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Climate Change Assessment for Water Resources Region 03 South Atlantic -Gulf A 2011 study by Obeysekera et al. focused on identifying climate (temperature and precipitation) trends for South Florida using historical data. This study examined a number of climate metrics with data extending back to the 1890s. For all of the metrics, including total annual precipitation and the occurrence of temperature extremes, no discernible trends were found for their study region. Two years later, Irizarry -Ortiz et al. (2013) quantified an overall decreasing trend in wet season (most evident in the month ofMay) precipitation for the state of Florida using an extended data set (1892 — 2008). In contrast, they also found evidence of an increase in the number of dry season (November — January) precipitation days in Florida. In North Carolina (at the Coweeta Laboratory), changes in precipitation variability have been observed (Laseter et al., 2012) (Figure 2.11). These changes include wetter wet years and dryer dry years compared to the middle of the 201' century. As an example, the wettest year on record occurred in 2009 at Coweeta, and only two years earlier (2007) the driest year on record was observed. This pattern of change is supported by the NCA report (Carter et al., 2014), which states that, "summers have been either increasingly dry or extremely wet" in the southeast region. This assessment is based on analysis of data dating back to the turn of the 201' century. a) 2600 2200 2000 180 1,600 0 1400 1200 1,, 4° 00 Annual Ora .. 6b I'D ors u 00 19,40 1950 NO) 1970 1980 1990 2000 21110 Figure 2.11. Total annual precipitation at Coweeta Laboratory (North Carolina). Lines show modeled 101' and 90'h quartiles as a function of time, 1940 — 2010. (Laseter et al., 2012). A study by Dai et al. (2011), for a climate station in South Carolina (at the Santee Experimental Forest), identified a generally increasing, but not statistically significant, pattern in the number of extreme storm events over the past 60 years. Similarly, they demonstrate a generally increasing trend in total annual precipitation at their study site, but without statistical significance. A 2012 study by Patterson et al. focused exclusively on the South Atlantic Region, investigating historical climate and streamflow trends. Monthly and annual trends were analyzed for a number of stations distributed throughout the South Atlantic -Gul Region for the period 1934 — 2005. Results identified little, if any, patterns of precipitation change in the area over this period. Some sites showed increasing trends, others showed decreasing trends. Overall, and for the full period of record, more sites exhibited mild increases in precipitation than decreases. USACE Institute for Water Resources 17 January 9, 2015