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BY THE NUMBERS: What's driving the active hurricane forecast for 2024

First to Know Chief Meteorologist Casanova Nurse explains
Posted at 7:05 PM, May 31, 2024
  • La Niña is expected to influence the 2024 hurricane season.
  • Warm ocean temperatures can also add fuel to developing storms.
  • Watch the video above to see what other factors can lead to an active hurricane season.

BROADCAST TRANSCRIPT:

The solid earth, the vast oceans, and the expansive atmosphere. In many ways, it's all connected. Temperature differences create wind that flows in various directions and at various speeds.

Around the equator in the eastern Pacific Ocean, the pattern of westerly winds alters the water temperatures.

Last year, those winds were weak, causing a pooling of warmer water that contributed to the El Nino global weather pattern phase.

Those warmer waters caused buckles in the upper-level wind flow, producing a belt of fast movement well above the Caribbean Sea, which effectively disrupted the development cycle of tropical systems in that region last season.

Those Pacific waters this spring have been cooling down. The west wind flow just above the east Pacific surface waters has increased, shoving water farther west and allowing cooler water underneath to rise to the surface.

This cool-down will lead to an adjustment in the upper-level wind patterns around the Pacific and Atlantic basin tropical regions. The changes are gradual and take months of transition. The early part of our hurricane season will be "neutral" but eventually enter the La Nina phase.

As has been seen in past La Nina events, the circulation in the atmosphere in the Caribbean Sea features lighter winds, causing less active shear.

Shear is the upper wind's effects on the upward structure of a tropical system. Strong shear tilts the structure and causes weakening. Weak shear has the opposite effect; tropical storms stay intact and grow into healthier, stronger systems under the right conditions.

Add to these factors the existing warm ocean water temperatures already in place in the southern latitudes where storms tend to form at mid-season, and we get all these ingredients connecting together to create a likely active hurricane season with many named storms anticipated.