29th could boost February

Rain or Shine Report for February 25th
Big Cypress in range of 25-yr February record (with help of 29th day)
Around 5 inches of rain has fallen in Big Cypress National Preserve so far this February. That puts the preserve in range of setting a 25-year February rainfall record, going way back to the 6.3 inches fell in February 1983 – which was an El Nino year. .

But first it has to inch out the 5.3 inches of February rain that fell 11 years ago in February 1998 – also an El Nino year.

Both those Dry Seasons dropped over 20 inches of rain in the preserve, and similar amounts across south Florida.

But we’re in a La Nina this year. So it is sort of surprising to be knocking up against El Nino numbers. .
A month does not make a dry season, and the real difference-maker during the dry seasons of 1983 and 1998 was not any single month of above-average rain, but rather the full course of dry season rain that accumulated over consecutive winter and spring months.

But even by that standard, this February has still been a chart-topper for the preserve: chalking up as the wettest dry season month that the preserve has seen since November 1998 (when over 9 inches fell from the remnants of a disbanded Hurricane Mitch).

That tally includes all the “pure” dry season months: November, December, January, February, March, and April. I don’t include May or October in the same category because they both straddle the beginning and end of the wet season, respectively. You can see from the graph above that a few years back, just under 5 inches of rain fell in March 2004. But other than that you have to go all the way back to Mitch, which technically was a tropical system, not a front.

So suffice it to say, it was a real deluge we experienced in the preserve by south Florida dry-season standards.

And don’t forget that this year’s Leap Year gives us one extra day – the 29th on Friday – to add to the February total. Last I checked the papers they were calling for another front to pass through by week’s end, so the extra day of the Leap Year may come into play, at least from a monthly book-keeping standpoint. (view SFL rainfall graphs by basin)

The Kissimmee continues to flow into the Lake through the S65E.

That makes it 7 consecutive months (since late July) that it has been flowing into the Lake: tipping over 1000 cfs for a couple weeks in early August and mid October, but for the past couple months its been flowing at just a few hundred cubic feet per second.

This time last year, the Kissimmee (S65E) had already been at a no-flow condition for around 3 months and running, a streak that eventually ran for 8 months (from Nov 2006 to Jul 2007). Prior to that no-flow streak, the S65E flowed continuously for almost 5.5 years (from Jul 2001 to Oct 2006).

Wet years follow dry years.

The end of one streak is the start of a new one.

The Lake stands at 10.12 ft above mean sea level.
It’s had more staying power above 10 feet than anyone thought just a few weeks back. The Lake is still at its lowest late February level on record (as shown below), beating out Feb 2001 by a half foot, and Feb 2007 by a little over a foot.


Further downstream, Loxahatchee and Water Conservation Area (WCA) 2 are at 5-year February high water marks. Slough water depths in Loxahatchee’s central slough have risen to around 1.5 ft deep, and an average of around 1,600 cfs spilled through the S10s last week (maxing out at a 3,200 cfs daily average); although the current flow rate is zero: the gates were closed on Friday.

Regulatory stage in WCA2 has risen close to a half foot in the past 2 weeks. But despite that rise, slough water depth is much shallower – only around a half foot deep – than the 1.5 ft slough depths in upstream Loxahatchee.

The S11s are still open: last week averaging around 1,500 cfs, and maxing out the week before at a daily high flow rate of 3,100 cfs. The S11A is currently closed, but the S11s as a whole have been flowing continuously since early October 2007, for the past 5 months. Most of that span was at a constant discharge of only 250 cfs.

The recent increase in discharge through the S11s has raised surface water stage in downstream Water Conservation Area 3. This is especially the case in the northeastern corner of 3A – north of I75 – where surface stage has increased around a half foot at Site 63, and sloughs are now holding 8-10 inches of water. Last year, those very same sloughs were about a half foot shallower, and went dry by mid March.

Farther south in southern 3A – close to US41 at Site 65 – sloughs are holding about 2-ft depth of water. In terms of flooding duration, sloughs in southern 3A have held a minimum of 1-ft depth of water for 6.5 years and running; and maxing out at over 3.5 ft deep as recently as Fall 2005. It’s been over 16 years since slough depth in southern 3A dropped below a half foot depth.

Down in the Park, Shark River Slough is tracking at a 5-year late February low-water mark, but just barely: stage at P33 is only an inch or so below last year’s late February level.

Over in Big Cypress National Preserve, the wetting front continues to linger up in the wet prairies, after its 1.5 rise after last weeks deluge.

The really good news is that Turner River is back up and flowing – at around 50 cfs. Water depth at the US41 bridge is currently 3 ft deep: that’s 2 feet higher than it was just prior to the front, and should keep the river corridor open longer into the dry season.

Last year river became un-navigable by early March due to low water.
Long live the Turner River – and don’t miss you chance to canoe its length before its too late – but if you miss it, no worries: the water cycle will replenish its channels again come wet season, but you may have to wait a couple months after that for the mosquitoes to subside, although that varies from year to year too. Photo of Turner River at its undercrossing with US41, showing a hydrologic monitoring station in the background — maintained in partnership between South Florida Water Management District and Big Cypress National Preserve.

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