Miami drenched

Rains drench Miami, move towards Lake

SFWJ: Sep 24-30

WEATHER.

Miami-Dade recorded a months worth of rain last week. Around 7 inches fell across the southeast Coast. If you’ll remember, August was unusually dry for Miami — recording only 3 inches of rain in comparison to the 8 inch August average. September was shaping up to be similarly dry until the off-coast tropical depression pumped in all that moisture — dropping a chart-topping 7 inches for the week.

Paradoxically, southwest Florida (Naples and Ft Myers) was relatively rainless for the week, ending an otherwise rainy September on a whimper. The Southwest Coast chalked up 8.5 inches of September rain. That turned September into rainiest month of the rainy season for the Southwest Coast — but still 1.3 inches below the 5-yr 9.8 inch September average. Since May, the Southwest Coast has recorded only 32 inches of rain. That’s 18 inch below the 50 inches of rain we’ve averaged over the previous 5 wet seasons (May through October), and 13 inches below last year’s Wet Season total.

With its 13 inches of June rainfall and 7-inch rally at the end of September, Miami-Dade has received 42 inches since May. At the other end of the spectrum, the Lake has only received 22 inches of rain since the start of May.

As I type, the showers that pounded Miami have spread north up towards the Kissimmee Basin. That could bring a much needed boost to the Lake.

WATERSHED FUN FACTS

Lake Okeechobee stage set an all-time low-water mark for September. Lake stage bottomed out at 8.82 ft mean sea level in late June — an all-time Lake low for any month. It’s currently at 9.85 ft msl, which is around 4 ft below late September of last year. One has to go all the way back to 1981 when lake stage was below 10 ft msl as far in the late season as August, let alone its current sub-10 ft level at the end of September. Even during the “then” drought-of-the-century back in 2000-2001, Lake stage had rebounded to almost 14 ft msl by the start of October, 4 ft higher than this year’s start of October.
In terms of wetland hydroperiods, Lake Okeechobee stage has been below the base of the interior-levee littoral zone for 17 straight months, matching a drydown duration of similar length in 2000-2001 (and with +3.5 ft still to rises back up to the base of the wetlands).

Lake Okeechobee’s historic plummet since Wilma passed through in October 2005 is captured in the figure below. Lake stage briefly touched up higher than water levels in nearby Loxahatchee, a rarity in modern times, but two year’s lower had dropped 8 feet and lower than wetland water stage in Big Cypress National Preserve some 60 miles to the south. Lake stage spent the Summer at a lower level than Big Cypress Swamp stage, but is on the cusp of rising above this inversion.


Inflows into Everglades National Park through the S12 structures have failed to materialize this Summer, placing downstream Shark River Slough at a 17-year September low-water mark, eclipsing the drought of 2000-01. For the record, the 1989-1990 drought was more severe for both the Park and upstream Water Conservation Area 3. Regulatory stage in WCA 3A is currently a full foot higher than during September 1989.

Big Cypress National Preserve is only at 7-year September low in comparison. Interestingly, wetter conditions have prevailed all Summer in the preserve’s southern half (south of the Tamiami Trail). Despite of a relative absence of flows across the trail, the wetting front down south is touching up at the base of our mesic pinelands, which translates into 2 ft deep of water in marshes and swamp forest habitats – our deepest wetland communities.

Visitors who stroll the boardwalk at Corkscrew Swamp Sanctuary are viewing a 37-year September low-water mark. But hold the press! Word from Corkscrew is that water levels have finally started to rise out of the low-water refugia and spread out into the tall cypress.

Just when we thought this would be the “Year without a Wet Season” we’re seeing some signs of life.

Be sure to tune in next week for an update on the rain that’s heading up into the Kissimmee.
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