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TAMPA, FL -- There is good news and bad news for Florida farmers. The bad news is that yet another cold front -- the third of this month -- is expected to frost the state Dec. 27-29. The good news, according to the National Weather Service station, here, is that the cold should be the last severe front of the season.

A weather pattern known as the Arctic Oscillation, a high-pressure, swirling mass over eastern Canada, has literally left the door open in December for the southeastern United States and Florida to be blasted by wave after wave of frigid air sweeping from extreme northern regions across the Dakotas. Typically, those winds would blow across the northeastern United States. But in an AO period, those winds are blocked and thus divert south.

That is the same weather pattern responsible for record freezing temperatures in Florida back in January and February of this year, when farmers in some parts of the state recorded as many as 31 nights of sub- freezing temperatures, including as many as a dozen consecutive nights.

The Arctic Oscillation "happens regularly, it's just the last couple of years it's been very strong, so we've noticed the impact a lot more," meteorologist Daniel Noah of the National Weather Service here told The Produce News Dec. 27. "When we do have the Arctic Oscillation kicking in, the cold air comes further south. It's horrible. But it looks like we're going to warm up to normal or just above normal for the next three months."

The December weather pattern has not seen the same sort of duration as the January and February freezes, but low temperature records across the state were shattered the weeks of Dec. 6 and Dec. 13, and more record-breaking cold is forecast for Dec. 27 and 28. Temperatures are predicted to plunge into the low 20s in central and southwestern Florida, and below freezing temperatures are expected in the eastern part of the state as far south as Belle Glade and West Palm Beach.

To date, December 2010 is the coldest on record in Florida, and regardless of temperatures the rest of the month, a finish in the top five coldest Decembers in state history is assured. Temperatures across Florida have averaged more than 10 degrees below normal and during the three main cold snaps have averaged 30 degrees or more below normal.

The good news, according to Mr. Noah, is that the AO pattern has begun to break down and should lose strength over the next couple of days. Frosty winds from the extreme north will be free to blow across the northeastern United States. A La Nina weather pattern should again situate the jet stream north of Interstate 4 (which runs east-west from Daytona to Tampa), creating a protective barrier that should spare Florida farmers from more winter misery. An occasional dip below freezing will still be possible in January and February, Mr. Noah said, but with the breakdown of the Arctic Oscillation, the worst should be over.

"There is hope," Mr. Noah said. "It doesn't mean we won't get the freezing temperatures again, but we'll be back to normal instead of this record- breaking cold. I might be 'wish-casting' but there's a good chance once we get through this one, we should be warming up, and hopefully we won't have to talk about this again for the rest of the winter. It's going to be nice for New Year's."

During the freezes of Dec. 6-15, row crops were destroyed throughout the state, and tomatoes took a significant hit. Strawberries and citrus appeared to have survived intact.

With extremely low temperatures forecast for Dec. 27-28, tomatoes are virtually assured of taking another beating. Strawberry and citrus growers will again mist groves and fields or cover plants in an effort to hold off Mother Nature.