EXPERIMENTAL Zonal/Meridional Wind Anomaly Forecast EXPERIMENTAL Specific Humidity Anomaly Forecast VERIFICATION/Climate Summary for July 2022 Valid: August through September 2022 Climate discussion: Since 2013, the evolution of a persistent large area of (mostly) anomalous warm surface/subsurface water in the middle latitudes (of both hemispheres) and somewhat independent of ENSO is observed. The first notable warm zone was the Northeast Pacific Marine Heatwave also known as the “warm blob”. The “warm blob” originated in the northeast Pacific surface and to depths of 300 meters in 2013. The unexplained large mass of warm water was discovered primarily due to the alteration of wildlife across the Pacific including bird migration and various fisheries. However, later research revealed this large mass of warm ocean water was influencing climate. The “warm blob” also warmed the atmosphere to create anomalous high-pressure ridging which reached across Alaska to Siberia and helped to create the “polar vortex winter” of 2013-14 with similarities the following winter. During the past nearly 10 years, this feature has been responsible for anomalous high-pressure ridging affecting western North America contributing to the long-term drought in California. The “warm blob” review is provided due to the evolution of another large mass of very warm surface water during the middle third of 2022 directly impacting Clearway Energy. The new area of anomalous warm SSTA (Fig. 1) is on either side of Baja California and extends well offshore and has recently expanded northward along the U.S. West Coast. Presence of this large mass of anomalous warm water has increased low-level atmosphere moisture to help make the 2022 wet monsoon season stronger. Of course, the attendant thunderstorm activity and increased cloud cover affects most of Clearway Energy solar stations across the southwest quadrant of the U.S. Fig. 1: Generation of a new “warm blob” of SSTA has occurred off the California and Baja California Coast during the 2022 warm season. July 2022 verification: The July 2022 U.S. zonal/meridional wind anomaly verification indicates minimal west-to-east (or east-to-west) wind direction anomalies (Fig. 2). The exception is across the Great Lakes region and Ontario where above normal westerlies were observed. However, meridional wind anomalies were stronger (Fig. 3) featuring above normal southerlies across much of California to Utah and across all of the Southeast U.S. The stronger southerlies were related to a stronger than normal southerly moisture feed associated with the Southwest U.S. Monsoon across California and stronger than normal southerlies on the backside of the “Bermuda high-pressure ridge” in the Southeast. Generally, wind was lighter than normal across a key wind generating area from the southwest Great Plains into western Texas. As compared to the July 2022 forecast, zonal wind was close to normal across most of the U.S. whereas the forecast was for below normal zonal wind speeds (Fig. 4). The meridional wind speed forecast was correct for California and had the right idea with below normal wind speed forecasts for the southwest Great Plains into Texas but not strong enough across the southeast quadrant of the U.S. (Fig. 5). Fig. 2-3: Verification of the July 2022 zonal and meridional wind anomalies. Fig. 4-5: The Climate Impact Company initial July 2022 zonal and meridional wind anomaly forecast. Not surprisingly, given this year’s robust wet monsoon, specific humidity (SH) at both 850 MB (5,000 feet) and 300 MB (30,000 feet) was substantially above normal for July. High level SH at 850 MB (Fig. 6) implies above normal presence of convective clouds (thunderstorms) while cirrus canopies from vast thunderstorm development produced widespread above normal SH at 300 MB (Fig. 7). The July 2022 forecast was reasonably accurate at forecasting above normal SH at 850 MB although not to the full aerial extent observed to the north across the Interior Northwest States (Fig. 8). The 300 MB SH forecast was much-underdone compared to verification across the important California/Southwest U.S. sector to Clearway Energy (Fig. 9). Fig. 6-7: Verification of the July 2022 low-level (850 MB) and high-level (300 MB) specific humidity to identify cloud presence. Fig. 8-9: The Climate Impact Company initial July 2022 850 MB and 300 MB specific humidity anomaly forecast. August/September 2022 wind forecast: August is already underway and consulting operational forecasts valid through 15 days is recommended for Clearway Energy. The Climate Impact Company constructed analog (CIC-CA) forecast projects below normal wind speeds across the Southwest U.S. during August and near normal across California (Fig. 10-11). The below normal wind speed is due the continuation of the wet monsoon which lowers thermal gradient in the lower atmosphere to drive wind speeds. Wind speeds are stronger than normal across Texas, especially near the coast in response to possible tropical cyclone activity later this month. In the south-to-east Great Plains wind speeds are below normal due to presence of dry/hot high-pressure. Note the above normal wind speed forecast across the Southeast U.S. and just-along the East Coast all in response to late August tropical cyclone risk. The September forecast maintains below normal wind speeds across the Interior Southwest U.S. likely related to the wet monsoon (Fig. 12-13). The CIC-CA forecast projects normal wind speeds across California in September. Interestingly, zonal wind speeds are stronger than normal across the East-central U.S. in September while meridional wind speeds are somewhat weaker than normal. Favoring zonal flow implies passing frontal systems are weaker than normal. Above normal wind speeds are forecast across the Southeast U.S. to Mid-Atlantic Coast in September likely due to tropical cyclone activity risk. Coastal Texas is more windy than normal in September while wind generating areas across western Texas to the southwest Great Plains are less windy than normal. Fig. 10-11: Experimental CIC-CA U.S. forecast of zonal and meridional wind anomalies for August 2022. Fig. 12-13: Experimental CIC-CA U.S. forecast of zonal and meridional wind anomalies for September 2022. August and September 2022 solar discussion: In August, the wet monsoon in the Southwest U.S. continues (Fig. 14) although the CIC-CA forecast may not be as strong as current operational models indicate. While the low-level cloudiness is abundant, high-level cloud is likely higher than indicated by the CIC-CA forecast for August (Fig. 15). Cloud cover forecasts for California are below normal both in lower and high levels of the atmosphere in August. One cautionary note…as mentioned earlier in this report, the SSTA pattern off the California and Baja California Coasts is somewhat warmer than normal and able to sustain for longer than normal any tropical system that may travel northward out of the East Pacific tropics. The low-level cloud forecast is above normal for East Texas/Louisiana likely in response to tropical cyclone risk. Southern Florida is also at risk of above normal cloud cover due to tropical activity. In September, there is concern in regard to expanding Central U.S. drought. The cloud cover forecasts imply widespread above normal solar intensity due to below normal low-level and high-level cloudiness (Fig. 16-17). Similarly, much above normal solar energy is forecast across most of the West U.S. except for parts of Arizona and New Mexico where the wet monsoon pattern lingers. Fig. 14-15: Experimental CIC-CA U.S. forecast of 850 and 300 MB specific humidity for August 2022 to estimate cloud cover. Fig. 16-17: Experimental CIC-CA U.S. forecast of 850 and 300 MB specific humidity for September 2022 to estimate cloud cover. Forecast methodology: The climate forecasts presented are based on a constructed analog. The Climate Impact Company constructed analog is based on regional SSTA plus ENSO and also considers soil moisture (during summer) and snow cover (during winter). Clearway Energy recommendation: The forecasts provided are experimental constructed analog projections. To engage in real-time forecasts of daily wind and solar projections to ensure highest accuracy, at least through the next 15 days, is recommended for Clearway Energy by Climate Impact Company.