March 2023 Solar/Wind Verification Report

Discussion: March 2023 featured a stormy pattern across California and into the Great Basin where top-5 all-time precipitation amount was observed including record snowfall in mountain areas. Interestingly, no climate forecasts prior to the winter/early spring season predicted this outcome. As a result of the storminess, 850 MB (5,000 feet) relative humidity (RH) anomalies were well above normal due to persistent low-level cloudiness (Fig. 1). Higher clouds were farther south across Southern California to the southern Great Plains associated with the subtropical jet stream (Fig. 2). In the East, low cloudiness producing precipitation was minimal as the Mid-Atlantic States were dry and new drought was emerging. Virginia observed a top-10 all-time dry month.

Fig. 1-2: March 2023 observed 850 MB and 300 MB relative humidity anomalies.

The Climate Impact Company forecast from February indicated the low and high cloud risk across California into Texas with reasonable accuracy (Fig. 3-4). However, the above normal sunlight forecast for the remainder of the nation was overdone especially in the coastal Northwest.

Fig. 3-4: March 2023 forecast of 850 MB and 300 MB relative humidity anomalies.

During March 2023, anomalous wind speeds were difficult to ascertain due to frequent wind direction changes. The only prominent speed anomalies were lighter than normal in the North-central U.S. (Fig. 5-6) and higher than normal north-to-south wind in the Great Basin centered on Utah.

Fig. 5-6: March 2023 observed zonal and meridional wind anomalies.

The CIC March 2023 zonal and meridional wind speed forecast featured a large area of below normal zonal wind across the Interior Northwest stretching eastward to Iowa (Fig. 7). Above normal zonal wind was forecast across Ontario and Quebec. Meridional wind speed forecasts were varied and generally light (Fig. 8).

Fig. 7-8: March 2023 forecast of zonal and meridional wind anomalies.