Rain

Rain Or Shine Report for 12/19
Hare wakes up from slumbers for short mid-December dash,
but doesn’t make up much ground with Tortoise still in rear view

RAINFALL

The Hare awoke from his winter season slumbers, at least for a week, but don’t expect that to slow the Tortoise for too long.

Last week’s rain was particularly pronounced in an east-west band centered on Lake Okeechobee. The East Caloosahatchee and Martin-St Lucie Basins have already overfilled their “average December” rainfall cup. Keep in mind that the December average is only around 2 inches, but still — every drop of rain counts during the dry season, especially when its a good “wetting” rain. In comparison, Big Cypress National Preserve’s December cup is half full — with just around 1 inch.

I had my eyes pealed to the south, watching the progress of Tropical Storm Olga — hoping, expecting to get some rain out of it. But then it was a front from the other direction that brought the rain, and some of that coveted cold air behind it. Here in Ochopee we carefully gage strength and duration of north wind from the giant American Flag at Wootens. As I look out my window, I see that its still pointing pretty resolutely to the south.

It was also a surprise to see such a late season storm develop in the tropics. That’s not unheard of. Usually they don’t have enough energy to reach hurricane strength, but they can be significant rainmakers, and/or feed moisture into frontal storms passing through from the north.

That latest season hurricane strength storm to make landfall in Florida?

That would be a Category 1 that made landfall in Sarasota on December 1st of 1925. More recently, Hurricane Kate — also a Category 1 — made a Nov 18th landfall in Port St Joe. In all, going back to 1900, only 4 hurricane-strength storms made landfall in Florida after the calendar turned its page into November.

But don’t forget the Super-storms that can also strike during the winter — like the one that struck between Tampa and Apalachicola in March of 1993. The storm center set barometric low-pressure records for several weather stations. That includes hurricanes! It was a very strong storm in every sence of the word — storm surges, fatalities, and damage. It resulted from a strong low pressure system from the Rockies colliding with an especially stout cold front from the north. The result was the 1993 “the storm of the century” – that continued its path up through New England. It was also a storm that even though it was hurricane strength, kind of slipped through the radar, and was stronger than projected. Storm tracking technology has advanced since then, but many people were caught off guard by that storms intensity.

KISSIMMEE VALLEY

The Upper Kissimee has received the least rainfall over the past 30 days — under a half inch — and has only received around an inch of rain since the start of November.

Its sort of surprising then to see the that Lake Toho stage — at 55 ft msl — is currently around 1 ft higher than the 5-year December average, and about 2 ft higher than mid December of last year. Lake Toho’s stage is regulated by the S61 structure. Flows through the S61 briefly peaked at over 1,000 cfs in early August, but has been at a no flow condition since mid August other than a 3-week stretch of flowing at a couple hundred cfs.

Compare that to the Lower Kissimmee where the river spills into Lake Okeechobee at structure S65E. It has delivered flow into the Lake at an average of 700 cfs for 150 consecutive days since it started flowing again in mid July after its 8-month haitus of no flows.

LAKE OKEECHOBEE

Lake Okeechobee stage continues to track at an all-time mid December low of 10.3 ft msl. This year marks the first consecutive summer and fall that Lake stage didn’t manage to rise into the lake’s lowest lying wetlands — the ones lying at a 11 ft elevation. During the 2001 drought, lake stage rose above 11 ft msl by August, and above 13.5 ft msl by late September.

Other drought years of note. in 1990, lake stage rose above 11 ft by mid July, and before that during the 1982 drought, lake stage rose above 11 ft in early September. The last time lake stage stayed below 11 ft msl for this long was way back in 1956 when it didn’t break the 11 ft plane until early October.

By any metric, that puts this year’s December lake level into unknown territory in the historical nautical charts.

EVERGLADES

Loxahatchee has been tracking at a new 5-year high water mark for the past 2 and a half months. Its dropped down about a half-foot from its October apogee, but its still tracking about 4 inches above the 5-year mid December average. That puts slough water depths at around 1.5 feet deep. Currently, around 4.25 feet of water is stacking up behind the S10 structures. The S10s have been closed since mid October.

Down in Water Conservation 3, water is still flowing in from the S11s at around 200 cfs, and have been flowing continuously since early October, peaking briefly at over 2,500 cfs in early November. Slough depths in southern 3A (near the Trail at Site 65) are currently at around 2.5 ft deep, and have been holding water continously since July of 1990. Compare that northern 3A (near I75, at Site 63) where current slough water depths are just over 0.5 ft depth, and have been holding water continuously for only around 5 months, preceded by a 5-month dry down.

Down in Everglades National Park, central Shark River Slough is tracking at a new 5-year December low-water mark, at about 8 inches below average. You have to travel back in time all the way to 1989 when December water levels have been lower in Shark River Slough.

BIG CYPRESS

Surface-water stage in upstream Big Cypress National Preserve is only 2 inches below its December average. Actually, since early October this year has tracked very closely to last year’s recession. Its been wetter to the south all summer and fall. The north, especially Bear Island, has been around a half foot below average all summer.

Up in Corkscrew this summer, the wetting front barely poked its nose out of the lowest lying swamp forest and marsh wetlands. That left pinelands, wet prairie, and even much of the cypress dry all summer. You have to travel back in time all the way to 1970 to find a similarly dry summer and fall period.

IN SUMMARY
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We’ll have to keep a close eye on the drought indices as the dry season progresses. You can get a quick overview of how drought conditions are unfolding with Florida’s Division of Forestry map.
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