Living with the cold does not come naturally on the Gulf Coast. After a winter storm in 1774, early settlers of British East Florida shared awestruck accounts of what they termed an "extraordinary white rain" covering the ground. The Inuit and Yupik languages have forty to seventy words for snow and ice.
True Floridians have zero.
So, as the Deep South grapples with the foreign language of snowflake icons making a (for some, repeat) appearance in weather apps, a reality check is in order. Is Florida's snow and ice potential next week another AI hallucination, or it is really about to get whimsical up in here?
The short answer: it is going to get quite cold next week, and it is probably going to rain at some point on Tuesday or Wednesday. As for North Florida frozen precipitation... well, I'm saying there's a chance.
Why snow and freezing rain are the 'ultimate trick shot' in Florida
The long answer is complicated.
Snow or ice in Florida is the ultimate meteorological trick shot, requiring a unique set-up that finesses a pristine Arctic airmass from the north and sufficient moisture from the south.
In Tallahassee, accumulating snowfall has only occurred eight times in the last 130 years, most recently a muscular 0.1" on January 3, 2018 that thrilled the masses and led to a small snowman boom in the capital city.
There are also a handful of impactful North Florida freezing rain or sleet events in the historical record, including the "Snolepocalypse" of January 29, 2014. Traces of snow or ice have occurred in Tallahassee about thirty other times since the early 1890s.
That rarity is because there is precisely one way for snow or ice to occur along the eastern Gulf Coast. Just as you can't make French toast without the bread, milk, and eggs necessary to survive any winter storm, frozen precipitation in North Florida requires a very specific set of ingredients.
In 2008, two forecasters from the National Weather Service's Tallahassee office published a study identifying the common elements that have preceded all significant North Florida snows.
Let's take a look at what those elements are, and how the wind-up to next week's rumors of snow measures up to the historical greats.
Factor 1: Extreme jet stream amplification
The first couple of criteria have to do with the big picture of how the jet stream lines up across the Northern Hemisphere.
The significant Florida snowstorms of 1895, 1899, 1955, 1958, 1973, and 1989 were all preceded by a broad ridge of mid- and upper-level high pressure over the western Continental United States and a very deep trough (and/or a "polar vortex") centered over the Great Lakes, northeast United States, or southeast Canada.
This highly amplified pattern dislodged Arctic air, sending it hurtling across the Plains and into the Southeastern U.S.
Does next week's jet stream configuration resemble the historical Florida snow composite? Yes, closely.
Leading computer models are in excellent agreement on a Pacific Coast ridge extending into western Canada and a powerful lobe of the polar vortex being centered over Southeast Canada on Monday afternoon, a day ahead of possible Florida snow or ice.
The ridging is a little farther west than the pre-snow average and the trough hasn't dug quite as far south as history's big guns, but overall, we're well within the ballpark of the right pattern.
Factor 2: A frigid low-level airmass
A key distinguishing Florida snow or ice from dry cold outbreaks is the presence of a bitterly cold airmass prior to storm development.
The NWS snow study identifies two critical low-level elements a day ahead of a winter storm: first, a cold surface anticyclone (high pressure) over much of the United States, and second, freezing temperatures about a mile above North Florida caused by a low-pressure trough angling in from the northeast.
Additionally, to actually get snow or ice, you need the column of air over North Florida to be (mostly) below freezing when precipitation starts.
Again, the set-up early next week checks these boxes.
Computer model averages suggest very strong surface high pressure will be spilling into the Deep South on Monday afternoon. This is a bit west of what preceded historical Florida snows, though next week's high may make up for that with its breadth.
A mile up in the atmosphere, model guidance indeed has a trough of low pressure from extending North Florida into the mid-Atlantic to keep cold air aloft flowing in ahead of the storm. However, the trough is a little weaker and faster in the models than it was ahead of Florida snow, which could be a problem for keeping it cold enough for snow or ice on Tuesday.
Factor 3: The trigger and 'Goldilocks Zone'
A conducive jet stream and pre-existing frigid airmass still require a spark to get air rising and precipitation falling along the Gulf Coast. The NWS Tallahassee forecasters found that all Florida snowstorms were immediately preceded by a mid-level trough propagating eastward from the southwest United States across the Gulf Coast, which triggered a weak wave of low pressure to develop and move east along a stationary front over the southern Gulf.
If no surface low develops, North Florida is very cold with no snow or ice; if the low moves along the northern Gulf Coast, it's too warm and the Panhandle gets cold rain.
The Goldilocks Zone is a ripple of low pressure crossing Central or South Florida.
This is where next week's event may well fall short.
While about half of the European model ensemble members do have a "shortwave" trough racing east across the Southwest U.S. on Monday afternoon, many do not, and the American ensemble is weaker with this disturbance.
A stationary front will be in place over the southern Gulf, but given how strong the surface high pressure is and how feeble the shortwave trigger may be, a coherent low might not develop along it in time to toss moisture into the Panhandle. However, models do appear to be trending stronger with the shortwave, and nothing is locked in at this point.
Let's be real: We're in the hunt, but it is a hunt for a Florida unicorn
If I can be real a second, for just a millisecond, I am deeply biased in favor of Florida snow.
While I strive for objectivity in forecasting, my personal truth is that I'm a nutjob-level winter aficionado.
To wit, I own a homemade snowmaker named "The Last Snowgun," which I volubly operate to my kids' delight and neighbors' chagrin whenever the temperature drops below 28F. Like Fox Mulder, I want to believe in that Tuesday snowflake icon, in the magical, joyful world it represents.
Rationally, though, rare events are rare for a reason, and everything has to go exactly right for the potential for Florida snow or ice to come to fruition. Right now, a close comparison of forecast maps with the weather charts preceding historical snows shows stunning similarities, yet some differences as well.
That means we're still in the hunt, winter lovers, but that is all that can be said at this point.
Snow, sleet, rain or dry? Stay tuned
Models do upper-level pattern prediction four to five days out quite skillfully, but struggle and vacillate with the messy details of moisture, precipitation, and storm track. I'm watching changes to the antecedent pattern on ensemble means much more intently than whether any random model run has snow, ice, or New Jersey-style 37F drizzle.
Will it be extraordinary white rain, obnoxious ice rain, banal clear rain, or merely cold in Florida next week?
I don't know, and no one else does either.
While NWS gives it a 10% to 30% chance of wintry precipitation, I'd bet against accumulating frozen precipitation in Tallahassee (inland areas further north have better chances). But it's a realistic enough possibility to review your emergency winter mirth plans.
Where would I sled? What would I sled on? Do I have all-conditions capacity to make French toast?
These are the kinds of questions to consider in the next few days, as you lower your expectations but keep watching the skies.
Dr. Ryan Truchelut is chief meteorologist at WeatherTiger, a Tallahassee company providing forensic meteorology expert witness services, and agricultural and hurricane forecasting subscriptions. Visit weathertiger.com for more information. Email Truchelut at [email protected]