The Wilmington Wave

By: Meteorologist Ian Boatman

We came off a 2023 season that was yet again, another active one. The season ended with 19 named storms, which was the highest we’ve seen since 2021 (there were 21 named storms that season). Unfortunately, 2024 may turn out to be an extraordinarily busy season when it’s all said and done, and we’re already trending in that direction. While there’s no way of knowing what exactly will happen around our area in northeast South Carolina and southeast North Carolina, it’s always pertinent to be prepared for the worst and hope for the best. Be aware of how the tropics change throughout the season, and start thinking about emergency plans now! Even when tropical cyclones are hundreds or even thousands of miles away, they can still produce life-threatening rip currents for the local beaches. Head over to our  Facebook ,  Twitter , and  Instagram  feeds, as well as our  local surf forecast page , for the latest information and forecasts.

NOAA’s  Climate Prediction Center (CPC)  gives a 90% chance of an above-normal season, and a 10% chance of a near-normal season. The forecasters predict a likely range of 17 to 24 named storms (winds of 39 mph or higher), of which 8 to 13 could become hurricanes (winds of 74 mph or higher), including 4 to 7 major hurricanes (Category 3 or higher on the  Saffir-Simpson Hurricane Wind Scale , with winds of 111 mph or higher).

The graphic above shows the names that are being used for this season. Tropical cyclone names are pre-selected by the World Meteorological Organization (WMO), and are repeated every six years. We last saw this name list for the 2018 season, though with a few exceptions. After that season concluded, the names Florence ( oh hey, that one ) and Michael were retired, and the names Francine and Milton were selected to fill the voids for the 2024 season. This exact list will be used again for the 2030 season, unless any names are retired at the conclusion of this season.

What is Normal?

Climatology often refers to “normals” or “averages” when talking about the frequency of different phenomena. Tropical cyclones are no different. We use 30-year climatologies to help give a sense of normal, which are updated every 10 years. The latest 30-year span that we use is from 1991 to 2020. Based on this 30-year interval, the average number of named storms that we expect in any given season is 14, with 7 of those being hurricanes, and 3 of those becoming major hurricanes. All of NOAA’s predictions for the 2024 hurricane season go well above these numbers, as shown in the first graphic of this article. In fact, this forecast is the highest NOAA has ever issued. Seriously, you need to pay attention. We already saw the significant flooding that Debby brought to this area, and that was “only” a tropical storm.

Why an Above-Normal Season? Blazing Hot Oceans!

Sea surface temperatures (SSTs) in the Atlantic basin are hot. REALLY hot. Above, you see the comparisons between SST anomalies in 2005 vs. today in 2024. In the 2024 image in particular, you see this dark red line that runs along and north of the Atlantic Main Development Region (MDR…where tropical systems love to form). Hurricanes are heat engines, and these record warm SSTs are the exact fuel that they need. While we don’t know exactly how many storms we'll have this season or how strong they will be, it doesn't necessarily matter in this case. The big picture is that the Atlantic Ocean is already extremely warm, and that's the most important seasonal factor in giving us an active hurricane season.

But warm waters are just part of the story. You’ve likely heard about El Niño and La Niña. As it turns out, we are in a Neutral period right now, but we are now in a  La Niña Watch . Why does this matter?

A Little Background on ENSO

Forecasters examine several factors that could lead to an active hurricane season. Perhaps the most famous example is the El Niño-Southern Oscillation (ENSO) pattern. This pattern includes three phases: El Niño, La Niña, and Neutral. Each phase is centered upon the water temperatures of the equatorial Pacific Ocean. El Niño represents above-normal sea-surface temperatures (SSTs) along the equatorial Pacific, while La Niña represents the below-normal SSTs. No surprise, the Neutral phase represents near-normal SSTs in the equatorial Pacific.

Obviously, the Carolinas are on the Atlantic side. Why do we care about what happens in the equatorial Pacific Ocean? The ENSO pattern is one of many “teleconnections” in the atmosphere. Teleconnections essentially show how weather or climate patterns in one part of the world affect patterns in another part of the world. In the case of ENSO, these patterns influence winds across the Northern Hemisphere and the associated weather patterns. For example, during La Niña (which is currently building in), cooler SSTs over the equatorial Pacific Ocean lead to weaker trade winds over the tropical Atlantic Ocean and weaker environmental wind shear. With less wind shear, tropical systems have less obstacles to overcome as they strengthen. Of course, this isn’t the only factor that goes into seasonal hurricane forecasts, but it's still a major player.

The table above shows recent 7-year tropical cyclone totals in each of the three ENSO phases. The most notable point here is that La Niña is typically associated with the most active hurricane seasons, while El Niño is typically associated with the quieter seasons.

*Data mentioned above were produced from the  National Hurricane Center Official Seasonal Storm Totals  publicized in Monthly Weather Review and accessed through the NOAA Miami Regional Library (online) and  ENSO Cold & Warm Episodes by Season from the Climate Prediction Center  (online).

ENSO: Where Are We Now?

According to the latest    NOAA ENSO Blog from August 2024 , we are currently in a La Niña Watch, which means that conditions are favorable for the development of La Niña conditions within the next six months. Though we are currently in the ENSO-Neutral phase, La Niña has a 66% chance of developing by this autumn, with a 74% chance of development during November-January. As mentioned above, in a La Niña year, you would expect a busier hurricane season. Time will tell of course, but unfortunately, there are already signs that this will become a very busy season over the next couple of months.

The 2024 Hurricane Season is Already Making Some Noise

As of this typing, we’ve already recorded five named storms (Tropical Storm Arlene, Hurricane Beryl, Tropical Storm Chris, Hurricane Debby, and Hurricane Ernesto). Beryl in particular became infamous by becoming the earliest-forming Category 5 hurricane on record, among other broken records. More locally, even though Debby was “only” a tropical storm by the time it rolled through the Carolinas, it dumped 10-15 inches of rain across the area, with some isolated spots edging closer to 20 inches. This was easily the most rain we have seen from one event since  Hurricane Dorian  in September 2019. Floodwaters wreaked havoc in certain spots, with places like Bladenboro, NC being barricaded off from 2-3 feet of flash flooding. Unfortunately, we also experienced a fatality in Robeson County, NC in the days following the storm, when a motorist tried to drive through flooded roads.

This is why we say to not focus on the category of the storm. Any tropical cyclone can alter lives in the worst of ways. Please have your preparedness plans ready to go ahead of time. Keep an eye on how the forecast changes, and listen to local officials when they announce road closures or evacuation orders.

Be Prepared: It Only Takes One!

No matter if an active or a dormant season is expected, it is always paramount to prepare for potential tropical cyclones. It only takes one storm to cause life-altering damage. Hurricanes Florence and Matthew prove that idea.

View the slideshow below to learn what steps you need to take in order to be ready for if/when a tropical cyclone approaches our area. Get your whole family  ready with an emergency plan . Look into  flood insurance  as soon as possible, as there is often a 30-day waiting period involved.

Resources

•  "Highly Active Hurricane Season Likely to Continue in the Atlantic" (NOAA) 
•  "NOAA 2024 Atlantic Hurricane Season Outlook" (Climate Prediction Center) 
•  "August 2024 Outlook: A La Niña Watch in the Dog Days of Summer" (Climate.gov) 
•  National Hurricane Preparedness (NOAA) 

By: Meteorologist Vicky Oliva

Introduction

Tropical cyclones produce a wide range of hazards: storm surge, heavy rain & inland flooding, high winds, rough surf, and tornadoes. Nearly 90% of all tropical cyclone-related deaths are water-related (surge, rain, surf, and marine). Unfortunately, the rough surf hazard can easily be overlooked or underestimated, especially with distant cyclones that may be hundreds or thousands of miles away. Long period swells from distant storms can lead to strong rip currents forming along exposed beaches. Large waves from nearby storms can create rough surf and rip currents. Nice weather may be occurring locally, increasing the chance of high beach populations at risk. Therefore, it is important to stay aware of the tropics, along with weather and beach forecasts, throughout the hurricane season.

It is estimated that 6% of fatalities from Atlantic tropical cyclones are surf related, including rip currents and high surf. On a local level, 10% of rip current fatalities in the Carolinas between 2000 and 2022 have been due to swells from tropical cyclones. At Wrightsville Beach, NC, there is a peak in strong rip currents reported in the month of September, correlated to the peak in Atlantic hurricane season (based on observations collected from Wrightsville Beach Ocean Rescue since 2004).

Atlantic Tropical Cyclone Surf Fatalities

A local study was done to create a database of surf fatalities attributed to Atlantic basin tropical cyclones in the continental U.S. using data from 2000 to 2022 (NHC reports, NCEI Storm Events Database, and media articles). A total of 147 surf fatalities related to Atlantic tropical cyclones between 2000 and 2022 occurred along the continental U.S. coastline, 103 of which were attributed to rip currents. In this study, a distant storm is any storm that led to only maritime and surf impacts at the fatality location, either causing additional impacts elsewhere or remaining out at sea. 87 (59%) of the surf fatalities related to Atlantic tropical cyclones were associated with distant storms - 42 (29%) were linked to truly distant tropical cyclones, mostly hurricanes, that remained far out at sea.

Hurricane Lorenzo (2019)

In 2019, Hurricane Lorenzo was a tropical cyclone in the eastern Atlantic from September 22nd - October 4th. Lorenzo was a powerful major hurricane for days and was the northern most Category 5 storm on record in the Atlantic. From September 26 - 30, Lorenzo was a Category 2 hurricane or stronger and was either moving right at the U.S. or moving slowly. This generated long period swells that traversed the Atlantic, taking four days for the swells to reach the East Coast. As a result, a deadly rip current outbreak occurred along the U.S. East Coast, despite Hurricane Lorenzo getting no closer than ~1,700 nautical miles from the coast. Strong rip currents and hazardous surf conditions were reported up and down the coastline. Eight lives were lost in total, six of which were rip current related, between September 30th and October 3rd. Four of these fatalities occurred in North Carolina. Lorenzo led to the most U.S. surf fatalities from an Atlantic tropical cyclone since Hurricane Gabrielle in 1989. The impact of Hurricane Lorenzo became a catalyst for an increased focus on the threat posed by distant tropical cyclones within the NWS. For additional information, check out our  StoryMap for Hurricane Lorenzo .

Messaging Efforts in the Carolinas

In the years since Hurricane Lorenzo, both  NWS Wilmington, NC , and  NWS Newport/Morehead City, NC , have ramped up their communication efforts with partners and the public whenever a distant tropical cyclone is forecasted to produce dangerous surf conditions along local beaches. In 2020, a new local policy was instituted to create dedicated one-page briefings before and during these events. These briefings are disseminated via email to partners and made available on the forecast office’s website, and are sometimes translated to Spanish with the support of NWS’s Multimedia Assistance in Spanish (MAS) team to help reach additional community members. Additionally, there has been an increased emphasis on leveraging social media channels to broadcast alerts when there is the potential for a rip current outbreak at local beaches, especially in cases involving distant tropical cyclones. In some respects, NWS Wilmington, NC has adopted a similar approach to communicating rip current threats as it does for other weather-related hazards, such as potential severe weather outbreaks.

There have also been several NWS product enhancements in recent years which help improve Impact-based Decision Support Services (IDSS) during potential rip current outbreaks. In 2020, NWS Wilmington, NC, in collaboration with several other East Coast NWS offices, initiated an experiment involving enhanced wave terminology in local Coastal Waters Forecasts (CWF) available on the web, an effort that began at NWS Eureka, California. The project’s objective was to incorporate wave detail components into NWS forecasts, highlighting multiple wave systems present within the local waters. As of April 2024, wave detail is now included in the  operational CWF  issued by NWS Wilmington, NC.

In the summer of 2021, NWS Wilmington, NC launched an  Experimental Surf Forecast Matrix product . The official  Surf Zone Forecast (SRF)  issued by NWS offices contains a full two-day forecast, providing a single forecast for each day per coastal county. However, surf zone conditions can change throughout the day and vary along the coastline. Leveraging recent advancements in wave modeling and rip current forecasting, NWS Wilmington, NC developed surf forecast matrices with parameters similar to the operational SRF product. These matrices provide 6-day forecasts, broken down into 3-hourly and 6-hourly increments, and there is an individual matrix available for popular beaches within the NWS Wilmington, NC forecast area.

Know Before You Go

One of the best ways to keep yourself and your loved ones safe when going to the beach is checking the beach forecast before going out. Coastal NWS offices issue Surf Zone Forecasts (SRF) during local beach seasons to give a heads up of potential hazards people may encounter at the beach. This includes a rip current risk, breaking wave heights, and other hazards such as shorebreak and longshore currents. Visit  www.weather.gov/beach  to view the beach forecast for your area of interest. And for additional information on rip currents, including safety tips and how to spot them, visit the Carolinas Rip Current Awareness website at  www.weather.gov/ilm/ripcurrents .

By: Lead Meteorologist Robert "Bob" Bright

As you’ve probably noticed, NOAA and NWS provide water level observations and forecasts relative to different datums (or starting points). The most common are tidal datums such as Mean Lower Low Water (MLLW), Mean Higher High Water (MHHW), and Mean Sea Level (MSL). MLLW represents the mean level of the lowest of the 2 daily low tides and is used since it is well known to the marine community for navigation purposes. MHHW can be a decent proxy for “ground level” in tidal areas, as most infrastructure is built higher than this level to avoid flooding impacts.

Due to the complexity of having to know your elevation relative to these tidal datums, the  National Hurricane Center (NHC)  storm surge forecasts during tropical storms and hurricanes are provided relative to above ground level (AGL), which is also referred to as inundation. Although storm surge is technically defined as just the extra water a storm brings above the normal astronomical tides (and thus isn’t relative to any datum), it is important to know that the NWS storm surge forecasts represent the combination of the storm surge and astronomical tides (i.e., storm tides) relative to ground level. Thus, there is no need to do any adjustments or conversions to the forecast values. For example, if the NWS storm surge forecast is 4 to 7 feet along a stretch of coast, some portion of that area is expected to see 4 to 7 feet of water above the ground.

With hurricane season upon us again, it's important to  know your vulnerability to storm surge inundation . Once a storm threatens, you can see how much inundation you should plan for by viewing the  Potential Storm Surge Flooding Map  (which always shows the reasonable worst case storm surge inundation and is best used early in an event when confidence is lower), as well as the  Peak Storm Surge Forecast Graphic  (which shows the storm surge inundation values that are more likely). Both of these products are available on the  NHC website .

You may also be familiar with the daily “total” water level (TWL) forecasts that NWS Wilmington, NC produces everyday for 3 locations across southeast NC and northeast SC, including Johnnie Mercer's Pier in Wrightsville Beach, NC, the lower Cape Fear River at Downtown Wilmington, NC, and Springmaid Pier in Myrtle Beach, SC. It’s important to understand that even during tropical storms and hurricanes, these forecasts are always relative to MLLW and thus, may be significantly different from the storm surge inundation values predicted along the coast by the NHC. The TWL forecasts, as well as the routine river level forecasts from the  Southeast River Forecast Center (SERFC) , are available through the new  National Water Prediction Service (NWPS) website .

Click  here  to learn more about storm surge and the NHC storm surge products. Check out our  local hurricane guide  to learn more about the storm surge risk across southeast NC and northeast SC and how you can prepare for hurricane season.

By: Meteorologists Adam Weiner and Lauren Warner

Have you ever thought about how much training National Weather Service meteorologists need to complete in order to issue watches and warnings? Even if you haven't, it is important to realize that NWS meteorologists are trained and tested extensively before they are allowed to issue warnings. In fact, today's training requirements involve about 100 hours of online training modules and experiential learning which culminate in a week-long residence course at the  National Weather Center  in Norman, OK.

Two of our newest meteorologists, Lauren Warner and Adam Weiner, are the latest to complete the Radar and Applications Course (RAC). Below, they'll walk you through some of the topics that are covered in the training, as well as how warning operations work overall. All of this training takes about 4 months to complete, and that's a good thing, because there is a lot of responsibility behind pushing that "Tornado Warning" button!

Just as you would want a well-trained surgeon performing surgery, you also want a well-trained meteorologist making warning decisions. This responsibility involves a repetitive process of scanning for storms, prioritizing the most intense storms, identifying the hazards they could produce, deciding what type of warning is needed for the identified hazards, and finally, drawing up and issuing the warning. NWS meteorologists are trained to conduct the whole process leading up to the warning decision in about 5 minutes or less, and the warning issuance process from drawing the polygon to sending the warning should take 2 minutes or less. After warning issuance, the warning meteorologist repeats this process as new storms develop, as new storm reports become available, or as the initially warned storm evolves. Warnings need regular updates to keep the polygon tight to the hazard area and to keep the expected hazards fresh. If a storm initially warned for the potential to produce quarter-size hail is now showing signs of producing golf ball size-hail, an updated warning is especially important to everyone in the path of this storm.

Module-based training starts with a comprehensive review of the Advanced Weather Interactive Processing System (AWIPS), including its various tools, data visualization capabilities, and ways to leverage it for severe weather prediction, analysis, and ultimately, warning decision-making and issuance. Since severe weather warnings are presently issued when hazards of severe caliber are imminent or occurring (i.e., wind gusts of 58+ mph, hail of 1+ inches, or a tornado), an extensive deep dive into  weather radar  operation and interpretation is necessary for all NWS meteorologists. These modules cover everything, from  how a radar beam is transmitted and received , to the various issues which can occur during data collection, to the various algorithms which derive useful information out of the available data. Crucially, the various  sampling issues , which can occur due to ground clutter, range folding, and velocity aliasing, help to raise awareness of how bad data may appear and how to properly interpret it.

Speaking of interpretation, understanding the base data, including  reflectivity ,  velocity , and spectrum width, as well as the  dual-polarization data , including differential reflectivity, correlation coefficient, and specific differential phase, is the bread and butter of this training. A variety of  derived products  and algorithms rely on these base data, including the  Multi-Radar Multi-Sensor (MRMS)  system, and warning decisions are heavily based on these data as well. While algorithms can help highlight areas of interest or provide guidance, nothing substitutes an expert interrogation of the base data.

With the above in mind, the next logical step in the training is a focus on the various severe weather environments, thunderstorm types, and structures one might see and where severe weather would normally occur. Forming an accurate conceptual model sets a meteorologist up for success when evaluating the threat for severe weather, both for the whole event and for individual storms. Keeping in mind where specific hazards are most likely to occur in a supercell (see below) versus a squall line versus a summertime pop-up storm allow one to anticipate what type of warning may be needed and the potential magnitude of the hazard(s). While severe thunderstorms are commonly known for their damaging wind, hail, and tornadoes, flash flooding can be just as devastating, or worse. Thus, an entire section of the training is dedicated towards understanding environments conducive to flash flooding, the various tools available to evaluate and interrogate the flash flood threat, and ultimately, when to issue a Flash Flood Warning.

Issuing severe weather warnings is a process and there are numerous considerations to take into account when drawing a warning polygon, including the speed of the storms, the magnitude of the hazards, and the likelihood of storms persisting. Besides these obvious factors, splitting storms, merging storms, training storms, and wavy squall lines with embedded circulations all present greater challenges to properly messaging the hazards. Furthermore, population density, the presence of outdoor events, lakes, outdoor recreation areas, and numerous other social factors play into the decision making as well.

Finally, after all the training modules are completed and experiential learning is done at the office, the time comes for a week of review and simulations to put all the knowledge and skills taught into practice with real events in real time. At least one instructor is available to assist each warning team of three meteorologists. Simulations are carried out in a variety of locations, terrains, and times of year to provide a well-rounded warning experience in only a few days, with the intention that additional training will be conducted locally after the completion of RAC to further sharpen the meteorologists’ skills after they return home.

Testimony from the experiences of two of our meteorologists, Lauren Warner and Adam Weiner, can be found below.

• Lauren: “If given the chance, I would likely take this class again in several years to keep my skills sharp. Science is always advancing, and there’s always a more efficient way to approach things. For example, my class was the first to be trained on new storm scanning procedures, and this was put into practice when I was at the class in-person. The efforts made by the instructors to simulate an actual in-office environment during the real-time simulations was amazing. Not only are your warning skills being tested, but it also simulates being part of a team with an emphasis being put on communication, which I deeply appreciated. The class is a great and effective way to remain knowledgeable in storm warning strategies.”

• Adam: “The simulation experience is remarkable - you can feel the stress and tension of warning operations when an event is unfolding in front of you in real time. Not only were my skills applied, but my capacity to handle multiple storms and stay mentally sharp was tested, especially when time is of the essence and decisions need to be made quickly. At the same time, extremely knowledgeable instructors are standing by to answer questions and guide students to ensure we are not left in the dark. The combination of a realistic simulation environment with instructors who made the modules assigned to each team makes this an invaluable experience.”

By: Meteorologist Ian Boatman & Information Technology Officer Carl Morgan

Where did you go to school, and how has your career path led you to the National Weather Service in Wilmington, NC?

• Carl: Being from North Carolina, NC State University was a logical choice for me to pursue a degree in meteorology. Prior to graduating, I began my NWS career as a Meteorologist Student Trainee with the Techniques Development Laboratory (now Meteorological Development Laboratory) in Silver Spring, MD. In this role, I learned about NWS software development, gained programming experience, and learned how the NWS functions from the perspective of National Headquarters. My true desire was to work in the field, so after graduation, I accepted a position as a Meteorologist Intern in New Braunfels, TX. From there, I spent a short time as a General Forecaster in Memphis, TN before having the opportunity to move back to my home state. I’ve called Wilmington home since 1998, and have served here as a General Forecaster, Senior Forecaster, and Information Technology Officer.

How did you become interested in the weather?

• Carl: Like most meteorologists I know, my interest in weather began at a young age, however I can’t point to a specific weather event that spawned my interest. I was always fascinated by thunderstorms and lightning. I loved to watch clouds evolve as storms developed, and hoped to one day see a tornado firsthand. Against conventional wisdom, when thunder roared, I went outdoors.

What is your current role at NWS Wilmington, NC?

• Carl: Currently, I am the Information Technology Officer (ITO) at NWS Wilmington, NC. The ITO position was created at Weather Forecast Offices across the country in the early 2000s as a result of a rapidly growing IT workload. In this position, my primary responsibilities include system analysis, software development, and user support. As boring as that may sound, the reality is quite the opposite. I still have the opportunity to forecast the weather, operate radar during severe weather, provide decision support to our local Emergency Management community, and conduct damage surveys after severe weather events.

What is your favorite type of weather?

• Carl: I’m not a fan of the cold, so snow, ice and various mixes of winter precipitation are out. I love heat and humidity (to a point), and one of my favorite sounds is the first rumble of thunder in the springtime. I’d have to give the nod to thunderstorms. I still find them fascinating.

What is the most memorable weather event you've experienced?

• Carl: Hands down, the most memorable weather event I’ve experienced was  Hurricane Florence back in September 2018 , which made landfall almost directly overhead. It was "only" rated as a Category 1 storm, and although I’ve experienced pretty much every hurricane or tropical storm to impact Cape Fear since Hurricane Floyd in 1999, I’ve never seen anything close to the widespread damage caused by Florence. I would never want to experience anything like it again, much less a direct hit from a stronger hurricane.

What do you do in your spare time?

• Carl: My favorite pastime is playing softball, and I’ve played many years in leagues in Wilmington, Wrightsville Beach, and Surf City. At one time I organized a team from our office, known as the “Absolute Zeros” (infer what you will from the name), but the challenges of fielding enough players from an office of rotating shift workers made it unsustainable. I also enjoy fishing, racquetball, and an occasional Spartan obstacle course race.

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