The pool of unusually warm water in the eastern Pacific Ocean that was observed earlier this summer has now mostly dissipated without a response from the tropical atmosphere, leaving climatologists wondering if El Nino will occur this winter as predicted earlier. In the strongest El Ninos, the atmospheric signature of El Nino is starting to be visible by August, and even weaker El Ninos often show some El Nino circulation patterns by late summer. It is not too late for an El Nino to occur, but as time goes on the likelihood of a strong one decreases. Climatologists still think that we may see a weak El Nino develop this fall, but the impacts of a minor El Nino are likely to be restricted to south Alabama and Georgia and south into northern Florida. Weak El Ninos generally provide wetter and cooler conditions than normal in these areas, but there is a lot of room for other patterns to dominate the climate when El Nino is weak.
The prevailing large-scale weather pattern this summer has been a persistent high pressure area on the west coast of the US and a matching broad low pressure trough across the eastern US. The high pressure in the west is linked to unusually warm water in the Gulf of Alaska which has been in place for several months. The high pressure in the western US has led to frequent periods of above normal temperatures and an increase in drought conditions over time, especially in California. Farmers in California were looking to a strong El Nino to bring drought relief to the area and are now concerned the drought may last for a fourth year or even longer if El Nino does not materialize. Meanwhile, in the east, the cool flow of air from Canada has kept temperatures cooler than normal for a good part of the summer, although only a few daily records have been set. Rainfall was plentiful earlier in the year but abnormally dry conditions have started to spread through southern Georgia and into Alabama. A small area of moderate drought has developed near Alma, where they set their record lowest July precipitation since 1948, a total of just 0.41 inches for the month compared to a normal of 5.33 inches.
There are no immediate signs of the warm Alaska waters going away, which may keep this persistent pattern in play for fall and perhaps even winter. That would mean that winter this year could be cooler than normal; a higher chance of snow and ice storms could be possible if this pans out. Climatologists will continue to monitor the situation to see whether or not an El Nino starts to appear later this fall.