‘Siberian Express’ Will Bring Coldest Air We’ve Seen in a Year


We can’t say this enough … this air is colder than any we have seen in a year. Our wind chills will be colder than we’ve been in several years. So when we say our air is Siberian, we’re not kidding. Just take a look at this map and trace our air from beyond the arctic … to Siberia.

I’ve shown similar maps in the past, but they haven’t been nearly as extreme as this one. We’re looking at an upper-level map (around 20,000 ft.). Winds at that level tend to follow the lines on the map. So we can start in Philadelphia and trace that line back. THIS IS NOT AN EXAGGERATION — IT IS THE “TRAJECTORY” of at least a part of the air that’s going to arrive this weekend. A flow like this has been called the “Siberian Express” in the past.


It’s not just about how low the temperature will go. It will be windy, too, so the wind chill will more closely represent just how cold it will feel to exposed skin. First, for the temps:

This is what the ground temperatures should be Sunday morning, Valentine’s Day (according to one computer model). First is a map of all of North America, and then a closer version with some actual numbers:

Remember, those are temperatures, not wind chills. A temperature of 5 degrees with a mere 10 mph wind equals a chill of -10 degrees. A 20 mph wind would make the wind chill -15. In Philadelphia, we’re going to go a full 24 hours without our wind chill having ever gone above 0 degrees!

It will be even worse in the Poconos, take a look at some of these unbelievable wind chills:


The record lows for Philadelphia are 3 degrees for Saturday and 2 degrees for Sunday. It’s interesting that the Saturday record was last tied in 1983-another year with a strong El Nino.

The key to record cold in winter is snow cover. Usually, it takes a significant layer of white to reflect sunlight back into space. Since there will be only a little, patchy snow around, the records may not be broken in Philadelphia. But other places that will have snow on the ground have a chance.

As of now, we’re predicting lows of:


In a word, no. This pattern is only temporary, and we’ll see a BIG warmup next week. That will be combined with a winter storm that could start as snow but will changeover. More on that in a blog to follow. That won’t be the end of Arctic air for the winter. There could be another round of the “Siberian Express” later in the month.

Glenn “Hurricane” Schwartz
Chief Meteorologist, NBC10 Philadelphia

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