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Florida Drought: How Did We Get Here?

5 May 2017, 4:36 am

Quick… If I say the word Florida, what images pop into your head? Palm trees, sandy beaches, rain and humidity?  However, rains were hard to come by this winter across Florida, leading to drought that currently ranks as the largest severe drought in almost five years for the state. As of May 4, an area of extreme drought has now been added to a half dozen counties.

In the latest update of the U.S. Drought Monitor, more than 66% of the state was currently in some degree of drought. More than 39% of the state was in severe drought, 5% in extreme drought. That represents the largest portion of the state in severe drought since the beginning of June 2012.  And drought conditions have developed relatively rapidly as no part of the state was in severe drought as recently as only a month ago. What happened?

Where did the rain go?

The better question is what didn’t happen. And the answer is rain. Rainfall totals during the winter were much below average. From December to February, central and most of southern Florida received 75% of its normal rainfall, with the driest areas seeing just 25-50%. And those months seem wet compared to the start of spring. In March, outside of localized areas in far southern Florida, the rest of the state recorded less than 50% of its normal rainfall, and large swaths of central and northern Florida were far lower, receiving less than 25% of their usual monthly rains. In absolute numbers, the driest areas saw less than an inch of rain in March. It was the ninth driest March on record back to 1895.

This map shows the percent of average precipitation for March 2017, compared to the 1981–2010 average, for the contiguous United States. The lowest amounts (approaching 0%) appear in shades of brown, and the highest amounts (approaching 300%) appear in shades of blue-green. Image by Climate.gov using data from NCEI.

A large lack of rainfall is one way to deteriorate ground conditions to drought levels. But extreme temperatures are another. While Florida remained relatively dry through most of the winter, it was also much warmer than normal. The 2016-2017 winter was the second warmest since 1895 for the state and March temperatures were above-average as well. Warm and dry weather were the impetus for the spreading drought.

These maps show temperature anomalies for the southeastern United States, from December 2016 (left) through February 2017 (right). Temperatures above the 1981–2010 average are red, and temperatures below the 1981–2010 average are blue. Image by Climate.gov using data from NCEI.

What happened?

The winter of 2016-2017 happened to coincide with a weak La Niña pattern in the tropical Pacific Ocean. Normally during La Niña, the southern tier of the United States is left drier than average as the jet stream—area of fast moving winds high in the atmosphere that serves as a storm highway—is located farther to the north than usual. These conditions were generally seen during the winter, which is consistent with La Niña.

As for temperature, dry conditions normally correlate with warmer than average conditions as well. Combined with the warming trend due to human-caused climate change, average temperatures were on the warm side of the ledger, with nearly record breaking average winter temperatures.

(4/24/17) – Firefighters worked to strengthen containment lines overnight on Sunday and saw great success as recent rains helped turn the tide in the favor of suppression efforts. According to officials the Florida Forest Service and Greater Naples Fire Rescue command are confident in the progress made over the past 36 to 48 hours but know a lot of work remains. “Today’s winds will be a challenge,” said Kingman Schuldt, Greater Naples Fire Rescue Chief. “While the weekend rains gave fire crews an opportunity to establish and improve containment lines, today’s test might be the shift and increase in winds.” The fire is 7,035 acres and remains 50% contained. All evacuations orders have been lifted. There is a 5-mile temporary flight restriction, including drones, surrounding the 30th Ave. Fire. It is a third degree felony to fly a drone in any area that has firefighting air support on scene. Video: Greater Naples Fire Rescue District

Images and information courtesy of Climate.gov (Author: Tom Di Liberto) and United States Drought Monitor

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