Texas A&M University-Kingsville

MOMENT WITH AN EXPERT: El Niño & Hurricane Season

KINGSVILLE - June 06, 2014

Contact: Adriana Garza-Flores
adriana.garza@tamuk.edu or 361-593-4979

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Dr. Brent Hedquist is a climatologist and assistant professor of geography in the Department of Physics and Geosciences at Texas A&M University-Kingsville. Dr. Hedquist explains how the weather event El Niño may impact the 2014 hurricane season and summer weather in South Texas.

What is El Niño?
El Niño is cyclical global event that occurs every 3-7 years and is characterized by unusually warm ocean temperatures in the Equatorial Pacific (especially off the west coast of South America), as opposed to La Niña, which is characterized by unusually cold temperatures in the Equatorial Pacific. El Niño can cause disruptions in the normal ocean-atmosphere system in the tropical Pacific, leading to an increase in drought and flood events world-wide. Specific examples include increased rainfall across the southern tier of the U.S. and Peru, causing flooding, and drought in the Western Pacific, sometimes associated with devastating brush fires in Australia. Much of the development of a strong El Niño event can be explained by a reversal of winds across the tropical Pacific. Normally, trade winds blow toward the west across the tropical Pacific, causing warmer sea temperatures and rainfall in this region. However, prior to and during a strong El Niño event, the trade winds relax and warmer water tends to build up in the normally cooler eastern Pacific waters, such as off the coast of Peru.   

How might El Niño impact both the Atlantic and Pacific hurricane seasons this year?
Generally, during a moderate to strong El Niño event, warmer water in the eastern Pacific tends to enhance hurricane activity, while decreasing activity in the Atlantic. In the Atlantic and Caribbean this is due to increased westerly winds at higher levels in the atmosphere, which tend to “shear” off the top of the tropical cyclones that develop, significantly weakening them. In addition, during the past few months, tropical Atlantic sea surface temperatures have dropped to anonymously low levels, which would further limit development of hurricanes.  The official hurricane forecast from the National Oceanic and Atmospheric Administration (NOAA) for the eastern Pacific and Atlantic tend to reflect this influence from a developing El Niño, with a below average number of named storms in the North Atlantic, and an above average number of named storms in the eastern Pacific. 

What effect could El Niño have on summer weather in South Texas?
Climatologically, South Texas tends to have warmer and drier than average summers prior to the onset of an El Niño. Long range climate forecasts reflect this dryness at least through July, although there is a lot of uncertainty with predictions this far out. Predictions of drier conditions in the early summer are due to prevalence of a strong high pressure system that typically sets up in the area around Laredo, Texas and the Northeast Mexico desert during this time of year. The strongest effects from El Niño are felt in the late fall and winter after the onset of the event. Once an El Niño forms in late summer/early fall, it typically lasts for around nine months, bringing the event to a close typically in late spring.

When is El Niño expected to arrive?
Most models predict the onset of El Niño to occur around July and August (greater than 65% chance). However, there is a still a slight possibility that El Niño will not develop and El Niño neutral conditions will continue according to NOAA climate scientists). Again, if a moderate El Niño develops this summer, the full effects in Texas may not be felt until late summer/early fall, when the subtropical jet stream (high winds moving from west to east at 15-20,000 feet) becomes more active and transports higher amounts of moisture from the warmer, evaporating eastern Pacific waters.

What should people living along the gulf coast do to stay prepared during Hurricane Season?
Even though hurricane activity in the northern Atlantic and Gulf Coast area should be lower than average this year, people along the coast should still be prepared for a possible land-falling storm. A good example of this would be when Hurricane Andrew struck Miami, Florida as a devastating Category 5 storm in 1992, which happened to be an El Niño year. Keep a close eye on weather forecasts for the region. An excellent source for information regarding hurricane preparedness can be found at: www.ready.gov/hurricanes. Some key preparation ideas before a storm hits include: building an emergency kit, make a family communications plan, know your surroundings (including the best evacuation route to reach higher ground), and make plans to secure your property.
 


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