NOAA Updates it’s Four-Season Outlook on April 20, 2023 – The Southwest Monsoon is expected to be less productive than usual. An El Nino Winter is Expected
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 May plus the weather and drought outlook for the next three months. I present 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. It is best to read the full discussion but here are some of the highlights:
- ENSO-neutral conditions are expected to continue through the Northern Hemisphere spring, followed by a 62% chance of El Niño developing during May-July 2023. An El Niño Watch has been issued, and the range of possibilities toward the end of the year includes a strong El Niño (4 in 10 chance of Niño-3.4 ≥ 1.5°C) to no El Niño (1 in 10 chance)
- The combination of elevated snowpack and high soil moisture across much of the West coupled with below normal SSTs currently observed in the Gulf of California and the Pacific off the west Coast of the Baja California Peninsula would favor a slower evolution of monsoonal circulation.
- El Niño is expected to become more of a factor and the pattern begins to increasingly reflect El Niño conditions during the cold months. As a result, enhanced probabilities of above normal temperatures indicated for the Southern CONUS late summer/early fall are reduced by the winter. Conversely, chances of above normal temperatures increase across the Northern Tier by the winter months.
- As we enter the fall and winter months, the pattern begins to increasingly reflect an El Niño signature. Increased probabilities for above normal precipitation depicted across the Ohio and Mississippi Valleys during late summer and early fall transitions to the East and Gulf Coasts during the winter months, consistent with El Niño. Conversely, an increasingly dry signal is evident across the northwestern CONUS by the winter with probabilities of below normal precipitation exceeding 40 percent across the Pacific Northwest from November-December-January (NDJ) 2023-24 through JFM 2024. A tilt toward below normal precipitation is also indicated for the Great Lakes Region westward toward the Northern Plains during the cold months, consistent with El Niño.
