How it could happen
The GFS model simulates precipitation developing over Tampa Bay in the same way snow forms downwind of the Great Lakes. “Gulf of Mexico effect snow” - as opposed to lake effect snow - could form as cold northwest winds blow over the tepid Gulf waters. The warm air at the sea surface would rise into cold air at high altitudes causing precipitation-producing clouds to form.
The big problem for Floridians hopeful for snow is that, while temperatures at high altitudes are likely to be cold enough for snow, milder air close to the ground is likely to melt snowflakes.
Denis Phillips, chief meteorologist for the ABC affiliate in Tampa, has posted frequent updates on the snow possibility on his Facebook page, but has consistently played down the potential.
“I would say the only chance of snow in our area COULD be a mix of rain with a few flakes in our colder areas if the winds aloft are strong enough to bring them [the snowflakes] down before entirely melting,” Phillips posted in an update Monday.
Despite the long odds Tampa faces to actually see flakes, Phillips is enjoying tracking them.
“As we’ve been saying for days, it’s fun discussing the possibilities, as remote as they are,” Phillips said.
Florida’s snow history is cause for skepticism
Snow? In Tampa? In March? You’re right to doubt it.
Measurable snow has only fallen twice in Tampa and never in March, according to National Weather Service data.
Tampa’s biggest snow event on record occurred on January 19, 1977, when all of 0.2 inches was measured (nearby locations received 1-2 inches, however). The only other known instance of measurable snow happened February 13, 1899, when 0.1 inch fell. (That same storm dumped 21 inches of snow in Washington, D.C.; blizzard conditions produced drifts to 10 feet).
Historic Arctic outbreaks preceded and/or complemented both of those Floridian snow events. To give you an idea:
1) According to the National Weather Service, the air mass that coincided with Tampa’s 1977 snow produced subfreezing temperatures for 10-14 hours over interior and western sections of south Florida. Snow fell as far south Homstead, Miami Beach and even in the Bahamas.
2) Prior to Tampa’s 1899 snow: An epic cold wave brought sub-zero conditions from Tallahassee, Florida to Maine. The mercury tanked to 15 below zero in Washington, D.C. on February 11 - its coldest temperature on record.
The arctic outbreak coming to Florida this weekend is unlikely to be historic, with temperatures generally about 10-20 degrees below normal (historic would be at least 25-30 degrees below normal). In Tampa, that means highs in the 50s to near 60 (rather than mid-70s), and lows near 40 (rather than mid-50s). To be sure, parts of Florida’s interior may see near-freezing low temperatures, prompting concerns for some crops... but this does not appear to be a devastating, high impact agricultural cold snap akin to January, 1977.
“Most agriculture interests taking typical precautions for a marginal frost or freeze should weather the cold spell just fine,” said AccuWeather meteorologists Dale Mohler and Dan Kottlowski.
The bottom line is that given temperatures near the ground probably too warm, the time of year, and that the cold air lacks historic punch (required for previous snows in the region), it is very unlikely (less than 10 percent chance) Tampa will see snowflakes. But I agree with Denis Phillips who wrote: “I STILL think it’s a blast to talk about.”