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Debby Slowly Intensifying

The 11AM advisory from NHC says that Debby is slowly strengthening, as thunderstorm activity has been centralized around the core of the storm (Figure 1). The cloud tops associated with the thunderstorms are not that cold, however a microwave satellite pass showed increasing organization. The storm is forecast to continue slow intensification over the next 5 days and should begin to curve further to the north and west over the forecast period (Figure 2).

Figure 1. Infrared satellite image of Tropical Storm Debby.
Figure 2. Five day track forecast from NHC.

In contrast to NHC, I am still bothered by the dry air. The current water vapor image (Figure 3) shows extremely dry air to the north and west of Debby. Whether this air moves into the central core of the tropical storm will, in my mind, be the key forecast issue over the next 24-48 hours. Also, on the water vapor image, you can see the improved outflow as the upper level clouds are racing away from Debby. Looking at the Saharan Air Layer analysis from UW-CIMSS (Figure 4), it seems like the dry air is being sucked into the storm. However, NHC does not find this as apparent as I do, hence their forecast for slow strengthening. Either way, Debby poses no threat to land in the foreseeable future. Stay tuned to the StormTrack for more.

Figure 3. Water vapor image of Tropical Storm Debby. The orangish-brownish color to the west of Debby is extremely dry Saharan air.
Figure 4. Saharan Air Layer analysis from UW-CIMSS. As usual, the hotter colors indicate areas where Saharan air is located.

Posted by Adam Moyer | Permalink