Erin now a hurricane but still not a serious land threat, while we watch Upper Midwest flooding risks this weekend

In brief: Invest 98L is about to move ashore in Texas, ending development risks. Erin has finally become a hurricane, and it is expected to intensify in the coming days as it avoids land. An additional tropical wave may or may not develop next week behind Erin. Flooding risks are noteworthy this weekend in the Upper Midwest and in the Grand Canyon.

Invest 98L in the Gulf

First off, let’s get the elephant in the room taken care of: Invest 98L, the tropical disturbance approaching the South Texas coast is becoming less likely to develop now, particularly because it’s quickly running out of runway to work with. Odds remain 50% per the NHC, though if it does develop, it would be a tropical depression for about 3 to 6 hours or less before reaching land in South Texas.

That being said, it looks somewhat interesting on satellite this morning, conversationally at least.

Invest 98L is basically a gnarly looking blob of thunderstorms. (Tropical Tidbits)

This may look a little scary, but in reality, there is no low-level circulation so while there are some heavy thunderstorms and heavy rain underneath this blob of clouds, the system is not organizing much. So you can disregard any meaningful tropical development (wind, coastal flooding) elements of this for the most part.

What we will watch for at least is rain.

A marginal risk (1/4) for flash flooding exists across the Houston area today, with slightly higher risks closer to the thunderstorms in the Valley. (NOAA WPC)

That heavy rain offshore is going to move ashore between Corpus Christi and Brownsville this morning. For the most part, these areas remain in abnormal dryness of lower-end drought, so this rain would be mostly beneficial in nature. Some additional heavier thunderstorms may fire off on the periphery of things late this morning and afternoon, spreading north toward Houston and Victoria and perhaps even as far inland as San Antonio. But by and large the heaviest rainfall will probably be where this stuff comes ashore this morning.

Invest 98L’s blob of rain will come ashore in South Texas later today. (College of DuPage)

We should then be able to close the books on Invest 98L.

We will update this image with the 11AM ET advisory package. (NOAA NHC)

Hurricane Erin

Erin has finally crossed the threshold into hurricane status this morning. While it certainly still has a number of structural issues, it’s got the underlying parts necessary to make hurricane status.

Erin is trying. Still. But it is now a hurricane. (Tropical Tidbits)

Erin is moving off to the west northwest now at about 15 to 20 mph, a little slower than in recent days. This heading and speed should ensure it stays north of the Caribbean islands. Still, some fringe impacts will bring outer bands with locally heavy rain and gusty winds to the Virgin Islands and Puerto Rico. In addition, strong rip currents and rough seas should batter the islands this weekend. I love the graphic below from the NWS in San Juan.

(NWS San Juan)

Erin pulls away late this weekend. Looking down the road, this should pass similarly north and east of the Bahamas and Turks and Caicos Islands in particular. Again, some fringy type impacts are possible there, particularly with respect to rough seas and rip currents.

From there, the song pretty much remains the same. Erin is expected to turn northwest and north and eventually turn out to sea. Erin should be pretty straightforward track-wise in terms of how it maneuvers around the gap in high pressure over the western Atlantic. I would expect some farther west adjustment of the track forecast from the National Hurricane Center, but in general, look for this to turn north just west of 70°W longitude.

Erin’s tropical modeling is in pretty good agreement overall with minimal outliers at this time. (Tropical Tidbits)

This should keep Erin comfortably east of the U.S. East Coast. This current forecast track also shoots the gap between Bermuda and the East Coast, which would be good for the island. Still, folks on the East Coast and near Bermuda should continue to monitor Erin’s progress in the coming days.

Erin is likely to gradually strengthen over the next couple days. I would not be shocked if we see a burst of intensification as Erin turns northwest on Sunday. It’s going to have to battle a little shear, but the environment may become much more favorable overall, especially with such warm water in the southwest Atlantic. We will almost certainly get our first major of 2025, and it may put on a show for a short while. But as with anything tropical, we’ll see.

Bottom line today: Erin does not appear to be a serious threat to any land mass at this time, but it will be good for folks in the Turks & Caicos, Bahamas, East Coast, and Bermuda to continue monitoring Erin’s progress through the weekend.

Elsewhere

We’ve got a tropical wave likely to follow Erin next week that has the potential to develop, but….uhhh…yeah. Good luck resolving anything today.

A wide dispersion of possible locations of a tropical wave next Tuesday in the Atlantic. (Google Weather Lab)

I won’t bother to try to resolve any of that for you. Just know that we will probably be tracking another tropical wave next week, though at this time it looks to be less organized than Erin.

Beyond the tropics, heads up in Minnesota and Wisconsin. A multi-day rain and thunderstorm event is likely to pile up some healthy rainfall and it stands out as being in a slight risk (level 2/4) the next 3 days for flash flooding.

Heavy rainfall will add up to as much as 2 to 4 inches from central Wisconsin back into Minnesota, including the Twin Cities. (Pivotal Weather)

Repetitive rounds of thunderstorms will move through this area, including a slight risk (2/5) for severe weather today. Hopefully the heaviest rains stay north of the Milwaukee area that was severely impacted by flooding last weekend. Right now it appears that will be the case, but this will merit some monitoring through the weekend.

Slight flash flooding risk (level 2/4) is posted today, tomorrow, and Sunday in the Upper Midwest. (NOAA WPC)

Additional flooding risk as a result of the large burn scar from the Dragon Bravo fire complex in Arizona exists the next couple days as well.

Flooding risks in the Dragon Bravo fire burn scar will be significant with any locally heavy rainfall. (NWS Flagstaff)

The fire itself is 56 percent contained as of yesterday evening, but any heavy rainfall from monsoon thunderstorms will ramp up flooding and debris flow risks in the Grand Canyon region. Anyone hiking or camping near the perimeter of the fire’s burn scar or in the Grand Canyon and along the Colorado River, particularly around Bright Angel Creek should be aware of these risks.

Erin putting itself together Thursday and should pass north of the islands this weekend

In brief: Tropical Storm Erin will pass north of the islands this weekend before likely beginning to turn north off the East Coast. Questions on the exact track remain that could influence impacts in various spots, so continued monitoring is recommended for the East Coast, Atlantic Canada, Bermuda, the Bahamas, and the northeast Caribbean. Invest 98L in the Gulf will probably produce mostly positive rainfall over South Texas tomorrow and Saturday.

Tropical Storm Erin

If we look at satellite this morning, it’s certainly the healthiest look Erin has had this week.

Erin looks like an actual tropical storm this morning. (Tropical Tidbits)

It’s clearly not the healthiest storm we’ve ever seen, but it’s doing enough to give the impression of slow intensification. As a result, Erin’s intensity is nudged up to 60 mph as of the 11 AM AST advisory. Using the latest map from Tomer Burg’s excellent site, it’s actually instructive to see what Erin has ahead of itself.

(Tomer Burg)

Erin is moving into an environment with very warm water temperatures, and it’s not going to exit that environment for at least 5 or 6 days. Erin should begin to tap into this environment over the next couple days, and it’s possible that we see a burst of rapid intensification at some point. Erin has not completely rid itself of dry air yet, so that may limit just how out of hand intensification can get. Whatever the case, given a favorable upper environment and warm water temps, one would expect Erin to start tapping the accelerator a bit today and tomorrow. After Friday and into this weekend, the storm may begin to “feel” some added wind shear to the west. This could slow the intensification rate a good bit. The models love this storm, and they’re quite aggressive with intensification over the next 3 to 4 days, with most pinning Erin at Cat 3 or above.

In terms of how close it gets to the islands, which is the first hurdle in terms of Erin’s track, there is strong agreement that it will pass comfortably north to avoid serious direct impacts. The Euro ensemble below shows this well.

The Euro ensemble’s 50+ members show Erin staying comfortably north of the islands, keeping serious direct impacts out of those areas. (Weathernerds.org)

What can we expect? Probably just a graze. As Erin passes north, it’s likely that some outer bands will graze Puerto Rico, the Virgin Islands, and the northeast Leeward Islands. Below is a forecast map for Saturday morning from the European operational model. Often, we tell you to ignore operational model guidance, but 2 to 3 days out, these deterministic models have value, particularly with established storms like Erin.

Erin’s Saturday morning forecast north of the Caribbean islands. (Pivotal Weather)

Mostly, however, the impacts will be marine-driven: Rough seas, high tides, rip currents.

(NWS San Juan)

Certainly something to monitor and keep track of, particularly if you have any marine interests or will be visiting the area this weekend. But this is mostly from a safety and awareness standpoint. No direct or major impacts are expected.

Beyond the Caribbean islands, what happens next? Well, there’s always some inherent uncertainty in tropical systems, but it’s not always equal. In other words, some 5 to 7 days forecasts have higher confidence than others. In this one, there is fairly high confidence that Erin is what we thought it was. Erin will turn northwest, then likely north and northeast rather quickly off the East Coast.

Erin’s forecast track has inherent uncertainty, but it is still expected to remain offshore of the East Coast. (Tropical Tidbits)

The questions I still have involve how close to the Bahamas and eventually Bermuda Erin gets. Additionally, how far offshore the storm will pass from the East Coast and Atlantic Canada. There has certainly been some “creep” to the west in the last couple days, which has undoubtedly made some folks on the East Coast a little uneasy. But at this point, all we can say is to keep an eye on things. We do not expect a track, plowing Erin into the Carolinas or New England. But it could always pass close enough for some impacts. We’ll keep you posted. Bermuda needs to watch Erin very closely. Hopefully we see some clarity on that in the next couple days.

One thing we can say for sure? Rough surf and rip currents will begin to increase by later this weekend or early next week on the East Coast. Please use caution in the water, particularly if you’re taking a late summer vacation next week.

We’ll keep you posted through the weekend.

Invest 98L

Meanwhile, in the Bay of Campeche, the tropical wave that we started watching a little more closely on Tuesday evening has now been designated Invest 98L. It actually looks okay this morning, though it lacks any sort of defined circulation center. So at this point, it’s just a coherent area of thunderstorms.

Invest 98L is well defined with thunderstorms, but it lacks any formal tropical organization. (Tropical Tidbits)

Invest 98L is going to track almost straight northwest over the next 24 to 30 hours. This should come ashore in Texas by Friday evening. Any development will be lower-end and rather disjointed. In other words, we could see a sloppy tropical depression come out of this, but we probably won’t see a named storm.

Invest 98L will move into Texas tomorrow evening. (Tropical Tidbits)

That said, given the thunderstorm organization here, we could see some locally heavy rainfall in South Texas as this comes in. I think as we saw last month, it does not take a well organized tropical system to cause problems in Texas. As this moves from the coastal bend into interior Texas, we will keep an eye on flooding risks that may emerge from this, although right now those risks are on the low to very low side.

5-day rainfall forecast focused over Texas shows generally 0.5 to 1 inch of rain on the coast, with lower amounts inland.

Overall, the thinking is that this will be more beneficial with increased rain chances over drier South Texas than anything else.

Elsewhere, no other specific waves are of serious concern right now, but we’ll keep an eye on that over the next few days and see if new areas of interest are introduced. We’ll stop there for now. Keep tabs on our Notes for any intermittent updates.

Erin remains a tropical storm as its long-term path comes into better focus

In brief: Today’s post discusses our increasing confidence in the track for Tropical Storm Erin, and takes a look at some of the near- and long-term risks from this system, which should become a hurricane by this weekend. We also discuss a new Blobby McBlobface in the Gulf.

Status of Erin

As of Wednesday morning the Atlantic season’s fifth named storm retains a fairly ragged appearance on satellite, with the National Hurricane Center (a bit generously, maybe?) holding Erin’s intensity at 45 mph. The system continues to encounter somewhat dry air, and sea surface temperatures that aren’t exactly sizzling. So Erin is just kind of slogging westward across the Atlantic. But it is making progress, having moved about halfway between Africa and the Leeward Islands; and Erin continues moving with purpose, at about 20 mph. On this path the storm should find more favorable conditions in the coming days.

Tropical Storm Erin is still facing some challenges this morning. (NOAA)

Those conditions include warmer water and, crucially, rising air that should support further intensification. Accordingly, the National Hurricane Center expects Erin to become a hurricane by Friday, and potentially a major hurricane by this weekend. This is well supported by a suite of models we look at, and seems like a reasonable best guess. Bottom line, Erin is still very likely to become this season’s strongest storm to date, by far.

OK, so where is Erin going?

After several days of uncertainty, our confidence in Erin’s track is increasing. Although it is moving west now, it should slowly turn west-northwest by Friday or Saturday, and then northwest on Sunday as it finds a weakness in the high pressure system to its north. By early next week the storm’s center should lie somewhere to the north of Puerto Rico or Hispaniola, and be turning further north.

Super-ensemble forecast for Tropical Storm Erin. (Tomer Burg)

If we look at the overnight guidance there is a lot of support for this track, and it helps build our increasing confidence. Along this track the center of the storm should approach Bermuda by Wednesday (give or take a day) next week. We’re not saying the track of Erin is a done deal here, as there remains a broad range of outcomes beyond day four or five of the forecast. And we’re going to discuss other risks below. But at this time our land mass of biggest concern is the island of Bermuda. Residents there should be keeping very close tabs on the system.

Other concerns with Erin?

Yes, we have some. Depending on how quickly Erin strengthens (i.e. a slower-to-organize storm would remain further south) we would advise people living in the northeastern rim of Caribbean islands, including Antigua and Barbuda, the Virgin Islands, and Puerto Rico to remain vigilant. These islands are unlikely to see a direct hit from Erin, but they are at risk of higher waves and heavy rainfall beginning late Friday and running through the weekend.

Areas of the US East Coast, such as the Carolinas and Virginias, should also keep an eye on Erin. The risk of a landfall there is very low, but it remains non-zero. More importantly, like the Caribbean islands discussed above, there could be impacts to seas along with heavy rainfall. Overall our concern level for the mainland United States is fairly low, but at a week out we cannot say anything definitive about impacts there.

What about the Gulf?

What about it? I like living there. Good people. Great seafood. This week even the waters near Galveston have even been blue-ish. Oh, you mean the new tropical blob there highlighted by the National Hurricane Center this morning.

Blobby McBlobface comes to the Gulf. (National Hurricane Center)

Well, I don’t have much to say about this this morning. On one hand, yes, the calendar says it is August. So anything tropical in the Gulf at this time of year raises one’s eyebrows. But I’m having a hard time getting too worked up about a tropical low that will find only marginal conditions for development. If we dig into the ensembles there does not even appear to be too much of rainfall threat. For example, based on the European model, the probability of rainfall amounts of 4 inches or greater is near zero for all but a few isolated areas of Mexico. So yes, we’re going to watch this thing. But no, we’re not going to get too excited about it.

What else?

Overall it’s fairly quiet out there today. We’re watching for some flood concerns in southern Kentucky and Tennessee, including the Great Smoky Mountains area. A flash flood watch is in effect for much of this area, where there could be some training rainfall and higher wind gusts. The threat of heavy rainfall should pass this evening or tonight.

Beyond that, it’s mostly just hot out there in the United States, which is to be expected in August.

Tropical Storm Erin chugging westward, but struggling to maintain thunderstorms this morning

In brief: Tropical Storm Erin is struggling this morning due to dry air, which may impact its track some over the next 3 to 4 days. While Erin should still eventually turn out to sea, folks in the northeast Caribbean will want to monitor the storm’s progress closely this week, and those on the East Coast should continue to just keep tabs on any further changes for the time being.

Tropical Storm Erin

This morning, Erin has pressed pause on intensification as a lot of the deeper thunderstorms surrounding the storm seem to have faded away. We figured Erin would struggle a little in the first couple days, but this is a fairly substantial drop off in storm activity.

Erin’s thunderstorms have weakened, though it still has a well defined circulation. (Weathernerds.org)

One reason for the diminished look of Erin this morning is likely a healthy amount of dry air that sits in the mid-levels of the atmosphere around the northern and western flank of the storm.

Erin is battling dry air right now. (Tropical Tidbits)

Hurricanes and tropical storms need warm water, low wind shear, and moisture to thrive. Absent one of those ingredients and you probably get a sloppy outcome. Indeed, this is where we are right now.

So, what does this mean going forward? Well, if you look at Erin’s forecast track from the NHC today, it has indeed shifted a bit farther south.

(NOAA NHC)

It hasn’t shifted dramatically so, but it has shifted enough to be noticeable. This is likely because Erin’s intensification timeline has slowed down a little. Less intense storms will track a little farther south and be less apt to turn poleward (north) quickly. One of the challenges in determining the forecast track of Erin over the next several days will end up being how much dry air it has to fight off. If you look at the envelope of track possibilities through Friday evening, at least based on the European and GFS ensembles, you do see a somewhat healthy spread in possibilities opening up. Since yesterday, this has shifted a couple hundred miles south

A comparison of Monday vs Tuesday morning’s ensemble guidance on Erin shows a slight southward drift in forecast track. (Tomer Burg)

This is not a dramatic change, but when you do the virtual math here, there has definitely been a trend toward a slightly weaker system, slightly farther south. Also notice a slight bend to the west-southwest that shows up on those maps as Erin tracks west of about 55°W longitude. It’s a minor difference, but for the islands, it could have some implications.

So what does this mean going forward? Well, in the near-term it doesn’t mean much of anything. Erin will probably continue to struggle a bit until it can insulate itself from the dry air that surrounds it or shake it off entirely. This could mean that we see an additional trend to the south of Erin’s track today, perhaps getting a bit closer than some would like to the islands. On the flip side, if Erin struggles more, it would be less likely to approach the islands as a hurricane. So you have to balance the bad with the good.

Still, once it nears the islands, the overall environment is expected to improve, allowing for Erin to intensify, turn north, and scoot out to sea, though Bermuda bears close watching of course in that scenario. All that said, I think there’s at least some evidence today that while the environment around Erin is expected to improve and allow for strengthening, that doesn’t necessarily mean it will. So folks in the northeast Leeward Islands, Virgin Islands, and Puerto Rico should continue to monitor Erin’s progress closely over the coming days.

For folks on the East Coast? Generally speaking, nothing has changed with respect to the risk profile there. Erin is still expected to turn out to sea, as the break in ridging over the Atlantic persists. As soon as Erin begins to intensify, it should begin to gain latitude and eventually turn back northeast. That turn looks a little more like a J-turn today than a U-turn, but the end result would be the same. All that said, the subtle changes we’ve seen since yesterday are a good reminder to never take a hurricane forecast as a given 7 to 10 days out. Continue to monitor Erin’s progress in the coming days.