The ACF Basin is drought-free with some D0 (Abnormally Dry) in southeast Florida and far eastern Georgia as well as some D1 (Moderate Drought) in southeast Florida according to the most current U.S. Drought Monitor (as of 12/06/2018).
Rainfall Departures Over the Past 14 Days
Well-above normal rainfall departures throughout the ACF basin. Portions of the lower ACF basin with 14-day rainfall departures 6-10 inches from normal.
Rainfall Over the Past 60 Days
Heavy rainfall departures throughout the ACF basin and much of the Southeast region. Portions of the upper and lower ACF with 60-day rainfall departures 5-8 inches from normal.
Official NOAA 3-Month Outlook
According to the most recent NOAA 3-Month Precipitation Probability Outlook, the CPC Winter Forecast (Dec. - Feb.) projects approximately 50/50 chances for above normal rainfall for the vast majority of the ACF basin.
28-day average streamflows of the Chestatee River near Dahlonega are in the much above normal range. The average streamflows of the Chattahoochee River near Cornelia are in the much above normal range. Further downstream on the Chattahoochee River near Atlanta and near Whitesburg flows are also in the much above normal range. Similarly, flows near West Point and Columbus of the Chattahoochee River are in the much above normal range. Average streamflows of the Flint River from Griffin to Carsonville, Albany, and Bainbridge are all currently in the much above normal range as well. Lastly, the streamflows of the Apalachicola River at Chattahoochee are in the much above normal range. (for more info: http://waterwatch.usgs.gov)
The 1-Month Mean Daily Streamflow Forecast from the Southeast River Forecast Center (SERFC) predicts above normal flows for the Apalachicola, Chattahoochee, and Flint Rivers. The 3-Month Mean Daily Streamflow Forecast from the SERFC predicts similarly above normal flows.
ACF Basin Composite Conservation and Flood Storage
Collectively, ACF reservoirs projects are currently in Zone 1 and expected to stay in Zone 1 over the next few weeks. US Army Corps of Engineers (USACE) is currently evacuating the flood pool at each project to prepare for the next event.
Drought Assessment Webinar Summary
*Entire ACF Basin is currently drought-free, moderate drought spreading in South Florida.
*The long awaited El Nino conditions are in place and impacting weather patterns
*Frequent and strong Southern Branch disturbances have brought much above normal rainfall to all parts of the ACF in the last two months
*Rainfall above normal at all time scales
*7-day forecast indicates more widespread rain over the northern Gulf Coast with the next system later this week.
* Climate Prediction Center official forecast (December-February) favors equal chances for temperature, higher chances for above normal rainfall
*Pacific Ocean has transitioned to El Nino, over 80% chance it continues into Spring.
*Weaker El Nino does not necessarily mean less rain, just less confidence in the forecast
*Real-time stream flows in the ACF basin are currently in the above normal to high range.
*28-day average stream flow at Chattahoochee River at Cornelia are in the normal range, and Chestatee River at Dahlonega are currently in the much above normal range.
*28-day average stream flow for the Chattahoochee River below Lake Lanier are currently in the much above normal range.
*28-day average stream flow for the Flint River are currently in the much above normal range.
*Groundwater levels range from much below normal to high across the ACF Basin.
*The Southeast River Forecast Center's 1 Month Stream flow Forecasts predict above normal flows for the entire ACF.
*The SERFC's 3-Month Stream flow Forecasts also favor above normal flows throughout the ACF.
*Note: stream flow forecast pie charts do not directly include any adjustments to the ESP forecast based on ENSO, CPC, or other factors, but are based on soil conditions relative to normal in concert with historical precipitation.
*All ACF reservoir projects are currently above the guide curve
*US-ACE is currently evacuating the flood pool at each project to prepare for the next event.
*The ACF system conservation storage is in Zone 1 and expected to remain in Zone 1 over the next few weeks.
Acknowledgments and Resources:
David Zierden, FCC at FSU
Brian McCallum, USGS
Jeffrey Dobur, SERFC
Cynthia Donald, USACE
Summary prepared by Rachel McGuire, Auburn University