Upcoming week - October 15-21

[Andrew92]

The following post 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

Two systems of note were noted for this past week. The first was Invest 97L, which looked like would be a very short-lived system before being absorbed in a frontal system. The other was an unknown at the time, but picked up by the GFS and Euro models as a potential troublemaker by the weekend.

I predicted no development for Invest 97L but that it would produce some rain showers in the Bahamas. Well it did not become absorbed as quick as the models were saying and managed to become a weak Tropical Storm Patty for about a day before fizzling out. I guess I kind of had the right idea that such a system would be weak and short-lived near the Bahamas, but I really didn’t think it would develop either with conditions appearing to go downhill for development and forecast to get even moreso at the time. At least it was a weak system that didn’t affect land too much though.

On the other hand, the system I did have becoming Patty – well, it became Rafael instead – I did reasonably well here. Two different solutions were provided in terms of track: the GFS suggested a quicker northwest track east of the Leeward Islands, while the Euro took the system over the islands. The GFS has done a marvelous job this year, and I therefore trusted that model again. However, the Euro beat the GFS this time as it did indeed head into the Caribbean. My prediction for intensity was pretty good, though Rafael did break my 50-60 mph window late Sunday by reaching 70 mph. Still, this was a decent enough prediction for this storm.

Overall, with what I had to work with, I didn’t do bad, but not that great either. I give myself a C for this past week.

Rafael continues to churn, but is heading away from the Lesser Antilles. What will he do, and will anything else come down the pipe? Let’s take a look.

Current situation and models

As mentioned, Rafael is churning north of the Lesser Antilles with maximum winds of 70 mph. The storm seems to be trying to develop some type of eye feature as it gets better organized. Rafael is forecast to strength into a hurricane Monday night or Tuesday morning while heading towards Bermuda, though likely staying just east of the island. Maximum winds are expected to be of the minimal hurricane type, at 80-85 mph officially, before Rafael likely weakens rapidly Wednesday south or southeast of Newfoundland. The storm should then dissipate or become extratropical sometime on Thursday. Rafael is not expected to threaten Newfoundland except in the form of surf.

The GFS shows some kind of weak-looking disturbance in the Main Development Region by the weekend, but the Euro does not really pick up on this. It would head northwest and be very short-lived if it does take place.

Recent history

Since 1960, these storms have developed or been active coming into this upcoming week (asterisks by typical El Nino years):

Gerda in 1961
Ella in 1962
Ginny in 1963
Isbell in 1964 (already active)
Elena in 1965* (already active)
Heidi in 1967
Gladys in 1968*
Laurie in 1969
Two unnamed hurricanes in 1970 (one of which was already active)
Kristy in 1971
Gilda in 1973
Evelyn in 1977* (already active)
Frieda in 1977*
Josephine in 1984 (already active)
Joan in 1988 (already active)
Jerry in 1989 (already active)
Nana in 1990
Fabian in 1991*
Roxanne in 1995 (already active)
Sebastien in 1995
Lili in 1996
Grace in 1997*
Irene in 1999 (already active)
Jose in 1999
Michael in 2000
Nadine in 2000
Nicholas in 2003 (already active)
Wilma in 2005
Omar in 2008 (already active)
Richard in 2010

32 storms this upcoming week since 1960! That averages to about two storms every three years. However, if you still believe 2012 is a typical El Nino year, the number drops to six storms in 17 years – becoming seven in 18 though. The vast majority of all these storms occurred in the Caribbean, the Gulf of Mexico, or in the Atlantic west of 60 degrees, crossing that latitude heading rapidly out to sea. Only three storms – Sebastien in 1995, Jose in 1999, and Nicholas in 2003 – occurred at all in the Main Development Region. Only Jose became a hurricane, though the other two briefly got close.

As for the tracks of the western Atlantic storms, all except Ginny in 1963 were in a hurry to get out to sea. Ginny was an erratic looping storm off the East Coast before it headed into Nova Scotia. Some did hit land areas like Bermuda or the Canadian Maritime Provinces along the way, but the common theme is fast-moving storms on their way to northern latitudes.

So what does this all tell us?

Rafael is heading out to sea. That is quite clear. But Rafael will likely intensify on its way out. Given that an eye feature has tended to develop, I would not rule out a little more intensification than the National Hurricane Center has been projecting. Still, Rafael is likely to become extratropical sometime in the latter hours of Wednesday and by that point should no longer be strengthening, so this storm will probably top out no more than 10-15 mph than the official forecasts predict. This storm should also speed up by Tuesday as it begins making this track, and miss Bermuda to the east and Newfoundland well to the south and southeast.

If we truly are to get another feature this week, historical odds suggest the Caribbean is the best bet, though the Gulf of Mexico and western Atlantic are still quite favorable occasionally. But the Main Development Region should really be shutting down by now. Then again, Rafael did just develop in this very area, so I guess looking at this year is more important than what history says. The GFS isn’t entirely inspired if such a system is to develop late this week in this area and keeps it very weak. On the other hand, the Euro just doesn’t see this system coming to fruition at all. The Euro has done the better job so far on Rafael, too.

The Prediction

The tropics are getting quieter, albeit slowly. Every time we get rid of one storm, another one has to come along. But I’m not sold on it this time. I predict Rafael will become a hurricane on Monday and reach maximum winds of 85-90 mph on Tuesday. After initially tracking slowly north-northwest through Monday night, Rafael will speed up on Tuesday and turn north-northeast. Rafael will weaken later that day as it passes east of Bermuda but remain a minimal hurricane that day. But the system will weaken to a strong tropical storm on Wednesday, and to a minimal tropical storm before becoming extratropical on Thursday afternoon or evening. Confidence is 80%.

Elsewhere, I predict no tropical cyclone development in the Main Development Region or anywhere else in the Atlantic this upcoming week. Confidence is 85%.

-Andrew92

[Andrew92]

This last week there was one active storm, Rafael. It was not yet a hurricane coming into the week, but I expected it to do so on Monday, and it did. Intensity forecasts peaked this storm at 80-85 mph but appeared to be trending upward as Rafael got better organized a bit faster than previously forecast. Based on that, I went a little higher with my intensity prediction and said Rafael would top out at 85-90 mph on Tuesday, which also happened – the peak intensity was indeed 90 mph. Rafael also began accelerating that day, which I correctly anticipated. I also was accurate in a weakening trend beginning on Wednesday, but the storm remained a minimal hurricane through the day and did not weaken to a tropical storm as I anticipated. In fact, Rafael never weakened like I thought it would, remaining a hurricane until becoming extratropical on Thursday. However, the storm did track north-northeast quickly and passed east of Bermuda, and well southeast of Newfoundland. Really, when looking at this storm, I did a pretty good job predicting what would happen, only incorrect on him not weakening nearly as fast as I thought on the way to becoming extratropical. Even the timing of all of these events with Rafael was nearly perfect.

On top of doing a good job on Rafael, I also correctly predicted no other tropical developments for the past week. One system is getting close in the Caribbean, with another threatening to develop over the open Atlantic, but neither have pulled the trigger just yet. Overall, I had a very decent week, though not quite perfect. Rafael’s lack of weakening trend does hurt but not much. I give myself a low-end A- for this past week.

New week coming up shortly. It's going to be a quite interesting one...

-Andrew92