The eternal drought: south FL will never win

[MiamiensisWx]

Several inches of beneficial precipitation have occurred across southern/central Florida, including the Orlando region and Kissimmee River watershed, during the past five days. Broad swaths of Lake Okeechobee's source of water in central Florida were impacted. Infiltration and overland flow from this region provides a source of water for the lake, so prolonged periods of rainfall are beneficial for areas farther south. Historically, similar periods of moderate rainfall (that affected the same areas) culminated in significant water level rises on Lake Okeechobee. I can recall several events during the 1990s and pre-2006 years. Additionally, the lake featured sustained periods of average or above average water levels, although there were numerous intervals of natural drought cycles such as the 2001 drought. However, we have not observed these sustained periods of average/above average water levels in recent years. From 2006 to the present, I can't recall any prolonged periods of average/above average lake levels. In fact, I believe that we have not observed a single period of sustained above average water levels during this period. The lake level only briefly rose to an average state after the passage of Tropical Storm Fay, but it quickly reverted to sub-average levels.

Let's examine the recent rainfall event. Note the significant decline in the KBDI (drought index) values across the Orlando area and Kissimmee watershed:

http://flame.fl-dof.com/fire_weather/KBDI/archive/kbdi-report-20090519.html
http://flame.fl-dof.com/fire_weather/KBDI/archive/kbdi-report-20090520.html
http://flame.fl-dof.com/fire_weather/KBDI/archive/kbdi-report-20090521.html
http://flame.fl-dof.com/fire_weather/KBDI/archive/kbdi-report-20090522.html
http://flame.fl-dof.com/fire_weather/KBDI/archive/kbdi-report-20090523.html

What is the trend of Lake Okeechobee's water level?

http://www.saj.usace.army.mil/h2o/reports/r-oke.txt

May 18: 10.55 ft (nearly 3 feet below average)
May 19: 10.60
May 20: 10.66 (about 2.6 feet below average)
May 21: 10.77
May 22: 10.75

The lake level only featured relatively modest gains for a brief period, and it actually dropped yesterday. It dropped, despite the recent rains. Unlike previous decades/years, these trends have been the norm from 2006 to the present. Similar rainfall events produced greater lake level rises in the 1990s and early 2000s. The lake eventually rebounded. Recently, sustained average/above average lake levels have been scarce, and periods of copious, widespread precipitation have not resulted in substantial lake level rises. It is remarkable that we are approaching the severe deficits of 2007 and 2008. Actual drought conditions have vanished across the peninsula, but Lake Okeechobee is lower than the preceding month. All of these trends are disconcerting, since we have essentially retained the Lake Okeechobee deficit for at least three consecutive years. I think it highlights the effects of greater water releases during discharge periods. The larger discharges have been partially influenced by the declining state of the Herbert Hoover Dike. Discharges are likely releasing more water than previous years. If these effects of human influence are not addressed, we will likely remain in a prolonged Lake Okeechobee drought. It's producing significant negative effects on south Florida's wells and the Biscayne Aquifer. Additionally, the Herbert Hoover Dike must be amended.

Human intervention harbors a stranglehold on Lake Okeechobee's water table.

[Tampa Bay Hurricane]

Sounds ominous. Nice analysis Miami!

[anniecros]

Well, duh. The water level will never again be allowed to be "average" for the lake. It's a rule.

This is why:

http://www.sun-sentinel.com/news/local/ ... 7380.story

Tropical Storm Fay in August gave the lake a record-setting boost. That prompted the Army Corps of Engineers to start dumping water out to sea to ease the strain on the lake's aging dike. Smaller releases have continued to send fresh water to the Caloosahatchee River to counterbalance rising salt levels that threaten sea grasses and drinking water supplies.

If that isn't enough to convince people screaming about lake levels, there is always this:

The corps estimated that since September, the volume of water released equates to more than 1 foot of water in the lake.

After Katrina, they will never let the water level in Lake Okeechobee up to average. That's all she wrote, and it isn't because of anything that Mother Nature is doing out there.

Lake Okeechobee is a man made disaster, but it is not because of the world getting ready to flip on it's axis or anything.

It is overmanaged. Leave it alone, but be prepared for many home owners to be flooded out in any given year.

Take your pick. But seriously dude, if they keep draining it, it just isn't going to get any higher. What do you want?

I'm kind of tired of the moaning and groaning over the lake levels. Sorry.

[gatorcane]

What a difference the rainy season makes. Since it started 10 days earlier than the historical mean (started May 11th in South FL with a mean start date of May 21st), huge dents have been made in the drought already:

The KBDI indices have plummeted...and we are pulling out of the drought.

A few months back I posted on this board projecting a rainy May for Southern Florida with SW windflow to push the storms towards the east coast metro areas, with no worries about the drought here. Indeed looks like that forecast is verifying with the next 7-10 days of SW windflow projected by ECMWF and GFS, with a trough hanging out to the NW of us. That will give a 60% chance of POPS for days and days here, each afternoon.

[jinftl]

KBDI speaks more of fire danger which can be dramatically changed by recent rains, as we have seen. I'm not sure it is really an accurate reflection of long-term drought conditions though. No doubt we have seen rain in May...some areas have had in excess of normal May totals....primarily north of south florida (although there are clearly areas that have had that in South Florida too).

I am going to contend, that based on actual May rainfall at both MIA an FLL airports, we have actually made no dent in the overall, long-running drought because actual rainfall has been 'normal'.

As of this morning, MIA has seen 5.83" of rain month to date...normal for the month of May is 5.96". As of this morning, FLL has seen 5.74" of rain this month, normal for May is 6.33".

What this means is that if we end May with 'average monthly rainfall', all we have done is effectively carry over the long-term rain deficits. 6" of rain will absolutely kill the fire danger....but it is not eating away at the long term deficits that range from 1 foot in West Palm to over 20" in Fort Lauderdale for the last 16 months. What we need is widespread above normal rains...not just in isolated neighborhoods.

June is the wettest month of the year on average in south florida....with most areas near or above 10" on average...that equates to almost a 1/3" each day. Even if we get that much this June, i would still claim the long-term drought is not over....we have to make up for the deficit, not just carry it along like bad debt we don't think has to be repaid just because we are paying our current bills!

Current kbdi detail still shows there are some dry areas...but you are 100% right, this is a much better picture for short-term fire danger.

What a difference the rainy season makes. Since it started 10 days earlier than the historical mean (started May 11th in South FL with a mean start date of May 21st), huge dents have been made in the drought already:

The KBDI indices have plummeted...and we are pulling out of the drought.

A few months back I posted on this board projecting a rainy May for Southern Florida with SW windflow to push the storms towards the east coast metro areas, with no worries about the drought here. Indeed looks like that forecast is verifying with the next 7-10 days of SW windflow projected by ECMWF and GFS, with a trough hanging out to the NW of us. That will give a 60% chance of POPS for days and days here, each afternoon.

[artist]

true jinfl, but I know there are areas in palm beach county that have gotten way above average rains in the last 2 weeks, we are one of those places. And the lake is not making any strides considering how much I have seen coming over the lake directly toward us. I do believe they are continuing to lower the lake level, as there has just been too much rain over it to not raise it more than it has as well as all the rain upstream. I do know they intentionally released for 11 days in May, that they have told us about, how much have they that they aren't letting us in on?
anniecros - you have it right, they aren't going to let it get to a normal height for the reasons you stated. It seems to me it is time for Fl to find the money to repair the dam there. Otherwise, we will always be suffering from manmade drought issues every spring.

[MiamiensisWx]

Here's another indicator of the Herbert Hoover Dike's poor maintenance:

http://www.sun-sentinel.com/sfl-levees-repairs-a060709sbjun07,0,6178849.story

The next large, intense hurricane landfall in south Florida would present a significant threat to the current system.

[Stormsfury]

Hopefully the trend continues for that region. All of the Southeast has now just about fully recovered from the devastating drought conditions that have plauged the region for 5 years now and all lakes, reservoirs, and rivers have fully recovered.