Impacts in the islands from Ernesto should be mostly manageable as it passes through

Editor’s note: PTC 5 is now Tropical Storm Ernesto, which has little to no impact on the discussion below, as this was expected today or tomorrow.

Headlines

  • Potential Tropical Cyclone 5 will slowly organize itself over the next 2-3 days as it crosses into the northeast Caribbean islands and Puerto Rico.
  • PTC 5 is expected to deliver mostly modest impacts to the islands, with gusty winds, rough marine conditions, and heavy rainfall.
  • As PTC 5 comes north in the Atlantic, it will strengthen and may ultimately threaten Bermuda.
  • Quieter conditions should continue behind PTC 5.

PTC 5 will slowly get itself together

Potential Tropical Cyclone #5 was declared on Sunday, which allows the National Hurricane Center to issue watches and warnings before a storm becomes an actual storm. In other words, we are expecting a tropical depression or tropical storm soon although it’s not there yet, but we need to get warnings out. Thus, the slightly cumbersome PTC language.

PTC #5 forecast track as of Monday morning showing a tropical storm in the islands and a hurricane to the north. (NOAA NHC)

Whatever the case, we are definitely expecting this system to gradually organize as it moves into the islands. If there’s good news today, it’s that models continue to slow walk development initially, despite the fairly warm water across the northeast Caribbean. So a slow transformation into a tropical storm is expected in the next 24 hours. By tomorrow morning, we expect Ernesto and its center to be just west of Guadeloupe. Tropical storm warnings are in effect between Guadeloupe and Puerto Rico.

It would appear on satellite that PTC 5 is battling a good deal of wind shear. It’s not quite consolidating, and while it has a lot of thunderstorm activity overall, it’s generally disorganized.

PTC 5 is loaded with thunderstorms, but at least on satellite it appears to be fairly disorganized, lacking the consolidation needed to be classified as a tropical storm at this point. (Tropical Tidbits)

Modeling suggests that over then next 24 hours or so we won’t see a whole lot of change to this. In that time, we should see PTC’s nascent center move into the northeastern Leeward Islands. While certainly a bit breezy and with some heavy rain, impacts there will probably fall short of anything too terribly serious. Around that time, we should begin to see PTC 5 begin to make a run toward a little organization as it approaches the Virgin Islands and Puerto Rico heading into the 36-48 hour timeframe. This system’s size seems to make it unlikely to become a hurricane now as it moves into that area.

PTC 5 should only slowly organize as it moves past the Leeward Islands and into the Virgin Islands and Puerto Rico. (Weathernerds.org)

So at this point all signs seem to indicate that PTC 5 will only slowly organize as it impacts the northeast Caribbean islands and Puerto Rico, staying under hurricane intensity until it gets comfortably north of Puerto Rico. The islands should again prepare for heavy rain and gusty winds, as well as rough marine conditions, but overall this looks like a mainly modest impact to these locations.

Rain totals from PTC 5 should be around 4 to 6 inches, though higher amounts are likely in portions of Puerto Rico and on Vieques. (NOAA WPC)

Beyond this point, PTC 5 will continue to likely curve northwest and northward, splitting the gap between high pressure over the Deep South and high pressure east of Bermuda. From here, we have two key questions: How strong does this storm get, and how close will it get to Bermuda? We can’t answer either one with a lot of certainty yet, but it’s pretty evident that this will be a very close call near Bermuda. We have a couple days to iron that aspect out.

In terms of intensity, the tropical models are all over the place, but they all show steady strengthening it appears.

Intensity guidance among the various models is very much all over the place, but in general shows steady intensification in the day 2 to 5 timeframe, suggesting PTC 5 will become a hurricane between the Caribbean and possibly Bermuda. (Tropical Tidbits)

The NHC forecast is a fine place to be right now, which shows PTC 5 on the cusp of major hurricane intensity by day 5. So because of all this, it would be important for folks in Bermuda to monitor the progress of PTC 5/Ernesto closely. We’ll keep you posted.

Beyond PTC 5, we continue to see the Atlantic basically shut itself down for the next 7 to 10 days. Don’t get too excited about that quieter period, but let’s just say during a hurricane season like this that has a lot going for it, that is a very welcome thing in August.

Invest 98L may stir up some trouble in the northeast Caribbean before likely turning out to sea

Headlines

  • Invest 98L is likely to develop in the next couple days as it tracks toward the northeast Caribbean.
  • Interests between Puerto Rico and Guadeloupe should be preparing for at least a tropical storm impact.
  • There is a chance that 98L could become a hurricane as well before it likely exits the northeast Caribbean and turns out to sea.

Invest 98L: A concern for the northeast Caribbean

We have been greeted this morning by a 90 percent chance of development in the Atlantic from now-dubbed Invest 98L.

Invest 98L is likely to develop in the next day or so as it tracks toward the northeast Caribbean islands. (NOAA NHC)

Looking at 98L this morning, it’s clearly slowly organizing east of the islands. That said, it’s a relatively large tropical wave, so this process is taking its time.

Invest 98L is spinning east of the Caribbean islands, but it’s only slowly organizing. (Weathernerds.org)

Relative to Friday, the expectations for 98L have not changed a whole heck of a lot: We still expect development as it comes toward the Caribbean, and interests in the Leeward Islands, Virgin Islands, and Puerto Rico should be monitoring the progress of 98L very closely.

Here’s what we know today:

  • Invest 98L is probably going to turn northwest and north and head into the open Atlantic after passing through the northeast Carribean.

Is there a chance it misses the exit ramp? Sure, but that’s not likely at this time. The odds of development are such that 98L is probably going to start to slowly gain latitude as it approaches the Leeward and Virgin Islands, followed by more rapid development after it passes. This should be enough for it to find its way “into” the rather strong trough off the East Coast. The forecast map below is the European model forecast for Tuesday, with a strengthening 98L or Ernesto likely to brush across the northeast Caribbean islands and into the trough off the East Coast.

The upper pattern should allow a strengthening tropical system to be “captured” by the trough off the East Coast around midweek, causing it to turn northward and off the East Coast. (Tropical Tidbits)

In a low likelihood situation, 98L would not develop much and could end up “trapped” in the northeast Caribbean, eventually forced back west or west-southwest by high pressure over the Deep South. That would change the equation entirely, but at this point there is little to no model support for that outcome.

In general, the hope is that once this passes the Caribbean islands, it will (mostly harmlessly) go out to sea

  • Invest 98L is likely to begin wrapping itself up *as* it moves into the northeast Caribbean islands.

Where it really gets tricky is what 98L/Ernesto’s intensity will be as it moves into the northern Leewards, Virgin Islands, and off Puerto Rico. At this point, it seems reasonable to say that a developing tropical storm will be moving through those areas by later Tuesday and Wednesday. Could this quickly intensify into a hurricane? I would not rule it out.

There is moderate to strong oceanic heat content in the area 98L is expected to track in the next couple days. This could help fuel steady strengthening as it moves into the northern Leeward Islands or Virgin Islands. (University of Miami)

The system is going to track through some decent areas of oceanic heat content in the next couple days. This, coupled with low wind shear should provide ample fuel for strengthening as it comes through. The biggest limiting factor in development of this system may be some dry air and lingering Saharan dust in the area of the disturbance as it wraps up.

  • The track into the northeast Caribbean will be tricky in terms of exactly what islands are hardest impacted.

Because of the track and turn of 98L as it comes west, the timing will be everything in determining which islands see the worst impacts from this system. Interests from Guadeloupe into the Virgin Islands should be watching this very closely and currently preparing for at least a stronger tropical storm impact. If 98L really wraps up quickly, then Puerto Rico and the USVI may not see much in the way of direct impacts. If the strengthening is more steady or slower, the odds of impacts there increase. We should hopefully get a little more clarity on this tomorrow, but I’d encourage that whole strip from Puerto Rico into about Guadeloupe to prepare accordingly.

Hopefully once past the islands that’s it for this one, but we’ll keep an eye on things.

More to come? Maybe not.

Behind 98L, there aren’t a whole lot of seedlings for development for now. The Euro says that in about 8 to 10 days we have another opportunity. It would appear that an extremely hostile background state in the atmosphere is going to track across the Atlantic over the next 10 to 14 days, with a lot of suppression and sinking air. This usually works against tropical development, so it’s possible we end up seeing a later August lull this year. I would caution that we’ve seen systems kind of materialize in the day 6 to 12 timeframe this season that didn’t necessarily appear like strong candidates initially. While it should be quiet for a bit, just keep that in mind.

I’ve already seen comments about this season possibly being a bust, which is understandable. But keep in mind that we still have about 90 percent of a typical hurricane season in front of us from an intensity standpoint, and between Beryl, Debby, and probably soon Ernesto, this will end up being one of the most intense starts to a hurricane season on record. Sometimes it’s quality, not quantity.

As Debby departs, we check on the odds of the next Atlantic wave becoming Ernesto

Headlines

  • Debby is causing localized catastrophic flooding in parts of northern Pennsylvania and the Southern Tier of New York.
  • Debby’s remnants will exit into Canada tonight, bringing more flooding risks to Quebec, including Montreal, as well as northern New York and northern Vermont.
  • The next wave has increasing development odds in the Atlantic.
  • While no development is expected before Monday, interests in the Leeward Islands, Puerto Rico, and Virgin Islands should monitor this wave’s progress closely.

Debby on the way out

Debby, no longer a tropical storm, is exiting to the north today, but not before leaving more destruction in its wake. Several flash flood emergencies are ongoing in Pennsylvania and New York this afternoon as Debby’s rains lead to damaging flooding, including reports of rooftop rescues and numerous trapped people in Westfield, PA.

Debby’s remnants lifting through Upstate New York this afternoon. (College of DuPage)

Debby’s remnants will move into Canada and bring more flooding rain, with rainfall warnings hoisted for much of southern Quebec and parts of New Brunswick as well. Portions of northern Vermont, very vulnerable to rainfall are also under a flood watch as Debby’s rains move that way. Isolated tornadoes are possible as well.

Watching the next wave’s development odds increase

As I noted yesterday, I felt that the 30 percent odds of development from the next Atlantic wave were going to increase. A little over 24 hours later, and those odds are now doubled up to 60 percent.

The next tropical wave is up to 60 percent odds of development by next week. (NOAA NHC)

The tropical wave itself is not much to look at today, just an area of clouds, showers, and thunderstorms in an otherwise rather dusty Atlantic. You can see it east of the islands on the satellite image below.

The next wave looks disorganized but holding thunderstorm activity as it rambles west across the Atlantic. (Weathernerds.org)

The first thing I can tell you about this one is that we do not expect any development probably before later Monday. So we have a couple days yet before this gets started. So for folks in the islands, this will probably not be bearing down on you as a big storm; it will probably just be getting organized as it arrives. Whatever the case, by Monday, we have a tropical wave on the cusp of organization, arriving just east of the Lesser Antilles and Virgin Islands.

The tropical wave will be arriving near the islands on Monday afternoon or evening, just likely beginning the process of development. (Pivotal Weather)

From here, the ballet begins. High pressure over the Southern U.S. and Texas, a trough digging into New England, and high pressure in the Atlantic will compete as this wave develops to help steer it. The current majority of modeling suggests this will develop steadily enough that it will probably go north in the islands and eventually into the open Atlantic. However, given that we’re about 6 days or so out from that happening and the inherent uncertainty from an undeveloped system, we can’t say much for sure. Here’s what we can tell you today:

  • The tropical wave is unlikely to develop before Monday.
  • Development may occur steadily, if not rapidly as the system enters the Caribbean or grazes the northeast Caribbean next week.
  • While the model consensus suggests an eventual north turn well off the East Coast, it is far too early to say much about this system’s future track.
  • A Gulf of Mexico track is unlikely at this time but not an impossibility.

I feel like when storms have had an opportunity to come a little farther west than expected this season, they’ve found a way, so I don’t want to write this off for Florida or the East Coast just yet. Right now, folks in the Leeward Islands, Puerto Rico, and the Virgin Islands should be watching this system closely, as once it gets going, it could start organizing fairly quickly. Beyond that, stay tuned this weekend for the latest. We’ll have another update for you on Sunday.

Debby will exit with more flooding, as we then refocus our attention back to the Atlantic

Headlines

  • Debby is moving inland across South Carolina, spreading heavy rain and flash flooding across the Carolinas.
  • Significant rain and flooding will continue in North Carolina and expand into Virginia today.
  • Debby lifts north and exits tomorrow and Saturday, spreading flooding risks into Pennsylvania, New York, and Quebec.
  • The next tropical wave to watch will arrive near the Caribbean islands early next week, and it will be worth watching closely.

Debby brings widespread flooding northward

Tropical Storm Debby has come back ashore today near Bulls Bay, SC, which is just north of Charleston. It continues to slowly migrate inland and will lose wind intensity through the day. One thing it won’t lose is moisture, and virtually all of east-central North Carolina and northeastern South Carolina is under a flood warning this morning. Just a huge spatial area of flash flood warnings.

Flash flood warnings in maroon cover a massive chunk of North Carolina, including Raleigh-Durham, the Triad, and Charlotte. Flood watches extend north up the Appalachians into Central and Northern New York. (Pivotal Weather)

That heavy rain will migrate northward today into Virginia, where a high risk of flooding (level 4/4) extends up through Roanoke, Blacksburg, Lynchburg, and Charlottesville.

A high risk (level 4/4) of flooding exists again today, this time from North Carolina into the Shenandoah Valley. (NOAA WPC)

Heavy rain will expand north into Pennsylvania and New York as we go into tonight and tomorrow, as well as into Quebec. Basically, we’re looking at 2 to 5 inches over a wide area, with isolated enhancement in the mountains of Virginia, where the flooding could be the worst. Everything should exit late tomorrow. Some additional heavy rain will be possible east of the this peak axis, but it will be a more manageable rain. Severe weather, including isolated tornadoes are possible too.

Peak totals will basically follow I-81 north into Upstate New York, with another maxima in the St. Lawrence Valley in Quebec, mainly east of Montreal. (NOAA WPC)

And we’ll say goodbye to Debby after this.

Next wave up is increasingly intriguing

As I noted yesterday, while modeling was mostly leaning toward the next wave not being a big deal, there was reason to watch it. It has indeed been added to the area of interest map today by the National Hurricane Center.

The next tropical wave to watch will arrive near the islands in 4 or 5 days and currently has about a 30 percent chance of development. (NOAA NHC)

They open the bidding at 30 percent, but I truthfully think we’ll see this increase some in the next day or two. This wave is going to have an interesting future. First off, development with this one will be slow. There is a lot of Saharan dust to contend with in the Atlantic, and there is no reason to think we see much of anything through the weekend. By the time we get to Monday, the wave should be approaching the Antilles. At this point, development may start to unfold slowly. But with high pressure basically in control from the Bahamas into Texas, this system will probably be cut off from “feeling” the tug of a trough in New England initially.

A slowly developing tropical system is likely to move into the islands and/or Caribbean early next week. (Tropical Tidbits)

From this point, it becomes a bit of a fight. If this system struggles a bit, it will stay suppressed, likely south of Puerto Rico and Hispaniola. This means it may miss its ride out to sea from the deepening New England trough. However, if development starts moving along more aggressively, we will likely see this system gain latitude toward Puerto Rico and Hispaniola or to the north, making it more likely to ultimately be captured by the New England trough and sent north. Additionally, the specific location and strength of the trough and areas of high pressure will play a big role too. It’s far too early to say how this ballet will play out, but I have to admit, the model data today was a little more sluggish with the pull north, which starts creeping this system a little farther west than we’d care to see.

In terms of timing, impacts will arrive in the islands early to mid next week, and if they come west toward Cuba, the Bahamas, or Florida, it would be late next week. Any risk to the Gulf, if any, is unlikely before at least next weekend. We have a lot of time to watch.

Additional waves may try to get going off Africa around the 20th, but we’ll see.