El Niño plays a big role in First State's lack of wintry December days
State climatologist Dan Leathers says that given the number of recent days that have been 20 to 30 degrees above normal, this month is well on its way to being one of the warmest Decembers on record.
“This will most certainly in the top 5--or even if it got cold, top 10--warmest Decembers going back to 1895 for the state," said Leathers.
He’s not certain how long it’s going to last, since meteorologists are only able to project about three weeks into the future. But what he can say is that even though this weekend will be colder, it’ll warm back up again over the next week. And it’ll stay warmer than usual going into January.
Leathers says it’s tough to say precisely what’s brought on these unusually warm temperatures.
“But certainly that El Niño is playing a big role right now."
And he adds it can be tricky to predict how El Niño, the warming of tropical Pacific waters, affects the eastern United States. But there is a tendency for El Niño to cause warm and wet conditions in our region.
He also notes that where we are, relative to the jet stream, is very different from this time last year. A year ago, the northeastern U.S. was under a trough in the jet stream, meaning it swung far to the south, blowing cold air in our direction.
Now, Leathers says that we’re under a ridge in the jet stream and the western U.S. is under a trough, which is why eastern states are warmer and western states are colder.
But even though it’s warmer than usual right now, there’s still plenty time for this season to get very cold.