The Atlantic hurricane season is taking a late August siesta. What’s going on?

In brief: Has the 2024 Atlantic hurricane season been a bust? In short, no. However, we are enjoying a rare period of quietude in late August, and with temperatures incredibly warm in the Gulf of Mexico at present we’ll take it. To get a better idea of what’s going on, and to understand why September is likely to be active, we are sharing this post which was originally published by The Eyewall this morning.

Forecasts called for an incredibly active season

Coming into this hurricane season, there were breathless forecasts calling for anywhere from 20 to even 30 named storms from some folks. Government forecasts were more conservative but even they were the most active we’ve ever seen from NOAA. Colorado State, too. So, as we sit here on August 21st with next to nothing showing up in modeling for the next 7 to 10 days, it’s reasonable for the general public to ask questions about those forecasts.

Back on day one of hurricane season this year, The Eyewall published a piece about ways this hurricane season could essentially fail, or at least turn out “less bad.” We advertise ourselves as no hype, which as comments occasionally show has good elements and bad elements (we seriously thank you all for your support and readership—and constructive feedback only helps us to do better!). But the question was basically “Are we overhyping this season?” And the answer was no: All the elements that you would want in place for a historically active season were in place. All those big time forecasts were justified.

Where are the storms?

One of our potential fail modes was if La Niña developed too slowly. Indeed, the pace of the La Niña development this season, while uneven, has generally lagged the strongest projections. At least officially. Here’s a look at the May 1st European model ensemble outlook for the ENSO 3.4 region, the box of temperatures we look at to basically designate La Niña or El Niño.

The spring forecasts for La Niña have (to this point) turned out a little too aggressive. But directionally, they’ve been fairly correct. (ECMWF)

We should begin closing in on an official La Niña designation in the next month or two, but we aren’t quite there yet. Keep in mind, this is by no means a perfect representation of things, and sometimes the atmosphere can behave more Niña-like even if we aren’t officially there yet. But this has not developed as aggressively as some modeling showed in developing in spring.

So, at a very, very distant level, perhaps that has something to do with it. Michael Lowry, in his excellent daily newsletter pointed out yesterday that wind shear has become almost too extremely reversed this month. Typically, during a La Niña, there is more of an easterly component from the wind that counteracts or reduces the usual west to east winds that can cause shear in the Atlantic, detrimental to hurricane development. In a twist of fate, there’s so much of an easterly component to the upper level winds this year that it’s actually causing easterly shear. Otherwise, we might be a good bit busier at the moment. If you look at the basin as a whole since June 1st, winds have been generally lighter than usual in the Caribbean and much of the Atlantic and a bit stronger than usual in the southwest Atlantic and in the Gulf.

Upper-level winds have been generally below average this summer in some key tropical development areas. As such, we’ve accumulated some bang for our buck this season so far. (NOAA PSL)

Let’s dig a little deeper. One thing that’s legitimately fascinating to me right now is what’s happening in terms of upper level background support in the atmosphere. Using a variable known as velocity potential, we can see that in historically active hurricane seasons, you would expect to see a significant area of rising air in the Indian Ocean, bleeding a bit into Africa (green on the top map below). Opposite to that, there would be a significant area of sinking air in the Eastern Pacific Ocean (brown colors below). Why is this important? In order to generate an active outbreak of storms in the Atlantic, you need disturbances tracking across Africa, which tend to get supported by rising air over and just east of there. You also prefer to see the Pacific undergoing sinking air, as a way to keep it from ‘robbing’ the favorable conditions for storminess. Sinking air suppresses thunderstorm development and tends to dry out the air a bit.

So what’s going on right now? So far this August, we’ve actually *had* what we would expect from a hyperactive season in the Indian Ocean. Click to enlarge the image below.

A comparison of velocity potential in hyperactive seasons (top) vs so far this August (bottom). While we have what we’d expect for a period of high activity, something is out of phase inhibiting things. (Eric Webb/NOAA)

We have a ton of rising air in the Indian Ocean this month (purple & blue on the bottom map above). We have that extending into Africa. This is what you’d expect for a busy season. Where it differs, however is exactly where the sinking air (red/orange in the bottom panel above) is located. In a typical hyperactive season, this is focused over the Eastern Pacific. This year, it’s focused on the eastern side of South America. This is Matt speculating wildly here, but: I suspect that we’re seeing the right ingredients in place, but I think we are seeing them out of phase. The rising air in the Indian Ocean extends deeper into the Pacific, and there is more of a neutral Eastern Pacific signal right now. This is helping boost activity in the Pacific.

Today’s 7 day outlook in the Pacific includes Hurricane Gilma and two other disturbances that are likely to organize. (NOAA NHC)

What is in the west will come east

The problem with the tropics is that support like this generally moves from west to east, and eventually this will change. So the quiet now may change in a very, very quick way come September when this (presumably) shifts. For now, the Atlantic is still seeing rampant dust and a slightly displaced intertropical convergence zone (ITCZ) which is sending disturbances off Africa too far north and into dust. So they die off earlier. This too will change.

Widespread Saharan dust (pink, red, orange) extends across much of the Atlantic, and as disturbances are coming off farther north than usual, they’re hitting the dust head on. (University of Wisconsin CIMSS)

In fact, if you look at the forecast of African Easterly Waves (AEWs) from the latest GFS model, you can see this southward shift approaching heading into the next week or two. The waves lined up over Africa are about 5 to 10 degrees farther south in latitude about 4 days from now, which means they will emerge farther south and in more of a traditional area less exposed to Saharan dust in late August and September.

Tropical waves are going to begin emerging off Africa farther south than they have been recently, which should ultimately lead to a boost in activity heading into September. (Quinton Lawton, University of Miami)

So, yes, things are almost certainly going to pick up soon.

Despite perception, this season’s current accumulated cyclone energy is running nearly 3 times higher than usual! We’ve amassed as much ACE so far this season as we’d typically see by the peak day of hurricane season (September 10th). We’ve done this on the backs of only five storms so far, three of which have been hurricanes, and one of which (Beryl) smashed early season records in the Caribbean and Atlantic.

Accumulated cyclone energy (ACE) this season has been historically high despite the perceived slow start to the season. (Kim Wood/University of Arizona)

So despite the perception that this season has been slow to start, it actually has not been. In fact, 2024 is in rarefied air in terms of ACE to date. This perception might have to do with storm inflation, or the idea that we are naming more storms today than we did, say, 20 or 30 years ago. In 2020, basically the benchmark for recent historically active seasons, today marked the formation date for Hurricane Laura, the 12th named storm of the season. Here we are in 2024 sitting at five, and it’s no wonder the perception is skewed. Despite having more than twice as many storms to this point in 2020, we only had half the ACE (26 vs. 55 this year). 2020 kept churning out mostly sloppy storms until Laura, and then things got nasty. We’ve had three legitimate hurricanes this year and only about one “throwaway” storm (Chris). The takeaway message here is that: We can make up ground in September very, very fast. Very fast.

In summary

So, no, this season’s extremely active hurricane seasons have not been a bust so far, and they probably won’t end up being a bust overall. We’ve had a “bang for our buck” season so far with quality storms over quantity as, say, in 2020. And while we are in a lull now, the setup is probably going to change in 7 to 10 days to allow things to crank up in September. Never call it a bust. If it is one, we can discuss why in November. For now, use this quiet time to review your hurricane preparedness plans and supply kits. And stay tuned here for the latest.


One more day of excessive heat, then slightly milder conditions for the rest of August

In brief: We’re nearing the end of peak summer in Houston, but today is still going to be excessively hot with temperatures in the low 100s. By Thursday we’ll see the start of a slow cooling trend, which will eventually bring us cloudier skies and improved rain chances by early next week.

Wednesday

High temperatures on Tuesday officially reached 102 degrees at Bush Intercontinental Airport, the warmest temperature recorded so far this year. Conditions today will be similar, with mostly sunny skies and very hot temperatures. Winds will be light, from the southeast. Lows tonight will provide scant relief, likely falling only to about 80 degrees. The good news is that today will probably be the hottest day for the rest of 2024. I cannot guarantee that, of course. But probably.

One more day of excessive heat. (Weather Bell)

Thursday

High pressure that’s been situated over West Texas will finally start to back away, and this will slowly start to moderate our conditions. It won’t happen right away, of course, as highs on Thursday could still reach 100 degrees in some locations. But it’s a start. I think there also will be a chance of some isolated showers and thunderstorms, although overall chances will remain quite low, on the order of maybe 10 percent.

Friday

Expect sunny and hot weather, with highs in the upper 90s. Rain chances will be about 20 percent, with isolated to scattered showers possible along the sea breeze.

Saturday and Sunday

Highs this weekend will be in the mid- to upper-90s and precise temperatures at your location will depend on the extent of cloud cover and whether any showers pop up during the afternoon hours. The bottom line is that it will be hot, but not excessively so. Low temperatures should fall back into the upper 70s.

More seasonable weather returns by Friday for late August, in Houston. (Weather Bell)

Next week

As high pressure moves further away, our weather will become increasingly influenced by the Gulf of Mexico. This means we should see partly cloudy days next week, with high temperatures likely in the vicinity of the mid-90s. Daily rain chances will increase throughout the week, starting in perhaps the 40 percent range on Monday, and rising to likely by the second half of the week. We’re not looking at a total washout by any means, but hopefully we’ll see some cooling rains that bring needed moisture to our soils. As I was discussing with a friend yesterday, it really does not get a whole lot better than that in Houston, in August.

Tropics

Nothing is happening. Later this morning we’ll have a post from Matt to explain why that is—during a season which seasonal hurricane forecasters predicted a hyperactive year in the Atlantic.

Houston in the midst of its hottest stretch of 2024, but modest relief is on the way

In brief: Temperatures in our region will likely reach their highest levels of the year this week, with most locations pushing into the low-100s. However, this is probably the worst of it for the year, with somewhat cooler weather arriving by this weekend, and healthy rain chances next week.

Peak heating

Our current stretch of weather will almost certainly be the hottest period of 2024. Houston recorded its hottest day of the year on Monday, 101 degrees, and it was the fourth day of triple digit temperatures in a row. Today could well even be a few degrees hotter, and Wednesday is likely to reach above 100 degrees as well. However, after this stretch we should slowly start to cool down and reach the mid-90s by the weekend. Better rain chances and possibly even cooler temperatures are on the horizon for next week, which gets us into September.

Tuesday’s high temperatures will be rather unpleasant. (Weather Bell)

Tuesday

Today will be extremely hot. Most of the Houston region will see daily high temperatures in the low 100s, with mostly sunny skies and only light winds from the west. This probably will be the hottest day Houston experiences this year as we feel the influence of high pressure and sinking air. Low temperatures on Tuesday night will only drop into the low 80s.

Wednesday

This will be another very hot day, with sunny skies. Temperatures, however, may be 1 to 2 degrees cooler than Tuesday.

Thursday and Friday

As high pressure backs off, our temperatures will ease slightly. Most of the region is still likely to see highs in the upper 90s to 100 degrees, however. Skies remain mostly sunny with rain chances near nil.

Saturday and Sunday

As high pressure backs off further, we should start to see some partly cloudy skies this weekend, and that will assist the downward trend in temperatures. It’s still going to be hot, mind you, but highs will peak in the mid-90s for most locations, with nights dropping into the upper 70s, probably. Rain chances will also return this weekend although they’ll start out on the low side, perhaps on the order of 20 to 30 percent daily.

We’ve got a couple of extremely hot days before relief arrives this weekend. (Weather Bell)

Next week

In the absence of high pressure, our region will lie exposed to the influence of Gulf moisture. This is likely to produce at least partly cloudy skies next week, and daily rain chances. I think highs will be in the low- to mid-90s, and much of the area is likely to pick up between 0.5 and 2 inches of rain—although I am getting deep into the realms of speculation with that prediction. The bottom line is that our overall pattern should change from what has otherwise been a very hot, sunny, and rain-free August.

It will be brutally hot for a few days, but a pattern change is on the horizon

In brief: Houston is likely to see its hottest weather of the year over the next couple of days. But after this, we should slowly start to cool down. Moreover, after a very dry month of August, rain chances should start to noticeably improve beginning this weekend or early next week.

August heat

We’re a little more than half way through August, and so far this month we’ve experienced four 100-degree days, and the lowest daytime high has been 94 degrees. Skies have been almost universally sunny, and many areas have experienced no rain. This is how it often goes in August, and our high temperatures for the next couple of days could be even hotter—many inland locations will reach the low 100s today and Tuesday.

It’s been a very hot start to the month of August. (National Weather Service)

However, over the course of this week we’ll see high pressure that has been anchored over West Texas begin to slide northward, and this will begin to ease the peak-summertime weather in Houston. High temperatures by this weekend should fall back into the mid-90s, and rain chances will start to improve this weekend or into next week. The details of all this are still somewhat in flux, but it’s likely that the end of August will feel different than the rest of the month.

Monday and Tuesday

There’s no way to sugarcoat this part of the forecast. With high pressure in place, today will see excessive heat with high temperatures in the low 100s for much of the region. These may well be the hottest days of this year, so please take heat precautions during the middle of the day. Skies will be mostly sunny with very light winds. There will be about a 10 percent chance of rain, as a few isolated showers may develop along the sea breeze. But mostly, these will be very, very hot days. Overnight lows will only drop to around 80 degrees.

High temperatures on Monday will be brutally hot. (Weather Bell)

Wednesday, Thursday, and Friday

These will also be hot days, but we may trend downward just a bit from the low 100s on Wednesday to upper 90s by Friday. Each day will also see a slightly better chance of rain, perhaps 20 percent, as there’s a little bit more activity due to increased moisture levels. Still, the overall pattern will be one of heat and sunshine.

Saturday, Sunday, and beyond

As high pressure eases off, I think most of the Houston metro area will see high temperatures dip back into the mid-90s this weekend. At the same time we may start to see the influence of low pressure from the Gulf of Mexico. I don’t know if rain chances will improve a whole lot this weekend, but at some point in the next week or 10 days, we’re likely to start seeing much better daily odds for rainfall. So for Saturday and Sunday I’ll say there probably will be some scattered showers and thunderstorms, with better chances for more coverage into next week.

Ernesto is headed to the exits. (National Hurricane Center)

Tropics

Hurricane Ernesto is in the northern Atlantic, and will pass not all that far south of Newfoundland today and tonight before it accelerates eastward across the open Atlantic. Beyond Ernesto, the tropics look to remain quiet for at least the next week.