Matt Lanza

A look back at the 2023 Atlantic hurricane season as we bid it adieu today

One-sentence summary

It’s November 30th, so today’s post will take stock of what was a very interesting hurricane season.

By the numbers

The 2023 Atlantic Hurricane Season was a busy one. It wasn’t so much that there were a lot of large storms; the season itself had “only” 7 hurricanes and 3 major hurricanes, which is spot on normal for a typical hurricane season. But we had a lot of storms that lingered for awhile, traversing the open Atlantic for a long time.

The 2023 Atlantic hurricane season featured an extremely active Atlantic, an extremely quiet Caribbean, and a mostly quiet Gulf. (NOAA)

Recall that ACE, or accumulated cyclone energy is calculated using just the wind intensity and duration of a storm. It’s an inherently imperfect calculation, but it serves us well in terms of putting a season into context. Examples of recent seasons with ACE values in the “hyperactive” category include 2020, 2017, 2010, 2005, and 2004. Not many would argue that those seasons were anything but busy. 2023 falls into the next bucket of seasons, which are considered above normal. Our ACE will finish the season around 145.5 units, falling short of the 159.6 needed to be a hyperactive season.

You can see how seasonal ACE behaved relative to climatology (normal) for 2023. Other than some differences in amplitude and slope, the season behaved normally but was a bit busier than usual. (Colorado State University)

Because of the duration of some of the stronger storms, the 2023 season certainly felt above normal. As noted, ACE is not perfect, but it tends to do better from a seasonal standpoint than number of storms. As our capability to name a greater number of storms increases, the actual storm count means a bit less than it used to perhaps. But ACE manages it better.

Speaking of, we will finish with 20 named storms this year. We managed to get to Tammy, leaving Vince and Whitney unused.

Why was the Atlantic so busy? Why were the Gulf and Caribbean not very busy?

Let’s talk for a quick moment about what happened this season. From the map at the top of this post, you can see that the amount of traffic in the open Atlantic was excessive. Other than Arlene, Idalia, and Harold in the Gulf and Franklin and Bret in the Caribbean, all of the action was in the open Atlantic. So why was that?

If you look at the upper air pattern for August and September, when 13 of the 20 storms occurred, you can sort of understand what happened. We’re looking 20,000 feet up here at what we call the 500 millibar (mb) level of the atmosphere. This is a good proxy for steering currents, or what will move tropical systems from point A to point B.

An annotated map of the 500 mb level (20,000 feet up) showing average August & September steering currents across the Atlantic Basin (NOAA)

What can we make of that map? A couple things. Let’s work left to right on the map above. First, over Texas, high pressure was stagnant. It was arguably the worst modern summer in Texas history in terms of heat, but it did keep storms out of the western Gulf. So that kept that part of the basin quiet. For the eastern Gulf, we managed Idalia in there, the one bad storm that found its way northward into the U.S. But overall, most storms would have been directed northward off the East Coast based on this map due to pretty persistent low pressure in the upper atmosphere off the New England coast. This is also to blame for the extremely wet summer in that part of the world.

We also had low pressure northeast of the Azores. When you have low pressure systems like that one and the one off New England, you are often going to induce a poleward motion to the tropical system. In other words, they feel the “pull” north. All tropical systems generally track west, then north, then northeast in Atlantic (with plenty of notable exceptions). But on the long-term average, that’s what we see. In this case, they had help this season, and that’s why so many “fish” storms occurred and so many impacts to Bermuda occurred out in the open Atlantic.

Did the much hyped warm oceans play a role?

When the season began, one thing we honed in on right here in The Eyewall’s early days were sea-surface temperatures. The Atlantic, the Caribbean, and the Gulf were all record warm at times this hurricane season. The August and September mean of sea surface temperatures (SSTs) was above normal virtually everywhere. Why is there that pocket of so much cool water off New England and southward? Hurricanes Idalia, Franklin, and Lee all worked to basically devour all the warm water there.

Sea-surface temperatures at the heart of hurricane season showed warm water everywhere — except the northwestern Atlantic, which was drastically cooled by Hurricanes Franklin, Idalia, and Lee. (NOAA)

When the season began, we noted that the extremely, if not record warm SSTs were enough reason to justify an active hurricane season forecast. Many articles were written across the media about this. And indeed, that is what allowed most seasonal hurricane forecasts to come close to verifying this year. Instead of the 16/7/3 consensus forecast for the season, we got 20/7/3 for our storm/hurricane/major hurricane slash line this year. I will say this: It takes courage to call for an active hurricane season in the face of one of the strongest developing El Niño events in recent memory. So kudos to those that stuck to that logic, despite what history has told us about El Niño.

What about El Niño? Did it matter at all? What else?

The answer to whether El Niño mattered or not this year is “sort of.” Wind shear is usually enhanced during El Niño summers, especially over the Caribbean. That did not actually happen, but we did see very strong shear near the Gulf Coast this season.

Wind shear was strong near the East Coast and generally weaker out over the open Atlantic. (NOAA)

While I think that was notable, the dry air in the western part of the basin didn’t hurt. With high pressure dominant and so much drought development on the Gulf Coast this summer, it definitely worked to help mitigate any storms.

Above normal relative humidity about 10,000 feet up dominated the open Atlantic, while dry air dominated most of the northern Gulf Coast. (NOAA)

So it was an interesting season. It’s worth noting that the average of the strongest El Niño hurricane seasons (taking the July-September ONI from NOAA) was 9 storms, 4 hurricanes, and 1 major hurricane. Suffice to say, 2023 will go down as one of the most active El Niño hurricane seasons ever recorded. That’s a little concerning given that an El Niño of this magnitude is usually enough to mitigate things. That only partially happened this year, in part due to the extreme warmth in the Atlantic. So does that mean that if we live in a world of more permanently warmer SSTs, El Niño might not matter as much when it comes to hurricane season? It’s a tantalizing and unsettling question, but it’s one we should be asking.

Thanks to those of you that joined us on this journey for the hurricane season and put your trust in our commentary. We are appreciative of your support. The Eyewall’s parent site, Space City Weather is holding a fundraiser for a couple more days. Any contributions you make will go toward both sites. If you feel compelled, click here to donate or purchase some Houston-focused swag. Thanks for considering! We will be back from time to time through winter with an update on big weather when we can. Stay with us, and enjoy the non-hurricane season!

Thanksgiving week weather outlook features mostly minor headaches in spots

One-sentence summary

Thanksgiving week travel looks a little sloppy in spots at times, but we can hopefully avoid any massive travel disruptions this year, at least due to weather.

Thanksgiving week outlook

It’s never easy, right? Travel anytime of year is a crapshoot to be sure, but of course during probably the busiest travel week of the year, we punctuate our mostly benign autumn with a fairly big storm. Different days this week will have different hazards in different parts of the country. As of now, it doesn’t look like we’ll see anything severely disruptive, but there are a couple things to point out.

Today: Severe weather risk in the Deep South

The main story for the Monday phase of this storm will be severe weather risk for the Southern US. Louisiana and Mississippi seem to be the prime spots at risk today for strong winds, hail, and possible tornadoes.

As of Monday morning, an enhanced (level 3/5) risk for severe storms was in place between extreme east Texas, across northern Louisiana and into parts of southwest Mississippi (NOAA SPC)

The tornado threat is not a guarantee, but if storms can maintain themselves individually in Louisiana or extreme eastern Texas (before “lining out” into bands of t’storms), a strong tornado or two will be possible. Either way, reports of hail and strong, damaging winds are possible, if not likely with storms today that should get going through the afternoon hours. The severe risk will push into Mississippi later this afternoon and evening and into Alabama and parts of the Florida Panhandle perhaps by the overnight hours, with a continued severe risk. Some adjustment of the above risk is possible before the end of the day today. If you’re traveling in this region today or tonight, please ensure you have the ability to receive weather warnings.

Tomorrow: Rain & wind in the Northeast and Midwest

The storm itself will track from about the Red River Valley into southern Michigan or near Lake Erie between today and tomorrow. This means that on Tuesday, we’ll begin to see widespread rain, thunderstorms, and gusty winds in the Eastern U.S. Gusty winds will likely delay some flights to and from places like Chicago, Detroit, Cleveland, or Pittsburgh.

Gusty winds will be strongest in Appalachia, as well as into parts of the Midwest, where gusts of 30 to 40 mph will be possible through Tuesday. (Weather Bell)

Rain may begin as a wintry mix for parts of the interior Northeast as well. Overall, this won’t be a massive storm up that way, but it will be enough to cause disruption.

The primary severe weather risk tomorrow will be with the continuation of storms overnight into the morning hours moving across Alabama and the Florida Panhandle.

Wednesday: Improving, except in the Northeast

Boston and New York may still see some gusty winds on the backside of the storm Wednesday as it exits in the morning.

Some fairly strong wind gusts on Wednesday may impact flights into Boston, southern New England, or the NYC metro airports. (Weather Bell)

Gradually improving weather is expected during the PM hours, but some of those wind gusts in the front half of the day may cause some travel headaches.

Elsewhere, there’s at least a subtle severe risk in eastern North Carolina before the front exits, but that’s not expected to be a big deal.

Thanksgiving Day: Showery Gulf Coast, snowy Wyoming?

Travel overall looks fine on Thanksgiving Day if you’ll be hitting the road. The two exceptions to this are on the Texas Gulf Coast and in Wyoming.

For Texas, showers are possible between about Laredo and Matagorda Bay south through Corpus Christi and the Valley. This won’t disrupt travel much, but it could put a slight damper on any outdoor Thanksgiving plans.

Potential snow from the National Blend of Models, most of which falls Thursday in Wyoming. This is subject to change, but some travel disruption is possible in this region into southern Montana. (Pivotal Weather)

The situation in Wyoming and southern Montana is a little trickier, as is always the case with snow forecasting more than a day or two out. A storm seems likely to deliver some wintry weather to the region on Thanksgiving Day, but exact amounts are TBD. Whatever specifically happens, if your travels take you to Yellowstone or portions of northern Wyoming and southern Montana, you will want to be prepared for some travel difficulties.

Friday: Storms in the Southeast, snow into Colorado?

The aforementioned winter storm in Wyoming on Thursday will probably slide into Colorado on Friday bringing a chance of winter weather there that could cause some travel issues.

A moderate risk for travel issues across Colorado exists on Friday as a winter storm slides in. Details and specifics will be sorted out in a few days. (NWS Boulder)

Travel impacts are currently expected to be on the moderate side across Colorado, so if you are traveling from Denver to go skiing or visit the mountains on Black Friday, you will want to be ready to deal with some weather.

Elsewhere, the showery system in Texas on Thursday will move across the Gulf Friday, bringing a chance of showers and storms to the Southeast, particularly Florida. The rest of the country looks pretty good.

This weekend: Some uncertainty

The weekend looks ok at this point, with the Colorado system diving into the southern Plains bringing a chance of showers. Additional showers are possible on the East Coast later Saturday and Sunday, but as of now nothing looks too serious. We’ll keep tabs on things.

November 17, 2023 Outlook: Last call for the tropical Atlantic and a sneak peek at Thanksgiving travel weather

One-sentence summary

Potential Tropical Cyclone 22 has a narrow window to develop before tomorrow when it slams shut in the Atlantic, and today’s post covers Wednesday travel weather which looks good with a couple big exceptions.

Potential Tropical Cyclone 22

We were expecting that Potential Tropical Cyclone 22 would become Vince later today as it races northeast across Jamaica, Cuba, and the Bahamas.

How to describe PTC 22? Quick and lower-end on the intensity scale. The main concern will be heavy rain as it races off northeast into the open Atlantic. (NOAA NHC)

But a look at satellite this morning suggests that 22 is still far from organized. The window for organization will remain open a bit longer before it slams shut, and 22 or Vince or whatever merges in with a non-tropical system in the open Atlantic, as it passes Bermuda.

PTC 22 lacks much organization whatsoever this morning, and it seems like getting to a true tropical storm will be an uphill battle. (Weathernerds.org)

So if PTC 22 were to become a tropical storm as it passes Jamaica, Cuba, and/or the Bahamas and Turks & Caicos Islands, how strong could it get? Not very. The ceiling on 22 is limited, probably to a minimal tropical storm. That said, it is going to bring a good deal of rainfall to the islands as it passes by, and as much as 8 additional inches could fall for portions of Jamaica or a bit more in southeast Cuba. As much as 4 to 8 inches or so will be possible in southern Haiti.

Rainfall from PTC 22 will be about 8 more inches in Jamaica, up to a foot or so in SE Cuba, and perhaps 8 inches or more in southern Haiti. (NOAA WPC)

So flooding is the primary concern with 22 as it trucks through the Caribbean and into the Atlantic today and tomorrow. With that, we suspect that the 2023 Atlantic hurricane season will come to an unofficial close.

Thanksgiving Wednesday travel outlook

With a lot of people hitting the road next week for the Thanksgiving holiday here in the U.S., we thought it might be helpful to give you an initial read on what travel conditions may look like for Wednesday.

The forecast map for Wednesday shows a stormy Northeast US and southeast Canada, a quiet central and western US, and some scattered storms in Florida. (NOAA WPC)

So, right off the bat, travel in the West looks fine right now. No issues are expected Wednesday. The Central U.S. looks quiet as well. A cold front will deliver scattered thunderstorms to Florida, this after some potential severe weather on Tuesday in the South. But overall, other than some minor issues, the expectation is that any travel to or from Florida will be fine.

The trouble spot on Wednesday looks to be the Northeast, Great Lakes, and Canada, where a potent storm will bring a bunch of issues for Wednesday. Chief among those issues will be wind, which is likely to cause delays at Northeast hubs like Boston, the NYC metro airports, and perhaps Philly and DC. Conditions should gradually improve later in the day Wednesday it appears, but there may be cascading delays due to airline issues there. I would also watch Chicago for potential issues with wind, which can always impact the air travel system. Aside from wind, some heavy snow is likely in parts of Quebec and interior Ontario, and some lake effect snow is likely in the snow belts of Michigan and perhaps off Lakes Erie & Ontario as well.

So if your travel plans take you north and east of about Indiana, you’ll likely want to have a little extra patience this year.

November 14, 2023 Outlook: South Florida flooding risks increase on Wednesday, while a separate Caribbean system makes a brief attempt to develop

One-sentence summary

Two separate systems are on the board, with one (non-tropical system) bringing heavy rain to Florida tomorrow and then heading off to the north, while another disturbance in the Caribbean has a chance to form before racing past Jamaica, Cuba, and Hispaniola later this week or weekend.

Florida flooding: Metro South Florida at risk for considerable flash flooding on Wednesday

Just a quick update this evening on what’s happening in the world of weather, and we’ll start in Florida. Areas just north of Miami have seen some heavy rainfall today, with two bullseyes of 4 inches or more, the first near Davie and the other around Pompano Beach, where over 5 inches has fallen.

Click to enlarge for impressive rain totals today north of Miami and west of Fort Lauderdale. (NOAA/RadarScope)

As showers diminish tonight, a quiet period will unfold before another, more widespread round of rain and storms tomorrow. This one will be capable of significant rain totals in excess of 4 to 6 inches to as much as 8 inches or even more tomorrow for parts of coastal, urban South Florida. Because of this, the NWS Weather Prediction Center has Miami-Dade, Broward, and portions of Palm Beach County under a moderate risk (level 3 of 4) for excessive rainfall and flooding risk on Wednesday.

A moderate risk (level 3 of 4) is posted for southeast Florida on Wednesday, as repeated rounds of heavy rainfall are possible, leading to more significant urban flooding. (NOAA)

Intriguingly (and somewhat confusingly), all of this may congeal into an area of low pressure off Florida’s east coast that has a low (albeit not zero) chance of developing into a tropical system as it races north and east. This is *not* the same system we’re watching in the Caribbean, but this one may produce a nor’easter type impact in eastern New England or Atlantic Canada by the weekend, including a chance of heavy snow on the back side of the storm for portions of Quebec, New Brunswick, or northern Maine.

Heavy snow is possible in portions of northern Maine and eastern Canada on the backside of this developing storm near Florida, as it comes north this weekend. (NOAA)

Tropical Update: Caribbean development remains possible later this week

Meanwhile, we continue to see at least the chance that a late season tropical system will form later this week in the Caribbean. The good news is that both the GFS and European model have tended to reduce the odds of anything significant developing.

Disorganized thunderstorms in the southwest Caribbean may develop into an organized system before it races north and northeast out to sea by the weekend. (Weathernerds.org)

So what was already a low chance of a significant storm is now quite low. Certainly heavy rain is possible, if not likely across the Caribbean, but getting this thing to depression status or even TS Vince, will take some effort. Can it get there? Sure, but I’m not sure it’s the most likely outcome. Regardless, interests in the central and western Caribbean should continue to monitor this thing until it passes.