The heat released into the atmosphere by the very warm seas in the eastern tropical Pacific has weather impacts that ripple across the globe.
It can disrupt wind patterns above the Caribbean and the Atlantic leading to increased wind shear, meaning winds that blow at different speeds and directions at different levels in the atmosphere.
This can rip storms apart before they have time to strengthen.
However this is not the only factor that determines whether hurricanes will form. While it reduces the odds, it does not make it impossible – as Isaias proves.
Isaias has formed over the Gulf of Mexico where sea temperatures are currently 30-31C – around 2C higher than normal.
It is the warm ocean that gives hurricanes their fuel, providing energy and moisture allowing them to grow.
There is currently limited wind shear meaning the storm has chance to strengthen. However, wind shear is expected to increase dramatically in the 24 hours before Isaias makes landfall which may limit how intense it can become.
However the range of factors influencing hurricane development is complex and exact forecasts are likely to shift slightly over the coming days.
