July 14, 2023 Outlook: We have Don, which should remain averse to land

One-sentence summary

Subtropical Storm Don formed overnight, the 4th named and 5th overall storm of the 2023 season, but it is thankfully no threat to any land.

Happening now: Don!

Invest 94L was upgraded to Subtropical Storm Don early this morning. The “subtropical” designation is technicality. Storms that are tropical in nature form within and feed off of warm, tropical water and air. Being subtropical doesn’t make it any less of a storm, but the process by which it forms and strengthens is more hybrid in nature…like a nor’easter or a tropical storm mashed together. Usually, subtropical storms are a bit lopsided and larger in size. Over time, a subtropical storm can transition to fully tropical, but it’s not clear if Don will do that or if it will even stick around long enough to have a chance.

The forecast track for Don brings it due north, then east, then southeast as it is pushed around by steering currents. (NHC)

As noted yesterday, Don’s forecast track resembles a horseshoe, going north, then east, then southeast. This is because it will be pushed around by various moving parts in the atmosphere over the open ocean.

STS Don is meandering over the open ocean and not expected to have much, if any impact on any land masses, including the Azores (the little islands on the right side of the map). (Weathernerds.org)

Don has 50 mph winds this morning. It’s a respectable looking system, but clearly not terribly menacing looking. The wind field is fairly large, with tropical storm force winds extending out over 200 miles east of the center. Don’s future intensity will be influenced in part by cooler waters, so we should see a slow weakening. It may or may not survive through the weekend, but if it does, it has some chance to get some of its bluster back as it moves south next week, back over warmer water. Eventually it should be picked up and sent away, however.

The medium range (days 6 to 10): Wave emerging off Africa may have a low chance to organize

Some models are picking up on a tropical wave in the Atlantic, which appears to be this big one emerging off Africa this morning. This is certainly one of the most robust waves we’ve seen this season.

A robust tropical wave is emerging off Africa this morning. This may become a feature to watch as it transits the ocean, but modeling remains lukewarm at best on its development chances. (Weathernerds.org)

This wave’s future is a bit sketchy. Some modeling is warming to the idea of slow development next week, but the vast majority is cool to that chance. I would say that it’s an item to watch but unlikely to be an item of serious concern. We’ll see where we are on Monday with this one.

Fantasyland (beyond day 10): Nothing else of note

Really, things look pretty quiet outside of this wave off Africa and Don’s meanderings in the open Atlantic. Modeling is fairly calm for days 11 through 15. The European model’s extended output ticked back up activity odds a bit in weeks 3 and especially 4 yesterday. I think sometime around August 10th, give or take, it will be time to watch the big picture a bit closer. We shall see.

July 13, 2023 Outlook: Short-lived, open Atlantic Invest 94L is the only item on the board

One-sentence summary

A disturbance in the north-central Atlantic presently remains the only area of note over the next 7 to 10 days, and it will not threaten any land.

Happening now: Mid-ocean madness!

That subheading is a bit dramatic, but it’s been quiet enough of late, so we’ll let that go. Anyway, as we gaze upon the open Atlantic between Bermuda and the Azores this morning, we can see an area of cloudiness and storminess sitting over that part of the world. Yesterday, it received the invest designation, meaning meteorologists have enough evidence to run some additional modeling on this area.

Invest 94L is a heavily lopsided system with a 60 percent chance of becoming a depression over the next couple days before runs into problems and likely fizzles out (Weathernerds.org)

Invest 94L has about a 60 percent chance of developing over the next few days before it runs out of support in the open Atlantic. It will not threaten any land, and at worst, it should become a minimal tropical storm. Chaotic steering currents and a weak system will make 94L, whatever it becomes, susceptible to being bullied around, and as such, the potential track looks a bit like a horseshoe.

The track of Invest 94L will likely bring it north, then east, then south again as it meanders over the open Atlantic. It’s likely to fizzle out before day 5 or so. (Tropical Tidbits)

This type of track, odd as it seems, is not that uncommon in this part of the world. When storms develop out in the hinterlands of the basin, they can do weird things, because they are often and weak and just going to get pushed around by whatever influences exist at the time in those areas. We’ve seen storms do loop-de-loops, curly-Qs, stutter steps, somersaults (ok not really), and more. So, yes, it looks difficult to wrap your head around perhaps, but it’s not uncommon. That it is happening in mid-July does make it a bit uncommon, as we’ve discussed this week.

Anyway, over the next few days, 94L will possibly rev up, rev down, and eventually falter as it has to manage shear and cooler waters.

The medium-range (days 6 to 10): Nothing for now

There is nothing of note in the medium-range that we can see at this time. I will note, however, that one way to get a homebrew-type storm (a system that forms somewhat unexpectedly close to the coast) is to pile complexes of thunderstorms into the Gulf of Mexico. Over the next week or so, that’s sort of what we may see happen, as areas of thunderstorms meander around the eastern periphery of high pressure anchored over Texas and the Southwest.

The European operational model forecast of rainfall for the next week shows occasional areas of thunderstorms drifting across the Southeast and/or into the far northern Gulf. Normally, we’d keep tabs on these to be safe, but it does not look as though any of this will threaten development. (Pivotal Weather)

As of today, I see no reason to think that any of this would form. But with enough “oomph” it becomes something to watch. For now, that’s not expected, but I at least want to point it out to you so you can see a little more of what we look at and why we don’t just rip and read models verbatum.

Fantasyland (beyond day 10): Let’s look way out beyond day 10

As of today, nothing is showing up out there in the distant future. Things look quiet into most of days 10 to 15 or so.

The ECMWF model recently completed a major upgrade that allows a 100 member ensemble to run once a day to produce a forecast 3 to 6 weeks out in time. In other words, it runs the model 100 times with various tweaks to produce various outcomes. One product it does produce out 3 to 4 weeks is a tropical cyclone frequency and accumulated cyclone energy (ACE) forecast. I try not to read too much into these, as they can be somewhat noisy. Just this week, they suggested more activity in weeks 3 and 4. But as of yesterday’s run, that had backed off.

The ECMWF week 3 tropical storm frequency forecast shows the Atlantic about average for week 3, July 31st through August 6th. (ECMWF)

Still, it’s a nice tool to have. It currently shows near average activity for weeks 3 and 4, sort of what I would have expected when looking at the bigger picture right now. That is not to say that things cannot get active in that timeframe, just that sitting here today, we don’t necessarily expect it to happen. There are some hints that later in week 4 or week 5 (mid-August), we may see the Atlantic develop a more favorable “background state,” which could lead to a more hospitable environment for tropical systems. We will see how that progresses forward in time. For now, rest easy and enjoy the quiet!

July 11, 2023 Outlook: North Atlantic development looking more plausible

One-sentence summary

The majority of the Atlantic will remain fairly quiet, but the far north may see a weak system develop by the weekend that could gradually drift toward the Azores.

Happening Now: No worries for most

The Atlantic has some action out there today, but none of the systems at this point looks like a serious threat, and certainly nothing that would threaten any land. There’s a tropical wave in the islands today, bringing some showers and storms. A rather robust wave just emerged off Africa, but it’s already losing some steam.

Several tropical waves and areas of storminess are present across the Atlantic, but the only area that could plausibly develop is near Bermuda and moving east. (College of DuPage)

But the main system we’re watching will come to fruition in the medium range, so we’ll get into that below.

All in all, things are currently quiet from an impacts standpoint.

The medium range (days 6 to 10): Can the North Atlantic do it?

When we look at formation points of northern Atlantic storms throughout history between July 11th and July 20th, one area we generally can usually rule out for storm origin is east of about 55°W longitude. We’re going to be watching exactly that area this week and weekend for potential development.

Click to enlarge the map of storm origin points between July 11th and 20th since the 1800s. The area we are watching for development would be an extreme north and east outlier. (NOAA)

The National Hurricane Center has a 50 percent chance of development over the next week as of this writing. Curious and puzzling are words that come to mind, but when the Atlantic is as warm as it is, I guess this should not come as a shock. Whatever the case, we are watching this disturbance east of Bermuda in particular that will slide eastward over the next few days.

A more zoomed in look at the disturbance in the North Atlantic and its proximity to the Azores and Bermuda. It has about a 50 percent chance of developing over the next several days. (Weathernerds.org)

We can say a couple things about this system, should it develop. First, from the spaghetti plot below, which shows all the European ensemble members, 51 of them run with different tweaks in their starting points (to generate a more realistic spread of potential outcomes), we get a broadly north then east-moving system for several days. The map stops at day 7, and that’s a pretty wide dispersion of outcomes. In time, there’s also some chance the system meanders as far as the Azores, which could lead to eventual impacts there, though I’m not ruling that in just yet. But a fairly broad spectrum of potential track outcomes leads to above average uncertainty over the next 5 to 7 days.

The “spread” in potential outcomes from this system as it meanders around the North Atlantic over the next week or so is rather high, with a lot of possibilities on the table, virtually none a serious threat to land though. (Weathernerds.org)

The other thing you can say is that most modeling does keep this system on the lower end of the intensity spectrum. Wind shear and relatively “cooler” water should eventually take a toll on whatever this is and cap it at a reasonably manageable intensity. Again, if it develops.

A lot of ifs here, but it’s something. Certainly unusual and a curiosity. Thankfully it remains relatively away from land impacts. We’ll see how this goes in the days ahead.

Fantasyland (beyond day 10): Quiet

No sign of anything menacing us in the extended range right now. Modeling continues to non-specifically hint at some more activity in this timeframe, but there’s nothing we can hang our hats on and focus on showing up out there.

July 10, 2023 Outlook: The “check engine” light flickers in the Atlantic

One-sentence summary

While tropical development is not expected over the next week or so, there are a couple features to keep tabs on in the Atlantic.

Happening now: Watching the Atlantic

After the weekend, we start the second week of July off with a couple items of note in the Atlantic. Just to be clear here, we aren’t necessarily expecting anything important to come from this, but given the warm ocean waters, it’s not the worst idea in the world to keep an eye on things.

Let’s start with the current picture of dust and disturbances.

A couple disturbances under the dust plume in the Atlantic are worth watching but not expected to develop, while a more robust disturbance in the far north Atlantic may well develop. (University of Wisconsin)

You can see a pretty healthy area of dust stretching across the Atlantic from Africa to the Caribbean islands. Surely not the most impressive we’ve ever seen, but it’s definitely there. Anyway, most of the dust stretches across 20°N latitude until you get close to the Caribbean. Underneath that band of dust is a tropical wave. This has shown flashes of coherence through the weekend, and the European ensemble model in particular has at times latched onto this becoming A Thing over the next few days. Frankly, it’s hardly impressive looking today, likely battling some of the dust on its periphery and running into a wall of shear on its west side.

The disturbance in question is in the center of the image above, several hundred miles east of the Caribbean. It does not look too well organized today.

Modeling has gotten a good deal less excitable about this wave, so I don’t think it merits close watching, but we’ll see how it goes over the next day or two.

The medium range (days 6 to 10): Watching the far north Atlantic

Outside of that disturbance above, we had mentioned last week that the far north Atlantic might see some noise this week. Indeed, we have a pair of disturbances sitting up there. An actual surface low should develop in the coming days from the smaller area of storms at left on the image below (exiting Bermuda) and we may see this area become a development one.

A pair of pretty robust disturbances in the North Atlantic (a large one in the middle and a second one near Bermuda at left) bears some watching with the Hurricane Center assigning a 30 percent chance of development over the next few days. (Weathernerds.org)

The National Hurricane Center is assigning about 30% odds for that to occur. If it does happen, the system would likely meander somewhat incoherently, as if it were 2 AM and last call around the North Atlantic generally toward the Azores over time. We’ll see if it become a threat to those islands. For now, we’ll say this is not a big deal but does bear a little watching.

Fantasyland (beyond day 10): Mostly quiet

The good news is that despite the slight uptick in “noise” today, the day 10+ period does not look that interesting right now. Not to say that things will not change, but at this point, I’m not seeing much of anything that warrants a lot of our attention.

Sidebar: New England flooding

Flooding in New England is not uncommon. The region has a long history of flooding events, often with remnant tropical systems. But what is expected today, particularly without the involvement of a tropical system is troubling. That region is in line for some serious rain and flooding today, as a pipeline of moisture extends from the warm Gulf up through the warm Atlantic into New England.

The purple area is a high risk area for excessive rainfall, a deleniation that the Weather Prediction Center only uses a handful of times each year. It usually correlates to serious flooding issues, and today that will focus on northwestern Vermont and northeast New York, including the Burlington and Plattsburgh areas. (Pivotal Weather)

The Weather Prediction Center has parts of northern New York and Vermont in their rare “high risk” category for excessive rainfall, which usually correlates strongly to bad outcomes. Significant to catastrophic flooding is expected in parts of New England and New York today because of this setup. Rainfall warnings extend into Quebec as well.

It’s also a good opportunity for us to look at sea-surface temperature anomalies and see just how warm things are right now.

Sea surface temperature anomalies remain just insanely warm across the entire Atlantic Basin, with few exceptions, one reason to not write off the hurricane season due to El Niño. (Weather Bell)

There is hardly any cooler than normal water to be found anywhere in the Atlantic, Gulf, or Caribbean. This is one reason why it’s tough to forecast a slow hurricane season. At any rate, our thoughts are with the folks in New England that will be dealing with a very rough go of it today.