It doesn’t look good for Gulf Tower Fledge Watch this weekend. As of this writing I have altered the schedule.
Today, Friday May 26: yes, I’ll make the attempt AFTER NOON. See you downtown at 1100 Liberty Avenue after the rain stops. (It’s pouring now.) Click here for directions.
Saturday May 27: no
Pittsburgh rain and thunder forecast, 26-27 May 2017 (image as of 26 May from weather.gov with relevant times framed in orange)
Sunday, May 28: yes. The forecast has changed for the better. See you at Flag Plaza.
Mild weather during the Cherry Blossom Festival in Washington, D.C., 2006 (photo by Andrew Bossi via Wikimedia Commons)
Ah, the mild days of spring! You know the days I’m talking about, the ones that are perfect for birding, gardening, picnics and outdoor weddings. The not-too-hot, not-too-cold, not-too-wet weather that makes you happy to be outdoors.
Unfortunately Pittsburgh will have fewer of them in the future. That’s what scientists from NOAA and Princeton University found out when they studied how the warming climate will affect our pleasant weather.
The loss has begun already though you may not have noticed it. For the last 35 years (1980-2015) earth’s climate has been converting 1 nice day per year into something unpleasant, mostly in Brazil, Africa and the Middle East.
By the end of the century the change will affect us. The world will lose 10 mild days out of 74 but the loss won’t be evenly distributed. The tropics will lose even more mild days while Canada, Maine and the Rockies can look forward to a pleasant future.
Here’s what our future looks like on the map. Notice how the eastern U.S. is light orange indicating a net loss.
Map showing the change in the annual number of mild days across the globe comparing 1986-2005 to 2081-2100. Areas of blue have increased in mild days. Areas of brown see a decline. (Van der Wiel/ NOAA/ Princeton)
That map shows the annual change but in fact it will vary by season. For instance, Pittsburgh will gain some mild days in the fall (maybe 15) but lose more than that in the summer (25 to 50). June-to-August will be hot!
Changes in the number of mild weather days by season for 2090 (maps from Van der Wiel/ NOAA/ Princeton)
(*) “Mild weather” is defined as temperatures between 64 and 86 °F, only a trace of rain (less than 0.04 inches) and low humidity (a dewpoint below 68 °F).
Icy trail in Schenley Park, Feb 2015 (photo by Kate St. John)
Snow, sleet, rain, freezing rain.
From 5 degrees F on Thursday night to 53 degrees with freezing rain today, we’ve had it all. And there’s more to come. Tomorrow night will be 15 degrees.
This yo-yo weather reminds me of what we learned during the polar vortex in January 2014: Climate change is making the jet stream wobble so we get shots of very cold air and then warm air soon after, as shown in drawing(c) below.
Jet stream Rossby waves (graphic from Wikimedia Commons)
Be careful today! It’s variably icy out there.
p.s. I’ve used an old photo of ice because it’s too icy to step outside this morning!
(photo by Kate St. John. Drawing from Wikimedia Commons; click on the image to see the original)
Uh oh! Blue light, though bright, isn’t better at night.
As cities switch from incandescent or mercury street lights to LEDs they’re saving electricity and money and providing more light. But brighter isn’t better if it’s blue.
The video above shows how the color temperature of light matters to our eyes and sleep patterns. Though the video doesn’t mention it, the color also matters to birds and animals.
It’s possible to buy yellow-toned LEDs but blue, because its bright, has been the default choice for city lights. We didn’t know that color mattered when the world began switching to LEDs and the bulbs have such a long life it’ll be decades before it’s time to replace them. Meanwhile humans, birds and animals will be coping with the change.
It makes me want to close my eyes.
(credits are in the captions)
p.s. Here’s a really helpful video showing the difference between incandescent, compact fluorescent and LED light bulbs in home use (the A19 screw base). You’ll also see the inside of an LED bulb. I was surprised to learn it’s a tiny computer.
If you’re planning to be here four billion years from now you’ll see an amazing slow-motion sky show when two galaxies collide — Andromeda and our own Milky Way.
What will the sky look like when that happens? (very amazing!)
Right now our cities and towns are switching out incandescent street lights for LEDs. It’s the perfect time to put on lampshades. You can shade your home lights, too.
That question would have been absurd 200 years ago because billions of stars were visible on every clear night.
But now with the prevalence of artificial outdoor light most of us cannot see the Milky Way and many children don’t know what it is.
Because of this, some ancient stories don’t make sense. In Genesis Abraham worried that he had no heir but God reassured him, “Look up into the sky and count the stars if you can. So many shall your descendants be.” Today we look at the sky and count 50 stars, not realizing that Abraham saw millions and was overwhelmed.
So what are we missing? Sriram Murali traveled in California recording time-lapse video of the night sky in places with high light pollution (San Jose) and almost no artificial light (Death Valley).
His video let’s us see the sky as our ancestors did.
Spring tide at Wimereux, France, Sept 2007 (photo from Wikimedia Commons)
Despite the fact that it’s autumn we’re going to have a spring tide next week.
In this case the word “spring” has nothing to do with the season. Instead it means the ocean will be “springing up” in the highest high tide.
Spring tides occur a day or two after a full moon and are highest when the moon is closest to Earth at perigee. On Monday the moon will be full and at its closest perigee since 1948. Watch for nuisance flooding on Tuesday in low-lying coastal communities.
Perigee also makes the moon look larger, an effect called the supermoon. Here are two photos of the full moon in 2007, perigee on the left on October 26, apogee (furthest) on the right on April 3.
Size comparison of full moon at perigee versus apogee (image from Wikimedia Commons)
The difference is about 30,000 miles. Closer objects look larger. (Duh!)
If you miss this supermoon you’ll have to wait 18 years for it to be this close again.
In the olden days the first killing frost in Pittsburgh usually occurred by Halloween and we had to wear winter coats over our costumes while trick-or-treating. … I always hated to cover my costume.
This year has been very warm, even hot. Only ten days ago it felt like August and today the temperature is 5-10 degrees above normal. When will we experience the first killing frost?
Some of you already have. If you live east or north of Pittsburgh the growing season is shorter (bluer), as shown on the USDA Plant Hardiness Map below. Bradford, Pennsylvania is three growing zones colder than Pittsburgh and the Monongahela and Ohio Valleys. I’ll bet they’ve had a killing frost.
Pennsylvania within the USDA Plant Hardiness Map retrieved October 2016 (map from USDA)
Here in Pittsburgh the weather forecast says we won’t dip near freezing for the next several days. Today it’ll be 10 degrees above normal.
When do you think we’ll have our first killing frost?
