The link you provided appears to show September dew points at BLI and the maximum reported value is 69F which occurred at noon - that much is clear. What I can't determine is the date this value was reported. Could you please help me out with this?
DeleteYes, 90 is unusual in a Seattle September, but don’t be misled by media hype. Hot happens here, including in September. I’m pretty sure that it’s happened at least a half dozen times in my life. Probably more. We’ll all survive.
ReplyDeleteIf the forecast for tomorrow on the weather channel is anything to trust, 91F and full sun tomorrow as well, then it drops after that, starting with partly cloudy skies and 85, before it slowly cools off. If so, then I'll have similar weather again for video taping University Place near Tacoma, thus, makes it 3 days in a row of filming with similar weather.
ReplyDeleteI did note that the sun was weaker today due to slight filtering, and as you say, due to the forest fires from Oregon, but the sun this time of year will often be of varying shades of yellow as it's lower in the sky for starters.
Yesterday, used an ND32 neutral density filter on my GoPro, it was a tad underexposed. Today, ND16 and it was nearly perfect despite the weaker sun from the filtering. We'll see what tomorrow brings... All with the same recommended settings for ND filters.
Winter Cliff...Winter outlook. I even watched A Christmas Story this weekend to see snow! Rumor has it going to be a bad one. I know the yellow jackets are worse than have ever seen. Think it's an old wives tale of a good cold harsh winter.
ReplyDeleteSmoky sunrise this morning (Friday, Sep 06, 7:06 AM) from east Capitol Hill in Seattle. In the foreground are tree tops from the Washington Park Arboretum. The residential hill in the background is Madison Park. The sometimes seen crest of Washington's Central Cascades Range including Glacier Peak was not visible through this morning's haze.
ReplyDeletehttps://www.flickr.com/photos/bwellsea/53975529894/in/dateposted-public/