September 27, 2019
If you're interested in staying up late and traveling a bit into northern Pennsylvania, you could spend the last weekend in September looking at the northern lights.
An unusually active weekend of geomagnetic activity is on the docket for this weekend, starting Friday night, according to the National Oceanic and Atmospheric Administration's Space Weather Prediction Center. A good chunk of North America, including a good portion of the United States' northernmost states, should be in range to see at least a little activity from the aurora borealis.
Here's what NOAA has to say:
"Geomagnetic activity is expected to rise on Friday, September 27 due to an increasingly disturbed solar wind field associated with effects of a positive polarity coronal hole high speed stream (CH HSS). The solar wind environment is anticipated to become enhanced and solar wind speeds are expected to climb towards 650 km/s later on the 27th; likely causing G1 storm conditions. Geomagnetic activity is expected to escalate further in reaction to elevated solar wind speeds approaching 700 km/s, likely leading to G2 storm levels on Saturday, September 28. Enhanced activity is anticipated to continue into early Sunday, September 29 - with an early period of G1 storm levels likely."
That sure sounds like science!
If you were going solely by this graphic from the Space Weather Prediction Center, and you noted the red ring swooping down into Virginia, you might think seeing this rare natural occurrence, normally only witnessed near the Arctic, would be a shoo-in for Pennsylvania stargazers:
Unfortunately, it's not that simple.
According to auroral forecasts from the University of Alaska-Fairbanks' Geophysical Institute, your best chances at seeing the auroral activity in Pennsylvania will come Friday night into early Saturday morning, and Sunday night into early Monday morning. You'll also want to travel north of Philly.
As shown in the image below, the outer green band in the Geophysical Institute's forecast shows where auroral activity will be visible on the low horizon, while facing the North Pole. In the forecasts for Sept. 27 and Sept. 29, the band slices through Pennsylvania's upper reaches, crossing through what would appear to include Lycoming, Sullivan, Wyoming, Lackawanna and Wayne counties.
So, no, it won't be "walk out of my South Philly apartment and look at the sky"-level easy. But if you're up for a Pennsylvania adventure, you just might see something amazing.