December 01, 2011

History is Made: Highest Pressure in Sea-Tac History!

We are living through historic weather.    UW's Neal Johnson ran the numbers and found that the sea level pressure at Seattle-Tacoma Airport today was the highest since record keeping began there in 1948.  Here are the top pressures since 1948, starting with the highest pressure first.

2011 12 01 08 1043.4
2011 12 01 07 1043.3
2011 12 01 09 1043.2
2011 12 01 10 1043.2
2011 12 01 11 1043.1
1949 01 28 16 1043.0
1949 01 28 17 1043.0
1949 01 28 14 1042.7
2011 12 01 06 1042.6
1949 01 28 13 1042.3
1949 01 28 15 1042.3
1949 01 28 18 1042.3
1949 01 28 19 1042.3
1957 01 16 10 1042.3
1957 01 16 11 1042.3

Last night at midnight Sea-Tac hit 1043.4 hPa, smashing the old record of 1043.0 hPa.

According to the Weather Underground site the highest pressure in Seattle occurred on 12/3/1921 (1043.90 hPa), but that was at a very different location (downtown Seattle, not the airport) and thus not a fair comparison.

I hope someone contacts Ripley's Believe It or Not. 


  1. This morning (Thursday, 1 December), from atop Tiger Mountain, I saw some flat-topped mountains above the fog, well to the south of the Olympics. Is it possible these were superior mirages? Has the vertical temperature gradient been high enough to produce such phenomena? "Fata Morganas", maybe?

  2. Would the high pressure cause the birds to act up? All the birds in my neighborhood are tweeting and flying back and forth! Then they suddenpy stop.

  3. We had 1044.2 in Bellingham at 11 pm Nov 30. How can we learn where that fits in the records?

  4. Also - BR or mist formed instantly with those very high pressures in Bellingham. Did this happen in Seattle? Why would mist form and go away like that with the pressure rise and fall?

  5. I always associate high pressure with decent weather. We're in gloomsville here on the Key Peninsula in western Pierce county.

  6. Our weather stations here in Port Alberni, BC on Vancouver Island have been reporting very high pressures as well!

    Mine at got up to 1045.9mb, same at other stations listed on

    And I just heard from someone at Environment Canada in Victoria that the Tofino station set a new record for the month of November.

  7. This is a good check on the accuracy of the barometer I recently inherited (no clue as to value. At some point yesterday it hit 30.92 inches (1047.3 millibars, according to the online converter). A little off!

  8. And you thought we were in for a spell of boring weather. I'm just glad I'm north of the Puget Sound Basin's stagnant fog zone.

  9. I've had a sinus/pressure headache all day, and wondered what was going on. My arthritic joints aren't so bad (low pressure is what drives them nuts) but this pressure headache is really distracting. Without mentioning your blog, I've asked several people, and everyone is having this intense head pressure, neck aches, teeth aches, and sinus aches, plus a few inner ear disturbances. Make it go away, Cliff.

  10. If there is record high pressure, why is it raining at my work at Boeing Field at 04:00 AM?

  11. I have a fair grasp of the low pressure systems and the overall effects in the NW as that is what we must worry about and prepare for. Dealing with high pressure is ho-hum, sunny warm sometime wind from the east and when the pressure system breaks down. Mostly ho-hum, sunny and warm and I can think about something else. However whenever there are records involved I know something is amiss and attempt to enlighten myself of the big picture. I had assumed that the changing Arctic would be involved but the interaction cause and effect eludes me. Thank you again for any enlightenment.

  12. thanks especially for physiological reactions, very interesting.

  13. I don't know if it is related to the high pressure but here on the east side of the Cascades, we had a sudden warming trend last night.

    Here is data from a station near Winthrop that showed a temp of 19 degrees at 12:30 a.m. but suddenly increased to 39 degrees less than 2 hours later.

    Somewhat similar the previous morning accompanied by a sudden change of pressure.

  14. The effect of high air pressure on the water level in Puget Sound is considerable. High air pressure pushes down on the water causing lower than predicted tide levels. I have see up to around a 12 inch difference in south Puget Sound. Go to,+WA+&flag=0 for a look at the situation yesterday.

  15. Hi Cliff. I always associate really high pressures around here with good weather and very cold weather, more like the "Arctic Blast" that's supposed to come next week. So, how come it actually rained last night and how come it just hit the low 30s. Finally, what is the underlying cause or reason for such an extremely strong ridge of high pressure this week? What's going on out there to cause this? Thanks! Oh, by the way, i'm a middle school science teacher. We're doing meteorology at the moment so your response, if possible, would be helpful and timely.

  16. Like Kissingfins, I've experienced the onset of arthritic pains and headaches with the FALL of the barometer. But, this is the first time I've felt any physical effects with it topping out: completely plugged ears & head; no pain - just all blocked and it started & crept up along with the barometer. Cliff - don't worry with all those sensitive inanimate instruments... just call one of us :)

  17. I'm with Kissingfins - make it go away, Cliff! Blocked up ears & head came on steadily as barometric pressure rose. Not painful, but - geez!

  18. For you that are bemoaning the pressure, take a drive up the mountains. You will not even have to go that high.

  19. Interesting! I've been having the same powerful sinus/headache/neck problems for the last few days, but figured it was just my usual stupid psychosomatic anxiety stuff. Maybe it's actually physical this time!


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