Upcoming week - September 13-19

[Andrew92]

Evaluating last week:

It was a shortened week due to Labor Day. Still, the last 24 hours of the forecast proved to be might unpredictable. I said at week’s end we would have Hurricane Igor and that was it. I also thought Igor would be just forming into a hurricane today, with maximum winds reaching 75-85 mph. Yeah, um, that worked out all right. I definitely, even if I had the hindsight to predict a somewhat stronger storm at least, would not have thought to predict a storm nearing C5 intensity. Also, Tropical Storm Julia has developed. So in short, late Saturday night through now have been pure disaster.

But can one bad day make a bad weekly prediction? Many elements to my forecast before the last 24 hours were very well executed. Of course, Hermine dissipating while producing a flood threat was pretty much a given to happen. However, some models were insistent that Gaston would still find a way to re-develop. I countered that argument by mentioning that this time of year is not an ideal time for storms to develop in the Caribbean, and the ones that do typically dissipate quickly. Such was the case, as Gaston never re-developed. The formation of Igor was interesting. It developed 24-36 hours before I predicted it would, but then oddly weakened to a tropical depression…at about the time I predicted the incipient depression to develop. It then re-intensified to a tropical storm on Friday. Even though it quickly reached maximum winds of 70 mph on Saturday, its intensification slowed down from there and I thought my forecast was looking like a solid A-, because the track was pretty much nailed near perfectly. Then, came the aforementioned last 24 hours.

So I give myself an A- for the first five days, and a D- for the last 24 hours. When it averages out, this week was still at least a fairly decent prediction. I give myself a B for this week.

So how will this week fare? Let’s take a look…and with a dangerous hurricane that may threaten land, and another tropical disturbance in the Caribbean as two highlights, I have another disclaimer to make, and a couple more to come:

These weekly forecasts are NOT official and should not be treated as such. These are my opinions based on what could happen based on a combination of what recent history suggests and what models also think will happen. Since I also look a whole week out when doing these predictions, there is the potential for large errors, especially later in the week. Therefore, I urge you to not treat these as official forecasts, but to listen to the NHC for official forecasts and your local authorities for what to do if being affected by a significant storm. Thank you.

Current situation and models

Igor has become quite the storm, with maximum sustained winds of 150 mph. Also, Tropical Storm Julia has formed tonight off the coast of Africa. Models re-curve both systems. Julia’s forecast is looking pretty cut and dry, as it will more than likely re-curve on out to sea, but gather a little more strength. Igor’s re-curve, however, can pose quite a nasty threat to Bermuda, while the Leeward Islands, Virgin Islands, Puerto Rico, the Bahamas, the East Coast, and the Maritime Provinces cannot let their guard up. The reason is crystal clear, as a weakness in a subtropical ridge of high pressure should steer them both northward, away from major land masses.

Elsewhere, Invest 92L is threatening to develop in the Caribbean. Most models do not intensify this disturbance very much, and the GFS doesn’t develop it at all. This is worth noting, as the GFS has done pretty well so far this year. The models also agree on a general track south of Jamaica and into the Yucatan Peninsula. Only the HWRF and Canadian take it north of Jamaica, and with the present west-northwest movement already not far southeast of Jamaica, that appears very unlikely. All of this said, there is very high oceanic heat content, which could potentially support a very intense hurricane. Going a little further, some many models take this into the Gulf of Mexico, which we have already seen recently with Hermine can be quite a breeding ground for storms to quickly spin up.

Recent history

When looking at storms during this upcoming week or within a couple days or so, there have been plenty of impressive storms during the last few years in a position close to where Hurricane Igor is now. Since 1995, these include:

Georges in 1998
Gert in 1999
Isaac in 2000
Isabel in 2003
Karl in 2004
Helene in 2006
Fred in 2009

Gert seems to particularly be fitting the mold for Igor. The dates are very similar, the track is very similar, and the intensity and location of that intensity are also similar! Could Gert very well be the best analog for Igor? The odds favor it may be at least a very solid one. Only two of these seven storms did not re-curve prior to hitting land: Georges and Isabel. Gert’s track from here, you ask? Turned northwestward a safe distance east of the Leeward Islands, and then re-curved a little east of Bermuda, but came close enough to produce tropical storm force winds there. At that time, Gert had also weakened to a C2 hurricane. As for other storms, being that Igor has 150-mph winds at this time, a C5 hurricane cannot be ruled out. However, of this sample set, only Isabel became a C5 hurricane.

As Gert passed near Bermuda, it also passed near Newfoundland a couple days later. This is also somewhat similar to Erin in 2001 and Florence in 2006. Erin past east and Florence west; both passed near or over the Maritimes. Of course, Fabian in 2003 stayed well south, but a threat there from Igor has to be considered, too.

As for Julia, it is playing the role of “Igor’s follower,” which could mean it stays weaker, which as I said earlier, models do suggest. Also remember that even this year, Earl played follower to Danielle and struggled to intensify for a while, and then Fiona followed Earl and never could get off the ground. Julia will be a little further behind Igor, but is also forecast to take a completely different track, further north. Earl took a further south track than Danielle, and was eventually able to intensify more. However, Earl re-curved west of where Danielle did; Fiona re-curved east of where Earl did. Therefore, even for this year, the odds favor that Julia will probably be weaker than Igor. Still, Gert followed Floyd right behind in 1999, and re-curved further east, but still gathered similar intensity to Floyd for a time. However, Gert was also quite far away from Floyd when it developed, allowing for such intensity to take place…then again, Julia isn’t too close to Igor, either. However, other than Karl in 2004 and Fred in 2009, I can only find Isidore in 1996 and Kate in 2003 as recent examples of storms becoming major hurricanes that far east after September 10.

As for the Caribbean, I can find only two new tropical storms that have formed in the Caribbean since 1995 during this upcoming week: Isidore in 2002 and Jeanne in 2004. Isidore did prove that a hurricane came also form from a developing disturbance in the Caribbean, and Jeanne was also pretty close. We also cannot forget that Gilbert became a C5 hurricane in the western Caribbean on September 14, 1988. That said, the odds are still against such a thing happening, and this system is taking quite some time to get going. Of course, if it reaches the Bay of Campeche or anywhere in the Gulf of Mexico, we just saw what Hermine did as it rapidly spun up. Other developing or just-developed Gulf of Mexico storms since 1995 during this week have included:

Hermine in 1998
Harvey in 1999
Gabrielle in 2001
Hanna in 2002
Humberto in 2007

While only Humberto became a hurricane, Gabrielle did come close (and did later on its way out to sea). Therefore, when looking at this disturbance as a whole, recent odds dictate that a hurricane is unlikely, but a respectable storm could still come out of this in that area. Then again, Humberto was also the one closest to the Bay of Campeche, while this year’s Hermine developed in that area and spent a little less than 24 hours over water. It could depend on how much time it has over water.

So what does this all tell us?

With the models and history suggesting it, Igor is almost a shoo-in to re-curve, and Julia is pretty much a lock to do so. With winds of 150 mph already, Igor will likely not strengthen too much more, but Isabel did prove that a C5 hurricane can come during this upcoming week in this part of the world. The location of the re-curve is also very much cause for concern in Bermuda. The Lesser Antilles, Puerto Rico, Bahamas, and East Coast will probably be spared the worst, but should not let their guards down. The Maritime Provinces may receive a more significant threat though, due to the fact that some storms that re-curve close to Bermuda also come close to that area.

Julia is likely to stay weaker than Igor, but models do develop Julia into a hurricane, and it will be a safer distance from Igor than Fiona was to Earl, so it has a better chance of pulling it off. A major hurricane is somewhat unlikely, as it is so far to the east and the odds of that happening, historically, are probably about 25-30%. Models do not seem to favor this, either.

Invest 92L has an uphill climb if it is going to develop into anything significant. The time and conditions are just not all the way there for a significant storm to develop in this area. A tropical storm could develop, but a better chance of doing something more significant could take place in the Gulf of Mexico.

Back to looking ahead

This is another challenging week. Igor is the top story, and Julia is a new story, while Invest 92L is trying to take away some of Igor’s thunder. Igor could potentially still threaten some land, and if 92L does develop, it will almost unquestionably hit land. So what do I think is going to happen?

Let’s start with Igor. I predict Igor will come just short of C5 intensity and will gather maximum sustained winds only up to 155 mph, occurring on Monday. The storm will continue west-northwest through Wednesday morning, with an eyewall replacement cycle occurring late Monday and Tuesday, weakening the storm to maximum sustained winds of about 125-135 mph. On Wednesday, a re-intensification trend will take place as the storm begins to curve northwest, safely north of the Leeward Islands. The storms maximum winds will again reach about 145-150 mph that day and Thursday, before the storm starts weakening again. Continuing northwest south of Bermuda, I predict Igor to weaken to a C3 hurricane on Friday night, and then a C2 on Saturday, but hold on to 100-105 mph winds on Sunday as it passes just west of Bermuda and start to re-curve. It will pass close enough to bring strong tropical storm force winds to the island. Confidence is 50%, but I urge residents of Bermuda and all areas I have mentioned previously to continue to watch this storm vigilantly. Bermuda, you could easily see hurricane conditions from this system. Everywhere else, keep your guard up in case this storm takes a different path than I am forecasting. And for all involved, do not treat this as official; heed advice from the National Hurricane Center and your local authorities first for critical decisions. Thank you.

Now let’s knock out Julia. I predict Julia to pass very near, but just south of the Cape Verde Islands on Monday with maximum sustained winds of 50 mph. I predict the storm will head west-northwest until early Tuesday. On Tuesday, Julia will become a hurricane with maximum sustained winds of 75-80 mph. As it turns northwest, it will stay a minimal hurricane for about 24 hours. I predict Julia will weaken to a tropical storm as it continues northwest over somewhat cooler waters. The northwestward motion will continue until Saturday, during which time the storm will steadily hold on to maximum sustained winds of 60-70 mph. On Saturday, a northward turn will commence well east of Bermuda, and the storm will continue north-northeast on Sunday, still gathering maximum sustained winds of 60-70 mph. Confidence is 70%.

Invest 92L is quite a difficult forecast, but here is my best shot. I predict no development for Invest 92L in the Caribbean. But the disturbance will reach the Bay of Campeche on Thursday night and develop shortly after emerging. Tropical Storm Karl will then quickly form on Friday while continuing west-northwest towards mainland Mexico. Like other systems in this part of the world, it will quickly organize and intensify, but also make landfall on Saturday near about Tampico, Mexico. With about 36 hours of time as a developed system over the BOC/GOM before landfall, I predict Karl to come just short of hurricane intensity, and make landfall with maximum sustained winds of 65-70 mph. The storm will dissipate in the mountains on Sunday. Confidence is 40%, and residents who could be affected by this are also urged not to treat this as official and to stay tuned to what the NHC and local authorities have to say should this thing develop more than expected. Also, keep in mind that any forecast for a disturbance yet to develop is always a difficult forecast. Thank you.

-Andrew92

[Andrew92]

OK, um, can we just say that recent history is tending to lie this week? Almost no way being where it is, not too far behind Igor, and moving west-northwest to northwest not far from the Cape Verdes, should Julia have made it to C3 intensity!

Yeah, Fred made it to C3 intensity in an El Nino year on a similar track in a similar location close to this date, but it wasn't right behind a borderline C5 hurricane. I can say this, the last time a storm like Julia took place right behind a storm like Igor, with both storms in similar locations, was not in the satellite era. I mean, you wanna talk crazy?

Not looking too good this week there....oh and a little thing about how difficult it is for storms to develop in the Caribbean in mid-September. Karl's sure debunking that theory, too.

Igor is starting to look like my only glimmer of hope. Only 48 hours in!!!

-Andrew92

[CrazyC83]

The Atlantic has just gone nuts all of a sudden. It feels like 2005 now. The only difference is that we aren't seeing devastating landfalls - YET - all of the craziness is going on in open waters.

[RL3AO]

Look where the GFS puts the ridge next week...



Euro takes a little longer. Day 9



Models think the GOM will be more open for business by next week.

[Andrew92]

Well, what a week! Let's evaluate:

This week was certainly a crazy one. Two category 4 hurricanes at once for the first time since 1926! There was also a landfalling hurricane in Mexico, and proof of just why I’m really glad I put up my own disclaimers. We’ll take a look at how I did with each storm, then figure out a decent grade for this week though.

Starting with Igor, this was a very good forecast, especially in terms of track and its timing. Even the intensity forecast was very close! For the track, I predicted a west-northwestward movement until Wednesday, with a gradual northwestward turn commencing that day, a comfortable distance from the Lesser Antilles. That’s pretty much what happened those first three days. I predicted that northwestward movement to continue all the way through Sunday, when it would start re-curving near Bermuda. That also was executed about as well as possible! So the track and timing certainly gets an A. Now for intensity, I predicted no more than 155-mph winds, and operationally that did happen. However, I predicted this on Monday, and it happened Tuesday night. But I did correctly predict an eyewall replacement cycle would happen late Monday and early Tuesday, weakening the storm to a borderline C3/C4 hurricane. While the strengthening on Tuesday was not expected, it did weaken again overnight into Wednesday before strengthening again, so Tuesday was at least acceptable in this area. I predicted on this intensification trend that maximum winds would reach 145-150 on Wednesday and Thursday, and they reached 145 on Thursday early morning (shortly after midnight). I then predicted a weakening trend to a C3 on Friday, which happened. Then, I started falling off a bit on the intensity portion as I predicted the storm to weaken to a C2 on Saturday, but it happened Friday night. That said, the storm was a C2 all day on Saturday, so that was still a very good day. But I did not foresee the weakening to barely a hurricane today, predicting still a C2 storm as it passed by Bermuda. Lastly, I did predict Igor would pass west of Bermuda and bring tropical storm winds, but never mentioned hurricane winds. As of the last possible advisory for the week, 74-mph sustained were reported in Bermuda, so I just barely missed this. Still, all things considered, the intensity was pretty good until late, and even then wasn’t terrible. I give myself an A- for intensity, and a solid A for Igor this previous week, when also considering this was tricky with Bermuda thrown in.

Looking at Julia, there is no way even with 20/20 hindsight that I would have predicted a C4 hurricane. That said, the first two days were good, with maximum winds indeed reaching 50 mph as it passed the Cape Verdes, and then becoming a hurricane on Tuesday while heading west-northwest. The northwestward turn was also correctly anticipated, and I also predicted that heading would last until Saturday. That day, I predicted a northward turn well east of Bermuda, followed by a north-northeast turn on Sunday. It turned a little sharper than I thought on Sunday, but this is a very slight error due to its location over open waters, well east of Bermuda. So the track gets an A, but the intensity is something else. I predicted Julia would be a minimal hurricane for about 24 hours. Well, it became a C4 hurricane within that time. That said, a weakening trend did begin on Wednesday, but no way by then would it have weakened to a tropical storm. That happened on Friday night, instead. During the time Julia was to move northwest and even north, I predicted a steady intensity of about 60-70 mph. It did fall to about 50 mph actually, but when you look at the FTP file, it did fluctuate back to 65 mph on Saturday night – so the idea was at least executed, just a little outside the window. The intensity was sure not good on Wednesday through most of Friday, but very good at all other times. I give myself a C+ for Julia’s intensity, and a B overall for this storm.

Igor and Julia were pretty good forecasts overall, even during this tough week. The same cannot be said, however, for Invest 92L/Karl. I predicted no development in the Caribbean, and that it would happen after emerging in the Bay of Campeche on Thursday. Well, development did happen in the Caribbean. Karl reached the Bay of Campeche on Thursday indeed, but then I predicted a landfall near Tampico as a 65-70 mph tropical storm. It ended up making landfall near Veracruz instead, quite a bit further south, and as a major hurricane (though I suspect it will be lowered to a C2 when the official report comes out). Even the timing after emerging into the Bay of Campeche was off by about 24 hours. I predicted the landfall for Saturday, and dissipation on Sunday. The landfall came on Friday, and dissipation Saturday instead. Besides the timing of reaching the Bay of Campeche, the only other aspect I nailed with Karl was time over water, about 36 hours. Yes, this was a difficult forecast. OK, the general westward track was well-executed. I also got timing of reaching the Bay of Campeche and how much over water right. That’s about all I can say for this forecast, however. I did put up disclaimers for this prediction to be prepared for those in Mexico, but I still give myself a D overall for Karl – only proving the point of the disclaimers a little more.

Lastly, I didn’t actually say it by accident, but I did mean to predict no other developments. Invest 94L is on the verge of doing so…but hasn’t done it yet! I may be being a little generous to myself for not actively saying it, but I will assume it was implied and give myself an A here – with only little weight though.

So two good forecasts, one bad one, and no other developments. The bad forecast was probably the most important one, unfortunately. But with another important forecast, Igor, that was executed almost to perfection, and a decent Julia forecast all things considered, this week was still a decent one, but not great. It is also one I can take some things and learn from for the rest of this season, and you will probably start hearing stuff like the “2010 factor” in light of especially Julia. I give myself a B- for this week.

September 20-26 coming up shortly!

-Andrew92