Typical autumn cold snaps that blast arctic-chilled air through the Sunshine State have yet to make forays into South Florida as La Nina takes control of the upper atmosphere.
The periodic climate phenomenon that usually follows El Nino can straighten out the polar jet stream – shooting the ribbon of fast winds straight across the country like an arrow and preventing deep dips into the south.
That means cooler air remains bottled to its north and that South Florida gets piddling fronts that spit rain but don’t do much to bring down temperatures.
“Florida is in its own little world right now because cold air just hasn’t been coming down,” said Dan Kottlowski, a meteorologist with the Pennsylvania-based Accuweather. “If the polar jet doesn’t dip far enough down over the central and eastern U.S., it’s not going to slip into Florida.”
This month, the average temperature is about five degrees above normal as measured at Palm Beach International Airport in West Palm Beach, with only three days near or below the normal daytime high of 77 degrees.
On Dec. 6, the record high temperature of 87 set in 1972 was tied in West Palm Beach, with the low of 74 degrees also tying a 1972 record for the warmest overnight temperature.
Monday’s high temperature of 83 was six degrees above normal, but was far from the 1997 record high of 87 degrees.
“By the time (the fronts) get to us, they’re not that cold anymore,” said Larry Kelly, a meteorologist with the National Weather Service in Miami. “All we are getting is our temperatures set back to normal.”
This week, the coldest air of the season is forecast to spill out of Canada into the northern Plains before moving east. Temperatures in parts of the Central U.S. could drop 20 to 30 degrees below average with Chicago likely dipping below 0 at night. Highs only in the teens are expected in areas from Washington, D.C. to Boston on Thursday.
“A lot of people think this is really cold, and they are right,” Kottlowski said. “It’s more typical of what you might see in January and definitely colder than last year at this time.”
While Florida will get a front meandering through on Thursday, it’s expected to only drop temperatures a few degrees. Thursday and Friday are still expected to reach into the mid to high 70s. Saturday could be back up to 80 degrees.
“With the jet stream being displaced so far north and the wind flow out of the southwest, fronts weaken significantly as they move down the Florida peninsula, resulting in our mild and humid weather for most of this month,” said Robert Molleda, warning coordination meteorologist for the NWS in Miami.