Prognostic Discussion for Monthly Outlook NWS Climate Prediction Center College Park MD 830 AM EDT Thu Jun 17 2021 30-DAY OUTLOOK DISCUSSION FOR JULY 2021 The July 2021 outlook was prepared based on dynamical model and statistical forecast guidance, current soil moisture/drought conditions, potential impacts from the MJO, and newly derived long term trends from the 1991-2020 base period. ENSO neutral is likely to continue through the outlooks period. The MJO may also influence the climate pattern. Model predictions for MJO indicate a strengthening over Africa and the western Indian Ocean, though there is another area of upper-level divergence over the Western Pacific. If the signal emerges, it would increase the variability throughout the month. That potential resulted in some lower probabilities for some regions, as explained below. Drought is largely entrenched over the western CONUS and Northern Plains, and the summer months are prime months when current soil moisture values can impact temperature and precipitation in following months. Above normal temperatures are favored along the Rockies and across the West, with the highest odds in the Great Basin and Four Corners region. The deeply entrenched drought, long-term trends, and numerical guidance (dynamical models and statistical tools) all indicate above normal temperatures are most likely. For the Pacific Northwest and Northern Rockies, an active MJO could result in more variable conditions, so the odds are more modest in those regions. Sea surface temperatures are also likely to be below normal near the California coast, moderating odds there as well. Equal chances for above, near, and below normal are indicated across the Southern Plains, Middle and Lower Mississippi Valleys, and portions of the Southeast. Temperature trends as indicated in the OCN are not as strong there. The suite of dynamical model guidance from the NMME, C3S, and CFS all indicate a relative relaxation of probabilities for above normal temperatures, while some statistical tools favor below normal temperatures, so the mixed indications from the tools result in EC. For the Great Lakes and Northeast, trends, dynamical model guidance, and statistical tools are all largely in agreement for above normal temperatures. Across Alaska, the signals are a bit more mixed as summer trends are not as strong as winter trends, and some NMME models indicate below normal temperatures. More recent model runs and some statistical tools (SST-CA and ENSO-OCN) support higher odds over southern Mainland and eastern Alaska in the outlook. Above normal precipitation is indicated from the Gulf Coast to the Ohio Valley, consistent with dynamical model guidance, though the guidance has shown variability in recent runs for the Carolinas and Florida, so odds in those places are low. Statistical tools and dynamical models show a consistent signal for below normal precipitation from the Pacific Northwest to the Northern Plains, though an active MJO could introduce short-term wetness in mid to late July (however this would be very atypical), so below-normal precipitation is still favored, but probabilities are lower along the coast. Some dynamical models indicate wetness into the Four Corners region, but half of the statistical tools (CCA and SST-CA) do not. The precipitation OCN shows a weak wet signal from Central California to Oklahoma in a broad swath, though amounts are low and the pattern is not similar to other tools, so equal chances is indicated in the outlook. NMME, C3S, and statistical tools support above-normal precipitation for western mainland Alaska. FORECASTER: Matthew Rosencrans The climatic normals are based on conditions between 1991 and 2020, following the World Meteorological Organization convention of using the most recent 3 complete decades as the climate reference period. The probability anomalies for temperature and precipitation based on these new normals better represent shorter term climatic anomalies than the forecasts based on older normals. An updated monthly outlook... for Jul will be issued on Wed June 30 2021 These outlooks are based on departures from the 1991-2020 base period. $$