Erika update: To be or not to be?

Written by: Bob Metcalfe

Tropical Storm Erika continues to ever so slowly meander west-northwest at a slow pace (less than 10 miles per hour), fighting many factors AGAINST a strengthening trend.

Tropical cyclones (hurricanes) are very picky storms. They have to have everything just right or else they become skittish and disappear.

The first factor against her: wind shear. Tropical storms like a nice, calm atmosphere at all levels to help form, so that no "tipping" of convective storms occurs. But in this case, the Hurricane Hunter aircraft and several radiosonde (weather balloon) observations continue to show windshear, specifically in the crucial upper levels of the atmosphere ahead of this storm.

Another strong negative: dry air. The water vapor image above shows the storm at the bottom center of the image. The purplish colors indicate the coldest clouds (strongest convection) contained within Erika. The dry air is fairly easy to recognize, even to the untrained eye. Look just northwest of the center of the storm... see that hazy burnt orange color? That's very dry air ahead of the storm. This is not something storms look forward to if they want to continue to strengthen.

With all that being said, Erika will continue her slow pace northwest, arriving in San Juan around 8am Friday, steering just northeast of the Dominican Republic by 8am Saturday. As the current forecast stands, she would be nothing more than a "remnant low" by the time she traveled into the Bahamas region.

Stay tuned though. Further down the road, this low may swing up the east coast, continuing the trend that has been ever so popular in recent weeks.