Watching Tropical Storm Erika

It has been a remarkably quiet summer season. Sure we dealt with some thunderstorms - at times severe - but for the most part they were your typical summer storms you can expect around the NYC area. Temperatures have been more on the milder side than I expected, but we also had our fair share of cool nights too. Precipitation from normal is below average to date which is what I predicted in my Summer Outlook. I will have a more detailed overview of how well, or poorly, the summer forecast came out sometime in September or early October.

I want to spend some time talking about Tropical Storm Erika. I am not going to go into extreme specifics and depth mainly because there is still a lot of uncertainty surrounding her.

For the most part, guidance is consistent in taking Erika either through or just north of Puerto Rico. Then continuing along the northern periphery of the DR and Cuba. The big question is, at what intensity will she be at once she's west of Puerto Rico? One thing is for sure, Erika is a much stronger and more robust wave than Danny was. She will also be moving into a slightly more favorable environment for further deepening than Danny had to work with. 

GFS 500 mb pattern by the weekend shows your classic Bermuda High which will help steer Erika into the western Atlantic. Will she continue west into either the Gulf or Florida, or will she make the turn north? This is a question I cannot answer at this time. A stronger storm, let's say Hurricane strength, is likely to keep her on a northern trajectory while a weaker storm should keep her chugging west. In the image above, notice I circled the H5 trough which the GFS forecasts to slide into the central Atlantic. If a piece of this trough  clips Erika this weekend, it will likely weaken her and quite possibly kill her altogether (that's pretty harsh word choice). However, if she follows the ridge and moves quickly enough, she could possibly deepen into a major hurricane. 

Major hurricane for a couple of reasons:

1. SST's (sea surface temperatures) in the southwest and western Atlantic are running above normal as shown below. 

     2. The Hurricane models, namely the GFDL, show a sharp rise in intensity by late weekend. The            GFDL has had a decent track record this year. 

     3. The EURO model is very robust with the ridging along the east coast. The Atlantic trough noted          earlier builds behind the ridge and the end result is an impressive rise in heights along the                    eastern CONUS. 

There are other reasons as well, such as the decline in wind shear by early next week (depending on how the ridge plays out), but it's far too early to even speculate on how strong this storm will get and where it will track. Let's watch her over the next few days and I will have a second update - if needed - over the weekend. It is tomato sauce making season in my household so I will be busy one way or another...

-Francesco Paparatto