NOAA Updates their Seasonal Outlook – El Nino coming but not here yet – May 27, 2023
Lightly edited at 5:54 p.m. EDT Saturday, May 27, 2023 mostly to compare the new to the prior Seasonal Outlook. They are very similar.
On the third Thursday of the month right on schedule NOAA issued what I describe as their Four-Season Outlook. The information released also included the Mid-Month Outlook for the single month of June plus the weather and drought outlook for the next three months. I present (apologies for the delay) the information issued and try to add context to it. It is quite a challenge for NOAA to address the subsequent month, the subsequent three-month period as well as successive three-month periods for a year or a bit more.
It is very useful to read the excellent discussion that NOAA issues with this Seasonal Outlook. In general, the overall level of confidence in the Seasonal Outlook is lower than usual for many reasons that are addressed in the NOAA discussion. It is best to read the full discussion but here are some of the highlights:
- Equatorial SSTs are near-to-above average across most of the Pacific Ocean and atmospheric conditions reflect ENSO-neutral conditions [Editor’s Note: The Atmosphere has not yet responded to the warming in the Eastern Pacific which is marginally at El Nino levels].
- At least a weak El Niño is likely given high levels of above-average oceanic heat content, but the range of possibilities include an 80 percent chance of at least a moderate El Niño and a 55 percent chance of a strong El Niño by the end of the year.
- This likely warm start to June along with monthly dynamical and statistical tools support increased probabilities for above-normal temperatures from the Pacific Northwest east to the Northern Great Plains.
- The NMME along with an increased potential for an early season TC [tropical cyclone] to emerge from the western Caribbean Sea favors above-normal precipitation [in June] for parts of the Southeast.
- The JJA 2023 temperature outlook favors above-normal temperatures over the western CONUS, the Southwest, the Gulf States, along the eastern seaboard, and for much of the state of Alaska.
- The JJA 2023 precipitation outlook depicts below-normal precipitation probabilities over the Pacific Northwest and parts of the Northern Rockies, the Southwest, and south coast of Alaska. NMME and C3S are in good agreement on below normal precipitation over the southwest and wet soil moisture over the Four Corners region may provide a sluggish start to the Monsoon this summer. Above normal precipitation probabilities are indicated over parts of the Middle and Lower Mississippi Valleys, the Ohio and Tennessee Valleys, the Southeast, and mid-Atlantic. Parts of the Central Plains tend to be anti-correlated with the monsoon region, and as such a weak tilt toward above normal precipitation is indicated.
- Confidence decreases in September-November (SON) 2023 and following seasons as lead time increases and dynamical models become more uncertain, however, El Niño is expected to become more dominant in the forecast(s), and the pattern begins to reflect El Niño conditions during fall and winter seasons.
- Decadal [Temperature] trends become the dominant player in spring and summer 2024, with below normal trends over the Pacific Northwest and above-normal trends over the Mid-Atlantic.
