What drought?

Rains fizzle Great Drought of 2008.

Rain or Shine Report for Apr 8

I’m at a loss of words in explaining the recent rain.

After all, it is the dry season.

And a La Nina one at that.

That was supposed to foreshadow a “dry” dry season. The truth is that the La Nina did what it was supposed to do: make the late Fall and Winter Dry. La Nina loses its spell over south Florida’s dry season in its later half.
That’s when other meteorological phenomena kick in – with emphasis added on the term “phenomena.”

What is a phenomena? It’s something that’s real, but intangible, ephemeral, hard to forecast with iron-clad accuracy, and that, just when you take it for granted and its momentum seems to be rising, quixotically disappears without a trace.

I’m talking about the drought.

So ends the Great Drought of 2008.

We’re note out of the woods – or should we say “water” – in every corner of every watershed. But we can breathe a sigh of relief that the wildfire season is momentarily doused, and that cypress – not saguaros – dominate the great state of Florida’s natural vistas. (South Florida’s drought – adding up to 40 inches of yearly rain – is four fold the 11-inch average year in southern Arizona’s Sonoran Desert.)

But when is a drought officially over?

According the Winsberg – whom, by the way, would be carved on Florida’s hydrologic Fount Rushmore, along with Hoffmeister and a few others – drought is defined as a prolonged period of unusually drier-than-normal conditions.

But that is where the agreement ends.

Defining it specifically is a subjective endeavor.

He points out that south Florida’s dry season is an example of a natural drought imbedded in its annual water cycle. Do you remember the 11 inches of Sonoran Desert yearly rainfall: it’s the equivalent rain that south Florida gets during its 6-month dry season.

For analysis purposes, Winsberg considers it a drought if 4 of previous 6 months were 40 percent under the long-term average.

By that definition, we’re out of the drought.

He also points out that more times than not, Florida droughts are broken during the winter, not the summer, when the rainy season kicks in.

That is also what has happened this year. And seems contradictory to the common wisdom of the summer rains saving the day.

But other factors like air-temperature and cumulative hydro-ecological effects on the landscape also come into play.

And we can’t forget the role that increased winter-time water demand plays.

That’s a part of the drought equation that has become more and more prominent as coastal populations grow, and shallow coastal aquifers are tapped. Some recent newspaper articles have highlighted this issue. The idea usually involves interception of summer surface flows, which are in turn injected and stored down into a deeper compartment of the aquifer for winter-time usage.

Looking into the future, no matter what happens this spring, Florida still needs plentiful summer rains to keep the drought goblins from creeping back into the discussion. Had by chance the recent rains not fallen, that would have been the straw on the camels back – but it was the Spartan summer rainy season that placed the bulk of the burden on the camel’s back.

Here’s a closer look at the watershed numbers.

Loxahatchee and East Palm Beach lead the dry-season rainfall race: both with just over a foot of rain since mid February, with Big Cypress National Preserve and Water Conservation Area 3 both at around 11 inches. South Florida wide about 9-10 inches has fallen, but that’s still a healthy 3-4 inches above the long-term average for February, March, and April – and don’t forget we’re not even at April’s midpoint.

Southwest Coast had been lagging behind, but last weeks rains helped it play catch up. It’s currently at 8 inches of rain since mid February.

The rains have been a funny mix of fronts blasting in from the northwest and afternoon summer-style showers back-flowing in from the Everglades, as highlighted in the Tampa Tribune. In either case, it’s the tropical moisture that is the miracle grow of south Florida’s meteorology: whether it’s a front or a sea-breeze shower.

There are some sizeable flows moving down the Kissimmee River. Over 1500 cfs has been flowing into Lake Okeechobee since start of April. Don’t forget that a year ago this time, the Kissimmee was in the middle of its 8-month no flow condition. That ended in July 2007, and hasn’t gone flowless since.
The big news is the Lake’s refusal to drop below 10 ft: it’s been glued at just above 10 ft for the past 6 months. Last week the Lake also crossed another important invisible threshold: it’s now 3 inches higher than early April of last year (2007). That’s amazing considering that just 7 months ago, in September, nearing the end of the wet season, Lake stage was 4 ft (48 inches) lower than the previous year.

But the Lake is still under 11 ft, and this Wednesday, it will celebrate its 400th consecutive day under that level, counting all the way back to March 2007.
Regulatory stage in Loxahatchee is about a half foot higher than early April of last year; and downstream in Water Conservation Area 2A is a full foot higher. That puts them at the same level as back in September. For Loxahatchee, you have to go all the way back to the water-laden El Nino winter of 1998 to see similar flooding levels. The same doesn’t hold true for WCA2A, where flooding levels are nowhere near winter 1998 levels.

Over in Big Cypress National Preserve, the recent rains have rewound the water cycle clock a solid 3 months: we’re at the same level as we were in mid December when we were poised for an especially deep and long dry season drop.

That never happened.

Now was levels are perched at the same level as the record wet dry season of 1998. Keep in mind that 1998 was consistently wetter throughout its duration, flooding up in the hydric pines (our mountain tops) through most of the winter. In comparison, this year’s dry season was tracking normal through its first half.
I hate to be the bearer of bad news.

But wasn’t summer of 1998 a really bad mosquito year. The snowbirds are gone, but the summer birds – some call them our state bird – may be on their way.

Yet again, another barometer of the water cycle to keep track of.

. . .
Morton D. Winsberg is author of Florida Weather (2003) and John E. Hoffmeister is author of Land from the Sea (1974).
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