Matt Lanza

July 25, 2023 outlook: A new area to watch in the Atlantic

One-sentence summary

Invest 95L is running out of time to do much, but in addition to future waves off Africa, we are keeping an eye on another feature northeast of the Bahamas that got outlined for possible development late yesterday by the National Hurricane Center.

Happening now: Southwest Atlantic is the hot spot

Just to tie a ribbon on Invest 95L (for now at least), the NHC has dropped 7-day odds of development to 10 percent. Surely not zero, but getting closer. This morning, 95L is producing showers and thunderstorms in the Lesser Antilles. The Caribbean is loaded with wind shear right now, so it seems fair to say that 95L has a steep uphill battle ahead.

Meanwhile, northeast of the Bahamas, there’s a rather beefy area of thunderstorms.

Showers and thunderstorms associated with a trough of low pressure have beefed up some overnight northeast of the Bahamas. (Weathernerds.org)

While the NHC only gives it about a 20 percent chance of development over the next 5 to 7 days, it certainly is worth keeping an eye on as it comes west. Right now, it has no real surface reflection, so despite looking a bit menacing on satellite, this is nowhere near ready to go. Wind shear may be a serious mitigating factor that keeps this thing from getting going, but dry air should not be a serious factor.

Slide back and forth to toggle between the GFS and European model forecast of this disturbance on Friday morning. Neither does much to organize it before it reaches Florida. (Tropical Tidbits)

It’s moving across a region of warm water temperatures, right around 85 to 86 degrees, which will get warmer closer to the U.S. coast. So, it has an opportunity here. Not to say that this has a great chance to develop significantly (and you can see from the model images above that neither the GFS or the Euro really tighten this one up at all), but it’s an item that stands out more today than previously. Regardless, it appears showers and thunderstorms will be on the increase Friday or this weekend in Florida. There is some chance this could make it into the Gulf, but that also remains to be seen. So we’ll keep an eye on it into the end of the week.

The medium range (days 6 to 10): Still watching off Africa

Our main medium range area to watch continues to be off Africa, as we watch waves emerge off the continent. I still think the next emergent wave has the best chance to emerge from the morass as the system to watch.

The next wave in particular that emerges off Africa may have a shot at developing as it comes west across the Atlantic. (weathernerds.org)

But exactly what comes of this stuff remains to be seen. The overall background state of the Atlantic should begin to become a good bit more hospitable to systems this weekend and next week. In other words, there should be a general reduction in shear and dry air. This guarantees nothing, but it does seem to suggest that something out of these emerging waves is possible. Modeling continues to bounce around and tells us nothing of much value right now, except that chances of development from this area are not zero.

Fantasyland (beyond day 10): Just keep watching

We’ve covered most of the bases today in the first couple sections. Anything beyond day 10 would likely come from those items, so we’ll keep watch and keep you posted.

July 24, 2023 outlook: Don’t invest in 95L, but there will be other investment opportunities to come

One-sentence summary

Invest 95L had a moment where it looked like it might become an interesting feature, but that has since faded so our attention will focus to the next wave to emerge off Africa.

Happening now: Invest 95L struggles & Don finally exits

At one point by Friday evening, the 7-day odds of Invest 95L developing had bumped up to as high as I think 70 percent? The odds were considered “high.” That is down to 20 percent this morning. Why? Invest 95L was unable to hold thunderstorms together enough to stay shielded from the dry air and shear that surround it. Back in Friday’s post, we mentioned that 95L would basically have to insulate itself from dry air to have a chance. The 30 knots of shear around it aren’t helping either.

Invest 95L’s development chances have lowered a good bit due to dry air and wind shear and the fact that it never held itself together over the weekend. (University of Wisconsin CIMSS)

Modeling has pulled back a ton on development chances with 95L since last week, and given the hurdles noted above, it will be tough for 95L to get its act together. That said, it will still deliver areas of heavy rain and thunderstorms to the Lesser Antilles, especially south of about Dominica and Martinique. But as far as organized tropical activity is concerned, it does not appear that 95L will be the one to make it so.

Meanwhile, to the north, Tropical Storm Don briefly became the season’s first hurricane over the weekend. It has since fizzled, and it will become an “extratropical” storm later today. Basically, it’s driven by cooler weather processes and looks more like a nor’easter than a tropical storm.

Don (center top) swirls its way into oblivion out to sea. (Weathernerds.org)

Don is the type of storm we hope we see much of this season: Out at sea, mostly harmless to any land, and working to cool ocean waters a bit. Fare thee well, Don.

The medium range (days 6 to 10): More action off Africa to come

So what’s next? For that, let us again look at Africa.

Two waves in the Atlantic are up next. The lead wave does not seem to have much model support and looks rather disjointed this morning anyway. The trailing wave over Africa has more potential. (Weathernerds.org)

Right now, the next wave up does not appear to have much to it, and model support is also lacking as it comes west. But the wave over Africa this morning will emerge into the Atlantic by midweek. Both the GFS and European models suggest this one has a chance to develop, with the GFS being extremely bullish and the Euro being extremely modest, a trend the Euro has won more often than not this season thus far. Ensemble support is moderate for this as well, with the European ensemble actually a little more excited about development odds than the GFS ensemble, a trend that the GFS ensemble seems to have won more often than not so far this season. Remember, ensembles differ from operational models because they are run 30 to 50 different times with small tweaks in their initial snapshots to help produce more “spread” to give us a better view on possible outcomes.

Regardless of what the models specifically say, it appears this will be the next area to watch heading into the weekend and next week. It seems that steering currents would suggest that anything developing would stay out at sea, but it’s far too early to say so with any conviction. For now, we will watch and wait.

Fantasyland (beyond day 10): Babysitter’s club

We currently don’t see any real specific concerns in the long range, with the exception of this wave emerging off Africa, as discussed above. The main theme heading into early August will likely just be to keep babysitting this stuff. We aren’t overly impressed with anything right now, but given the time of year and water temperatures out there, it makes a lot of sense to keep tabs on everything.

July 21, 2023 outlook: A new “Invest” in the Atlantic worth watching over the next week

One sentence summary

Don continues to menace the open waters of the North Atlantic, while odds for development of a wave east of the Caribbean inch upward.

Happening now: Don & development chances

Let’s get the easy one out of the way first. Tropical Storm Don is swirling out over the open North Atlantic. We’re beginning to see Don turn northwest, and it will turn north and eventually northeast before exiting and being absorbed by the jet stream this weekend.

Tropical Storm Don will exit the picture later this weekend, ultimately being absorbed into the jet stream. (NHC)

Meanwhile, farther to the south of Don, the area of tropical “noise” in the main development region (MDR) between Africa and the Caribbean has been deemed Invest 95L. For those new to this stuff, “invests” are just classification systems for more intriguing tropical waves than usual. Basically, it’s the first step in the process (not always, but much of the time). Some invests never become storms. The classification goes from 90 to 99 and then recycles. The “L” indicates that it’s in the Atlantic basin. Other ocean basins have other letters to define them. All it does is give meteorologists a center point to focus on and run additional tropical-focused modeling on.

Invest 95L in the Atlantic has about a 40 percent chance of organization into a depression or storm over the next 5 to 7 days, though it will be facing some obstacles. (Weathernerds.org)

Over the next 3 or 4 days, 95L will not move a whole lot. Basically, at this point it’s just trying to get itself together. As we have been noting through the week. this disturbance is going to have to fight off some dry air as a potent dust event pushes across the Atlantic. Since earlier this week, it does look like the dust may ease up or push away somewhat which won’t hurt development chances.

By Monday, Invest 95L will be east of the Caribbean islands, still not organized, but modestly insulated from the drier air surrounding the system.

On Monday afternoon, Invest 95L will be several hundred miles east of the Lesser Antilles. It will be somewhat insulated from the drier air surrounding it, though not completely. This strikes me as a system that is going to make a real effort to organize but one that will probably struggle a bit. Wind shear will also be at play here, though it looks a bit less menacing than the dry air to me at this point.

The bottom line: Watch for slow organization from Invest 95L through Monday.

The medium range (days 6 to 10): Watching the MDR

For next week, the main story will continue to be Invest 95L and whatever it decides to do. In general, a track from the Atlantic into the Caribbean seems likely, and it will likely continue to march across the Caribbean next week. I don’t want to speculate too much on what comes of this right now because, as noted above, the dry air and to a lesser extent wind shear will probably act to keep this a bit slow to really get going. Still, it certainly bears watching. Outside of 95L, nothing else is particularly notable.

Fantasyland (beyond day 10): More Atlantic noise?

It is tough to really pin down anything specific behind Invest 95L, but it seems like there will be some noise to consider out in fantasyland. The Atlantic, in general, should slowly become more hospitable to tropical development so we will continue to keep eyes on things.

July 19, 2023 Outlook: Calvin passing Hawaii, as the Atlantic maintains the status quo for now

One-sentence summary

Impacts from Calvin will diminish later today in Hawaii, while in the Atlantic Don swirls and a couple tropical waves will stir.

Happening now: Calvin hitting Hawaii, while Don swirls in the Atlantic

Heavy rain continues to fall across Hawaii as Calvin passes through today. As of 2 AM Hawaii time, over 5 inches has fallen just west of Hilo in the upslope terrain there, while Hilo itself has seen just shy of 2 inches. Continued rain bands are likely over the next 6 to 12 hours before things settle down.

Tropical Storm Calvin is passing Hawaii this morning, with a few more hours of decent moisture inbound to the Big Island and Maui before things start to improve. (Weathernerds.org)

Winds have been mostly gusting into the 30 mph range in spots, with gusts as high as 45-50 mph or so right now at high elevation. Winds should be near their peak now before things slowly improve this morning. The strongest winds over the next few hours will be over and just downwind of terrain across the islands. Overall, things will improve later today from east to west.

Meanwhile on the Atlantic side, Tropical Storm Don continues its maneuvering in the open waters.

Tropical Storm Don, will remain out at sea for a few more days before accelerating off to the north and northeast and being absorbed by the jet stream. (NHC)

We’re starting to see the exit strategy come into view now, with Don expected to continue its loop and turn northwest, north, and eventually accelerate northeast out to sea. Don’s remnants will likely be absorbed into the jet stream and head into Europe next week as part of a storm system there, as is often the case with recurves.

The medium range (days 6 to 10): Atlantic waves march west but have a lot of dry air to fight off

Two days ago, I wouldn’t say I was bullish on the medium range, but I saw a pathway toward a depression or storm. Today? Not so much. I just really think the dust is too extensive out there to allow for anything to get going. That said, the National Hurricane Center did peg a tropical wave in the eastern Atlantic with a 20 percent chance of development over the next 5 to 7 days as it comes west.

In about 5 days, the tropical wave being monitored for development will be 500 miles or so east of the islands. It will continue to have ample dust and dry air to its north which should keep any organization or development sluggish into days 6 to 8. (Tropical Tidbits)

You can see from the map above that any waves will have to navigate this drier air to get going. That won’t necessarily be easy. These waves are worth monitoring, but I really do believe they will struggle a bit through days 7 or 8 as the lead wave approaches the islands.

Meanwhile, in that dry air is a lot of Saharan dust, and that will be making its way across the Caribbean and into the Bahamas, Cuba, and Florida over the next couple days. Eventually, that should arrive in the Gulf and impact the U.S. Gulf Coast and parts of Mexico too.

A rather healthy burst of Saharan dust is moving across the northern Caribbean and will begin to impact the Bahamas, Cuba, and Florida heading into the weekend. It is likely to surge across the Gulf and impact the U.S. coast and Mexico next week. (Weather Bell)

So look for haze, milky or brown colored skies, some airborne irritants, and hopefully some above average sunrises or sunsets in those areas next week.

Fantasyland (beyond day 10): One trick ponies

The GFS operational model is essentially a one trick pony until August. It usually fires up storms, mostly unrealistic ones, and then eventually corrects to reality in time. We may be seeing that now with the tropical wave in the Atlantic that it periodically tries to blow up as it moves toward the US Southeast coast.

There remains very little ensemble support for this type of outcome. Remember, ensembles differ from operational models in that they are run multiple times with tweaks in the initialization that allow for a broader and more realistic array of potential outcomes. That ensemble support has held steady this week, meaning a small minority show it happening, but we have not added any to that. This tells me that there is not much support for this outcome, and as discussed above, I think this dry air is really going to hamper things. So, yes, we’ll keep watch, but right now, we don’t expect a lot to come of things through the end of July.