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December Briefing. Outline. Current Conditions Primary Factors 2 nd Year La Nina Drought Region / Feedback Role of AO/NAO Streamflow Outlook Historical SERFC Ensemble Streamflow Prediction. Past 30 Day (% of Normal) Rainfall. Past 60 Day (% of Normal) Rainfall.
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Outline • Current Conditions • Primary Factors • 2nd Year La Nina • Drought Region / Feedback • Role of AO/NAO • Streamflow Outlook • Historical • SERFC Ensemble Streamflow Prediction
Recent enhanced inflows have stabilized but not increased pool elevation
Typical US Temperature, Precipitation and Jet Stream Patterns during La Niña Winters Jet Stream / Active Weather Generally North of ACF
ENSO vs Rainfall Surplus/Deficits (Climate Division 2 and 3) El Niño El Niño La Niña La Niña La Niña Take Away: Correlation between ENSO & SE US Rainfall never fully made up deficits from past drought?
Lake Lanier Pool vs Rainfall Surplus/Deficits (Climate Division 2 and 3) Lanier Pools recover In 2009 Lanier Pool (ft) Rainfall Deficits Increase from Winter 2007 to Spring 2008
1stvs 2nd Year La Niña Composites Year 2 Year 1 Year 1 - worked out fairly well Year 2 - generally drier
‘Double-Dip’ Las Niñas Data courtesy of Melissa Griffin (Florida Asst. SC)
Historical Data – Second Year La Niña December – April Period Lake Lanier Inflows Upper Flint Lower Chattahoochee Apalachicola Watershed
Ensemble Streamflow Prediction For Jan 1 - March 31 Lake Lanier Inflows Lovejoy Whitesburg Albany Blountstown
Summary •La Niña will dominate this winter. Generally, this will continue to reinforce reduced rainfall and overall drought across the Southeast U.S. •AO/NAO can tend to either enhance or override the ENSO signal. • Extremely low stream flow and soil moisture will reduce inflows. •Very tight rainfall gradient over basin north of Lake Lanier. • A switch to El Niño by next fall, the record of the last decade would favor an end of the 2010-12 drought.
weather.gov/serfc SERFC Journal 2-3 times a week Water Resources Outlook – bi-weekly Questions