Upcoming week - July 26-August 1

[Andrew92]

Evaluating last week:

The previous week is a tough week for tropical cyclones to develop. The favored area is close to home, preferably in the western Caribbean or Gulf of Mexico. I went against the Caribbean disturbance development, which was correct. However, the Leeward Islands wave eventually became Invest 97L and then Tropical Storm Bonnie, whiffing my prediction of no tropical development. Granted, it only gather maximum sustained winds of 40 mph, but this part was blown. I was also correct, though, in predicting no development near the African coast.

But in hindsight I probably should have seen the movement further north, avoiding Cuba, which might have allowed me to predict further development, albeit not very strong given the reliable models’ prognostications. Therefore, my grade for last week is a D.

You can see last week’s prediction at this thread:
viewtopic.php?f=31&t=108609

Now let’s look at this week and see if I can do a little better.

Current situation and models

The remnants of Bonnie have moved inland over Louisiana and will continue inland, and will therefore not re-develop. We also see that Invest 99L was declared for a disturbance moving onshore into Mexico from the Gulf of Mexico. Given that it, too, is moving inland, this will also not develop further. Looking elsewhere, nothing is currently threatening to develop. However, a few models, such as the Canadian and the GFS, are trying to develop a tropical wave southwest of the Cape Verde Islands on about Saturday. The Saharan Air Layer (SAL) appears to also be weakening, which can favor tropical development a little more in this area. The NOGAPS does not agree with this, but it and the Canadian do show a reflection in the western Caribbean Sea at the same time, near the coast of Nicaragua and Honduras. Jeff Masters from Weather Underground also mentioned this on his most recent blog on Saturday, July 24. He did not, however, make much note of the African disturbance.

Recent history

Since 1995, there have been six new tropical storms develop:

Dean in 1995
Erin in 1995
Alex in 1998
Alex in 2004
Chris in 2006
Chantal in 2007

That’s an increase by one storm from last week, but two of the storms, Dean and Chantal, came from frontal lows. Therefore, tropical waves still seem to have a hard time developing this week. It should also be noted that three of these storms, Erin, 2004 Alex, and Chris, all came at the tail end of this upcoming week.

Looking further at this sample set, Dean, Erin, 2004 Alex, and Chris all developed relatively close to home. 1998 Alex and Chantal did not, and were both very weak. The same can also be said for Dean, but it came from a frontal low. Erin, 2004 Alex, and Chris all got quite a bit stronger (albeit Alex’s strength comes later, and I’ll talk about that more next week).
During this week, only one of these storms became a hurricane, Erin. It did so in the central Bahamas while heading towards the east coast of Florida. By week’s end, it was a mere couple hours from landfall near Vero Beach and had maximum sustained winds of 85 mph.

As for 1998 Alex, its development near the Cape Verde Islands was the first such development this upcoming week since Tropical Storm Cesar in 1990. However, this storm was also the first to develop in this area during this upcoming week since Tropical Storm Anna in 1969. However, a few other storms, which included Subtropical Storm Alfa in 1973, Hurricane Blanche in 1975, Tropical Storm Anna in 1976, and Hurricane Bertha in 1990 all came from non-tropical origins during this upcoming week. That means there’s much closer to a 50/50 chance that development could come from a non-tropical entity versus a tropical wave this week. The strongest of these was Blanche, gathering maximum sustained winds of 85 mph – further indicative that anything higher than a C1 hurricane is unlikely during the last week of July.

Also, only one of these storms lasted longer than a week after developing this week: Anna in 1969, and she even nearly dissipated before re-strengthening further west.

And by the way, you may also note and this was not a typo: No storms developed during this week in 2005.

There were also two storms previously intact coming into this week:

Cesar in 1996
Franklin in 2005

Cesar had just developed into a tropical storm in the southeastern Caribbean, and this week went on to become a C1 hurricane with maximum sustained winds of 85 mph before making landfall in Nicaragua and then crossing into the EPAC to become Hurricane Douglas. That means that during this active period, two storms became hurricanes, but both got no stronger than 85 mph.

Franklin, however, had already nearly become a hurricane off the East Coast, and was skirt the coast, never really threatening to make landfall. It weakened, but then re-surged during this upcoming week, gathering maximum sustained winds of 60 mph before becoming extratropical on July 31. So although no new storms developed this week during 2005, Franklin was still an ongoing, lazy, long-lasting storm that just could not pull off becoming a hurricane.

So what does this all tell us?

The best area for significant development is in a home-grown area, probably off the East Coast, and recent trends suggest from a tropical wave. However, a frontal low can still occasionally produce a tropical development. Hurricane development is also not very common either, usually coming off the East Coast. Sometimes a storm can develop in the Main Development Region (MDR), but it usually comes short of hurricane strength if it does. Cesar in 1996 also appears to be an outlier in the Caribbean, as this area is typically unfavorable for development during the last week of July.

Back to looking ahead

So when we come back to our situation this week, we see no imminent development for at least a few days. By Saturday some models try to develop a couple of systems – one off the coast of Africa and one near Nicaragua. Since I have ruled 1996 Cesar as an outlier, the Nicaragua development , while possible seems extremely unlikely. However, the development near Africa should at least be considered a little further. Even the Euro sees a reflection in this area next week, but that’s for a later discussion as it does not show much at the end of the week. If we see Colin develop, it will likely be in this area at the end of the week, but likely not be a very strong storm going into next week (I’m thinking 45-50 mph at the strongest). However, right now I’m not buying it without further model consensus. However, it would not surprise me if this supposed wave, if it exists later, persists with convection enough for an invest to be declared. Beyond that is for next week, however. And if even 2005 doesn’t see new development during the last few days of July, I think that says a little something about this week in that category.

I predict no tropical cyclone development this week.

Confidence is 90%.

-Andrew92

[KWT]

Yeah history also seems to back the idea that there will be very little of note in the coming week.

[hurricaneCW]

I think this week everything will be setting up for development and we should see something develop the following week (August 2-8).

[Macrocane]

I agree about no development this week, I wouldn't be surprised if we saw another big SAL outbreak and a strong TUTT, but after this week I think that the patterns will begin to change.

[Hurricane Andrew]

My forecast for this week
Later in the week, it is possible we MIGHT have a chance of a storm in the atlantic. it depends on the SAL.

Prob. of a TS-20%
Prob. of a hurricane-10%
Prob. of a MH-<1%
Prob. of a SAL outbreak-50%

[vacanechaser]

all you have to do is look at the mjo... downward pulse... not favorable... nothing this week...



Jesse V. Bass III
http://www.vastormphoto.com
Hurricane Intercept Research Team

[Macrocane]

I've said this several times on the last few weeks (KWT has said it a lot of times too), the MJO has been weak most of the year and will probably remain that way, it is not the most important factor this year I agree that it can enhance the activity but this year may not be one of those MJO driven years like 2008 was.

[Andrew92]

I have to agree with a couple posts about next week. This week may actually be a transition week of sorts before the season begins to pop a little bit. I just have this suspicious feeling Colin may just end up forming next week sometime. Perhaps that African wave will initially be slow to develop, but then form a little closer to home.

But we still need this disturbance that's forecast to actually become a presence first! Until then, it's all speculation, and in seven days we'll see if my feeling about Colin next week stands (assuming he isn't born this week of course).

-Andrew92

[StormClouds63]

all you have to do is look at the mjo... downward pulse... not favorable... nothing this week...
Jesse V. Bass III
http://www.vastormphoto.com
Hurricane Intercept Research Team

Confirms downward pulse MJO

[Andrew92]

I know the real evaluation comes Sunday night, but just looking back a little at what my prediction has looked like.

So far, so good. The supposed wave does indeed exist off Africa and Invest 90L has been declared. Development still looks like it will be slow (i.e., likely not until at least Monday) due mainly to an unfavorable MJO, but also another wave coming off Africa may hinder its development at least a little. Combine that with climatology working somewhat against this, and my forecast of no development still has lots of hope to stand.

There is, however, a tropical wave in the eastern Caribbean. However, it is very disorganized and no invest is declared for it yet. This may very well be that Nicaraguan disturbance coming soon that some models saw last weekend. The MJO does also show a little more favorability close to Central America. But with no invest, the NHC giving a 10% chance of development during the next 48 hours, and the odds historically stacked majorly against it, I am also very confident this prediction will stand.

Back on Sunday!

-Andrew92

[Andrew92]

With no 11 PM advisory looking like it is about to come out on Invest91L, I am ready to give my evaluation for this past week.

I predicted no tropical cyclone development and no real players to talk about until Saturday. Well, they came late Friday, but being off by a few hours is not a bad thing. Despite my prediction for no new development, an African wave was thought to be watched by the end of the week for potential development, or at least into becoming an invest. That is exactly what happened, the invests as it turned out were declared, but no further development....yet. A nice, easy, quiet week comes to an end and my grade for this week is an A.

-Andrew92