Late season mild spell comes to an end as the first of two surges of cold air hits Friday evening sending temperatures plunging

New rain threat late Saturday night/Sunday followed by a reinforcing blast of chilly air that could include the season’s first snowflakes by Halloween

FRIDAY LATE AFTERNOON SET-UP

Markedly colder air just to the west of Chicago and poised to move in

FORECAST HIGHS/DEPARTURES FROM NORMAL

Markedly colder pattern takes hold ending string of 10 consecutive days with temperatures at or above normal

EARLY SEASON SNOWSTORM PRODUCES 1-2 FEET TOTALS

U.S. snow cover grows by nearly 5 times in just two days

New round of rain arrives Saturday night into Sunday followed by the season’s first snowflakes on Halloween

Kristin Laidre — Narwhals and Polar Bears
“Laidre is an ecologist who specializes in arctic mammals, which are especially cornered by global warming:
”Narwhals spend most of their time in deep water, in and under dense ice. They need cold water. The other species I study is polar bears. Everything about being a polar bear is tied to the ice. It’s how they move around. It’s how they find mates. It’s how they find food and eat. It’s how they get enough nutrition to successfully reproduce.”

Keith Parker — Salmon
“Parker is a senior fisheries biologist for the Yurok Tribe in Northern California. Across the West, salmon stocks have been devastated by dams, water diverted for agriculture and climate change:
”The loss of the size of the (salmon) run has hurt not only people, but Mother Earth. All those fish were breaking down and being absorbed into the forest. That’s how you get ocean nutrients in trees hundreds of miles upriver.”

Andrés Rivera — Mountain Glaciers
“Since Rivera started studying glaciers in the 1980s, a series of globally monitored glaciers have gone from losing almost seven inches a year to losing almost three feet a year:
”The glacier was retreating. It was my first clue that something was going on. Now the glacier is about three kilometers farther away than it was in 1982.”

Hanna Mounce — Hawaiian Forest Birds
“Mounce leads a team trying to save forest birds on Maui, where warmer weather is expanding the range of mosquitoes that transmit bird-killing avian malaria:
”When we used to go into the forest . . . the forest was full of birdsong. You would hear kiwikiu when you woke up in the morning . . . Now when we go out there, you might hike half a day before you encounter one of the birds.”

Dee Boersma — Penguins
“For 40 years, Boersma has studied a single colony of Magellanic penguins in Argentina’s coastal desert, documenting a decline of about 1 percent a year:
”Penguins die from heat strokes . . . we had the hottest day we’ve ever recorded, 111 degrees in the shade. The best way for the penguins to get cool is to jump in the ocean, but some of them have to walk more than a kilometer to get there. We had 264 dead penguins just littered over the colony. Some were within five feet of the water, but they just couldn’t make it.”

David Obura — Coral Reefs
“Obura has been studying coral reefs since 1992. During that time, the world’s oceans have lost perhaps a quarter of their coral:
”What’s driving the decline of coral reefs is carbon dioxide and fossil fuels and overconsumption.”

Patrick Gonzalez — Trees in the Sahel
“Gonzalez is a forest ecologist and climate-change scientist who studies tree deaths in the Sahel region of Africa.:
”Seeing those dead trees in Africa and the hardships of the local people motivates me to work even harder to take action on climate change, to cut my own emissions, to encourage others to live more sustainably.”

TO READ THE COMPLETE ARTICLE IN THE NEW YORK TIMES, VISIT:

TRACKING TEMPERATURE DROP

Temperatures to plunge some 35+ degrees from Friday’s balmy 72-degree high to the predicted 37-degree low Saturday morning

A NEW ROUND OF RAIN ARRIVES LATE SATURDAY NIGHT, CONTINUING AT TIMES INTO SUNDAY

Some far NW suburbs may even see mixed wet snowflakes — various precipitation snapshots late Saturday night into Sunday

TRACKING THE SEASON’S COLDEST AIR INTO CHICAGO WHICH ARRIVES ON HALLOWEEN

Forecast 850 mb temperature departures (about a mile above the surface)

The darker blue and purple colors depict the largest temperature departure from normal. Temperatures are expected to moderate closer to normal by late next week and following weekend.

FORECAST LOWS MONDAY, TUESDAY, WEDNESDAY, AND THURSDAY

Growing season to end as temperatures dip below freezing several consecutive mornings next week

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