Prognostic Discussion for Monthly Outlook NWS Climate Prediction Center College Park MD 830 AM EDT Thu Jun 20 2019 30-DAY OUTLOOK DISCUSSION FOR JULY 2019 For the month of July, a weak El Nino is predicted to continue. There is a 66% chance of El Nino continuing through Northern Hemisphere summer, and a 50%-55% chance that El Nino will persist through the upcoming fall and winter seasons. For discussion of sea-surface temperature anomalies, as well as subsurface anomalies, lower and upper-level winds, and convective anomalies, please refer to CPC's Seasonal Outlook message for July-Sept. Following a brief period of interference from westward-moving modes of tropical variability, the Madden-Julian Oscillation (MJO) signal has renewed its eastward propagation and the enhanced convective phase is now over the Maritime Continent. Linkages between the MJO and CONUS impacts are generally weak in July, so the MJO is not forecast to play a significant role in the U.S. monthly temperature and precipitation outlooks. Multiple bouts of heavy rain over the past 30-45 days led to very high soil moisture and flooding over much of the Great Plains and Mississippi Valley. The July 2019 outlooks are based primarily on dynamical and statistical model guidance, the latest available official CPC temperature and precipitation outlooks for Week-2 and Weeks 3/4, the ongoing El Nino, very high soil moisture, heavy rainfall observations during the past 30-days, and July climatology. The monthly temperature outlook indicates that above normal temperatures are favored across Alaska, ranging from 33%-40% odds in the northeast part of the state to over 60% odds in the southwest part of the state. Contributing factors include above normal sea-surface temperatures near the coast, strong historical temperature trends, Week-2 and Weeks 3/4 temperatures, most of the NMME model suite, and available statistical tools. Above normal temperatures are also favored from the West Coast of the contiguous U.S. to near the Continental Divide, and across the Gulf Coast and Atlantic Coast states. Probabilities for upper-tercile temperatures peak between 40%-49%. Support for this relative warmth comes largely from the NMME PAC (Probability Anomaly Calibration), and to a somewhat lesser extent most of the remaining inputs of the NMME dynamical model suite, in addition to the IMME, statistical models including the CAS (Constructed Analog on Soil moisture), historical trends, and the latest Weeks 3/4 temperature outlook. Below normal temperatures are favored across a broad region of the Central CONUS, from Kansas, Oklahoma and northern Arkansas north and east into the Upper Great Lakes region. Probabilities for anomalously cool temperatures peak between 40%-49%. A significant contributor to these predicted below normal temperatures is the very high soil moisture (95th percentile or greater) across this area, with approximately half of this region at or above the 99th percentile. This broad expanse of near-saturated, or saturated, soils has been the result of frequently recurring heavy rainfall. During the past 30-days, rainfall amounts ranged from 2-8 inches or more above normal. Viewed from a slightly different perspective, percent-of-normal precipitation ranged from 150%-400% of normal (locally greater). Lower-tercile temperatures are favored over the Central CONUS by a majority of models and statistical tools, but the exact placement and size of this area of anomalously cool temperatures is uncertain. Elsewhere, Equal Chances (EC) of above, near, and below normal mean temperatures are forecast. The monthly precipitation outlook indicates that wetter-than-normal conditions are favored from southwestern Alaska northeastward across the Central Interior, with maximum probabilities ranging from 40%-49%. This is supported primarily by a majority of the last 9 days of CFS runs and the uncalibrated NMME, but also the NMME PAC, both GFDL models (FLOR and CM2.1), and to a lesser extent, the latest Weeks 3/4 precipitation outlook. Upper-tercile precipitation is also favored over a large portion of the Central CONUS, as far south as Texas. As was the case in Alaska, maximum probabilities range from 40%-49%. Of the statistical tools, the CAS bears the closest resemblance to this predicted pattern of upper-tercile precipitation, which also looks fairly similar to recent observations of both heavy rainfall and very high soil moisture. The CFS precipitation anomaly forecast for July lends some support to this area of anomalous wetness. However, it predicts the lion's share of the rainfall to be focused farther west, over the Pacific Northwest, the Northern Intermountain Region, and the Northern and Central Rockies. A majority of input models for the NMME generally predict this corridor of wetter-than-normal conditions, though there are variations on the overall theme. The NASA, CMC2 Canadian model, and the IMME also extended the favored area of above normal rainfall farther west as indicated by the CFS. Finally, there is a slight tilt in the odds for drier-than-normal conditions across most of the Alaska Panhandle, and west-central portions of the Gulf Coast region. These areas have modest support from the CFS, CAS (CONUS), NCAR, GFDL FLOR, and the CMC2 Canadian model. July climatology also provides weak support for the relative dryness in the west-central Gulf Coast region. Elsewhere, Equal Chances (EC) of above, near, and below normal precipitation are favored. FORECASTER: Anthony Artusa The climatic normals are based on conditions between 1981 and 2010, 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 Sun June 30 2019 These outlooks are based on departures from the 1981-2010 base period. $$