If we were to use the current conditions of the Savannah River Basin as indicators, it would seem reasonable to conclude we are facing imminent drought.

First, the upper basin has experienced below average rainfall for the last three months. Thurmond fared better than Hartwell by receiving about 86 percent of average rainfall in the past 90 days. But in the same period Hartwell has only received about 69 percent of average.

Second, the result of this rainfall deficit has left portions of the basin abnormally dry, and a few places in moderate drought, as shown in the image released Aug. 6 by NOAA here.

Third, inflows are currently dismal. At Hartwell inflows are 22 percent of normal, and at Thurmond we are observing a painful -19 percent of normal. The negative inflow at Thurmond means evaporation is greater than local inflows to the reservoir. Even assuming inflows improve to 75 percent of normal, our 10 week projection has us brushing up against Drought Level 2 in October.

If the projections are close to the mark, reservoir levels will reflect a sharper naturally-induced winter drawdown that hangs in the Drought-Level 1 vicinity, and maybe in Drought Level 2.

But by December we have good reason to expect a turn of events. We may even be dealing with the opposite challenge: high water.

The most recent ENSO forecast shows all models remain equal to or above +0.5ºC through spring 2016, and most predict a +1.5ºC or higher, as shown below.

This means El Niño conditions are now present and we are facing a near-certain “strong El Niño” for the winter. El Niño conditions are warmer-than-average air currents in the Pacific that typically translate to above-average precipitation in the southeast, as indicated in the winter outlook map below.

As a reminder, the cooler winter weather significantly increases the rainfall-to-runoff ratio. Historical data demonstrates reservoir levels are very responsive in the winter, which is why successful refills occur even with below-average rainfall.

In fact, I spoke with Todd Hamill, a hydrologist with NOAA’s Southeast River Forecast Center, and he said the last time we experienced a comparable El Niño was the winter of 1997-98. In October of 1997 both Hartwell and Russell were about a foot away from Drought Level 2.

Starting in December that year we began receiving above average rainfall. In January 1998 Hartwell received more than 9 inches and more than 7 inches the following month. As a result we were dealing with high water issues beyond June of that year.

“We got rain every three days [that winter],” Hamill said. “There are other factors that can come into play [besides El Niño] but it looks like we’re facing a chance of flooding – which is a bigger problem than people think.”

If the ENSO forecast is a reliable prediction of what’s to come in the winter, we may experience a refill that exceeds expectations earlier than usual – perhaps even causing a high-water event.

~Russell Wicke, Corporate Communications Office

– See more at: http://balancingthebasin.armylive.dodlive.mil/#sthash.zrp0DBKg.dpuf

If we’ve learned one thing about rainfall at the sub-basins in 2015, it’s that it is anything but average.

July’s observed rainfall fell in line with the pattern established by previous months this year, where the odd numbered months fell short and even numbered months surpassed the averages at each of the sub-basins.

While there is nothing impressive about receiving three inches of rain in 31 days (Hartwell: 3.1; Russell 3.2; and Thurmond: 3.6), especially when the sub-basins average 5.2, 4.3 and 4.3 inches, respectively, a closer look at how those three inches were dispersed provides support for the “every little bit counts” mantra.

At Hartwell, the wettest day of the month was July 3, which, after raining most of the day, netted six-tenths of an inch. Similarly, the 48-hour period from July 2-3 at Russell and Thurmond garnered 1.7 and 2 inches, respectively, more than half of each sub-basin’s total for the month.

Throughout the rest of the month, the sub-basins basked in the early- to late-evening mist, which rarely exceeded three-tenths of an inch.

And though these miniscule amounts combined to push the observed rainfall over three inches at each sub-basin, they left much to be desired, especially considering just two years ago in July Hartwell received more than 13 inches, with Russell and Thurmond hovering around 10 inches.

Yet at the same time, these numbers definitely could have been worse.

Hartwell didn’t even top three inches in July for six straight years between 2006-2011; and Thurmond and Russell shared similar struggles between 2009-2011 (Russell was the star performer when it squeaked over that bar in 2009 by posting 3.14 inches).

So as summer winds down and students head back to school with high marks on their minds, is expecting the sub-basins to just be average too much to ask for? Here’s to putting hopes in August.

~ Jeremy S. Buddemeier, public affairs specialist

– See more at: http://balancingthebasin.armylive.dodlive.mil/2015/08/06/july-rainfall-update/#more-2102

The erratic spring cycle of high highs and low lows appears to have leveled off in June, as each of the sub-basins arrived much closer to its 67-year average for the first month of summer.

While Russell and Thurmond exceeded their averages with 113 percent and 107 percent (4.32 and 4.07 inches versus 3.83- and 3.81-inch averages, respectively), Hartwell fell just below the mark, receiving 4.5 inches — or 94 percent — of its 4.82-inch average for June.

According to the records generated by the National Weather Service, which uses a spatial average of stage 3 doppler radar, the sub-basins gathered most of their “take” within the first 2 weeks of the month.

During this period, the rain fell steadily throughout the day, whereas for the rest of the month the sub-basins received their rain in the evening and early morning hours.

Looking into the rainfall crystal ball for July, which on average receives slightly more rain than June, it is likely the sub-basins will settle into a regular rhythm like this month, where they receive closer and closer to their average rainfall.

Historically (in the last decade), the first week of July has been mostly dry, so there’s more than a good chance for a beautiful weekend.

I’m no meteorologist, though, so the best I can offer is optimism for a sunny, fun-filled (and safe) Independence Day weekend.

Courtesy Corp of engineers