rain OR SHINE

Rain Or Shine Report for January 15, 2008

2008 beckons as Year of Tortoise

Chalk another week up for The Tortoise.

But also don’t forget that January is our coldest month, so even without the rain, The Tortoise (evaporation) is only crawling at a snails pace, and not making up much ground on The Hare (rainfall).
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It isn’t until the later half of the dry season kicks in — after honeybell season has passed — that the pace of The Tortoise starts to accelerate, and water levels really start to drop precipitously.

That being said, the District has received only 2.3 inches of rain since November. That’s about half the 6 inches of rain that south Florida typically sees through the first half of the dry season (Nov, Dec, Jan) — based on the past 10 years of record keeping.

Blame it on the La Nina.

I’ve read in the papers that the past 2 years have been the driest consecutive years on record.

Check it out for yourself by clicking on South Florida rain history.

Year 1: (for the 365 days starting on May 1st 2006 and ending April 30th 2007) around 40 inches of rain fell south Florida wide. We’re in the middle of Year 2 which so far has received 38 inches since the start of the rain year (May 1st 2007).

Don’t forget that south Florida gets around 40 inches of its 52 inch annual average during the summer and fall (from May through October).

The rainiest dry season we’ve had in recent memory?

Just a few years ago, 17 inches fell from Nov 2002 through April 2003. Before that, it was the El Nino amplified winter rains of 1997-1998 that brought a whopping 26 inches of dry season rain, which was similar in magnitude to El Nino influenced dry seasons of 1982-1983 and 1994-1995.

The lowest dry season total was the 7.3 inches that fell back during the 2000-2001 dry season.

The long-term dry season average is 12 inches — and the last two dry season’s have been right around 8 inches (south Florida wide).

We still have the rest of January, February, March, and April to make up for lost ground. But don’t expect The Hare to make a major appearance any time soon, especially with the moderate La Nina in play.

Watersheds Watch

The Kissimmee River is still flowing into Lake Okeechobee — through the S65E. It was flowing at a few hundred cubic feet per second through last week. Last year, the Kissimmee River descended into an 8-month no flow condition by November 2006. So the fact that the Kissimmee River is still flowing in January puts it a few months ahead of last year’s condition.

The Lake is at its all-time January low water mark. Its current stage — at 10.1 ft msl — is around 2 ft lower than mid January of last year, and 5 ft below the 5-yr January average.

Note that lake stage was 7 feet higher than the current condition during Januarys of 1983 and 1998 — both El Nino amplified dry seasons. Also note that the current January lake level is a foot lower than January of 2001, the previous January low-water mark for the lake.

Loxahatchee set a new 5-year high water mark back in October and November, but since then water levels have returned to normal. Current stage is tracking around 2 inches above the 5-year January average. Sloughs in the central marsh are holding 16-20 inches of water, with the wetting front still reaching up into or above the ridge landscape type. Currently over 4 ft of water is pooling behind the S10s, which have been closed since mid October.

Regulatory stage in Water Conservation Area 3 is around 3 inches lower than mid January of last year and around 6 inches lower than the 5-year January average. Slough water depth in southern 3A (at Site 65) — just north of Tamiami Trail — are around 2 ft deep. In comparison, slough water depths in northern 3A (at Sites 62 and 63) are at or below a half foot deep.

This was the first summer since 1990 that flows through the S12s into downstream Everglades National Park did not exceed 500 cfs at any point during the summer or fall wet season.

Down in Everglades National Park, this is the lowest that wetland water levels have been at the start of the calendar year since the early 1990s. Slough water depths in central Shark River Slough (at P33) are just under a foot deep. That’s more than twice as deep as January 1990 and 1991, but a foot shallower than January 2006 and two feet shallower than January 1995.

Wetland water stage in Big Cypress National Preserve is tracking at a new 5-year January low-water mark. That places the water table at about a foot lower than the 5-year January average, and 2-3 inches below January of last year. The wetting front continues its retreat into the the deeper wetlands. The wetting front retreated out of the hydric pines in early November and out of the wet prairies by mid December, but still has a foot hold in the interiors of our cypress domes and strands, and the deeper swamp forest that lies within.
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After its last stand there, its down into the aquifer until The Hare (rain) gets back into the race.

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