04/25/2023, 8:52 am EDT

U.S. Rainfall Needed to Neutralize Palmer Drought Severity Index

During the past week, rainfall required to end dry Palmer Drought Severity Index (PDSI) increased in western Kansas, eastern Colorado, and southwest Texas while the remainder of the Great Plains drought area remain unchanged although shifting wetter in the Houston Area on the Texas Coast. The Mid-Atlantic drought worsened. Rainfall needed to end drought in northern Virginia/Washington D.C. is now in the 12-15 in. range.
04/24/2023, 2:46 pm EDT

Subsurface Equatorial Pacific is Key to ENSO Forecast

Almost the entire equatorial Pacific Ocean is warmer than normal in the subsurface (upper ocean heat) except to the immediate east of the Dateline. The warming during the past 2-3 weeks is dramatic with a big assist from the Madden Julian oscillation and an eastward surging Kelvin Wave. Despite the eastern equatorial Pacific subsurface warming, the bulk of the upper ocean heat remains west of the Dateline as ENSO 2023 is looking more complicated.
04/22/2023, 1:00 pm EDT

May/June 2023 U.S. Wind and Solar Forecast

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.  
04/22/2023, 12:53 pm EDT

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.