Weather
The NOAA just released its long-term outlook covering May, June, and July. Here is what the beginning of your summer looks like:
Confidence is high for a warmer than usual period during May through July across nearly all of the U.S. Below-normal precipitation is favored for the Pacific Northwest in addition to parts of the Rockies and the Great Plains. Odds for a wet 3 months increase for the Great Lakes, the East Coast, and northwestern Alaska.
Temperature
The MJJ 2021 temperature outlook favors above-normal seasonal mean temperatures for nearly all the contiguous U.S. (CONUS) and for the Alaska Mainland and the Aleutian Islands. The greatest probabilities for above-normal temperatures are located over the Southwest in the Four Corners region. Modestly elevated probabilities for above-normal temperatures extend eastward across the Southeast and northward along the Eastern Seaboard to New England, supported by model guidance and positive decadal trends. Greater uncertainty, related to the early impacts of La Nina and an MJO event, lower historical forecast skill in model guidance, and weaker decadal temperature trends decrease probabilities for above-normal temperatures in the north-central CONUS. Consistent with possible lingering La Nina impacts as indicated by ENSO regressions and hybrid statistical-dynamical “bridging” tools, equal chances of above-normal and below-normal temperatures are forecast for southeastern areas of Alaska and parts of the Pacific Northwest, and the probabilities of above-normal temperatures have been decreased for the southern Alaska Mainland. Negative trends in sea ice coverage and thickness and positive decadal temperature trends favor above-normal temperatures for northern areas of Alaska.
Precipitation
The MJJ 2021 precipitation outlook favors above-normal seasonal total precipitation amounts for central and eastern areas of the Great Lakes region, the Ohio Valley, the Mid-Atlantic, and most of the Eastern Seaboard, excluding northern Maine. There is considerably greater agreement among dynamical models for a region of likely below-normal precipitation from the central and northern Pacific coast across the Rockies into the Central and Southern Plains. Higher probabilities for below-normal over the Northern Rockies are supported by typical La Nina impacts and dynamical model forecasts.
The area of likely below-normal precipitation is forecast to shift slowly northward and eastward during the summer and southward into the west-central CONUS during the autumn. Above-normal precipitation is predicted to persist along much of the Eastern Seaboard through the summer months, and an area of likely above-normal precipitation continues for parts of the southeast Atlantic coast and the eastern Gulf Coast into the early autumn, consistent with the impacts of the likely La Nina or ENSO-neutral climate conditions, with a very low probability of El Nino conditions over the tropics.
