GOES-14 visible channel image of TD #8

A strong tropical depression has been moving west-northwestward through the Caribbean, and is north of Honduras on August 19th. The visible image loop above, using data from GOES-14 (over the Equator at 105º West Longitude), shows the disturbance at 1330 UTC on August 18th and on August 19th. Some modest increase in organization is discernable, as well as the motion to the west-northwest.

Stereoscopic view of TD #8

Data from GOES-14 and GOES-13 can be used to produce a stereoscopic view of the tropical depression, above. Three dimensions become visible using this technique. This allows the strong thunderstorms near the depression center to pop up out of the screen, and it also facilitates viewing the thin cirrus at the edges of the disturbance.

Data available at the CIMSS Tropical Weather Website shows the tropical depression over very warm water and in an environment of low shear. Despite proximity to land, it is expected to strengthen to Tropical Storm status on the 19th; if it does, it will be named Harvey.

(Update: Harvey achieved tropical storm status at 1800 UTC on 19 August)

GOES-13 / GOES-14 visible channel image

The Atlantic Tropical Season’s seventh named storm, Gert, was southeast of the island of Bermuda on Monday August 15th on a projected path that keeps it well to the east of Bermuda. The morning full-resolution visible imagery (above) from GOES-13 (left) and GOES-14 (right) show a well-defined Central Dense Overcast through which are penetrating a few overshooting tops. These tops are far more easily visualized with the more oblique viewing angle afforded by GOES-14 (overhead at 105º West Longitude vs. 75º West Longitude for GOES-13). AVHRR Infrared Imagery from NOAA-16 shows brightness temperatures below -75º C with the coldest of the overshoots.

GOES-13 Enhanced Infrared and Observed Shear

Gert is at present in a region of small shear, as shown in the analysis above taken from the CIMSS tropical weather website. However, the projected path is towards higher shear. Strengthening to hurricane status may be difficult because of the increase in shear and because of progressively colder water along the projected path of Gert into the northern Atlantic. There has not yet been a hurricane season in the Atlantic during which none of the first 7 named storms — ‘A’ through ‘G’ — achieved hurricane status. (In 2002, Gustav was the first Hurricane after 6 Tropical Storms).