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Record Hurricane Season on Tap? Official Outlook Released

2024 Atlantic Hurricane Season Forecasts

National Hurricane Center Forecast

The National Hurricane Center (NHC) issued its official 2024 Atlantic Hurricane Season forecast, calling for 17-25 named storms, 8-13 hurricanes, and 4-7 major hurricanes (Category 3-5). This is above normal from the climatological averages ("normal") of 14 named storms, 7 hurricanes, and 3 major hurricanes.



Colorado State University Tropical Weather & Climate Research Center Forecast

Similar to the National Hurricane Center, Colorado State University (CSU) is calling for an "extremely active" season for the Atlantic Basin. Their official forecast calls for 23 named storms, 11 hurricanes, and 5 major hurricanes - again, well above average. Their forecast goes deeper to estimate the number of hurricane days and Accumulated Cyclone Energy (ACE), both which are used to describe the overall tropical activity of a hurricane season. In addition, CSU anticipates a well above-average probability at 62% for a major hurricane making landfall along the continental United States coastline. Read their full forecast here.



Why Such an Active Year?

The 2024 Atlantic Hurricane Season is expected to be an extremely active (potentially record?) year for several reasons, but we'll discuss a few in particular:

  • Sea surface temperatures already at record warm levels

  • Quick Transition from El Nino to a La Nina

  • Potential for an above-normal west African monsoon, which can produce African easterly waves that seed some of the strongest and longer-lived Atlantic storms

  • Light Trade Winds

  • Historical hurricane seasons with similar conditions (analogs)


Sea Surface Temperature Anomalies

Sea surface temperatures (SSTs) in the tropical and subtropical Atlantic basin, including the Main Development Region (MDR) are at record warm levels.


In general, tropical systems need SSTs of at least 27 degrees Celsius, or 80 degrees Fahrenheit, for convection to occur and allow for the development and/or sustainment of tropical storms and hurricanes. Currently, temperatures in the tropical Atlantic are 2-4 degrees above normal, and have already climbed to 25-29 degrees Celsius - supportive of early season tropical activity.



Sea surface temperatures warm on a lagged timeframe and will continue to increase into the Fall months, even when air temperatures begin to cool from their Summer peak. This is cause for concern, as SSTs will be able to warm even further than usual and remain warmer into the late Fall, possibly extending the tropical season.


Transition to La Nina

The El Nino Southern Oscillation (ENSO) plays a significant role in overall hurricane activity, and can either suppress (El Nino) or increase (La Nina) tropical development. We've been under the influence of El Nino conditions since last Spring, but are quickly transitioning into La Nina conditions. We should reach official La Nina conditions according to SSTs in July or August, just in time for the statistical peak of hurricane season in mid-September. With the cooling of SSTs in the eastern equatorial Pacific, this causes the air temperatures above to cool and sink, and allows for more rising motion in the Atlantic.


However, ENSO is an oceanic-atmospheric phenomena, not just oceanic. Under the influence of La Nina, the trade winds weaken and lesser wind shear helps tropical systems develop. This is opposite of the severe thunderstorms that we experience more often - wind shear is needed for their development, but tears tropical systems apart.


Past Hurricane Seasons with Similar Conditions

One method tropical meteorologists use to predict how active this hurricane season may be is looking at past years with similar atmospheric and oceanic conditions. These are called analog years. Colorado State University identified 5 top analog years to assist in their seasonal forecast: 1878, 1926, 1998, 2010, and 2020. These analog years produced an average of 17.2 named storms, 10.8 hurricanes, and 4.6 major hurricanes. Their analog years were chosen based off of those characterized by El Nino conditions the previous Winter that transition to La Nina conditions near the peak of the Atlantic Hurricane season. They did note, however, that the SSTs in the analog years were not as warm as we are observing now, lending to the idea that this year could feature even more tropical activity.


Tropical Tidbits' Analysis Tools page prepares two sets of hurricane season forecast analogs based on 30-day CDAS Global SST Anomaly Analysis and NMME Global SST Anomaly Analysis. These analogs are not specifically focused the equatorial pacific SST conditions, and do not take into account atmospheric phenomena, and therefore are not as helpful for predicting Atlantic tropical activity specifically. These analogs produced an average of 15.3 named storms, 7.3 hurricanes, and 3.1 major hurricanes. We would not be shocked to see 1.5 times these values end up occurring. One thing of interest in these analogs is the historical storm track anomalies suggesting greater landfall probabilities along the Gulf Coast and southeast coast of the United States, as depicted in the images below.



The Consensus

Confidence is high that we're going to see a very busy Atlantic Hurricane Season- potentially one of the most active on record. The atmosphere and ocean are at, or will be at, prime conditions for tropical cyclone development. The official start to the Atlantic Hurricane Season is June 1st and lasts through November 1st, but hurricanes can and do develop outside of these timeframes.


Reminders

  • The National Hurricane Center (NHC) began issuing outlooks for the Atlantic Basin on May 15th, which include 2-day and 7-day graphical forecasts. The NHC is the official source for tropical forecasts.

  • Refer to your local National Weather Service office and TRUSTED weather sources for information. Be cautious of "click bait" and fearmongering posts on social media.

  • Know your evacuation zone prior to storms developing.

  • While wind speed is the determining factor for what category a storm is rated, storm surge, tornadoes, and inland flooding are all threats with tropical systems. Storm surge is the most deadly threat.

  • There are 21 pre-determined names that will be used for systems that reach tropical storm strength or greater. If there are more than 21 named storms, names will be taken from an alternate name list instead of the previously-used Greek Alphabet.


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Thermodynamic Solutions (“TDS Weather”) provides professional weather consulting services to a variety of industries including: professional and minor league sports, snow removal and landscaping, golf courses and turf management, colleges and universities, and hospital networks. With nearly two decades of living and forecasting in the Ohio Valley region, our meteorologists provide custom, reliable forecasts that help clients SAVE and MAKE money in their daily operations. Our services include commercial and agricultural forecasting in the short and long ranges, lightning alerts and on-site hazardous weather monitoring, 24/7 on-call decision support services, forensic weather reporting, and more! For weather consulting inquiries, please contact us at info@tdsweather.com.

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