Matt Lanza

Rafael strengthening as it moves in on the Caymans and toward Cuba

Headlines

  • Tropical Storm Rafael is likely to become a hurricane soon.
  • It is moving through the Cayman Islands and will approach Cuba tomorrow with hurricane conditions there.
  • The Florida Keys will experience tropical storm conditions tomorrow and tomorrow night as Rafael passes comfortably west.
  • Heavy rain will spread into portions of Southeast Georgia and South Carolina leading to localized flooding.
  • Rafael is expected to weaken significantly as it approaches the U.S. Gulf Coast and no significant impacts are currently expected.
(NOAA/NHC)

Rafael to impact Cuba and the Caymans, then the U.S., sort of

Tropical Storm Rafael is on the cusp of hurricane intensity this evening as it bears down on the Cayman Islands. A look at the storm on satellite shows a lopsided but otherwise tidy storm that is clearly on the upswing.

Rafael is likely to become a hurricane tonight as it passes through the Caymans en route to Cuba. (Weathernerds.org)

I would anticipate that Rafael becomes a hurricane tonight as it tracks toward Cuba. While further strengthening is likely, the good news today is that models are in decent agreement on there being a functional ceiling for Rafael, probably up around category 2 intensity. That certainly is not meant to minimize the potential impacts to the Caymans and Cuba, but it would be nice to have a storm not do a worst-case scenario thing again. Either way, hurricane conditions are likely tonight for the Cayman Islands, while conditions will deteriorate in Cuba. Heavy rain will continue a bit longer in Jamaica as well before Rafael maneuvers into the Gulf tomorrow night.

Flash flooding is a good bet for the higher terrain of Jamaica, as well as potential mudslides. Same for the higher terrain of western Cuba. (NOAA WPC)

Rain totals could exceed 8 inches in spots, particularly the higher terrain of western Cuba. This should produce flash flooding and the potential for mudslides.

Rafael should peak in intensity either before it feels some impacts from Cuban terrain or not long after it moves back into the Gulf of Mexico. From that point on, the combination of dry air and wind shear should begin to enact a weakening trend on Rafael.

Rafael should peak in intensity around hours 48-60 in the southern Gulf and then begin a steady weakening trend before it gets to any further land engagements. (Tomer Burg)

You can see how most tropical and operational model guidance supports this weakening trend outcome. From this point of view, I don’t believe that this will deliver any serious impacts to the United States Gulf Coast, but it still is worth watching. The track is less confident, with a wide possibility of options but a weak majority favoring a general path toward Louisiana.

High confidence in Rafael’s forecast track exists until it gets to about 25°N latitude. From there, it will take a somewhat circuitous route whilst undergoing its demise. (Tomer Burg)

Whatever happens here should not matter much, and in fact it’s even possible that a weaker Rafael meanders in the Gulf until just getting absorbed into a cold front next week. The official NHC forecast has Rafael as a weak tropical storm once near Louisiana.

The moisture out in front of Rafael is another story though. The Florida Keys will see tropical storm conditions likely on the heavier weighted east side of the storm as it passes Cuba. A few tornadoes are possible there as well.

(NWS Key West)

Moisture will link up with a trough on the East Coast as well, spreading heavy rain up into Georgia and South Carolina, again south of areas severely impacted by Helene earlier this season.

Heavy rain will move into Georgia and South Carolina tomorrow, leading to localized areas of flash flooding. (Pivotal Weather)

Rain totals will be on the order of 3 to 6 inches between Macon, Savannah, Charleston, and Columbia. This won’t cause catastrophic flooding, but it may lead to localized flash flooding in spots. Conditions should improve on Thursday.

Beyond Rafael, there is a slow increase in odds that something may form north of the islands this weekend or next week. For now, I wouldn’t worry a ton about this, but we’ll look at it closer in a day or two if development odds keep increasing.

Tropical Storm Rafael to clobber the Cayman Islands tomorrow and western Cuba Wednesday

Headlines

  • Tropical Storm Rafael is expected to become a formidable hurricane as it tracks toward the Cayman Islands and western Cuba tomorrow and Wednesday.
  • Heavy rain and localized flooding are possible there and in Jamaica with Rafael.
  • Once in the Gulf, there is some uncertainty on Rafael’s track, but models are in good agreement that a surge of dry air will wrap into the storm at some point, likely leading to its demise before it can find land again.
  • However, locally heavy rainfall is a possibility, particularly in central Georgia and southern South Carolina (south of Helene’s hardest hit areas) as Rafael’s moisture surges north and interacts with a cold front.
(NOAA/NHC)

Tropical Storm Rafael is born

Apologies for the later than hoped for post today, as today was a busy day at work!

We have run up the ladder since yesterday’s post, going from PTC 18 to TD 18, to now Tropical Storm Rafael. The storm has winds of 45 mph, and it appears to be in an environment that will promote steady, if not rapid intensification over the next 24 to 36 hours.

Rafael is expected to become a category 2 storm as it passes the Cayman Islands and moves toward western Cuba. (University of Wisconsin CIMSS)

Model guidance is in good agreement through tomorrow and Wednesday on a track taking Rafael due northwest just west of Jamaica, across the Cayman Islands, and right into western Cuba as healthy hurricane. Tropical storm force winds extend out about 105 miles from the center, so a tropical storm watch has been issued for the Lower and Middle Florida Keys. Hurricane Watches are posted for Cuba, and warnings are posted for the Cayman Islands.

Around 4 to 8 inches of rain is possible from Jamaica and the Caymans into Cuba over the next several days. (NOAA WPC)

In addition to the tropical storm and hurricane conditions, heavy rain and flooding are a possibility for Jamaica, the Cayman Islands, and Cuba as well. Heavy rain will eventually work into portions of Florida and the Southeast as well as Rafael comes north. More on that in a second.

So where will Rafael go on the other side of Cuba? That’s a tough question right now, as there are several factors in play once the storm gets into the open Gulf of Mexico. Moisture surging out ahead of Rafael will “pre-saturate” the Gulf to make it somewhat more hospitable for the storm to maintain intensity as it comes halfway across the Gulf of Mexico. But once it gets into the northern Gulf, the combination of significant dry air and wind shear may be Rafael’s undoing.

As Rafael comes across the Gulf, the initial surge of moisture (green) will get clobbered by dry air (brown), likely leading to steady weakening once the storm is halfway across the Gulf. (Tropical Tidbits)

The wind shear is always a bit of a question mark; sometimes as storms come north, the shear can help to actually vent the storm a bit, which can unintentionally cause further strengthening. In this case, I think the shear is too strong, and this ample dry air (and there’s a lot of it) will likely take its toll on Rafael. Because the storm will likely be weakening, it would reason that it should keep going northwest or even west northwest across the Gulf, almost like an aimless wanderer. If Rafael maintains its intensity longer than we anticipate, it could turn more north-northwest toward the Panhandle or the central Gulf Coast. For now, impacts on the Gulf Coast are probably limited to pockets of heavy rain, rough seas, and minor tidal flooding issues. But as with any storm during hurricane season, it makes sense to monitor it closely in the coming days.

In terms of rain, it will be interesting to see how that initial surge of moisture interacts with a cold front approaching the Southeast on Wednesday and Thursday. There are model uncertainties on exactly how this will play out, but it appears that a significant rainfall event may unfold over central Georgia or southern South Carolina. This will be south of the hardest hit areas from Hurricane Helene. But it still means heavy rain and flooding are possible. Right now, the forecast calls for about 3 to 6 inches of rainfall, but some models do drop bullseyes closer to 10 inches in some areas southeast of Atlanta or west of Charleston.

Locally heavy rainfall may front-run Rafael into the Southeast, south of areas hardest hit by Helene. But as Rafael weakens due to dry air, there should not be a serious second round as seen during Helene. (Pivotal Weather)

The important takeaway here is that with Rafael expected to weaken due to dry air, there should not be a second surge of rain that follows this like we saw with Helene. So, it’s something to monitor closely in central Georgia and South Carolina, but the hope is that it will be manageable beyond localized issues. We’ll keep an eye on this.

Once Rafael dissipates, that’ll do it. Another area just north of the Caribbean may try to develop in several days, but it’s not a concern right now.

Caribbean development chances a near-certainty, as forecasts keep things somewhat interesting in the Gulf

Headlines

  • The Caribbean disturbance now dubbed Invest 97L is likely to become a depression or tropical storm in the next 24 to 36 hours.
  • It will reach Jamaica later tomorrow, then Cuba, then the Gulf on Wednesday.
  • From there, uncertainty is very high, with models spread out all across the Gulf of Mexico both in terms of track and intensity.
  • While wind shear is still expected to generally protect the northern Gulf Coast, this system should probably still be watched over the next 5 days to see how forecasts evolve.

Rafael on the horizon in the Caribbean

Last week we expected Patty to develop in the Caribbean by today or early this coming week. Patty front ran us all by forming way out in the northeast Atlantic. While that storm is not a land threat right now, what develops in the Caribbean likely will be.

Invest 97L is beginning to organize in the southern Caribbean today. (Weathernerds.org)

The disturbance has been dubbed Invest 97L for now, and it will likely become a tropical depression or tropical storm tonight or tomorrow. Its first stop on tour will be in Jamaica probably tomorrow afternoon. Tropical storm conditions and torrential rain are a good bet there.

From there, 97L or Rafael will likely continue northwest across Cuba and into the Gulf of Mexico by Wednesday. Once in the Gulf, Rafael’s motion will be dictated by the upper pattern which features weakening high pressure near Florida. This will steer Rafael to the northwest into the open Gulf but as the high falls apart, it’s likely that the motion becomes slower and more erratic. This is why the forecast out 5 to 6 days with respect to likely Rafael’s track is very uncertain.

A wide range of possibilities exists from a track continuing west to a track north to something back toward Florida with the next system later this week. (Weathernerds.org)

The good news is that wind shear in the northern and western Gulf is expected to be decent, which should allow for weakening before it does whatever it will do. However, there is a fair bit of uncertainty with all this admittedly. It is November, and you expect November things to happen here normally. But this is not a normal year. The Caribbean remains at near record warm levels, which is to say warmer than normal for any time of year, let alone November.

The Caribbean is near-record warm levels for November, which may aid in development in the coming days. (University of Arizona/Kim Wood)

The Gulf is at near record warm levels for the date as well. So from an ocean support standpoint, this system will have a good bit going for it given the time of year. Could Rafael become a hurricane? Absolutely. Could it ultimately threaten the U.S. Gulf Coast? Certainly, though I would not call that “likely” at the moment, and the most aggressive modeling seems to be the GFS, which has historically had a bit of a tough track record in the autumn in the Gulf. But the bottom line is that this will be a system that merits attention, first in Jamaica, then Cuba, and then for the Gulf Coast. We’ll see where things point tomorrow.

Additional development is possible in the western Atlantic over the next 10 days, but nothing has the robust agreement we see with Invest 97L right now.

Caribbean system set to try and form this weekend or next week and another wave causes flash flooding in Puerto Rico

Headlines

  • We are getting a clearer picture of the Caribbean development potential this weekend and next week, with a disturbance possibly developing as it approaches Jamaica from the south Sunday or Monday.
  • From there, it should turn west or west-northwest, threatening Cuba, the Cayman Islands, and perhaps the Yucatan as a tropical system.
  • As it likely tracks into the Gulf next week, it will encounter hostile wind shear that should weaken it considerably.
  • A tropical wave is also producing heavy rain and flash flooding in Puerto Rico.

Caribbean system starting to come into better focus

Our potential system in the Caribbean continues to see support grow for its organization. The NHC is up to 70 percent odds this morning, and it’s possible those increase further today.

Disorganized thunderstorms continue to percolate in the Caribbean, with development odds increasing this weekend or early next week. (Weathernerds.org)

Thunderstorms remain broad and disorganized today in this region, so I think we’ve got at least a couple days before anything happens here. Modeling seems to agree that a piece of the Central American Gyre (CAG) will break off north of Panama tomorrow and track generally northward toward Jamaica. I doubt we’ll see rapid development here, but it is possible that by Monday, we have a depression or something close to that near Jamaica.

The Euro ensemble is in agreement on a possible system near Jamaica on Monday evening. (Weathernerds.org)

This is good model support, though the details and specifics are always tricky. But support from the ensembles and most operational guidance now exists on this as the most likely outcome through Monday evening. From this point, the system will likely begin to be steered by high pressure anchored over Florida. This should turn it northwest and then possibly due west toward the Yucatan. This will be the timeframe that is most critical in terms of potential impacts for Cuba, the Cayman Islands and Mexico. Most modeling keeps the system in check, only strengthening it a bit, but there are a handful of models that are aggressively intensifying this as it comes northwest.

The Euro ensemble is in good agreement on a track that places it broadly between Cuba and the Yucatan next Wednesday. (Tropical Tidbits)

By next Wednesday, we should have a tropical system somewhere between Belize and Cuba. From here, the future track of this system becomes uncertain. High pressure should allow the system to keep going west or west-northwest into the Gulf of Mexico. But by late next week, assuming it starts to turn more northerly, it’s going to get hammered by wind shear. So even if it does come northward toward the central or eastern Gulf of Mexico, it is likely going to deal with November headwinds which should keep its intensity in check. So, for now, we continue to suspect that this won’t be a big concern for the U.S. Gulf Coast. But you should check back in later this weekend or early next week just to make sure. For areas between Belize and Jamaica, including Cuba, this will be a system to watch closely through the weekend. We’ll keep you posted.

Elsewhere: Flooding in Puerto Rico

The NHC is highlighting two other areas, one north of the islands and one near the Azores. Neither has much more than a 10 to 20 percent chance of development and none are a serious concern, although heavy rain in Puerto Rico has been causing flash flooding concerns, and additional rain will continue to cause flash flooding in the eastern and northern portions of the island.

Puerto Rico is under threat from heavy rain and flash flooding through tonight as a robust tropical wave passes. (NWS San Juan)

Most of this should hopefully ease up over the weekend.