July 05, 2009

Firework Pollution? and a Major Change

Many times I have noticed that particles in the atmosphere tend to increase rapidly on July 4th...with a reduction of air quality. I took a look this morning...and it was there again..above is the trace at Puyallup and Queen Ann Hill from the excellent web site of the Puget Sound Clean Air Agency (http://www.pscleanair.org/airq/aqi.aspx). As you might suspect, fireworks probably has something to do with this (the pale of smoke is often profound after all the official and unofficial fireworks). According to Mike Gilroy, the chief meteorologist for the agency, July 4 brings the worst air quality of the year.

Today is the last warm day west of the Cascades. A look outside or the latest high-resolution image shows an obvious change...more clouds--both at low levels and aloft (see image). I plotted the temperatures the last few days (see plot)...temps have been 10-15F above normal. Last night had very high minimum temps--in the 60s in several locations.

The ridge of high pressure over us is in the process of shifting east and the clouds are associated with an approaching offshore trough (see upper level maps for situation this morning and tomorrow). This trough will initiate an onshore push tonight and marine air will fill the western lowlands. So boaters should be prepared for the influx of marine flow from the SW tonight! Today will not be cool...the temperatures aloft are just as warm as yesterday and the clouds will thin...getting back into the 80s. But tomorrow will be very different...highs near 70F. Lots of clouds and a few scattered light showers...particularly on the western slopes of the Cascades. The trough should stay in place the entire week...so expect temps a little below normal.


  1. correct about the fireworks smoke last night, although the economy cut down on the amount. The sunset was incredible, possibly from the volcano in Russia and the local fires too. I thought I saw a "sun dog" in the sunset last night over the Narrows.

  2. The sunset last night really was lovely. I'm so very happy to hear about the cooling trend. What a good blog you have here. I got the link from Valerie Easton's blog. This is a great place to live for weather-watchers!

  3. Believe me I could smell the burned fireworks last night here in unincorporated snohomish county. Lot's and lots of explosions throughout the night. Probably not too good for anyone's health.

    I wonder, though, what is it going to take to break our drought here in the lowlands? Is it possible to get a pineapple express during the summer? A couple of weeks ago a fairly windy frontal system swept thru, but no rain for the lowlands so it makes me wonder what has to happen to get rain in the summer.

  4. Tatoosh Island at 3pm increased to SSW 32knots. Destruction Island was SSE 22G25kt. Shelton SW 20G24kt. Most other land stations in the 5-15kt range at 3pm.

  5. The evening and early AM of the 4th and 5th of July is always our worst air quality of the year. Fireworks are particularly bad as they contain a lot of heavy metals. The results from last night were not as bad as other years because we had good dispersion.
    Other monitoring sites like Bremerton show more of a microscale result at the street level.

  6. Mainstreeter:
    I don't know where you were July 4th evening, but where we were in rural western Pierce County we, and most folks we talked to today, believe it was perhaps the noisiest 4th experienced here in many years, maybe ever. The Tribes must have made a killing selling the banned explosives. A pall hung over the area all day yesterday and this morning until the onshore breezes picked up.

    One must wonder why folks throw away hundreds or even thousands of dollars in order to pollute the sky, scare off the wildlife, panic house pets, and fill the sound with plastic from spent rockets. The beach is a real mess.

    Thankfully the winds off the bay have cleared out much of the stench of burning pyrotechnics. Even now, though, it sounds like the fall of Baghdad is underway outside. I wish it would pour down rain!

  7. I moved to SEA 8 years ago, and it seems as though every year I hear the same comment on July 5th: "Wow, you should feel lucky because we never have bright, warm, sunny days for 4th of July. Enjoy this year, because next year will be rain!"

    Of course I haven't been paying attention every year, but it does seem like all of the 4ths that I can remember up here have been bright, warm, sunny... Anybody know when the last time it actually rained on the 4th of July was?

    (I did try to the NOAA historical site, but the monthly data was difficult to interpret without a legend of what all the acronyms are)

  8. SEA recorded .02" of precip in 2006.

  9. Jim, I've been going to west Tacoma for the last several years. Several of us noted less noise and how late the neighborhood got started this year. I think it's the economy. Still a nuisance, but it may have been worse where you were. I did drive into a fog of smoke going back through the Nisqually area but couldn't tell if it was fireworks related since it was midnight.

  10. Just in case anyone else was confused by the 5 day AQI index plots: they do have a bug in applying the date legend to the bottom of the chart (see 4 dates that don't align with midnight on a 5 day chart). THey use the same positioning as the 3 day charts (that's the bug).

    Times given are local not UTC (though the odd offset of the date might make a weather geek think otherwise!).

  11. imav8n:

    Conditions on July 4 the past 30 years (at Sea-Tac Airport):

    2009: High 87, Low 57, 0.00" rain
    2008: High 71, Low 59, 0.00" rain
    2007: High 84, Low 61, 0.00" rain
    2006: High 75, Low 54, 0.02" rain
    2005: High 79, Low 53, 0.00" rain
    2004: High 71, Low 57, 0.00" rain
    2003: High 75, Low 54, 0.00" rain
    2002: High 65, Low 52, Trace rain
    2001: High 77, Low 54, 0.00" rain
    2000: High 67, Low 52, 0.00" rain
    1999: High 67, Low 52, Trace rain
    1998: High 63, Low 56, 0.10" rain
    1997: High 88, Low 57, 0.00" rain
    1996: High 69, Low 52, 0.06" rain
    1995: High 75, Low 57, Trace rain
    1994: High 65, Low 54, Trace rain
    1993: High 68, Low 55, 0.00" rain
    1992: High 61, Low 56, 0.57" rain
    1991: High 76, Low 51, 0.00" rain
    1990: High 79, Low 57, Trace rain
    1989: High 71, Low 49, 0.00" rain
    1988: High 67, Low 51, 0.00" rain
    1987: High 64, Low 54, 0.07" rain
    1986: High 65, Low 49, 0.04" rain
    1985: High 80, Low 54, 0.00" rain
    1984: High 80, Low 54, 0.00" rain
    1983: High 78, Low 53, 0.00" rain
    1982: High 69, Low 51, Trace rain
    1981: High 82, Low 55, 0.00" rain
    1980: High 65, Low 49, 0.04" rain

    So in the past 30 years, only 13 (43%) Independence Days in Seattle have had rain of any kind, only 7 (23%) have had measurable rain, and only one (3%) has had more than a tenth of an inch (a tenth of an inch is not very much). 17 of the 30 (57%) and every one of the last seven have had high temperatures higher than 70 degrees.

    So your observation is absolutely correct; the Fourth of July is usually warm to hot and dry here.

  12. I have heard that barbecues and yard machinery contribute to smog. I would expect both of those are much more active around the fourth of July.

  13. Very interesting about the pollution levels. A good example of how humans can have an environmental effect with mass behavior.

    I've often thought we could solve global warming immediately if we mandated CO2 come out of tailpipes as green fog instead of an odorless, colorless gas. People just don't believe what they don't see.


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