Fourth Tropical Depression in Eastern Pacific Set to Fizzle
Hurricane Season 2007: Tropical Depression 4 (Eastern Pacific)
Hurricane forecasters are watching the fourth tropical depression (TD) in
the eastern Pacific Ocean on Tuesday, July 10, 2007. So far, two of the
previous three tropical depressions made it to tropical storm strength
and received names. Those were Tropical Storms Alvin and Barbara. If TD-4
strengthens into a tropical storm it would be named "Cosme,"
however, forecasters expect it to weaken in the two days before
Click image for higher resolution.
This satellite image of TD-4 is from the National Oceanic and Atmospheric
Administration's Geostationary Operational Environmental Satellite
(GOES-11). This image, taken at 14:15 Universal Time (7:15 a.m. Pacific
Daylight Time (PDT)) was created by NASA's GOES Project Science Office at
NASA's Goddard Space Flight Center, Greenbelt, Md.
The center of TD-4 was located near 18.6 north and 120.8 west as of 1500
Zulu Time (8:00 a.m. PDT) on July 10. TD-4 was moving northwest at 7
knots (8 mph), and had an estimated minimum central pressure of 1006
millibars. Its maximum sustained winds were at 30 knots (34 mph), with
gusts to 40 knots (46 mph).
The National Hurricane Center reporters that the depression
is currently being steered around the western periphery of a ridge of
high pressure to the east and a weakness to the north caused by presence
of a mid-level trough (and elongated area of low pressure).
Computer models forecast a northwestward track for the next 24 hours or
so followed by a turn more toward the west-northwest. As the
cyclone weakens it will likely be steered by the low-level winds.
Despite the current deep convection (rising air that helps created
thunderstorms) both atmospheric and oceanic conditions are not favorable
for intensification. The sea surface temperatures are below 25
degrees Celsius (77 degrees Fahrenheit) and upper-level winds forecast to
increase. Waters need to be at least 80 degrees Fahrenheit to power
tropical cyclones, and they're just too cool in that area to help the
storm strengthen. Upper level winds can shear a storm apart, and the
current winds are expected to help gradually weaken TD-4 into a remnant
Low pressure system in 36 hours.
Caption Credit: Rob Gutro, Goddard Space Flight Center, from National Hurricane Center reports