Upcoming week - October 17-23

[Andrew92]

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

Evaluating last week

It was a rather simple prediction this past week, as I called for no tropical cyclones to develop. One can debate all they want if Invest 93L did in fact develop into a tropical or subtropical cyclone of some sort, and there is certainly merit to that. The system appeared to have a tight but weak circulation, but it just wasn’t clear enough if it was warm core or a hybrid of some sort. Even so, I was correct in the general threat being primarily rain. Also, Invest 95L is threatening to develop in the Caribbean, but hasn’t done so yet. Therefore, even with the debate, it stands that no storms developed this past week. However, I am going to very slightly dock myself just in case Invest 93L gets re-analyzed one way or the other. My grade for this past week is an A- as a result.

Not bad after a prediction a couple weeks ago was fully blown! How will I do this week? Let’s take a look…

Current situation and models

There are two areas being monitored for tropical development. One is, of course, Invest 95L off the coast of the Yucatan. This disturbance is trying to develop, but just doesn’t seem to be all the way there yet. However, winds have been reported by ships to tropical storm force, so any circulation that Hurricane Hunters find on Monday will pretty much indicate the birth of Rina here. Shear is light to moderate, at about 10-20 knots and forecast to remain that, if not gradually increase, as this system is likely to head towards Florida in a couple days, most likely the southern or central parts of that state. No model makes this a hurricane, but the SHIPS model does indicate a chance at a strong tropical storm, with winds around 60-70 mph before reaching Florida on most likely Wednesday. Also do not forget, this is uncharted territory this season for any tropical system, so waters will be plenty warm enough to support the development of a system like this.

The other area is in the Main Development Region. The system in question is not currently an Invest, but has some strong thunderstorms associated with it. However, the National Hurricane Center is forecasting a less favorable environment in a day or two, and no models seem to do anything with it or anything else this upcoming week.

Recent history

Since 1960, the following storms have developed this upcoming week in the Western Caribbean:

Laurie in 1969
Gilda in 1973
Frieda in 1977
Fabian in 1991
Lili in 1996
Mitch in 1998
Richard in 2010

Seven storms for this upcoming week may seem a bit surprising to some. I did delve into the week prior, and that is when other big-name October storms such as Wilma, Gladys in 1968, and Irene in 1999 developed. Also, of this bunch, four became hurricanes. Of course, one of them was the infamous Mitch. From the time they became named storms, Laurie, Lili, and Mitch each took close to 24 hours to become hurricanes; Richard took the longest at almost 72 hours. As for the tracks, Laurie, Frieda, Mitch, and Richard all went into Central America or Mexico. The other three quickly headed northeast. Actually, so would Mitch at a much later time, and he was also the only one of these seven to eventually reach Florida or anywhere in the United States.

Also of note, do not forget that wind shear increased with Wilma as she turned northeast, but she was going with that shear, and as a result was able to really ramp up before her South Florida landfall.

Since 1960, the following storms have developed in the Main Development Region during this upcoming week:

Heidi in 1967
Holly in 1976
Sebastien in 1995
Jose in 1999

Ouch. That’s only four storms, though only Sebastien failed to become a hurricane and did get close at one brief point. Also, all of these storms except Sebastien re-curved out to sea. However, Jose did not do so without first scraping the Leeward and Virgin Islands. Sebastien was also seemingly in the process of a track like that, but the actually turned southwestward, an unusual direction.

So what does this all tell us?

History would actually say Invest 95L will not hit Florida this upcoming week. However, its location and the model consistency says that situation is very likely to happen. If it were to become Rina tomorrow (which seems very possible if not likely), it would possibly have about 36-48 hours to work with over the Gulf of Mexico, which could be just enough time to try to become a C1 hurricane if shearing conditions are just right. The SHIPS model certainly supports this possibility, taking the storm to 57 knots in 48 hours, and this has been trending upward lately. Also, don’t forget, the trend is your friend. Afterwards, Invest 95L/likely-to-become Rina should continue northeast over open waters.

The chances are much less likely for the disturbance in the Main Development Region to get going. No model supports it, only four storms have successfully done so in that area this upcoming week, and the National Hurricane Center gives a 10 percent chance of developing into anything in the next 48 hours as shear picks up around it. The Cape Verde season is winding down.

The Prediction

So we have a tricky situation with Invest 95L here! It isn’t all the way there, but winds would support a tropical storm if it gets a circulation by tomorrow. The track looks clear towards South or Central Florida, but the intensity is a whole other ballgame. While no model takes this to a hurricane, the SHIPS does amp this up into a very strong tropical storm, and the trend has been to intensify it further as well. With Laurie, Lili, and Mitch needing a scant ~24 hours to become hurricanes from being named, the possibility is very much there. Then again, Richard took much longer, and three other storms just didn’t become that strong altogether. Then again, the waters here have not even been tapped by any tropical system this upcoming week, and they are very warm and would support a fast developer. It all depends on how it handles the light to moderate shear around it, and if this potential storm will be going with the flow of that shear, like Wilma did in 2005. Alright, what do I really think happens? I predict Tropical Storm Rina will develop on Monday in the Yucatan Channel. She will first move slowly northward, then turn northeast on Tuesday and speed up. Rina will also intensify into a strong tropical storm with winds of 60-70 mph by then. Rina will just fall short of becoming a hurricane before making landfall near Fort Myers or Punta Gorda, Florida, on Wednesday morning. Rina will then continue northeast quickly and become extratropical on Thursday. Confidence is 70%.

And briefly, there is that other disturbance in the Main Development Region. The odds are slim on all fronts for anything significant, and my prediction is simple here. I predict no development in the Main Development Region or any other area in the Atlantic except for Rina this upcoming week. Confidence is 90%.

-Andrew92

[Andrew92]

And it's time to evaluate.

This past week I predicted we would see the development of Tropical Storm Rina. I was correct on that…but it happened with the wrong system. I expected it would happen on Monday with Invest 95L. However, that disturbance never developed tropically, though it did become an impressive nor’easter by Wednesday and Thursday. Actually, the track and timing of it were not too far off, as this system headed into Florida early on and produced some heavy rains as predicted. About the only thing I really got wrong with Invest 95L was developing it, and then of course intensifying it into a strong tropical storm.

Unfortunately, if Rina did form, it obviously came from something else. She developed tonight in the western Caribbean from a surprise disturbance that models didn’t see coming until late in the week. Granted, she only has just become a tropical storm, but appears to be on an organizing and strengthening trend, so my grade is definitely hurt for this past week.

Still, Invest 95L, other than the development and intensification part, wasn’t an otherwise horrendous prediction. And all things considered, seeing Invest 96L developing into a tropical storm on Sunday night was a very tall order to pin down with what I had to work with. I give myself a C- for this past week.

New week coming up shortly.

-Andrew92