Matt Lanza

Rafael moves along in the Gulf with one of the oddest November forecast tracks you’ll ever see

Headlines

  • Rafael will continue west and eventually turn southwest, steered by high pressure over Florida and the northeast Gulf.
  • Rafael unlikely to cause serious land problems at this point for Mexico or the U.S. Gulf Coast.
  • Higher tides are likely for Texas and perhaps Louisiana, but as we explain below, they will fall well short of levels seen during Alberto earlier this season.
WYD, Rafael? (NOAA/NHC)

Hurricane Rafael doing some unique things for November

Hurricane Rafael is motoring along this morning in the Gulf of Mexico off to the west and west northwest.

Hurricane Rafael is heading west and slowly beginning to feel dry air and some wind shear. (Weathernerds.org)

Rafael is a category 2 hurricane with 100 mph winds, down a bit from its peak on approach to Cuba yesterday. It will likely hold steady or gradually weaken in the next couple days as it tracks west.

A storm tracking west in the Gulf is not uncommon. However it is virtually unheard of in November.

November hurricanes in the Gulf of Mexico. (NOAA)

Only Hurricane Jeanne in 1980 tracked west in the Gulf in November, and interestingly, it followed a very similar path to Rafael, just farther west of Cuba and then died off before getting to Texas or Mexico. Hurricane Juan in 1985 also had a noteworthy track in that it did several loops over the northern Gulf before eventually making a final landfall near Pensacola. But most Gulf storms in November come due north or track northeast out of Central America as weakened systems. Rafael will definitely be a historically noteworthy system.

While a handful of outlier models still linger a weak Rafael in the northern Gulf, our best guidance generally takes Rafael southward into the Bay of Campeche as a slowly weakening system, much like the NHC track at the top of this post. (Tropical Tidbits)

Model guidance is actually in decent agreement today that Rafael will track due west and then inexplicably southwest into the Bay of Campeche. I want to tackle two questions here. First, what in the <redacted> is happening here? Second, someone asked why this storm is not as concerning as Tropical Storm Alberto, which did something kinda sorta similar back in June and caused some considerable coastal flooding on the Texas coast. The two questions are somewhat related.

So, the what is fairly simple to explain. If we look at a map of the upper air pattern, or what will steer Rafael at 48 hours when that turn to the southwest begins, we see high pressure over Florida and the Southeast pushing Rafael to the west.

The upper air map on Saturday morning shows high pressure directing Rafael off to the west. (Tropical Tidbits)

By Monday morning, the high pressure center has moved east of Florida, but it has also kind of strung itself out more. This imparts more of a northeast to southwest type of motion on Rafael. Keep in mind that during this time, Rafael will continue to slowly weaken, so it will also become more susceptible to these steering currents as well, making it easier to sort of “bully” the system into the Bay of Campeche.

High pressure will be directing more of a northeast to southwest steering current on Sunday night and Monday which, when combined with a weakening Rafael should allow it to get shoved into the Bay of Campeche. (Tropical Tidbits)

Is this a threat to Mexico? It seems like it won’t be a real serious threat, but it at least bears some watching to make sure everything behaves as expected.

So this leads us to the second question: Why is this storm not really a major flooding concern for Texas, whereas Alberto was back in June. Here’s what the upper air pattern looked like for that event.

THIS MAP IS NOT CURRENT! A map from Tropical Storm Alberto shows a tighter pressure gradient establishing over the entirety of the Gulf due to both the storm in the Bay of Campeche and high pressure to the north. (Tropical Tidbits)

During Alberto, high pressure to the northeast of the Gulf, combined with low pressure in the southwest Gulf led to a broad, strong pressure gradient flow across the entirety of the Gulf. That is what we call a long “fetch,” meaning moisture and waves had an opportunity to pile up in the western Gulf eventually. That led to coastal flooding in Texas and Louisiana. In Rafael’s case, we have the system in the southwest Gulf, but it’s a bit smaller. We also lack high pressure to the north that would enhance Gulf moisture and fetch. Will tides increase on the Gulf Coast? Probably. Will they reach Alberto levels? Almost certainly not. So this is why we aren’t especially concerned about coastal flooding.

Rafael will hopefully be a meaningless blurb by Monday, but we’ll see. Meanwhile. another weak system has a slight chance to develop north of the islands heading into next week. At this point, we don’t view that as a particularly serious concern.

Rafael chugging into the Gulf Wednesday night, as south Georgia sees severe flooding

Hurricane Rafael hammered Cuba earlier on Wednesday, and it is now on its way west across the Gulf of Mexico.

(NOAA/NHC)

There have been significant forecast changes since yesterday, and it now appears we have two very distinct camps regarding Rafael’s future. Camp 1 takes Rafael northward toward the central Gulf Coast by next week or meanders it in the northern Gulf. Camp 2 takes Rafael west and then southwest around the periphery of a ridge of high pressure over Florida and the Deep South.

Two distinct camps of possible options for Rafael have opened up since early Wednesday. (Weathernerds.org)

It is too early to know which camp is correct, but clearly the NHC forecast near the top of this post is on board with something more like the second camp.

The good news is that there seems to be a clear signal in modeling that the storm will weaken as it transits the Gulf. This is not August. It’s November, and although the waters remain fairly warm, the reality is that wind shear and dry air usually play a big role in November storms. This case should be no different.

Strong wind shear should help disrupt Rafael as it comes west, likely weakening it from a borderline major hurricane to a tropical storm by this weekend. (Tropical Tidbits)

This should allow Rafael to begin to wind down after Thursday, slowly weakening back to category 1 strength and then tropical storm strength this weekend.

From that point of view, any threats to land from here seem limited. However, folks in Mexico and on the central Gulf Coast should continue to watch Rafael’s progress to see if anything changes.

Apologies for the extremely late update on Rafael today. A sick kid and a day full of obligations will do it!

Valdosta flood emergency

The Valdosta/Lowndes County area of Georgia is being blasted by rainfall this evening with a flash flood emergency in effect. Streamflow values are extreme right now over Valdosta itself.

Extreme streamflow values noted around Valdosta likely correlate to severe, catastrophic flash flooding in that area. (NOAA NSSL MRMS)

Return periods on some these rainfall values are in the 250 year or higher range, meaning this is an exceptional event for Valdosta. Rain totals are in the 6 to 10 inch range as estimated by radar for Valdosta today.

Valdosta has seen anywhere from 6 to perhaps 10 inches of rainfall today. (NOAA NSSL MRMS)

We have been warning of potentially localized flash flooding in Georgia or South Carolina for a couple days now, and that’s indeed what has happened. Numerous other flash flood warnings are in effect across the region, including some serious ones not far from Valdosta right now also. Thankfully, the rains should hopefully wind down in the next 2 to 4 hours.

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.