dry season

Dry season review
A holiday guide to the dry season

How did a relatively normal dry season …

appear to be so darn wet?

Months or holidays: Which interval do you prefer for comparing rain? The advantage of months is that they are equal units. The advantage of the holidays is it allows us to partition the dry season into its various acts (i.e. opening gate, cool season, green out, spring ebb, etc.). We were headed for a “dry” dry season until the April unexpectedly kicked in.

Answer: It’s not how much but when the rain fell. And I’m not talking summer rains or fall hurricanes, which together give us about 43 inches per year. And I’m not even talking the thirteen inches of dry season we recorded this year for the 6-month span between the start of November to the end of April, which for the record was about 1-2 inches above the normal dry season total. The big difference maker when it comes to the swamp batting back the descent into deep spring drought is April rainfall. No April rain means deep drought in the swamp. This year, as indicated by the yellow bar above, the swamp recorded a solid 6 inches of rain from the spring solstice (March 22) until now. That’s twice as much as the year before (2021) and three times as much as the year before that (2020) and just the right amount of rain necessary to keep standing water in the cypress domes and strands.

Did I mention we had a subpar summer? It didn’t matter thanks to the timely April rains!

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Question: What’s your favorite dry season holiday?


April Showers
Bring May sheet flow?

The end of the water year …

Usually ends on a dry note.

Monthly rainfall chart for Big Cypress National Preserve

Not this year. The long-term normal for the month is around 2 inches. This year we doubled that total, which much of it coming towards the end. The start of the new water year in May typically begins the deepest and driest part of the spring dry down. This year, the start of May feels more like the start of June. Afternoon showers have been the norm. Will they last? At this point the only thing I can say for sure is that the mosquitoes can’t be far behind.

dry season

Average rains
But still a drought

So far this winter dry season …

Except for December, we’ve had normal monthly rains.

Monthly rain in Big Cypress National Preserve

Compare that to last year where despite a wet November and December (of 2020), every month from January through May (except April) fell below the normal range. You’d think that would mean we’re much wetter today as a result, yet we’re not. Although we are not super dry either. The water table is hanging shallowly under land’s surface and the deeper holes are still wet. Take home points, there are two: (1) During the winter in south Florida, normal monthly rains still equates to a spring dry down and (2) no matter much rain the swamp gets the rest of the year, subpar rain in April and May causes the water table to nosedive into a deep spring drydown.

Best (and worst) decade?
How high phosphorus undermined LORS

Lake Okeechobee’s regulation schedules (1950-2020)
Lake Okeechobee performance over same time period

The above two charts are good companion pieces for understanding the evolution of how Lake O has been managed over the years. In 2008, a new regulation scheduled called LORS was implemented to lower Lake stage while the Hoover Dike was being rehabilitated. In terms of stage alone, LORS was fabulously successful. High and low-water extremes were kept in check on par with the 1950s and 1960s. That success story was undermined by the worsening water quality in the pelagic part of the Lake. The Lake’s interior wetlands and coastal estuaries are both intolerant and easily harmed by the eutrophic water.

Read more

Sheet flow gets stifled

The concept on sheet flow …

Is that water spreads out evenly everywhere.

OK Slough is slumping
well below its normal wet
season level

But the rise of the water is variable, too.

Cowbell Strand is in full summer saturation mode.

Meanwhile, OK Slough is just now barely getting wet.

As for the reason? 

Blame some combination of the residual effect from the deep spring drought, lack of recent rains in that area, and the nearby canal that is whisking water away at a healthy rate.

Pines go under!

There’s the “wet season” …

And then there’s “peak water” wet season.

A graph showing this year so far,
compared to last year and long-term norms

I‘m not saying the water may not inch up higher yet,

Or just as quickly drop down a notch.

What I can say is water is up in the mesic pines.

That means pretty much the entire preserve is submerged

Very shallowly of course.