Based on a combination of the just released +0.1C May-June-July ONI (Niño 3.4 trimonthly sea surface temperature anomaly vs normal) and July OHC (subsurface equatorial Pacific temperature anomaly vs normal) of +0.81, will there be El Niño later this year (based on the ONI table) and into the winter? History back to 1979 says likely but 2012 says look at me as I didn’t become El Niño. Other than 2012, all years with July OHC near or warmer than July of 2018’s +0.81 and similar or warmer 3.4 SSTs (1989 was too cool at surface to count as analog) went on to become El Niño if they weren’t already. The closest analogs (those not yet at +0.5 in MJJ for ONI) are 2004, 2006, 2009, and 2012. 3 of these 4 went on to El Niño later in the year. El Niño has to still be favored imo but 2012 says don’t be the ranch on it just yet.
If El Niño occurs, would that mean a mild winter in the NE US and Midwest? Not necessarily. As a matter of fact, a cool to cold winter would be favored for much of the US, especially the southern 3/4 of the eastern 2/3 of the US, if El Niño were to occur based on history because of a combination of a “Modoki” type of El Niño being the kind that would likely occur if there is El Niño and last winter being La Niña. That combo has usually resulted in a cool to very cold winter for especially the eastern 2/3 of the US other than the far north based on history back to the late 1800s. I may post more details (data) on this later. The only kind of El Niño that strongly favors warmth dominating most of the country is the superstrong kind (examples: 1982-3, 1997-8, and 2015-6) because the subtropical jet stream is so strong that it tends to limit the number of widespread Canadian airmass outbreaks from coming down into the US. But any El Niño this winter wouldn’t be anywhere near that strong and would also probably be Modoki. Furthermore, last winter was La Niña as mentioned.
Super topic for discussion Larry!
Here is the latest from NOAA(last week to be updated tomorrow):
ENSO: Recent Evolution,
Current Status and Predictions
Here are the NWS seasonal forecast maps, that do take the weak El Nino into account:
December/January/February forecast below:
NOAA technical discussion for long lead seasonal forecast:
DURING THE FALL AND WINTER 2018-19, THE TEMPERATURE AND PRECIPITATION OUTLOOKS ARE CONSISTENT WITH INCREASING ODDS OF EL NINO DEVELOPMENT AND ITS TYPICAL INFLUENCES, WHILE ALSO INCORPORATING MODEL OUTPUT AND TRENDS. THE TEMPERATURE OUTLOOKS WERE MODIFIED TO BE MORE CONSISTENT WITH MODEL OUTPUT AND TRENDS OVER THE SOUTHEAST, ESPECIALLY DURING THE FALL OF 2018. FOR OUTLOOKS VALID DURING THE WINTER OF 2018-19, THE AREAS OVER THE NORTHERN GREAT PLAINS WHERE THE HIGHEST ODDS FOR ABOVE NORMAL TEMPERATURES ARE INDICATED HAVE BEEN SHIFTED WESTWARD, TO THE CORE AREA TYPICALLY ASSOCIATED WITH A MATURE EL NINO. THE PRECIPITATION OUTLOOKS ALREADY REFLECTED THE CANONICAL PATTERNS ASSOCIATED WITH EL NINO, SO LITTLE CHANGES WERE MADE.