10/18/2020, 7:17 pm EDT

Southern Company Summer 2020 Verification Report

Highlight: Warmer/wetter than normal summer for Southern Company. Fig. 1: Meteorological summer 2020 state temperature ranks. Fig. 2: Meteorological summer 2020 state precipitation ranks. Discussion: Meteorological summer was warmer than normal across Southern Company (Fig. 1). Alabama rainfall was wetter than normal while Georgia rainfall was close to normal (Fig. 2). After an unusually cool May the summertime temperatures turned hotter than normal peaking during July and easing only slightly in August. Unlike the last two hot years September was temperate (Fig. 3). During the 2020 warm season Mobile was slightly cooler than normal each month while Atlanta and Macon produced the hottest anomalies in July and August. The system average precipitation was close to normal in May and June although the near normal values were the result of wet (Mobile) and dry (Macon) extremes (Fig. 4). West/north Alabama was wet in July while Mobile observed very little rainfall. The System Average in August was wetter than normal. Macon was excessive wet in September while Birmingham very dry – a System Average slightly wetter than normal. During the 2020 warm season the monthly CDD totals in Alabama were close to normal and not as hot as the last two years (Fig. 5). Georgia was near normal and similar to last year in June (Fig. 6). July was the hottest of the past four years for both states. August CDD count was as hot as last year. September cooled to near normal unlike the last two years. The verification of the Southern Company System temperature and precipitation forecast issued last spring produced mixed results. The temperature verification was reasonable for the meteorological summer months but too warm for the unusually cool May and (also) too warm for the temperate September (Fig. 7). The precipitation verification was reasonable for May and June but out-of-phase for July through September (Fig. 8). Fig. 3: Southern Company System temperature summer 2020 verification. Fig. 4: Southern Company System precipitation summer 2020 verification. Fig. 5: Alabama population weight CDD for warm season 2020 versus last 3 years. Fig. 6: Georgia population weight CDD for warm season 2020 versus last 3 years. Fig. 7: Southern Company spring 2020 forecast for monthly system temperature anomalies versus verification. Fig. 8: Southern Company spring 2020 forecast for monthly system precipitation percent of normal versus verification.