Upcoming week - August 30-September 6

[Andrew92]

Yes, with Labor Day weekend, I have decided to account for that and have this week go until next Monday. September 6 is not a typo. Also, as a word of warning, this is going to be a long post with red text and disclaimers in it. Onward and upward from here!

Evaluating last week:

Let me set this straight: this was not a perfect forecast. In both cases of Danielle and Earl, the intensities were off. I predicted Danielle would only become a C2 hurricane, and Earl to be a 50-60 mph tropical storm by the time this week was up. I underestimated both by a decent amount. There were other lesser discrepancies in both forecasts that I’ll bring up below.

Now, on with the good stuff, starting with Danielle! I’ve already mentioned how it became a C4 hurricane and that part was off, but let’s dissect the rest, with quotes from my prediction from last week. I said it would “continue west-northwest over the next three days” for Monday through Wednesday. That’s exactly what happened in terms of track those three days – to even the point that it was, by Tuesday “already at a latitude equal to the northernmost Virgin Islands.” I did predict a hurricane on Tuesday, but it came Monday. Still, the early fluctuations forgive that element a little bit. I then predicted Danielle to “become a C2 hurricane with maximum sustained winds of about 100-105 mph on Wednesday and Thursday” and “During this time period, the storm will also begin gradually curving toward the northwest, passing safely northeast of the Leeward Islands.” Could I have timed that part of the forecast any better? Wednesday was when it became a C2 hurricane, and on that day and Thursday it was moving generally northwest. Friday is when it got more intense than I had predicted. Also, I did predict the re-curve within 5 degrees of Longitude 55, and it occurred at 61, so I was one degree off, but since it was far away from land, I won’t dock myself too much there. Besides, I still predicted it would stay east of Bermuda. But then I really nailed it: “On Friday, Danielle will begin to weaken, and by week’s end, the storm will have weakened to a minimal C1 hurricane with maximum sustained winds of 75-80 mph, well south of Nova Scotia and Newfoundland and heading northeast away from land.” Friday is when peak intensity took place, and weakening began that evening. Now, Sunday night, the storm is heading rapidly northeast, positioned well south of Nova Scotia and Newfoundland, and its maximum sustained winds are 80 mph. I mean, I hate to brag too much, but to predict this so many days in advance…you can’t do much better than that that far out! Really, the intensity of C4 does hurt my overall grade for Danielle. However, when couple with an otherwise near-perfect forecast for this storm (the timing of becoming a hurricane and the recurvature point are minute mistakes when taken into comparison, all things considered), I have to give myself a B+ here (and would be an A if I had called for a C4 hurricane, and probably even an A- if I had picked a C3).

And how did I do on Earl? I predicted a slow development, taking place on Thursday, with a tropical storm forming on Friday. Well, both took place on Wednesday. That said, the slow development did continue from there, and I predicted as such, as it didn’t intensify again until Saturday. But I predicted that would happen on Sunday instead, so that too was 24 hours off, and as a result it was able to become a hurricane, and a C2 at that tonight. The track and timing of it, however, were excellently done. I predicted it would be a little northeast of the Leeward Islands, and it is in fact just approaching those islands, but the latitude itself is off by about two degrees or so – again, about a week in advance. A lot of forecasters would call that a pretty good forecast, though I did think it would be starting to head northwest by this time. It is, however, moving west-northwest and gradually bending right, so even that part wasn’t far off either. Overall, there were some mistakes with Earl’s forecast, but the track was near perfect. Considering my 45% confidence in this forecast and the slight disclaimer that came with it, this was a good forecast. I give myself a B here.

But Danielle and Earl were not the only ones being talked about. Several members on this board talked about a Gulf of Mexico disturbance that might develop. I gave it consideration, but also refuted that it would not develop, and that’s exactly what happened. I also predicted no other development elsewhere the rest of the week. Well, 97L sure gave that element a good scare, didn’t it?! But, as of right now, the end of the week, it has still not developed into a tropical depression yet. Therefore, on these two areas, I have no choice but to give myself an A.

So overall, two good forecasts on Danielle and Earl, and also accurately predicting no other developments the rest of the week. Sure, I was off on some areas of Danielle and Earl’s forecasts (*cough*INTENSITY*cough*), but there were too many elements that were spot-on nailed, even over five days in advance. When you throw all that with an accurate (and looking back, very bold!) prediction of no other developments and the week being a pretty tough one, my overall grade for this week is a B+.

Of course, if you haven’t noticed, one week my forecast is really good and the next is bad. My goal is to end that this week! Here we go…but before I state this prediction, I have a very important statement to make:

These weekly forecasts I do are UNOFFICIAL and should be treated as such. This is only something I do to help others and myself learn about what is going on and what very well could happen, through looking over the current situation, model projections, and recent history. Especially this week, there will be very dangerous predictions made with confidence being low. It must also be reminded that a hurricane is not a point but a large storm with strong winds extending for potentially over 100 or 200 miles. I urge you, please do NOT use this forecast to plan life-and-death situations. Listen to official forecasts from the National Hurricane Center for official watches and warnings, and local officials for what to do if a dangerous situation occurs. Thank you.

Current situation and models

Hurricane Danielle is still out there, but will become extratropical soon as it continues weakening and heading out to sea. OK, that part is easy. But now it gets tricky, and fast. Hurricane Earl is about to strike or veer just north of the Leeward Islands as a C2 hurricane with 100-mph winds currently. After that, nearly all models take Earl to major hurricane intensity, and re-curve it from there. Generally, most models are keeping Earl off the East Coast, and west of Bermuda. However, it should be noted that models can shift west or east, and only a slight shift west could put Earl onshore, or bring hurricane-force winds onshore at minimum. At the end of the week, Earl looks to become a threat to Nova Scotia and/or Newfoundland, while weakening as most storms do that far north.

But Earl isn’t alone. Invest 97L is threatening to develop to its east. Several models develop this thing slowly over the next few days, and not taking off in intensity until it gets closer to the Leeward Islands. Also, from there, several models that it northwest and threatening the Carolinas and East Coast. The Euro, however, thinks 97L could head towards Cuba and the Gulf of Mexico in about a week. Nearly all of the global models have a well-formed hurricane before the end of the week, while at least approaching the United States (or Cuba, in the Euro’s case).

A disturbance in the Gulf of Mexico is being talked about, but this was also talked about last week, and nothing came of anything there. Still, this is a different week from last, so I’ll take a closer look at what could happen in this part of the world. Model support is very lacking in this area for development this week, though.

Elsewhere, some models predict a tropical wave to come off the African coast on about Saturday. However, it is getting little support in terms of development. Nothing else appears imminent elsewhere either. And lulls were not supposed to happen in 2010, right?

Recent history

First, there have been ten storms at some point during this upcoming week in a position near where Hurricane Earl is right now:

Luis in 1995
Edouard in 1996
Fran in 1996
Erika in 1997
Ernesto in 2000
Erin in 2001
Fabian in 2003
Frances in 2004
Florence in 2006
Ike in 2008

Note that while the sample size is small, only Ernesto and Florence failed to become major hurricanes of these four (though Ernesto is a terrible analog, and 2006 was an El Nino year). Also of note is that only three storms ultimately did not re-curve to the north and stay out to sea: Fran, Frances, and Ike in 2008.

The irony to that last statement? Two storms that didn’t re-curve after being close to this location started with the letter “F,” and that is the next letter we face for 97L. Recent history also, like I mentioned last week, says that disturbances on the heels of stronger storms also take longer to develop or intensify. Fran’s incipient disturbance became a depression on August 23, but didn’t become a tropical storm until August 27. Incidentally, Gustav was also right behind Fran, and it never got stronger than 45 mph before fizzling out. On Erin’s heels in 2001 was Felix (albeit after this time period a bit), and after becoming a depression on September 7, didn’t become a tropical storm until September 11. And right behind Ike was the fledgling Josephine, another storm that just could not get off the ground and, like Gustav (in 1996, not 2008), dissipated seemingly prematurely.

Incidentally, going back to Fran, Frances, and Ike, I can’t help but notice something further in common among two of the storms. Fran and Ike were both followers of storms ahead of them! (Fran behind Edouard, and Ike behind Hanna)

As for the disturbance in the Gulf of Mexico, if it were to develop, it would join these storms that have since 1995 for this upcoming week:

Earl in 1998
Fay in 2002
Grace in 2003
Henri in 2003

Only four storms in the last fifteen years, with only one (Earl) becoming a hurricane (and it never really looked like one, to be frank). Besides Earl, only Fay was anything remotely impressive during this upcoming week that developed in the Gulf of Mexico. Grace is the penultimate controversial one that some people believe was never a cyclone, and Henri was also pretty pathetic-looking.

Finally, it is not out of the realm of possibility for even the most active of hurricane seasons to have a lull after a big storm. There were fairly significant wait times (meaning at least a week) for development in the Main Development Region after Luis in 1995, Fran in 1996 (excluding Gustav), Dennis in 1999 (excluding Emily), Fabian in 2003, and Frances in 2004. Therefore, if there is no other development beside 97L’s this week, it would not be a surprise.

So what does this all tell us?

All too typically, storms in Earl’s current position, during this upcoming week, often re-curve before striking the United States. The vast majority also become major hurricanes, if they aren’t already (which is Earl’s case of course). The couple or so that do not re-curve before reaching the East Coast typically follow another storm like Earl. However, several storms trailing developed ones take a bit longer to really get going. Some do not survive, but those that do often become nasty storms down the line.

And in the Gulf of Mexico, it is just too hard for storms to develop from a disturbance into anything significant here. When you’re comparing storms to Grace or Henri from 2003, I mean, what does that say for Gulf of Mexico developers this week? Yeah, yeah Earl, but tell me, even though he was, did he ever look like a legit hurricane?

Back to looking ahead

When looking at the setup for both Earl and 97L, I can’t help but think of one setup for this upcoming week that took place with very similar timing: that of Edouard and Fran in 1996. Both models and history suggest that Earl is going to re-curve and miss the East Coast. Yet, models and history also strongly suggest a major hurricane out of Earl before all is said and done. As for 97L, much like Fran, it has already proven to be a slow developer, and it would be no surprise if that continued – per both models and history, yet again! However, models do hint that 97L will eventually develop, and that the ridge of high pressure that Earl could re-curve around will get stronger. That could, as I said, lead for the Edouard-Fran setup to be quite similar to this one. Now, will that happen? Just to say, one more time, from just before I began this week’s forecast:

These weekly forecasts I do are UNOFFICIAL and should be treated as such. This is only something I do to help others and myself learn about what is going on and what very well could happen, through looking over the current situation, model projections, and recent history. The following predictions on Earl and 97L are also low-confidence and both systems have very dangerous potential. It must also be reminded that a hurricane is not a point but a large storm with strong winds extending for potentially over 100 or 200 miles. I urge you, please do NOT use this forecast to plan life-and-death situations. Listen to official forecasts from the National Hurricane Center for official watches and warnings, and local officials for what to do if a dangerous situation occurs. Thank you.

We’ll start with Earl: I predict Earl will graze the northernmost Leeward Islands on Monday as a C2 hurricane with maximum sustained winds of 100-105 mph. As Earl approaches the northernmost Virgin Islands later in the day, it will become a C3 hurricane with maximum sustained winds of 115-120mph. A northwest turn will begin on Tuesday, couple with intensification into a C4 hurricane. Maximum sustained winds will reach 140-145 mph by late that night and early Wednesday, before the storm begins to weaken. On Wednesday, the storm will be about halfway between the Bahamas and Bermuda. Earl will weaken to a C3 hurricane east of the Outer Banks on Thursday while curving north and expanding in size. Then on Friday, Earl will pass just off shore of New England as a C2 hurricane with maximum sustained winds of 100-105 mph, but bring tropical storm-force winds onshore, along with heavy rains. On Saturday, Earl will strike Nova Scotia with maximum sustained winds of 75-85 mph, before becoming extratropical later that night. I am thinking a track similar to Luis and Edouard as most likely for Earl this week. Due to the precise nature of this forecast, the possible land threats, and shifts in track producing potentially significant errors, confidence in this projection is 30%. A slight deviation to the left could produce drastically significant effects on the Lesser Antilles, the Outer Banks, the Mid-Atlantic States, and New England.

And now let’s look at 97L: 97L will indeed be slow to develop, but will become a tropical depression on Tuesday and Tropical Storm Fiona later that night, still to the east of the Lesser Antilles. Fiona will past just over the Leeward Islands on Wednesday and gather maximum sustained winds of 50-60 mph during that time. Fiona will also begin tracking west-northwest to northwest along a similar track to Hurricane Earl as it passes through. Cooler waters from Earl’s wake will cause only slow strengthening at best until it reaches a point due east of the southernmost Bahamas, while also due north of Puerto Rico on Thursday night. On Friday, Fiona will become a hurricane over warmer waters and begin paralleling the Bahamas. As strong as the ridge will be by this time, it too will eventually will cause Fiona to re-curve, but not before an East Coast landfall as a significant hurricane. Passing over warm waters, I predict Fiona to become a C3 hurricane with maximum sustained winds as high as 125 mph by Sunday, now north of the northernmost Bahamas and making a beeline toward the Carolinas. Landfall will occur on Monday with maximum sustained winds of 120-125 mph near the NC/SC border, give or take about 100 miles either way. The storm will also be re-curving north to north-northeast by this time. The storm will begin weakening over North Carolina that night. Much like Earl, due to the precise nature of this forecast, the possible land threats, and shifts in track producing potentially significant errors, confidence in this projection is 30%. Any slight deviation, to the left or right could produce drastically significant effects on the Lesser Antilles, Puerto Rico, the Bahamas, Cuba, and the Southeast Coast. This is also a high-risk projection when considering that this is currently a disorganized disturbance that has not yet developed into a tropical cyclone.

Also, even though I didn’t really mention it, since it is still technically there and advisories being written, I’ll do a quick forecast on Danielle: As it continues rapidly northeast out to sea, Danielle will weaken to a tropical storm on Monday and become extratropical on Tuesday. Confidence is 90%. This forecast will be given little weight in terms of evaluating this upcoming week.

Elsewhere, I predicting nothing will form in the Gulf of Mexico or elsewhere this week. Confidence is 90%.

OK, I rescind my hot-and-cold statement from earlier. I would love to be wrong this week and have everything stay away from land or not develop!

Everyone in hurricane territory: prepare for the worst, prepare for the best, and STAY SAFE! It's going to be a very interesting week this week, no matter what happens.

-Andrew92

[Macrocane]

You're right and it would be better if you're wrong this time. 97L has one of the most difficult forecasts of this season, the GFS does not even develop it, the HWRF and GFDL likes the Earl-Fiona interaction scenario and the CMC and ECM have Fiona as an US threat, it will be a very interesting and important system to watch.

[Andrew92]

I did analyze what the GFS, GFDL, and HWRF do with 97L too, but after reading what others have said, I had to discount those models. But like I said, slower development is more likely anyway. Also, while the GFDL/HWRF scenario is a plausible one, by Thursday Earl should most likely be even with the Outer Banks, as I indicated. If the two do interact and 97L is in the position I'm projecting for the same time (between Puerto Rico and the Bahamas), Earl would have to be quite a large system.

Now as I said, I do predict Earl to expand in size as it moves north, and it could certainly bring some shear to curtail 97L/Fiona's strengthening, like Danielle did to Earl itself. But by Friday, if indeed Earl's rapid movement north and east continues, there should be little to no more shear related to Earl over 97L/Fiona. Therefore, if 97L/Fiona keeps moving further to the west of Earl's forecast, I see no reason not to favor intensification, with warm waters present there not upwelled by Earl. 125 mph may be a tad generous though, but I wouldn't rule out quick strengthening, particularly over the Gulf Stream. Remember, one particular storm became stronger than that over similar conditions back in 1989, its name being Hugo.

You also have no idea how much I was shaking inside typing this forecast up. A lot could happen this week.

-Andrew92

[Andrew92]

Well the Earl prediction is looking pretty good! But that's all I have to go for so far this week it appears....and in Fiona's regard, that's a very good thing. However, neither the models nor myself saw Gaston coming! Looking like it's gonna be another "cold" week. (though if Earl's forecast fully verifies, which to this point pretty much is, at least I have one reason not to give myself an F)

-Andrew92

[Migle]

You did well with Earl, but missed both the short lived Gaston and the current Hermine. Look forward to see your upcoming week forecast tonight or tomorrow.

[Andrew92]

I'm actually typing it up right now on Word!

[Andrew92]

Alright, I'm ready to evaluate....

It may have been an extended week by a day, and therefore more challenging there by default. However, this was easily the most difficult week we have faced yet this season, with Earl and Fiona forming as expecting, but also Gaston and Hermine came along. These two I did not see coming, and are going to hamper my grade a fair amount. I did not predict much other than Earl and Fiona for this past week, and boy was that wrong! (Even if Gaston hasn’t amounted to much)

Starting with Earl: This forecast was fairly decent, I have to say. Earl did indeed graze past the Leeward Islands as a C2 hurricane on Monday. It also became a C3 hurricane as it left the area later that day, which I also correctly anticipated. A northwest turn and intensification to a C4 hurricane were predicted for Tuesday, and that’s exactly what happened. The storm made it a little further west on Wednesday than I thought (halfway between the Bahamas and Bermuda), but that error means little considering it wasn’t really affecting land other than for surf at the time. I predicted maximum sustained winds to reach 140-145 mph, and they did so on Wednesday night and Thursday morning; I actually predicted this for 24 hours earlier, on Tuesday night and Wednesday morning. I did think about the possibility of an eyewall replacement cycle, but I thought it would start Wednesday as opposed to Tuesday. Still, this error is only a slight one. I did predict weakening to a C3 on Thursday as it passed east of the Outer Banks, which indeed happened, but it came more rapidly than anticipated as it also weakened to a C2 that same night. Friday’s track of just south of New England also materialized, but the more-rapid-than-predicted weakening continued; I predicted a C2 hurricane passing back, but it was a tropical storm. Still, I predicted tropical storm force conditions in this area, and that did happen. Then on Saturday, Earl hit Nova Scotia (again, correctly predicted), but as a tropical storm, albeit with 70-mph maximum sustained winds; not horrifically outside the 75-85 mph window I gave it. It then became extratropical that night, as predicted! So looking back overall, for such a difficult forecast (with the possibility of moving onshore or not affecting the East Coast at all other than surf), this was a darn good forecast! Not perfect, but despite some mistakes, it’s hard to have been able to do much better here. I give myself an A- for this part of the forecast (also sealing a passing grade for the week).

Now to Fiona: This forecast was (thankfully) badly botched. I ultimately predicted a major hurricane to make landfall out of this! Still, the earliest part of the forecast sees a little silver lining. However, it became a tropical storm a day before I thought it would; that said, slow development was the call before the Leeward Islands, and that did happen. I predicted a close approach to the Leeward Islands on Wednesday with maximum sustained winds of 50-60 mph, which is also exactly what happened. But from there, well if you read last week and know what actually happened, I horribly blew this part. Fiona never really got off the ground after that and was only a minor threat at worst to Bermuda; quite a contrast from the major hurricane threat I foresaw for Labor Day weekend! Early part of the forecast gets an A, the latter part gets an F, but considering the drastic latter part of the forecast, these do not average to a C. Even given the difficulty of this forecast, it is still best to give myself a potentially still very generous D for this part of the forecast.

The Danielle portion of becoming extratropical and continued weakening was correct. I get an A there but this counts to like 1% or so of this week’s total. I predicted no other developments, and while Gaston probably wouldn’t lower my grade too much (maybe to a B), Hermine definitely does, even if it came late in the week. I give myself a C- here.

Overall, with a very good Earl forecast, a good early Fiona forecast that became terrible after that, and not accurately seeing Gaston or Hermine, this wasn’t the best week for me. Still, the Earl forecast was the crucial one as it turned out, so my grade for this week will be a bit higher than if it didn’t take place. I give myself a C+ for last week (but would be a D or so without Earl).

-Andrew92