In case you missed it — and you’ll be forgiven if you did — we had our first landfalling tropical cyclone of the 2020 hurricane season on Wednesday. Tropical Storm Bertha, which was classified as such when it was 30 miles southeast of Charleston, came ashore around 9:30am with maximum sustained winds (primarily offshore) of 50 MPH. Bertha was not a major wind-maker on land, but dropped enough rain at low tide to cause flooding in downtown Charleston. Its heavy rain spread inland, adding to rain totals on what has been a soggy second half of the month already. Charleston Airport set a new rainfall record on Wednesday, as well; 2.08″ broke the record of 2″ set in 1977.

Bertha’s place in history

Bertha’s landfall in Charleston County as a tropical storm in May puts it in fairly rare company. Looking through NWS Charleston, SC’s tropical cyclone archive, you’re hard-pressed to find too many May landfalls in our neck of the woods — in fact, only two in the historical record prior to Wednesday.

Unnamed 1916 tropical storm

The unnamed 1916 tropical storm began north of Cuba, made a first landfall in Florida, and then made a second landfall on Fripp Island and continued northeast across the Carolinas as it lost tropical characteristics, according to HURDAT re-analysis research in 2008. There is unfortunately not a lot of other context around what happened here in the Carolinas, though research suggests maximum sustained winds around 35 knots (roughly 40 MPH).

Bonnie in 2016

The most recent May B-storm, Bonnie, also made landfall in South Carolina at Isle of Palms, roughly ten miles southwest of where Bertha came ashore on Wednesday. Bonnie had weakened to a tropical depression before landfall, but still managed to dump quite a bit of rain in spots, with one CoCoRaHS station reporting a storm total over 8.5″. It was not the best-organized system as wind shear moved much of the convection west of the center. After landfall, the storm stalled out and hung around for a day or so, bringing scattered showers and thunderstorms but little else.

Where Bertha fits in

As far as May tropical cyclones go, Bertha was unique in several aspects:

• Its classification 30 miles offshore of Charleston is the closest we’ve had a tropical storm form in May.
• Bertha was the strongest tropical cyclone by wind speed to make landfall in the Charleston area in May, with estimated maximum sustained winds upon landfall of 45 knots (~50 MPH, rounding down). Most land-based stations did not exceed 40 MPH, though.
• Bertha continues an odd trend of B-storms in May in leap years. This started with Beryl in 2012, Bonnie in 2016, and now 2020. It’s also worth noting that each of these storms had effects on our weather in some way, direct landfall or otherwise. (Here’s NWS Charleston’s post-storm report on Beryl 2012.)

Hurricane season officially starts Monday

Arthur and Bertha getting started in May are good reminders that we are about to enter the official start of the Atlantic hurricane season. With no imminent threats, now is the time to start working on your stockpile of supplies if at all possible. It’s a lot less stressful to start preparing now with no storm on top of us than when one is bearing down, especially with a pandemic on top of everything else. Don’t feel the need to buy everything at once — the beauty of being early is that you can buy a little at a time.

Check out the National Weather Service and South Carolina Emergency Management Division hurricane guides for lots of useful information on how to prepare, evacuation routes, and more.

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