Tropical Discussion 2025

[tireman4]

re
Erin remains a tropical storm as its long-term path comes into better focus
And as a result, we have some concerns.
Eric Berger and The Eyewall
Aug 13






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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

[Stratton20]

Wouldn’t be shocked to see our gulf disturbance develop, reconnaissance flight potentially tommorow and friday, it already has a skeleton in place for development, sustained convection over land and a pretty decent mid level spin, I dont trust ths one at all

[Rip76]

Wouldn’t be shocked to see our gulf disturbance develop, reconnaissance flight potentially tommorow and friday, it already has a skeleton in place for development, sustained convection over land and a pretty decent mid level spin, I dont trust ths one at all

Maybe a little North of Brownsville creeper?

[Cpv17]

Wouldn’t be shocked to see our gulf disturbance develop, reconnaissance flight potentially tommorow and friday, it already has a skeleton in place for development, sustained convection over land and a pretty decent mid level spin, I dont trust ths one at all

We’ll see. I’m also interested in what the Euro and EPS is showing in a couple weeks from now.

[Cpv17]

We now have invest 98L over the Yucatán.

[Stratton20]

Cpv17 yep, i have a feeling 98L has a trick up its sleeve lol, but yeah the afternoon euro long range run was pretty interesting

[Cpv17]

I’m mainly interested in what could be coming behind Erin. Ensemble support increasing.

[Pas_Bon]

I’m mainly interested in what could be coming behind Erin. Ensemble support increasing.

I will certainly be checking models with regular frequency throughout the weekend. I know you will, too.

I recommend you all do the same. Antennae raised a bit.

[Pas_Bon]

Erin grew to a Cat 4 overnight.
60mph increase in max sustained winds in less than 12hrs.

Jesus Christ.

[Kludge]

If this were any other model I would start worrying...

[tireman4]

Hurricane Erin, still unlikely to directly threaten land, undergoes a historic round of intensification, now flirting with category 5 intensity
A remarkable 24 hour change in Erin
The Eyewall and Matt Lanza
Aug 16







In brief: Erin enters the record books as one of the quickest intensifying Atlantic hurricanes on record, now flirting with category 5 intensity. It remains unlikely to directly threaten any land, but fringe impacts will continue to impact the northeast Caribbean, possibly the Bahamas, and perhaps Bermuda. No threat to the U.S. or Canada.

Erin exploded overnight into a category 4 hurricane. As of the 11 AM AST advisory it has 155 mph maximum sustained winds, just a sneeze away from category 5 intensity.


Erin's forecast track. (NOAA/NHC)
Why? Well, it always was expected to strengthen quickly. But Erin was able to close itself off from external dry air and shear and basically insulate itself, contract in size, and explode.


Hurricane Erin's satellite appearance in the last 24 hours has evolved dramatically. (Tropical Tidbits)
Erin's small size works to its benefit, as hurricane-force winds extend out a mere 30 miles from the center. This is good news for the islands, as they'll be a comfortable distance from the powerful winds. Erin should intensify a little further today. After today, the storm will likely become prone to fluctuations and internal processes that impact intensity (things like eyewall replacement cycles, etc.). So it may wax and wane a bit after today or tonight.


Calm seas in the eye vs. rough seas in the eyewall of Erin from the hurricane hunter mission this morning. (NOAA)
Let's talk real quick about Erin's intensification rate. Erin is the quickest intensifying Atlantic hurricane by a significant margin (before Sept 1) that we have data on, according to Sam Lillo. A 70 mb drop in 24 hours is incredible. The warming oceans are certainly one factor playing a role in this. By every metric, Erin will go down as a historic Atlantic hurricane.

Heading into next week, Erin will begin to feel some wind shear and start advancing toward cooler water, so we'll see a slow decline in intensity for Erin, with most modeling bringing it back below major hurricane intensity by Tuesday or Wednesday.

How about track? Well, we've got good agreement today. At present, we're seeing some wobbles and subtle shifts southward, so there could be some additional adjustments to the track forecast above, but in general, modeling agrees that this will slow down and turn northward by early next week, pass well off the East Coast and west of Bermuda and south of Atlantic Canada while heading out to sea.


Various ensemble modeling is in pretty good agreement on track with Erin, with Bermuda still perhaps at some degree of risk as Erin exits. (Tomer Burg)
Erin is going to grow in size, so for folks in Bermuda, it will be important to recognize that even though Erin is likely to weaken on its way out, it will be larger in size, which means a close pass, even west of Bermuda could bring some direct or fringe impacts. The biggest questions right now are on the exact timing of various turns.

I don't want folks to pay too much attention to the wobbling or even track shifting we see north of the islands right now. I see this with every strong storm that occurs. While that stuff does matter in the near term, it should not have a major impact on things in the long term. Powerful storms like Erin tend to wobble and meander a little on the general heading they're moving in, and it's not at all uncommon for a storm to deviate from the forecast track by a good bit in the short term before correcting back in time.

For folks in the islands right now, experiencing heavy rain and gusty winds, yes, continue to monitor Erin, but again, the worst of this will stay north of those islands.


Hurricane Erin passing northeast of the Virgin Islands and Puerto Rico. (RadarScope)
On the East Coast of the U.S. and in Atlantic Canada, get ready for rough surf and strong rip currents. That will be increasing in the days ahead. Folks planning a late summer vacation next week to the Jersey Shore or Outer Banks or wherever just want to keep in mind that swimming conditions may be suboptimal or even unsafe at times.

So, bottom line on Erin:

Should become a category 5 storm, as it is one of the fastest intensifying Atlantic storms known in the historical record.

Track will wobble and meander off course at times; this is normal for elite hurricanes and it doesn't portend a significant forecast track change.

Currently not expected to directly impact any land.

Locally heavy rain and gusty winds in the northeast Caribbean today and tomorrow from outer bands and squalls.

Rough surf and rip currents likely to become an issue on the East Coast next week.

Bermuda should continue to monitor Erin's progress closely.

[Pas_Bon]

If this were any other model I would start worrying...

What people should take from this are a couple things......

1) yes, it's the GFS operational at 10+ days. I'd trust an election in North Korea more than that.
2) various operational models have shown this scenario a few times in the past several days
3) ensembles support the possibility of a large hurricane in the Gulf of America in the coming days/weeks
4) all that said, it is way too early to get hung up on potential landfall locations and even the formation of such a storm
5) if that scenario were to pan out, it would be catastrophic for Galveston and points far inland; that's a Cat. 5 depicted
6) no need for anyone to get worried at this point
7) that could change, but again, the likelihood is low

8) ***Always stay extra aware this time of year.

[Kludge]

If this were any other model I would start worrying...

What people should take from this are a couple things......

1) yes, it's the GFS operational at 10+ days. I'd trust an election in North Korea more than that.
2) various operational models have shown this scenario a few times in the past several days
3) ensembles support the possibility of a large hurricane in the Gulf of America in the coming days/weeks
4) all that said, it is way too early to get hung up on potential landfall locations and even the formation of such a storm
5) if that scenario were to pan out, it would be catastrophic for Galveston and points far inland; that's a Cat. 5 depicted
6) no need for anyone to get worried at this point
7) that could change, but again, the likelihood is low

8) ***Always stay extra aware this time of year.

Agreed.
Note that the 0z had a major moving into Mobile on the 28th, so it's like the model knows the what, but not the where.
The 12z is running now.

[DoctorMu]

If this were any other model I would start worrying...

IKR?

Tropical forecast porn.

[Stratton20]

Yeah its far out, but its gaining model support and a kelvin wave could help to boost this next tropical wave, GFS also saw ERIN before the euro did 8 days out , anything beyond 10 days is fantasy though, but its persistence in developing this one has to be watched a little more closely

[DoctorMu]

Now Alabama is the target on the 12z.

Either the Sharpie or another GFS wet dream.

[tireman4]

12 Z GFS

[tireman4]

Erin Rapid Intensification

[DoctorMu]

Erin Rapid Intensification

80 mb drop in 24 hours.

South of the cone - probably a wobble, but still...

[DoctorMu]

It won't happen, but just sayin' as Erin wobble south of the cone...

That ridge is supposed to move west (over us to the Four Corners) and allow allegedly the Bermuda high to take charge.