A little bit on the tropics and the ENSO.

 It's been quite a few weeks since I posted anything on the tropical Atlantic. The National Hurricane Center was watching a few areas.  But I didn't think anything would come of these, so I really didn't post on that.

Conditions in the tropical Atlantic.

After three tropical storms formed the Atlantic basin. It  become quiet over the last several weeks. The reason for this is the set up and conditions in the Atlantic still are fairly hostile for tropical cyclone formation.

Image credits National hurricane center.

Image credit Tropical Tidbits

While sea surface temperatures in the main development region (MDR) are starting to warm up. The region is still clogged with quite a bit of Saharan air dust and dry air. There is also quite a bit of wind sheer out over the Atlantic Basin. But the Set up over the Atlantic basin is becoming a little  less hostile than it has been over the last several weeks.

So it's going to be hard for anything  to develop over the next 5-7 days. But it's worth watching three areas in the Atlantic basin for the possibility for something to try and develop. As we get into the first week of August We are going to see wind shear weaken near the Southeast Coast. At the same time we look to have a front that's going to be moving offshore at that time. There's a chance we could see something develop on or near this front. We also have a tropical wave that has moving off to west African coast heading out into the Atlantic toward the Lesser Antilles over the coming weekend. Here too wind shear will become moderate; but as I mentioned earlier there is a lot of dry air over the Atlantic. So the odds of these developing is really low and I don't expect much to come from them. But they're  worth  watching just in case.

 There are signals that as we get in towards the middle of August We're still going  likely have anything that tries to  develop would still have to deal with some dry air. If something does develop In the main development region and come west it would still have to deal with the high terrain of the lesser Antilles So that could also give it a hard time. By the time we get into the second week of august We will likely see that southeast ridge develop enough weakness in the pattern allowing a chance for some kind of tropical mischief to move into the Gulf of America. or into the Southeast Coast. Climatology wise something developing by the middle of August would fall in line. So for now we just have to see what happens. The next name on the Atlantic hurricane list is Dexter.

The El Nino Southern Oscillation.

As many of Y'all know The ENSO consists of three phases. The first is El Nino which is the warm phase in the tropical eastern and central Pacific Sea surface temperatures (SST) Then we have the Neutral Phase which is when temperatures are near average. In the third plase, we have La Nina when we have cooler than average Sea surface temperatures (SST)  in the central and eastern tropical Pacific. Currently the ENSO is considered neutral.

When we look at the SST anomalies in the tropical Pacific. We can see they appear to be cooling The ENSO Nino indexes show a dramatic drop in SSTs Which  make it look much more likely that we're gonna go back into a la Nina during the Fall. Another good indicator that we could have a la Nina developing Is all that warm water north of Hawaii in the North Pacific. So as we get into the 2025/2026 winter we will likely be at least in a weak La Nina.

Image credit Coral Reef Coral  Watch (NOAA) and Tropical Tidbits

The ENSO is the biggest driver of global climate.  No two La Ninas are ever exactly the same. But there are certain patterns that we can expect. During La Nina we often see strong high pressure north of Hawaii this in turn creates a big ridge in the polar jet stream. The polar jet separates that cold polar air from the warmer air to the south. During the fall and winter moisture and warm air coming in on the Pacific jet interacts with the polar jet stream and we see storms move along the polar jet across North America. Typically during La Nina the cold polar jet becomes much more wavy and variable. Here in the Northeast, it experiences colder and more in the way of overall wet conditions. But, the volatility of the polar jet means we can see many swings between warm and cold air masses. The precipitation types depend on which side of the teeter-totter were sitting on at the time.

Well that's for now.