The 2020 Atlantic Hurricane Season is off to a fast start

Today is June 10, 2020, and while that date is rather insignificant, it is the 10th day of the 182-day-long Atlantic Hurricane Season. It is rather hard to believe we are only 10 days in and have already seen our third named storm – Cristobal.

To review, Tropical Storm Arthur formed on May 16 off the east coast of Florida and brought rain and storms to the Outer Banks of North Carolina. For local meteorologists, this was an unwelcome start to the season when, on average, the first storm forms on July 9.

We saw our second named storm of the season, Tropical Storm Bertha, just 11 short days later. Bertha became a tropical storm shortly before landfall and tracked over the North Carolina mountains. That track placed central North Carolina in the often-dangerous quadrant of the system. This is the northern or eastern quadrants between 0° and 120° with respect to the tropical cyclone’s motion. In this area, low-level wind shear and storm relative helicity are usually highest (McCaul 1991). As was anticipated, we saw rain, storms and a few tornadoes.

Two systems formed and two systems impacted North Carolina before the official start of hurricane season. Then came June 1 and the formation date of Tropical Storm Cristobal. Cristobal broke a few records – the first was forming earlier than any previous “C” storm.

Tropical Storm Cristobal’s second record broke when it tracked farther west than any other post-tropical system since record keeping began in the mid-1800s. On Tuesday, tropical rain bands brought not only the rain, but wind to the Midwest. As much as 3-5” of rain fell in eastern Iowa while Chicago’s O’Hare International Airport recorded a wind gust of 60 mph. As you could imagine, gusty rain bands from a tropical system is something the Windy City does not experience often.

On June 4, Colorado State University released their updated tropical forecast for the remainder of the season calling for it to be “well above-average.”

So, why will this hurricane season continue to be active?

The answer lies within water temperatures in the equatorial pacific that influence atmospheric oscillations. The El Niño-Southern Oscillation (ENSO) is that oscillation we track, and it has three phases – El Niño, Neutral and La Niña.

When water temperatures in the equatorial pacific are 0.5° above/below average, then an El Niño/La Niña exist.

The primary reason why ENSO impacts Atlantic tropical cyclone activity is through alterations in vertical wind shear (e.g., Gray 1984) along with alterations in fluctuations in near-surface and surface temperatures (Tang and Neelin 2004).

Smith et al. (2007) found that landfall frequencies in La Niña were significantly enhanced along the U.S. East Coast when compared when ENSO Neutral and El Niño conditions exist.

Colorado State University’s forecast is “well above-average” because of the current phase of ENSO:

"Current neutral ENSO conditions may transition to weak La Niña conditions by later this summer. Sea surface temperatures averaged across portions of the tropical Atlantic are somewhat above normal, while the subtropical Atlantic is much warmer than average. We anticipate an above-normal probability for major hurricanes making landfall along the continental United States coastline and in the Caribbean."

The 2020 Atlantic Hurricane Season is off to a VERY fast start and forecasts show that it will continue to be a rather active year. Nonetheless, trust WRAL's team of meteorologists to keep you up to date on every tropical system this hurricane season.