EXPERIMENTAL Zonal/Meridional Wind Anomaly Forecast EXPERIMENTAL Relative Humidity Anomaly Forecast Valid: May and June 2023 Executive summary: The wind and solar forecast for late spring into early summer prominently projects above normal sunlight for most of the U.S. except (surprisingly) California into the Great Basin and the Northeast Corridor Coast. The remainder of the U.S. can expect above normal sunlight intensity for MAY/JUN 2023. On average, the only zone with marginally stronger than normal wind speed risk is the Great Plains/SPP region. Methodology discussion: There were no changes in the methodology of the May/June 2023 wind/solar forecast techniques. However, a chance considered for next month’s forecast is projecting 1000 MB wind anomalies due to the slight elevation at this level versus current ground-level forecasts. Climate discussion: As mid-spring passes El Nino is in the forecast for mid-to-late 2023. There is uncertainty in the intensity of El Nino this year with dynamic models favoring a strong warm ENSO while statistical models are weaker. ENSO forecasts have diminished skill during MAR/APR/MAY therefore a confident projection likely waits until June. May/June 2023 wind forecast: The outlook for May 2023 zonal wind speed anomalies is above normal speeds in the SPP region (Fig. 1). The meridional wind speed anomalies are stronger than normal on the East Coast and Western Texas (Fig. 2). The outlook for May has stronger zonal wind anomalies in the Central U.S. and stronger meridional wind anomalies on the East Cast compared to the previous outlook (Fig. 3-4). Fig. 1-2: Experimental Climate Impact Company constructed analog forecast of zonal and meridional wind anomalies for the U.S. during May 2023.  In June, the outlook features above normal zonal wind speeds across the Mid-Atlantic region and the Southeast States particularly Florida (Fig. 5). Unusual is above normal zonal wind speed anomalies in Florida during June. Zonal wind speeds across California, Texas, and SPP are generally near normal. Meridional wind speeds during June are below normal on the East Coast and above normal in the southern half of the SPP region (Fig. 6).   Fig. 3-4: Experimental Climate Impact Company constructed analog forecast of zonal and meridional wind anomalies for the U.S. during June 2023. May/June 2023 solar forecast: The May 2023 solar outlook calls for above to much above normal sunlight across most of the West and Central U.S. (Fig. 7-8) with the exception of an occasional low cloud issue in California. SPP region is generally observing above normal sunlight during May. In the East, above normal high cloud is projected to dim sunlight intensity. The outlook features increased sunlight compared to the previous forecast (Fig. 9-10). Fig. 5-6: Experimental Climate Impact Company constructed analog forecast of 850 MB (low cloud) and 300 MB (high cloud) relative humidity anomalies for the U.S. during May 2023. Previous below. The sunlight outlook for June 2023 features above normal amount for all of the U.S. with two exceptions. The Great Basin and California are susceptible to low clouds to suppress sunlight intensity at times (Fig. 11). Low clouds also suppress potential sunlight in New England and the Mid-Atlantic region (Fig. 12). Fig. 7-8: Experimental Climate Impact Company constructed analog forecast of 850 MB (low cloud) and 300 MB (high cloud) relative humidity anomalies for the U.S. during June 2023.  

EXPERIMENTAL Zonal/Meridional Wind Anomaly Forecast EXPERIMENTAL Relative Humidity Anomaly Forecast Valid: April and May 2023 Executive summary: Forecast highlights for mid-to-late meteorological spring for key wind power generation areas including California and SPP identify northern Texas, the southern Great Plains, and Missouri Valley for above normal north-south meridional wind in May. Stronger than normal (zonal and meridional) wind speeds are forecast for April from the Upper Midwest to New England. Above normal meridional wind is forecast for San Francisco to Sacramento to the Los Angeles basin for each month. Notable solar conditions are indicted for California to Nevada during April where both low and high cloudiness is forecast below normal. The Gulf States to the Mid-Atlantic region is the sunny zone for May. Methodology discussion: A glitch was found with the February 2023 verification as California to the Midwest U.S. was wetter than normal which was anticipated by an above normal cloud cover forecast for much of this stretch in the CIC-CA 850 MB relative humidity (RH) anomaly forecast. However, the RH anomaly for this zone was drier than normal. The specific humidity (SH) verification was slightly better. The CIC-CA cloud cover forecasts continue to rely on 850 MB (5,000 feet) for low clouds/precipitation and 300 MB (30,000 feet) for cirrus high clouds. However, the forecast remains EXPERIMENTAL as these methodologies are not well-proven (yet). The zonal and meridional directions for wind speed anomalies remains intact. Producing a wind speed anomaly forecast accounting for both parameters is a goal for 2023 for this climate forecast product. Climate discussion: Major changes to the global climate system (GCS) are likely in 2023. The primary issue is ENSO. Oceanic La Nina ended during the past couple weeks although a La Nina climate remains. Oceanic La Nina is defined using the conventional Nino34 SSTA index which is neutral. Atmospheric La Nina remains due to a weak negative phase of the multivariate ENSO index (MEI) which identifies the reaction of the atmosphere to the equatorial Pacific Ocean sea surface temperature (SST) regimes. Most dynamic models are forecasting a potentially vigorous El Nino to develop after mid-year. Statistical/analog forecasts are not as aggressive. The solar/wind forecasts in this report are based mostly on a fading La Nina climate. Forecasts for June (and beyond) are likely to strongly favor an El Nino climate. Additionally, the mid-latitude North Pacific and North Atlantic are very warm and forecast to trend warmer (compared to normal) into the upcoming summer season. The warming mid-latitude oceans will carry as much (if not more-so) influence on U.S. climate compared to ENSO phase. Of interest to the West Coast is the presence of marine heat waves NEP22A and NEP23A which have shifted westward during the winter season with strong cooling off the U.S. West Coast fueling a persistent cool phase of the Pacific decadal oscillation (-PDO). Global SSTA forecast models indicate the warming associated with NEP22A and NEP23A will shift toward the West Coast during summertime which is required if a stronger El Nino is going to develop. A lot to follow over the next few months regarding potential large changes in the global SSTA regime. April/May 2023 wind forecast: The projected upper air pattern for April features a polar vortex in North-central Canada, upper ridge shifting into the Gulf of Alaska, and a persistent ridge just off the Mid-Atlantic Coast. The CIC-CA April 2023 wind anomaly pattern responds to this upper air pattern by producing above normal zonal wind speeds across the Upper Midwest/Great Lakes region while zonal wind anomalies are weaker than normal across Western Texas (Fig. 1). The Southeast States also observe below normal zonal wind anomalies in April. On the West Coast, zonal wind anomalies are near neutral. However, meridional wind is stronger than normal from San Francisco to Los Angeles to the central San Juaquin Valley (Fig. 2). The wind direction is likely northerly due to the offshore high-pressure system forecast by the constructed analog. Meridional wind speed anomalies are also stronger than normal from the Great Lakes to the northern Mid-Atlantic region. Elsewhere, meridional wind speed anomalies are weak or near normal. Compared to the previous forecast, the zonal wind anomalies are slightly different while meridional wind speed anomalies are adjusted slightly stronger. Fig. 1-2: The experimental Climate Impact Company constructed analog forecast of zonal and meridional wind anomalies for the U.S. during April 2023.  The May upper air pattern anticipates the polar vortex shifting eastward and stretching from Hudson Bay to the Canadian Maritimes. An upper ridge remains locked-in on the Mid-Atlantic U.S. while a weak upper trough resides over the Southwest U.S. The wind pattern response to the constructed analog upper air projection features below normal zonal wind speeds across Montana and into the northwest Great Plains and across the Gulf States especially Florida and marginally weaker than normal in Texas (Fig. 3). The Northeast U.S. observes above normal zonal wind speeds. The meridional wind speed anomalies are stronger than normal across Northern Texas, Oklahoma and the Mid-south States which encompasses the southern half of the SPP region (Fig. 4). Above normal meridional wind speeds are also likely in the central/south coast and central San Juaquin Valley portion of California. Fig. 3-4: Experimental Climate Impact Company constructed analog forecast of zonal and meridional wind anomalies for the U.S. during May 2023. April/May 2023 solar forecast: The April outlook maintains a below normal RH anomaly regime from the West Coast to the central Great Plains and eastward to the southern Appalachians (Fig. 5). Implied is below normal precipitation in this zone which favors above normal sunlight. The cloudy zone is across the Great Lakes to New England and Florida. During April high clouds obscure the sky more than normal across Northern Mexico and into the Southwest U.S. plus Washington. Elsewhere, below normal cirrus cloudiness is forecast outside of the U.S. in Southern Canada and the Gulf of Mexico region (Fig. 6). The outlook is similar to the previous forecast except more low cloud risk in Texas and Florida. Fig. 5-6: Experimental Climate Impact Company constructed analog forecast of 850 MB (low cloud) and 300 MB (high cloud) relative humidity anomalies for the U.S. during April 2023.  During May, above normal 850 MB cloudiness to obscure sunlight and suggest above normal precipitation is forecast across Montana/Wyoming to the Missouri Valley and into Texas (Fig. 7). Presence of an upper trough increases the risk of low-level atmosphere cloudiness across Southern California to the Great Basin. Below normal low-level cloudiness promoting sunlight is projected across the Gulf States to the Mid-Atlantic region due to the influence of a semi-permanent high-pressure area. The Northwest Coast also observes below normal low-level cloudiness. High clouds are likely above normal in the Mid-south States and below normal (increased sunlight) in most of California, the Gulf States, and the Upper Midwest (Fig. 8). Fig. 7-8: Experimental Climate Impact Company constructed analog forecast of 850 MB (low cloud) and 300 MB (high cloud) relative humidity anomalies for the U.S. during May 2023.

Discussion: The September 2022 climate across the U.S. was characterized by anomalous warmth dominating the West alongside a stronger than normal Southwest wet monsoon while the East-central/Mid-south U.S. observed very dry conditions. The zonal wind anomalies observed in September were lighter than normal across the Southwest U.S. and Continental Divide region while slightly above normal in Pennsylvania (Fig. 1). In the East, meridional wind was lighter than normal (Fig. 2). There was an area of stronger than normal meridional wind across Southern California. The September forecast anticipated a much stronger zonal wind across the Southeast U.S. (Fig. 3). That result is surprising as the projected upper air pattern (high pressure West/low pressure Northeast) verified. The forecast indicated above normal west-to-east flow south of the Northeast low-pressure area, but observation reveal the wind was lighter than normal (from the west). The meridional wind anomaly forecast indicated light wind across the Central U.S. (Fig. 4). However, observations reveal wind speeds in the north and/or south direction were near normal during the late warm season. Fig. 1-2: September 2022 observed zonal and meridional wind anomalies. Fig. 3-4: Original Climate Impact Company zonal and meridional wind anomaly forecast for September 2022. In September 2022, the above normal strength of the wet Southwest U.S. Monsoon was dominant. Heavy convection leads to well above normal moisture at 850 MB (Fig. 5) extending westward to California (at times). In opposition to that pattern was generally clear skies across the expanding drought zone in the Mid-south U.S. The high cloud regime (at 300 MB) also followed the low cloud pattern closely (Fig. 6). The September forecast completely understood the expanding dryness and drought risk to the Central/Mid-south U.S. (Fig. 7-8). However, the low specific humidity (SH) forecast at low and high levels of the atmosphere in that zone were too strong due to the under forecast SH in the Southwest States. Fig. 5-6: September 2022 observed 850 and 300 MB specific humidity anomalies. Fig. 7-8: Original Climate Impact Company 850 and 300 MB specific humidity anomaly forecast for September 2022.