No tropical activity is expected over the next week in the Atlantic.
The first days of November remain likely to be our next window for possible development in the western Caribbean, but details are sketchy.
Quiet for now
As we begin to slowly hit the final weeks of hurricane season, things are behaving relatively normally right now. We don’t have any activity expected over the next week, and that should get us to the end of October with Oscar as the last used name on the list.
Caribbean noise remains
Modeling does continue to perk up the western Caribbean beginning later next week and into the early days of November, however. A sloppy plate of spaghetti exists on the GFS ensemble through the end of its run today, with numerous ensemble members trying to develop something in that region and either keep it buried there or lift it north-northeast toward Jamaica, Cuba, or Hispaniola.
Model noise continues to open November in the Caribbean. For now, it does not appear to be U.S. bound, but interests in the western Caribbean should monitor upcoming forecasts. (Weathernerds.org)
Now, the GFS model as shown above does have a tendency to get a bit overeager on the tails of hurricane season about development in the Caribbean. A bigger surprise would be if the model showed nothing here. That being said, this has some legs via broad background support for development over the western half of the basin, as well as some other less-robust but nevertheless present model support from the European model. I’ve written a lot and been quoteda good bit in other media publications about the increasing AI model usefulness we’ve seen this year. For what it’s worth, the AIFS too shows this kind of broad outcome right now, but it is being quite aggressive in pushing a cold front into the Gulf of Mexico around this time which is likely kicking this northeast and out to sea quickly. It’s more aggressive than the GFS and Euro with the front, so that will be something to monitor.
For now, we’ll keep babysitting and come back at you with more on Friday.
Tropical Storm Oscar will continue to dump heavy rain on parts of Cuba and the Bahamas as it exits out to sea this week.
We take a look at why we wrote Invest 94L off on Friday before it became Oscar, and in our Monday morning quarterbacking, we look at hints we could have missed.
Conditions may become favorable for further tropical development next week in the western Caribbean; we discuss who is usually still on the hook in early November.
Tropical Storm Oscar’s route to surprising us
Oscar is still lashing parts of the southwest Atlantic with heavy rain and gusty winds today. According to Michael Lowry, Oscar was indeed the smallest known Atlantic hurricane on record. He also accurately described Oscar’s development pathway as “nightmare fuel” for forecasters, and this forecaster could not agree more. Oscar went from nothingness to probably a category 2 or even 3 microstorm over the course of hours. This has happened in the Pacific as recently as this past summer with Hurricane John. To a lesser extent, we saw Otis last season defy forecasts and go ballistic to a category 5 storm. But every so often these storms serve as a reminder that modeling is imperfect, very imperfect.
Here’s an animated loop of Invest 94L’s forecast from the GFS model last Friday morning. You can see it takes 94L/Oscar to the west over the Turks and Caicos Islands north of Hispaniola but never develops the system and has it fall it apart rather quickly.
Friday morning’s GFS model failed to capture much development risk for Oscar as it came toward the Turks and Caicos Islands and Cuba. (Tropical Tidbits)
The European model from Friday morning offered a somewhat more realistic outcome, but even it did not look foreboding at the time and probably justified somewhere between a 10 and 30 percent chance of tropical development.
The European model was more aggressive but it even fell well short of what actually happened, though doing a much better job than the GFS in reality. (Tropical Tidbits)
Still, a minimum pressure of around 986 mb was reported over the weekend from Oscar, well under the minimum of about 1003 mb shown here on the Euro. Somewhat surprisingly, the European AI model did fairly well here, or at least was somewhat similar in nature to the Euro shown above. The ICON model did not do well, which marks one of its worst forecasts of the season.
I am somewhat intrigued by the European performance though. Small storms are tough to forecast, and we’ve noted in the past that model resolution has a lot to do with this. You simply cannot capture a hurricane that is basically the size of a typical thunderstorm complex. However, there remains something of an “art” to forecasting where one can paintbrush in some accents to improve on an otherwise finished canvas. This is a situation where looking at the Euro probably would give most of us some pause at least for writing something off. Perhaps that’s something I should have noticed more back on Friday. There are whispers of 2007’s Hurricane Humberto in cases like this. I think it just goes to show you never to take anything for granted in the tropics. You’re constantly humbled in this world.
Oscar is a much weaker tropical storm right now, and it is expected to head out to sea as such over the next day or two. (NOAA NHC)
Anyway, Oscar will turn back away from Cuba and head out to sea over the next day or so. But it will dump extensive rainfall over Cuba and the southeast Bahamas.
Additional rains in excess of 12 inches (300 mm) are possible over Cuba, with upwards of 6 inches (150 mm) in parts of the Bahamas as Oscar exits. (NOAA WPC)
Rains in excess of a foot (300 mm) are possible for small portions of southeast Cuba and up to 150 mm in the southeast Bahamas.
Beyond Oscar: Quiet, then what?
No additional tropical development is expected across the Atlantic for the rest of this week. Typically, we would begin talking about the season shutting down around now. While November storms do happen at times, they tend to be infrequent, and on an ACE basis, hurricane season is now 90 percent over. And after this week it will be about 93 percent over. But that said, the background state of the Atlantic appears as if it is going to get more favorable for development again just as we head toward November. Where would you expect storms to form in November?
Early November climatology favors the western Caribbean and open Atlantic. (NOAA NHC)
Typically, you’d look in the open Atlantic north and east of the Caribbean or in the Caribbean, just east of Central America. The latter area is the one to watch heading into November, as numerous ensemble members are beginning to pick up on activity there. Where it goes is TBD, but the water in that area remains very, very warm, which could more than support a significant storm for portions of the western Caribbean, perhaps including Central America. These storms typically get brushed off to the north and east relatively quickly by wind shear and cold fronts, so the western Gulf is probably off the hook. The eastern Gulf should still keep an eye on things, but the Caribbean should definitely keep tabs on anything that tries to develop next week. For now it’s just speculation and model hints. We’ll keep you posted as things clear up some closer in.
Nadine is moving inland in Central America and Mexico, producing locally heavy rainfall.
Oscar is a micro hurricane north of Hispaniola bringing rough conditions to the Turks and Caicos Islands and perhaps the southeastern Bahamas and parts of Cuba.
Tropical Storm Nadine
Yesterday we noted that Invest 95L had a shot to become a depression or low-end tropical storm before moving into Central America today. That is indeed what happened, as Tropical Storm Nadine formed from the mess, and it is now moving inland.
Total rainfall from Nadine should be in excess of 12 inches (300 mm) in portions of Mexico. (NOAA WPC)
Nadine is primarily a rainmaker, and flash flooding is a good bet for portions of the Yucatan, Belize, and Veracruz and Oaxaca. No further strengthening is expected.
Hurricane Oscar
The Oscar for most surprising storm of the season goes to Oscar! Not only did we get a tropical storm out of Invest 94L, we got Hurricane Oscar.
Hurricane Oscar is a tiny, tiny storm with 80 mph winds. (Weathernerds.org)
Hurricane-force winds extend out a total of 5 miles from the center, while tropical storm force winds extend out about 45 miles. Oscar could best be described as a “microcane.” Still, those winds are bearing down on the Turks and Caicos Islands and moving toward the southeastern Bahamas. Widespread tropical storm and isolated hurricane conditions are likely with this as it passes through.
Oscar is expected to drift southwest-ward into or near Cuba by Monday before turning northeast out to sea. (NOAA NHC)
Nothing about Oscar is simple. Storms this small will periodically be big misses in the model world, underscoring the value of reconnaissance flights and other observational tools. Modeling completely whiffed on this yesterday and even up to this morning. This is another post for another day, but thankfully the forecast has been updated, and it now appears we have some solid footing on Oscar for folks in the Turks and Caicos and Bahamas, as well as in Cuba. At this point, no threat to the U.S. is seen, as wind shear is too high just west of here, something that should make Oscar grouchy early next week. Interests in Cuba and the southwest Atlantic should continue monitoring Oscar’s progress.
Invest 94L just north of the Caribbean islands is going to fall prey to epic amounts of wind shear in the southwest Atlantic this weekend, ending any low-risk development potential.
Invest 95L has a very narrow window through Saturday morning to organize before moving across land in Central America as a rainmaker.
The tropics look fairly quiet heading into next week.
Thanks to Eric for covering me this week while I underwent oral surgery for orthodontia. I’ll just say it’s about as glamorous as it sounds. Thanks to Methodist Hospital here in Houston for a good procedure and great quality care afterwards.
Let’s take a dip into the tropics.
Invest 94L’s last gasp
What is left of Invest 94L is moving just north of the Lesser Antilles and Puerto Rico today. This is a rather robust area of thunderstorms, but it lacks any organization.
Invest 94L is producing widespread thunderstorms mainly north of the islands on Friday afternoon. (Weathernerds.org)
Over the next couple days, 94L will continue westward over the next 24 hours or so before it’s completely enveloped by significant wind shear that has overtaken the Gulf of Mexico and southwest Atlantic. Wind shear is as high as 90 knots right now across Florida, which is completely inhospitable for tropical development and some of the strongest shear I’ve seen here this time of year. So, thanks for the memories, Invest 94L and we wish you well.
Invest 95L to dump rain on Central America
Meanwhile, Invest 95L is in a bit of a different situation. This disturbance is located off the coasts of Belize and Honduras this afternoon. It is also showing robust thunderstorm activity.
Invest 95L has a short window to become a depression or low-end named tropical storm before moving inland over Central America tonight. (Weathernerds.org)
This one has a much less hostile environment to develop in than Invest 94L to the north does. However, it has a key limiting factor: Time. Invest 95L has about 24 hours or less left over water before it moves inland across Belize and Central America. In that time, it could become a tropical depression or low-end tropical storm, but no further development would be expected. Still, heavy rainfall is likely in Central America this weekend from Invest 95L that could cause some flooding issues. There is a chance that the remnants of 95L merge with another Pacific disturbance to form a storm next week that rides westward away from Mexico. But beyond this weekend’s rainfall, 95L is not a threat to land.
Beyond the Invests
At this point, there is nothing to speak of in the tropics once 94L and 95L exit the picture. That’ll give us a few more days of rest here. There are signs that the tropics could get active again heading into November, but it’s important to note that as the Northern Hemisphere pattern begins to shift toward winter, the typical behaviors of tropical systems don’t always continue. We’ll touch more on this next week.
