As Hurricane Season Gets Takes Its Position as “Next Up”

Here we are on the 20th of May and in Central Florida it's turning into full-on summer, while still a few months from turning into Crematoria. We're in the last couple of days of what may well have been the last cool front of the year, with highs that haven't actually gone over 90, and won't be close to that until the weekend. Hurricane season starts on June 1st. 

What's it going to be like?  

The big things to look at are sea surface temperatures, the El Niño Southern Oscillation (ENSO), and the overall weather. I'll take a little look at these and some of the predictions from the pros. Let me point out my standard disclaimer: I reserve the right to be wrong. I try not to be, but while I'm mostly just relaying other people's content, I might make some mistakes. Don't let my look affect your planning if you're in the parts of the US where hurricane preparation is part of your life. 

That said, let me start with sea surface temperatures, which were the big story last year. Back near the end of last July, I passed along a story that I'd read about the monstrous underwater volcano called Hunga Tonga-Hunga Ha'apai that erupted in January of '22.  Within a week of the eruption it was being noted as one of the most violent eruptions ever seen, with this startling statement from a group that monitors nuclear explosions. 

Titled “A nuclear-test monitor calls Tonga volcano blast 'biggest thing that we've ever seen',” it reports that an international group that monitors for likely atomic detonations has reported that at every one of their sites around the world - 53 of them - the infrasonic wave from the Tongan volcano is the largest thing they've ever measured, even bigger than the Soviet Union's Tsar Bomba, the biggest nuclear detonation in history. [BOLD added - SiG]

The point of that article was that the volcano (which I've come to call just Hunga-Tonga - which is probably like using the volcano's wrong pronoun) injected three times more water into the upper stratosphere than was originally estimated.  It injected 150-million metric tons or almost 40 Trillion gallons of water vapor into the atmosphere.  The concern expressed then was that water vapor is a potent greenhouse gas and it was going to affect the weather for years.  

Guess what. They were right in that last sentence. Not only were sea temperatures higher last year than any year going back to 1981, they're higher so far this year than last year. 

Something that worked in our favor (not just Florida, but the whole US) was that the ENSO switched to the El Niño phase, which tends to produce large scale winds that keep storms offshore and watching storms last year clearly showed a tendency to curve to the north farther out to sea than in La Niña years. The current ENSO state as shown on Watts Up With That looks like this:

Don't ask me to try to remember where it was most of last season, but I think it was in the yellow region around 1.0 to 1.5. It got higher than that, into the orange "strong" band, but never into the red "extremely strong" range. Right now, the forecast is for a 60% chance it will decline further into the La Niña range by June to August and an 85% chance it will be there for fall and early winter. August through September is the peak of hurricane season.

Both the temperatures and the La Niña state of the ENSO are indicators that we probably have a nasty hurricane season coming up. It's probably pointless to talk about Colorado State University forecasting 23 named storms with five category III or higher while University of Pennsylvania is forecasting 33 named storms. It's unusual to get more than one or two in a year and that's the ones you're going to care about. I tend to regard Weatherbell as worth following; they're an expensive subscription service that puts up a season forecast for free. They're calling for an active season as well and provide this map with the red area denoting the highest risks with "Accumulated Cyclone Energy" at 2 to 3 times the averages for a typical hurricane season. (ACE is basically wind strength times the number of hours at that speed)

They also predict 25-30 named storms, pretty much what CSU and UPenn are saying, of which 13-17 become hurricanes and 5-9 become Category III or higher. 

All of which says it seems like it's a nasty season coming. Since we're still 12 days away from the start of the season, some sort of tropical depression or storm isn't out of the question but the NHC says models don't show anything for the next seven days. We tend to see one form in May, typically in the Gulf of Mexico, every couple of years. If you're anywhere in the reddish area on that map, this is a good time to refresh your preps and check the status of things. "Two is one and one is none" and all that.