Prognostic Discussion for Monthly Outlook NWS Climate Prediction Center College Park MD 300 PM EDT Tue May 31 2022 30-DAY OUTLOOK DISCUSSION FOR JUNE 2022 The updated monthly temperature and precipitation outlooks for June 2022 are based on the latest dynamical model guidance, WPC temperature and precipitation forecasts during the first week of the month, the CPC 6-10/8-14 day temperature and precipitation outlooks, and climate linkages to current soil moisture. The GEFS and ECMWF ensemble means depict either another Kelvin wave or an emerging Madden-Julian Oscillation (MJO) propagating eastward over the Western Hemisphere during early to mid-June which would maintain an elevated chance for tropical cyclone (TC) development across the western Caribbean Sea or southern Gulf of Mexico. Please refer to CPC’s Global Tropics Hazards for updates on the MJO along with TC development forecasts throughout June. The most notable change to the previous June temperature outlook, released on May 19, is the introduction of a favored area of below normal temperatures from the north-central CONUS westward to parts of the Pacific Northwest. The Arctic Oscillation (AO) index rapidly became negative during late May as positive 500-hPa heights developed over the higher latitudes of the Northern Hemisphere. This transition to a negative AO is likely to contribute towards below-normal temperatures for the northern tier of the CONUS during the first two weeks of June. The GEFS and ECMWF week 3-4 temperature outlooks support a continuation of the cooler-than-normal temperatures for the Pacific Northwest, northern Rockies, and northern Great Plains through late June. High soil moisture (above the 90th percentile) across the Red River Valley of the North was also a factor for increasing probabilities to above 50 percent for below-normal temperatures. Temperature tools at all time scales throughout June generally predict above-normal temperatures across the southern tier of the CONUS, California, and along the East Coast. The largest probabilities (above 60 percent) of above-normal temperatures coincide with the lowest soil moisture across eastern New Mexico and western Texas and are also consistent with temperature tools during early to mid-June. As of May 31, model solutions remain consistent that there is an increased chance of an early season TC forming across the northwestern Caribbean Sea or southeastern Gulf of Mexico during the first few days of June. Given the most likely track of this potential TC northeastward and WPC 7-day rainfall amounts of more than 5 inches, probabilities for above-normal precipitation exceed 60 percent across south Florida. Above-normal precipitation is favored for parts of the south-central Great Plains eastward to the middle Mississippi Valley due to periods of moderate to heavy rainfall during the first week of June and favored near to above-normal precipitation associated with northwest flow aloft along a thermal gradient, through mid-June. Although there is expected to be a favorable pattern for episodes of convective rainfall for the northern Great Plains, equal chances (EC) of below, near, or above-normal precipitation are forecast since the storm track is expected to be displaced southward to start the month. The GEFS and ECMWF ensemble means depict a longwave trough over the northeastern Pacific for much of June which favors above-normal precipitation across parts of the Pacific Northwest and northern Rockies. Due to predicted anomalous 500-hPa ridging for much of June, probabilities for below-normal precipitation are slightly elevated for parts of the Great Basin, Southwest, and western to central Texas. Based on the expectation of a variable precipitation pattern during early to mid-June, mixed signals among the week 3-4 guidance, and inherent uncertainty spatially with convective rainfall, EC is forecast for the precipitation outlook across the Corn Belt and much of the eastern CONUS. Ensemble means depict above normal 500-hPa heights persisting over Alaska through mid to late June, favoring above normal temperatures for the state. A mean 500-hPa trough over the northeastern Pacific and week-2 precipitation tools support a slight lean towards above-normal precipitation for the Alaska Panhandle. Based on a likely dry start to the month and good consistently among daily CFS model runs, below-normal precipitation is favored for western Mainland Alaska. ********* Previous discussion, released on May 19, is below *************** The June 2022 temperature and precipitation outlooks are based on dynamical model guidance (including the North American Multi-Model Ensemble (NMME) and the week 3-4 model solutions), statistical tools, current soil moisture conditions, and La Niña composites. The Madden-Julian Oscillation (MJO) remains weak as multiple Kelvin waves (KWs) continue to propagate rapidly eastward over the global tropics. The MJO is not expected to provide any significant influence on the mid-latitude circulation pattern across North America during June. However, the passage of KWs over the Western Hemisphere from late May into June and its potential contribution to the development of an early season tropical cyclone across the western Caribbean Sea was considered as a factor in the precipitation outlook. During early to mid-May, anomalous 500-hPa ridging resulted in much above normal temperatures throughout the southern Great Plains with positive anomalies of more than 6 degrees F across the western half of Texas. Although there could be brief periods of weakening of this subtropical riding, ensemble means depict the anomalous 500-hPa ridging over the southern tier of the CONUS likely persisting through the first half of June. Based on good agreement among dynamical and statistical tools, above-normal temperatures are favored across the southern two-thirds of the CONUS. The largest probabilities (above 60 percent) are forecast for western Texas and New Mexico, coinciding with the lowest soil moisture. Conversely, anomalously wet soil moisture was one reason for equal chances (EC) of below, near, or above-normal temperatures across much of the northern Great Plains and upper Mississippi Valley. Also, the calibrated NMME supports EC for the northern tier of the CONUS. The EC forecast along much of the West Coast was due in part to negative sea surface temperature anomalies nearby. The week 3-4 tools, covering the first two weeks of June, along with most of the inputs to the NMME support slightly elevated probabilities of below normal temperatures across western parts of Oregon and Washington along with the Alaska Panhandle. Due to conflicting and weak signals among the tools, EC is forecast for the remainder of Alaska. The NMME supports elevated probabilities of below-normal precipitation across much of the central to southern Great Plains, extending westward to parts of the Great Basin, Pacific Northwest, and northern California. The slightly larger probabilities, focused from southern Wyoming southward to the Texas Panhandle, was due to La Niña composites and week 3-4 tools. Since June is typically a dry time of year for southern California and the desert Southwest, EC was forecast for these areas. Regardless of any effects from a potential early season tropical cyclone, the GEFS and ECMWF models depict broad upper-level divergence over the Gulf of Mexico and adjacent areas of the northern Gulf Coast and Florida during early to mid-June. This is expected to promote enhanced sea breeze convection. Based on this expectation and support from the NMME, above-normal precipitation is slightly favored for Florida and areas along and close to the northern Gulf Coast. For the remainder of the eastern and northern tier of the CONUS and Alaska, a large area of EC was necessary in the June precipitation outlook due to weak signals among the dynamical model solutions. This large coverage of EC and prospects for an early season TC, potentially emerging from the western Caribbean Sea, will be reevaluated with the updated June outlook, released on May 31. FORECASTER: Brad Pugh 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. The next monthly outlook...for Jul ... will be issued on Thu Jun 16 2022 These outlooks are based on departures from the 1991-2020 base period. $$