Up to now most of the Summer forecasts had been based on the premise or the idea that we are going to see a weak to moderate El Nino. When the initial El Nino forecast start appearing in December and January for Spring and Summer seasons, there was some speculation that a strong El Nino might be the offer. But most forecasters saw this as a weak to moderate El Nino and the data over the past few months has generally held to that idea. However there are problems developing with possible El Nino event and the latest data suggests that the event is actually falling apart. This is important because most of the Summer forecasts and the Hurricane season forecasts are premised on the idea of seeing an El Nino.
During the Summer months a weak to moderate El Nino in the U.S. typically means above normal rainfall with a distinct lack of sustained heat for any prolonged period of time.
This image shows the subsurface temperatures from last Friday across the El Nino regions. (the El Nino region run along the equatorial Pacific from Peru towards Indonesia.) This image looks at the subsurface sea surface temperature anomalies (SSTA) which are important in forecasting the development of El Nino events, since the all El Nino and La Nina events begin by warm or cold water deep underneath the surface that pushes towards the surface. As you can see there is very little warm water along the surface and a lot of cold water just underneath it. This is not how El Nino event typically develops.
In addition the latest few runs of the Australian El Nino model which is probably the best one out there, has consistently downplayed the developing El Nino. The latest information as of April 23 clearly shows that the El Nino does not reach the threshold required to have a significant impact on weather patterns. The Australians have this value set at 0.8C+ in Enso region 3.4 and that value is generally agreed to buy most climatologists and meteorologists when they study El l Nina.
In addition the previous Australian El Nino forecast also showed a significant delay and weakening of the all Nina event.
There is other data out there which is also showing a problem with this El Nino event developing as forecasted. This image shows the latest CFS El Nino forecast (the CFS model is run by the NWS) . The image on the TOP shows the LATEST CFS forecast based upon the data from late APRIL and early MAY. As you can see the general trend - the DASHED LINE - now shows actual weakening . And when we compare this image to PREVIOUS CFS forecast late March and Mid APRIL... the changes have been well STUNNING
In addition if we look at the actual sea surface temperature anomaly map in the equatorial Pacific we can see that the temperatures are not warming.
What this means is that climatologists and Meteorologists which engage in seasonal forecasting now have to come up with an alternate scenario. The odds No longer favor even a weak El Nino event developing at some point in the Summer months. If that were to happen it would changes the entire equation or forecast for the U.S. grain areas. It also has implications for the hurricane season as well South America, Australia, and India .
WxRisk still sees a 40% chance that the El Eino event is going to develop. But if it does it should be fairly weak one. But that also means that we see a about a 60% chance -which is fairly significant - that El Eino event is not going to develop or have the impact that the typical event might have during the late Spring and Summer months in the U.S. grain areas.
Of course there are other features to keep in mind you consider when you make a summer forecast a specially hurricane seasonal forecast but this is part of the pitfalls are risk that we have in making seasonal forecasts four hurricane forecast too early in the season. This image shows the distinct differences in the ACE - Atlantic Cyclone Energy -in the Atlantic hurricane basin between EL nin s and one La Nina events and you can see there quite significant during the heart of the hurricane season.
In this image we can plot hurricanes which ended at making landfall along the East Coast - SQUARE ....Florida DIAMOND ....Gulf coast TRIANGLE. When the symbols are darkened or filled in they represent category 3...4...
Yes its time to come up with a 2nd SUMMER FORECAST...