Last week was the coldest week of dry season
SFL Weekly Watersheds Summary: Jan 22-29

WEATHER. Last week turned out being the coldest week of this year’s dry season so far. The average weekly night-time low dipped down to 48 degrees last week. That beat out this year’s previous weekly low-temperature mark (of 49 degrees) that passed through the southern peninsula earlier this Thanksgiving. The weekly day-time high dropped down into the low 70s, which means that daytime highs on a couple days stayed in the mid 60s. You know that a frigid arctic cold front has descended in south Florida when day-time highs drop below 70 degrees, especially over the course of a couple days. Last year’s coldest weather occurred in mid-February when the average weekly day-time high and night-time low fell to 65 and 43 degrees, respectively.

We’re at the half-way point of this year’s dry season, and to date in the Big Cypress we’ve received about 4.3 inches of rain. Over the past 5 years the preserve has averaged 11 inches of dry season rain (from the start of November to the end of April). So this year’s dry season has been below average. And don’t forget that the rainy season ended early this year. October is a camelion-like rainfall month that can either generate wet-season-esque rainfall amounts (when tropical systems hit the southern peninsula) or, as was the case this year, can swing in the complete opposite direction (with no rain) and mark an early start to the dry season. A rainless October can make a difference down the road in the dry season, especially in a “dry” dry season like we’re having this year.

BIG CYPRESS. Preserve-wide stage rose a little over an inch last week in response to the steady drenching of rain we received on Superbowl Sunday. Currently, surface-water stage in the preserve is still about 8 inches lower than early February of last year, and about 3 inches below the 5-year early February average. Don’t forget that last year the Preserve was deluged with about 3 inches of rain from a single frontal storm in the beginning of February. That 3 inches was pretty much our only rain of last year’s otherwise rainless dry season. But it was enough to rewind water recession clock back to early December levels. This year we haven’t had such a storm, and this year’s start-of-February water levels have already dropped to last year’s mid-March level.

EVERGLADES. Over the past 5 years, combined flows from the S12s come to a halt by early February. This year, flows through the S12s came to an end in early December, almost 2 months earlier than the 5-year average. Water is currently pooling up around 1.5 ft behind the S12s, 2.25 ft behind the S11s, and 3.7 ft behind the S10s.

LAKE O. Lake stage dropped below 12 ft msl in the middle of January, and is currently in the mid 11 foot range. Historically speaking, current lake stage is around 3.2 ft lower than early February of last year, around 3.2 ft lower than the 5-year early February average, and around 8 inches higher than early February of the 2001 drought year. During that drought year, Lake O stage eventually dropped to 9 ft msl by late May of that year, and persisted at that level through most of June. By October of 2001 Lake stage had risen to over 14 ft msl thanks to the above-average 38 inches of wet season rainfall that fell on the lake that year. (The lake averages about 33 inches of wet-season rain).

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