A little to watch in the Atlantic, while Hawaii may see another storm this weekend

In brief: A couple tropical waves will emerge off Africa in the coming days, with some at least a little risk of development as they push across the Atlantic. Meanwhile, Hawaii may be faced with another tropical storm by the weekend, along with heavy rainfall.

Happy Thursday. Trying not to inundate your inbox all week with mostly a repetitive outlook, hence why we were dark yesterday and Tuesday. But let’s check in on things today and see what has changed. The answer is not a ton. That said, we do have a couple things to watch.

Atlantic waves

We have two tropical waves over interior Africa. One will emerge today. The second is expected to emerge in the Atlantic by about Monday or early Tuesday. There seems to be a good bit of model agreement that the first one will fizzle but the second one has a chance to try to organize. I wouldn’t be shocked to see this area flagged on NHC outlooks by tomorrow. (There will be a third system in the open Atlantic but we’ll conveniently ignore that one for the time being)

The next couple tropical waves off Africa. Wave #2 is the most interesting. (WeatherFront)

That said, as we saw last week, there can be a fair bit of model support for something to happen and it never happens. We’ve seen that more than once over the last 2 to 3 seasons. The last go around last week saw Google’s Deep Mind operational model correctly be unenthused about tropical development. This go around? Well, there’s at least a little there there.

The second tropical wave off Africa may make a slight attempt at developing next week. (Google Weather Lab)

The overall weather pattern off Africa next week suggests that we’ll see a good bit of dry air, especially north of the waves. The first one will probably fall prey to this, and development odds seem quite low. The second one has at least some chance to fend the dry air off for a bit. We’ll also have a modest amount of wind shear around. The combination? It may be enough to allow for some slow development and also cap the system at a lower ceiling of potential intensity. Indeed, very few ensemble models, even on some of the more aggressive models intensify any potential system much.

Obviously, we’re getting a little ahead of our skis here going out a week and trying to predict the environment of a system that has yet to even emerge off Africa. Whatever the case, it is something to watch. But it is probably not going to amount to much. Model agreement is also good that we’ll see this system eventually turn northwest or north in the open Atlantic, meaning it probably won’t impact land. Again, it’s a ways out, so we’ll keep tabs on this for the time being.

Aside from that, there is nothing else notable in the Atlantic for the next week or more.

Hawaii again?

As Hawaii continues to recover from Lala, the next system to at least keep tabs on is in the wings. Invest 90E is a disturbance about 1,000 miles southeast of the islands. Most modeling keeps this system on the weaker side (unlike Lala which most had forecast to be a hurricane when it approached Hawaii). Google’s operational ensemble only has about 20 percent of members actually developing this. However, some prior iterations of GDM and some of the other AI modeling is more aggressive here.

Google’s 1,000 member ensemble likes development of Invest 90E. (tcatlas.org)

Even Google’s 1,000 member ensemble is pretty aggressive with things. So for a storm that’s likely to impact the islands this weekend, we have uncomfortably high disagreement among modeling. Whatever the case, another round of potentially heavy rainfall and gusty winds is a plausible outcome for some of the same areas impacted by Hurricane Lala. While it’s impossible to really pin down the specifics yet, a 5 to 10 inch type rainfall is a possibility in some of the eastern/southern facing slopes of the Big Island and Maui. More to come on this one tomorrow.

Groundhog Day in the Atlantic with mercifully quiet conditions continuing

In brief: Hurricane Lala did quite a number on Hawaii, and we review some of the numbers. Meanwhile, the Atlantic basin remains mostly void of anything interesting, as we officially begin the peak 45 days or so of hurricane season.

Lala wrap-up

I won’t delve too much into the actual impacts to Hawaii, but as of this morning, roughly 115,000 customers remain without power across the islands, which is down a good bit since yesterday. For the latest on impacts across the islands, check the coverage at Honolulu Civil Beat or the Hawaii Tribune-Herald. Meteorologically, what played out was indeed fascinating.

Big Island rain totals. (NOAA)

Over 37 inches of rain was reported on the south end of the Big Island, at Nene Cabin, which is on the upslope of Mauna Loa reportedly at over 6,000 feet of elevation. Downwind, in the rain shadow of Mauna Loa? Under 1.5 inches of rain fell near Captain Cook. Incredible rain shadowing. Either way, the totals were impressive. On Maui, on the upslope of Haleakalā, over 24 inches fell at Waikamoi.

Maui rain totals. (NOAA)

Similar impressive rain shadowing occurred there. Honolulu didn’t see much rain, but the mountains got hammered. Same story on the other islands as well.

Oahu rain totals. (NOAA)

In terms of wind, peak gusts topped out around 70 to 90 mph in the higher terrain from Oahu through the Big Island. A fair bit of wind also occurred at lower elevations, as evidenced by the number of outages, but they were not quite as potent as what we saw in the mountains.

A sampling of peak wind gusts during Lala. (NOAA)

Lala will be a memorable storm for Hawaii, though certainly not the worst they’ve seen.

Atlantic on lockdown

Back in the Atlantic basin, it’s been a little busier this month, with Cristobal and a couple invests, but both of those invests are now off the board. A look at the Atlantic this morning tells us, well, not much. It’s dead quiet, with the exception of the next robust wave emerging off Africa.

Thunderstorms about to emerge off Africa for the next tropical wave to watch. (WeatherFront)

This one is likely to meet the same fate as its predecessors. The one behind it seems destined to reach invest status eventually, but the models are in good disagreement on development, with both the Euro ensemble and Euro AIFS trying to do something with it by late this week. Google’s Deep Mind is unimpressed. I would not be expecting much from these waves. They seem destined to eventually extinguish.

We’re now officially entering the peak of hurricane season. From now through about October 7th, the Atlantic basin climatology adds about 1 unit of ACE (accumulated cyclone energy) per day, taking us from around 15 units of ACE to 102 units. In other words, this is the window you historically see the bulk of hurricane activity in the Atlantic basin.

(NOAA/NHC)

With El Niño, and a near-record one at that, the equation changes and “bulk of hurricane activity” tends to have a different, lower adjusted meaning. We are already seeing plentiful signs that El Niño is influencing hurricane season, and there’s absolutely no reason to expect change. Looking ahead to next week, the European model’s 45-day outlook continues to show below normal Atlantic activity.

Next week should see below average activity continue. (ECMWF)

Subsequent weeks? Much the same. And keep in mind that the European model has tended to be a little overzealous with recent tropical waves. So 40 percent of normal ACE the next 2 to 3 weeks may be generous.

Whatever the case, we shall see where this all goes. But for now, calm remains the word across the Atlantic.

Atlantic risks dissipating, while Lala approaches Hawaii

In brief: Invest 94L’s future is obliteration, as the Atlantic settles back down. Tropical Storm Lala will bear down on Hawaii today and tomorrow with strong winds and heavy rainfall.

Atlantic update

The risk of any tropical development in the Atlantic has all but vanished at this point, with the odds of Invest 94L developing down to 10 percent today.

Satellite view of Invest 94L on Saturday morning. (WeatherFront)

This is very reminiscent of 2025, when the models would get a little excited about a wave in the Atlantic, only to have it stumble and faceplant in the end. Invest 94L looks to be obliterated by wind shear and dry air issues.

The next one to watch will be the next wave to emerge off Africa. At this point, I see no reason why this won’t meet a similar fate to 92L and 94L. We’ll keep watching.

Tropical Storm Lala

Meanwhile near Hawaii, Lala is beginning to bear down on the Big Island. Some of the higher elevation locations are gusting over 50 mph now.

Tropical Storm Lala approaching the Big Island on Saturday morning. (WeatherFront)

There is still some chance that Lala could attain hurricane intensity on approach to the Big Island, but it’s not going to change the forecast impacts much. Strong winds, heavy rain, and rough seas remain the story.

As Lala passes the Big Island, the interaction with the mountains is likely to lead to some erratic movement and weakening. It will re-emerge on the other side, jostle north a bit, and then go back on its west-northwest track.

Rain forecast from Tropical Storm Lala as it passes Hawaii. (NOAA WPC)

The total forecast rainfall from Lala has not changed a significant amount since yesterday, with upwards of 25 inches possible on the windward side of the Big Island. Yesterday, when I was discussing major impacts to the Big Island, I neglected to include 2018’s Hurricane Lane. Although it passed well south and west of the islands, it slowed, weakened, and allowed for punishing rains of almost Harvey levels to impact the Big Island. Lane’s problem was that it slowed and nearly stalled. In this case, Lala should continue moving. So generally speaking, while there will be serious rainfall with Lala, we probably aren’t looking at something like that.

Winds will likely cause some damage, especially in Maui and on the Big Island. The strongest winds will be in the high terrain and downwind from the higher mountains, with tropical storm force winds a possibility across the entire island chain. For places like Oahu, the intensity of the wind may depend a bit on how far north Lala comes before turning back west-northwest.

The forecast track of various Google AI models and the European ensemble around Hawaii. (Google Deep Mind)

There’s a lot of spread still, with some model ensemble members coming only within about 60 to 80 miles of the other islands. So folks outside the hardest impacted areas will need to take this seriously.

After tomorrow, Lala will be on its way west and the cleanup can begin.

Tropical Storm Lala anything but boring as it tracks toward Hawaii

In brief: Neither Atlantic system appears to have much of a future ahead of itself. However, Tropical Storm Lala will hit Hawaii, probably as a hurricane this weekend. We detail the impacts and put some historical context around it below.

Atlantic update

Development odds on Invest 92L have been nudged back this morning, while Invest 94L is basically unchanged. Neither system looks especially great and neither has particularly good long-term prospects.

(WeatherFront)

For Invest 92L, it will continue into the islands tonight and tomorrow, then across the southern Caribbean as a remnant. No further development is expected once in the Caribbean.

For 94L, the prognosis might be a little less grim. It’s playing the Tortoise and the Hare game, where slow and steady wins the race. In this case, “winning the race” is basically just acquiring status as a depression or tropical storm. It will move slowly west and west-northwest across the Atlantic, arriving at the doorstep of the islands by about early to midweek next week. The slow movement likely exposes it to strong wind shear at times. This will likely keep a lid on development prospects to some extent, which is why this carries about a 50/50 chance versus an 80/20 chance or something.

Of the 51 members of the AIFS, as an example above, only about 5 to 10 percent keep 94L coherent past the islands, most on the very low end of intensity too. (Tomer Burg)

Neither Google Deep Mind, nor the AIFS really do much with this system. Even the occasionally robust European ensemble has little. Basically, 94L seems destined to be not much of anything.

Behind 94L, we don’t have any real specific systems of note, so the Atlantic continues onward quietly.

Tropical Storm Lala and Hawaii

Lala was named yesterday, shortly after our morning post. It’s a strong tropical storm now, with max sustained winds of 60 mph. Expect Lala to become a hurricane later today.

TS Lala this morning. (WeatherFront)

Lala is in an environment of low shear now, only around 6 kts or so out of the west, per tcatlas.org. If there’s one health issue with Lala, it’s that it’s got a bit of dry air stuck in the mid-levels of the storm. So while it’s doing well, it has some underlying issues that could impede it at some point. But for now, we’re on the way to hurricane intensity with Lala by later today in all likelihood.

As Lala comes west, it will begin to “feel” the impact of the Big Island of Hawaii. Mauna Kea is almost 14,000 feet tall, so that obviously has some impact on approaching storms. In this case, it will likely slow Lala down and may lead to erratic motion. As this happens, a boatload of rain will fall on the east/southeast facing side of the Big Island.

Forecast rain totals for Lala (NHC NOAA)

Upwards of 25 inches of rain could fall on the eastern part of the Big Island, on the east slope of Mauna Loa, south of Hilo in Puna, and just inland from Kilauea. Of course, having two monster peaks in Mauna Kea and Mauna Loa means the west side of Hawaii gets rain shadowed. So the Kona region may only see 1 to 4 inches of rain. Look for high totals on the east shore of Maui from Hana into the Upcountry, heading up to Haleakalā. Lower totals are likely for the other islands.

Obviously, concerns about flooding and mudslides will be high in southeastern parts of Hawaii and flood watches are posted for the Big Island and Maui.

Beach erosion and coastal flooding are possible in the islands, especially on the Big Island. And obviously, rough surf advisories are posted with the increasing swells likely ahead of Lala.

With breezy and dry conditions ahead of Lala’s circulation, there could be some elevated wildfire risk today (Friday) in the islands.

Lala is expected to be a category 1 hurricane as it passes the Big Island, so wind gusts will be strong, especially given the terrain impacts of the Big Island and Maui. Winds will be less of a concern farther to the north and west in the island chain.

Google Deep Mind intensity forecast for Lala over the next 72 hours. (tcatlas.org)

Intensity-wise, Google’s Deep Mind shows Lala becoming a borderline category 2 storm as it passes the Big Island. Notice how it weakens after 48 hours. Land interaction may significantly disrupt Lala and it will need some time on the other side of the islands to get itself back together. Either way, this is likely to be a significant storm in terms of impact for Hawaii. This may be the most significant storm since 2014’s Tropical Storm Iselle on the Big Island.

Known hurricane history around Hawaii since the 1800s. (tcatlas.org)

Iselle was a hurricane ultimately, but a tropical storm as it passed through the Big Island. With Lala expected to be a hurricane and coming dangerously close to a direct hit, this could be a historic storm for the Big Island. A Hawaiian island last took a direct hit from a hurricane in 1992, when much stronger Hurricane Iniki hit Kauaʻi.

Folks in Hawaii should be prepared for Lala.