Day 237: Active Atlantic

Posted by pmarsh on 25 Aug 2010 | 0 comments

After a relatively slow start to the Atlantic hurricane season, the Atlantic Ocean is showing signs of becoming more active. The National Hurricane Center (NHC) is currently issuing advisories on two tropical cyclones, and monitoring a third area of showers and thunderstorms for (low probability) potential for tropical cyclone development.

Hurricane Danielle (contained in yellow circle below) is currently located in the central Atlantic (southeast of Bermuda). Danielle is currently undergoing intensification, but poses no threat to the United States and only an indirect threat to Bermuda at this point. This is the result of a large trough located over the eastern United States. (Thick white dashed lines below indicate the mean long-wave trough axis.) In addition to this large trough, several smaller troughs are rotating through the larger scale flow (indicated by thin white dashed lines). This trough will tend to act like a protective barrier for the east coast. This is because of the southwesterly wind and increased wind shear that can be found on the east side of the trough. The southwesterly wind will help steer Danielle back to the north and ultimately northeast over the next few days, as was discussed on Day 234.

To the south and east of Hurricane Danielle, Tropical Storm Earl (forecast track contained in red circle) is also strengthening. This tropical cyclone is far enough removed from the previously mentioned trough, that it will have an opportunity to avoid being steered out to sea. All model guidance develop Earl into a hurricane over the next few days, and I see no reason to doubt this. Interests in the Gulf and East Coasts need to be aware of Earl as the potential will exist for a US landfall late next week. (It’s still too early to know any specifics, this is just one of many possibilities.)

In the southwestern Gulf of Mexico, the NHC is monitoring showers and thunderstorms along a remanent frontal boundary. It appears that the showers and thunderstorms will make landfall in either far south Texas or Mexico before having a change to develop into a tropical cyclone. However, to play it safe, the NHC has given a 10% chance of tropical cyclone development in this general area.

(Note: Since I didn’t describe it above, the orange contours above are 500mb height contours from the latest RUC model analysis.)