Upcoming week - September 6-11

[Andrew92]

Evaluating last week

After being in a rut for most of August, this week was an improvement overall. I correctly called for two storms to develop this week, Katia off the coast of Africa and Lee in the Gulf of Mexico. I also had a general feel for the tracks of both storms, and also did well on the intensity portion for Lee. I had a feel for Katia taking a general west-northwestward track, followed by a northwesterly track later in the period, and also nailed her becoming a C4 hurricane during the week. I also even did a good job with some early details, such as timing of development, timing of becoming a named storm, and only off by a few hours for becoming a hurricane. As for Lee, 60-70 mph was the range for that storm along a northerly track, both of which very much materialized, as the winds were 60 mph at the strongest. I also did well in seeing a possible development on Labor Day, but not calling for it as it hasn’t happened yet. True, the disturbance is there and poised to develop as Invest 95L, but the criteria there is to become a tropical depression at the minimum, not a mere Invest. Overall, there were plenty of positives to take from this past week.

However, this was still not a perfect prediction. First, Jose dissipated a little earlier than predicted, though not by much and that’s hardly a big deal given how weak and insignificant he was. Looking at everything else, for one thing, it is probably easy to figure out that the intensity of Katia was not well-predicted. This storm has had to battle stronger shear and dry air than predicted, and was only on the threshold of hurricane intensity or slightly below from the time it became a hurricane on Wednesday night all the way until Sunday. I had instead predicted a steady intensification into a C4 hurricane on Friday, and it just happened tonight. I also underestimated the forward speed Katia would take. I foresaw a slightly slower moving storm overall, gaining about 5 degrees of longitude per day and ending up a little northeast of the Leeward Islands. But Katia chugged at speeds of 20 mph or so, and is now about halfway between the Leeward Islands and Bermuda, a bit further west than I thought. For Lee, I predicted development during the weekend, and it instead happened Wednesday heading into Thursday, a good three days off. Lee’s general slow motion did save me a little for when it would approach the coast, but it did so further east than I thought. I predicted Lee would make its way into Texas, but it went into Louisiana instead, and did not bring the rains into Texas that I thought. Instead of approaching the coast, Lee is dissipating inland now. Timing apparently still remains a bit of an issue for these later-in-the-week storms, regardless of how well I did early on with Katia.

When meshing the pros with the cons of this past week, I did an overall very good job with Katia, and about average with Lee. Katia was a tricky storm to predict for intensity as most are anyway, but she seemed harder than normal. The track was very well-executed, just a tad slow. Lee was also a solid prediction with the intensity and general track, just a little further east and a few days off in terms of timing. No development late in the week off Africa, but at least seeing the potential there, was also a major plus. Overall, I give myself a B+ for Katia, a C+ for Lee, and an A for elsewhere. Lee was probably the most important, but Katia and Invest 95L do bring more of an average somewhere in the middle between those two and Lee, especially considering overall this past week was an improvement over much of August. With an average of A- for Katia and Invest 95L, and a C+ for Lee, I will give myself an overall grade of a B for this past week.

Katia is still churning, and Invest 95L could develop at any time. Could anything else also develop or threaten? It is the peak week this week, so let’s take a cold hard look.

Current situation and models

Hurricane Katia is a C4 hurricane with maximum sustained winds of 135 mph, about halfway between the Leeward Islands and Bermuda. It is currently moving northwest somewhat slowly and forecast to continue in that general direction until about Wednesday. By then the National Hurricane Center predicts she will start to curve north and then northeast by late Thursday or Friday, staying off the East Coast and south of the Canadian Maritime Provinces. However, there has been an overall trend of shifting the track west, especially when considering the models, so the East Coast is definitely not out of the woods from this storm. There should, at minimum, be very dangerous surf along the coast until this large storm passes. Katia is not forecast to get much stronger over the next couple days, and should start to weaken by Wednesday night or Thursday, and this is supported by pretty much all of the models. Predicting when she will become extratropical is another matter, but with her forward motion likely to increase during the weekend, it would not be a surprise at all for it to happen on Saturday or more likely Sunday.

Invest 95L has a 60% chance of developing in the next 48 hours off the coast of Africa. This is of course the same area where Katia developed a week ago, and I even foresaw the possibility of this happening in the previous prediction. Now it is time to look for a possible development and the future track. Overall, perhaps the models learned a little from Katia as most are not calling for as strong of a storm for Invest 95L until it gets further west. The SHIPS model does not even make this a hurricane through 120 hours. The track looks roughly the same as Katia’s for this upcoming week, a general west-northwestward track with a possible threat for the Leeward Islands. However, models with Katia were showing a clear path that would probably take it north of there; the same cannot be said with Invest 95L. The GFDL shows a C1 hurricane approaching Puerto Rico on Saturday, while the Euro shows a weaker version of this same disturbance heading a bit further south by Friday. The FIM also shows a path towards the islands, potentially as a developing hurricane. The much later track looks similar to about Emily or Irene, but it’s tough to say at this point and is probably more for next week. Basically, the Lesser Antilles, Virgin Islands, Puerto Rico, and maybe Hispaniola could be dealing with a tropical storm or hurricane during the weekend unfortunately. This will definitely not be an easy prediction.

There also appears to be another potential troublemaker in the Gulf of Mexico getting together during the weekend from a frontal disturbance. The Euro shows a developing storm on Friday in the Bay of Campeche heading slowly northward during the weekend, still over warm waters. I mean, the Euro shows this being very slow-moving, near stalling on Sunday into next Monday. It also shows a rather smallish storm, but more organized than Lee ever was. The GFS also supports the idea of a developing storm in this area during the weekend.

Recent history

We’ll start with Katia. Storms in a similar position during Katia at some point during this upcoming week since 1960 have included:

Dora in 1964
Ethel in 1964
Floyd in 1981
Gabrielle in 1989
Claudette in 1991
Luis in 1995
Ike in 2008

It’s very interesting that there are two storms from the same year 1964 that were in a similar position as Katia during this upcoming week. However, they followed very different paths. Dora continued west and went on to strike near Jacksonville, while Ethel was quick to re-curve north and northeast out to sea. Only one other storm of these seven reached the United States of this set: Ike, which was moving along an unusual west-southwesterly motion in that position. All of the other storms were moving northwest or north, and would re-curve well east of the East Coast. Some weakened slowly like Ethel and Luis; others were quicker to do so, such as Floyd and Claudette.

When looking at Invest 95L, there are a myriad of storms that have developed during this upcoming week in the Main Development Region where this one will do so – 21 in all since 1960. Invest 95L/potential Maria will be coming off the heels of a C3 storm Katia, so which storms of these 21 have done the same during this upcoming week? How about:

Esther in 1961
Ethel in 1964
Gert in 1981
Hortense in 1996
Gert in 1999
Felix in 2001
Isabel in 2003

That’s a little more manageable. And yes, Ethel is being compared to both Katia and this Invest. What is very interesting is that all seven of these storms became hurricanes, and only Gert in 1981 failed to become at least a C3 storm. Even she was no slouch as she garnered maximum winds of 105 mph at her strongest. Also, only Felix did not pose a threat to any land area as he just quickly turned northward (not the more famous one in 2007 though). This isn’t to say that they all hit land, as Gert didn’t either, but all except Felix did threaten somebody.

And lastly, what has taken place in the Gulf of Mexico this upcoming week in terms of developing storms? Here’s the sample size since 1960, though since this is a possible weekend development we will spill into next week by a few days for a better look:

Ethel in 1960
Ella in 1970
Felice in 1970
Fern in 1971
Edouard in 1984
Florence in 1988
Frances in 1998
Gordon in 2000
Hanna in 2002
Humberto in 2007

That’s ten storm total around the time frame of the weekend, of which six became hurricanes. Only two became C3 hurricanes, 1960 Ethel and Ella. Ethel is also often debated for its intensity as it is listed as briefly becoming a C5. I highly suspect this storm was not really even a C3 ever in her life, making Ella the only one. Still, six hurricanes developing in this area is nothing to scarf at. Another noteworthy storm that could easily be lumped in here is Carmen in 1974. Carmen was on the verge of dissipating over the Yucatan when she emerged into the Bay of Campeche. She gradually re-intensified into a hurricane and briefly became a C4, but then weakened slightly before landfall. As for the tracks, Ella, Felice, Fern, and Frances took more westerly paths into Texas and Mexico; the remaining six all went north, including Carmen. Humberto also hit Texas, but did so moving north so I am not lumping that storm with the first four. Most of the storms were tropical storms or C1 hurricanes with maximum winds at peak intensity in a range of 60-90 mph. However, Humberto also occurred during that period and intensified rapidly during landfall as we all know.

So what does this all tell us?

It is slightly possible for a US landfall for Hurricane Katia, but extremely unlikely. All of the models are taking Katia away from the East Coast, and history also says the odds are very low. Katia will still cause dangerous surf and rip currents, and it will very likely be advisable for everyone to stay out of the water as the storm passes offshore. With forecasts of staying south of Bermuda and the Maritimes, Katia appears destined to be a fish storm.

Invest 95L is less likely to be a fish than Katia though. Too many models are taking this disturbance into the Lesser Antilles as either a strong tropical storm or minimal hurricane, though probably no stronger than that. Given that many storms that follow on the heels of the first major long-tracking hurricane like Katia often like to pose threats to land, potential Maria absolutely has to be considered for that possibility. She may not intensify quickly, but she may be trouble down the road.

Lastly, it’s not entirely easy to get a feel for the Gulf of Mexico until it starts forming. However, with the Euro and GFS on board for a developing organized storm there during the weekend (read organized, moreso than Lee ever was), it could easily happen. These same models correctly anticipated Lee coming down the pike, and there is little reason to doubt them this time. It may be a small storm and slow-moving, but will have the makings to be a nuisance nonetheless.

The Prediction

To be blunt, there are going to be a lot of tropical troubles this upcoming week when looking at the whole picture. Katia should cause rough surf on the East Coast, Invest 95L should become Maria and maybe cause problems during the weekend, and we could even see Nate in the Gulf of Mexico by the time the weekend is over.

Let’s begin with Katia. I predict Katia will maintain its northwesterly track until Wednesday with little change in intensity, gathering maximum winds in this time frame of 120-135 mph. Katia will then turn northward Wednesday night and northeasterly by Friday morning. During that time, a more pronounced weakening trend will take place with her weakening to a marginal C2 hurricane with maximum winds of 100-105 mph, and then a C1 hurricane by Friday morning. Also during that time, there will be a lot of rough surf and rip currents along the East Coast, with numerous heavy surf advisories in effect. Katia will weaken to a tropical storm on Saturday as she rapidly accelerates south of the Maritime Provinces, and then become extratropical on Sunday. Confidence is 75%.

Invest 95L is a bit lower confidence overall until it develops, but here is my best shot. I predicted a tropical depression will develop on Tuesday and become Tropical Storm Maria on Wednesday. Maria will not intensify very quickly as it west-northwest across the tropical Atlantic. However, this will be a quick-moving storm like Katia, and will approach the Leeward Islands on Friday night. Maximum winds at that point will still be around 60-70 mph. Maria will become a hurricane on Saturday as she approaches the Virgin Islands and Puerto Rico with maximum winds of 75-85 mph, and on Sunday start to turn northwesterly while maintaining its strength. Confidence is 50%.

Finally, we look at the Gulf of Mexico. I predict a tropical depression will develop on Friday in the Bay of Campeche and become Tropical Storm Nate on Saturday as it heads north into the central Gulf of Mexico. The forward speed will slow to a crawl, and Nate will gradually intensify into a strong tropical storm with winds of 60-70 mph over warm open waters. Confidence is 50%.

-Andrew92

[South Texas Storms]

I love reading your articles. You ain't that bad.
Anyway, I was really bummed out that your prediction of Lee coming to Texas didn't materialize. I thought it was coming here too. Oh well...

Any chance the possible Gulf of Mexico storm could give TX some rain next week?

[Andrew92]

I'm not too optimistic at this point that Texas will get much, if any, rain out of this possible system later this week. Thanks for your comment though!

-Andrew92

[Macrocane]

Very good discussion as always, I agree with you about Katia and 95L, the gulf system is hard to predict as all the global models have been flip-flopping with it both intensity-wise and track-wise, let's see how all this verifies or not.

[JtSmarts]

I definitely agree with your B grade for last week. I think you did really good job all things considered. For this week I'm most interested in potential "Nate". The models were excellent with the development of Lee, and I'm eager to see if they are as good with a potential "Nate".

[cycloneye]

Another good analysis Andrew. Interesting week ahead to see how things will evolve with the two prospects for development.

[Andrew92]

Well it's time to evaluate, with the 11 PM advisories now up.

With three storms to track this past week, Katia, Maria, and Nate, it’s probably best to just look at each storm individually. We’ll start with Katia. Looking at Katia, the track and timing of it were pretty much perfectly nailed. I predicted the northward turn to start Wednesday night and a northeastward turn on Friday morning, both of which happened at about their prescribed times. I also predicted Katia would stay offshore of any land areas, including south of the Maritime Provinces, and this also happened; though rough conditions were still present as the storm was not too far offshore either (this was also a correct prediction). The issue with Katia was the intensity. Katia was a C4 hurricane with winds of 135 mph as the week began, and I predicted she would hold her own if not gradually weakening for the first couple days. But Katia was in a big hurry to weaken instead, dropping to a C1 in only a little over 24 hours. After that, Katia started to hold her own in intensity, and on Friday remained the C1 storm I had predicted her to be by then. But she didn’t weaken to a tropical storm on Saturday, though did become extratropical that night, close to when I said she would. Overall, a very good track prediction, and a so-so intensity prediction, means I did slightly above average overall this week for Katia.

Now we’ll evaluate Maria. Maria was another storm that I had a good handle on in terms of track, and unlike Katia, I actually didn’t do too shabby all things considered on intensity. First off, I predicted Maria’s development on Tuesday, followed by intensification to a tropical storm on Wednesday – both of which were correct. I also predicted a very quick-moving west-northwestward track across the tropical Atlantic, which indeed happened. I was a little off on the timing of reaching the Leeward Islands, but not too much – I called for this to occur on Friday, and it happened early Saturday morning instead. Maria then did go a little further north than projected, passing north of the Virgin Islands and Puerto Rico on Sunday, but is moving close to northwest at least. Now, when looking at the intensity, I was not high on much of a storm until Friday, thinking Maria would struggle. This happened, though by the time Friday rolled around, I was predicting a more steady intensifying trend. This did not happen, and Maria is still struggling as a tropical storm, though doing a decent job of overcoming some moderate shear as she gathers winds of 60 mph – but not the hurricane winds I had been expecting. Overall, the errors with Maria were again mostly with intensity, but came late in the period when it is harder to get these things right. All in all, I think I did a very good job with Maria this past week with what I had to work with.

Finally, we have Nate. This was decidedly more difficult to predict than either Katia or Maria. On one hand, I did correctly see a very slow-moving storm out of this, and the maximum intensity I had for him was 60-70 mph by week’s end, and it indeed reached winds of 70 mph but no stronger. However, this storm developed two days earlier than anticipated, on Wednesday instead of Friday. I also went with a slow northward crawl over the weekend, and it instead drifted west. I don’t think I would have been able to see Nate having its northern most latitude be as far south as it was, but this storm’s track was overall very shaky for me. I never saw the landfall coming for Sunday, I would have predicted it for this coming week instead. Overall, I did not do the best job ever on Nate.

So let’s average it all out. I did slightly above average with Katia, very good with Maria, and not so good with Nate. Overall, this was not great, but not a bad week either for me. I give myself a B- for this past week.

Back to normal this upcoming week, and it will be posted shortly.

-Andrew92

[Macrocane]

You did it pretty well Andrew92 even the NHC and the models had problems with the track and intensity of Nate, it was a very weird storm.

[underthwx]

Wx Underground:

The second area is in the Western Caribbean. We have a classic setup for September/October tropical development in this region by the end of the week. A strong area of High Pressure will be moving out of Canada and into New England by the end of the week wedging all the way down into Northern Florida this weekend. This normally creates Pressure Falls in the Western Caribbean which can lead to tropical development. The GFS model shows these pressure falls and the NOGAPS model does develop a tropical system down there by Friday/Saturday. Again, nothing down there yet, but it will be an area to watch for later this week. For a more in depth analysis of the tropics please view the video above.



The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products