Tropical Storm Don May Bring Drought Relief to South Texas
Hurricane Season 2011: Don (Gulf of Mexico)
Tropical Storm Don formed at 5 p.m. EDT last night, July 27, in the southern Gulf of Mexico and appears to be a small storm on GOES-13 satellite imagery. NASA compiled two days of GOES-13 imagery in a 30 second movie that shows how and where Don formed.
GOES-13, the Geostationary Operational Environmental Satellite, watched on July 27, as the low pressure area called System 90L strengthened quickly into tropical depression number 4, and then tropical storm Don. Data from the NOAA managed GOES-13 satellite was processed at NASA's GOES Project at the NASA Goddard Space Flight Center, Greenbelt, Md. and made into an animation that showed Don's quick birth.
The 30 second movie of Don's birth in the southern Gulf of Mexico runs from July 26 at 1315 UTC (9:15 a.m. EDT) to July 28 at 1045 UTC (6:45 a.m. EDT). GOES-13 imagery shows Don to be around 100 miles in diameter, and tropical storm-force winds extend 45 miles from Don's center.
As of July 28, a tropical storm watch is in effect for Texas coast from the mouth of the Rio Grande northward to west of San Luis Pass and those conditions are possible by late Friday.
GOES-13 data was compiled into an animation by the NASA GOES Project at NASA Goddard that shows the development of Tropical Storm Don in the southern Gulf of Mexico, west of Cuba. The animation runs from July 26 at 1315 UTC (9:15 a.m. EDT) to July 28 at 1045 UTC (6:45 a.m. EDT). (Credit: NASA/NOAA GOES Project)
At 5 a.m. EDT on July 28, Don had maximum sustained winds near 40 mph (65 kmh). It was located about 495 miles (795 east-southeast) of Brownsville, Texas near 23.0 North and 88.7 West. Don's estimated minimum central pressure is 1000 millibars. Don is moving toward the west-northwest near 10 mph (17 kmh) and is expected to continue on this track through Friday, according to the National Hurricane Center. Don is also expected to speed up.
The Brownsville, Texas National Weather Service office posted the tropical storm watch and forecasts "isolated to scattered showers and some thunderstorms and tropical storm force winds will accompany Don as it eventually makes landfall in south or deep South Texas."
Rob Gutro, NASA's Goddard Space Flight Center
, Greenbelt, Md.
July 27, 2011
NASA's TRMM Satellite Sees Heavy Rainfall in a Caribbean Tropical Depression Candidate
A low pressure system in the Caribbean appears primed to develop into the Atlantic Ocean season's fourth tropical depression, as NASA's TRMM satellite noticed powerful "Hot Towers" around the center of circulation.
On July 26 at 1435 UTC (10:35 a.m. EDT) the Tropical Rainfall Measuring Mission (TRMM) satellite passed above System 90L, a low pressure area associated with a tropical wave in the Caribbean Sea southwest of Cuba. On July 27 this area was given a high (80%) probability of development into a tropical cyclone by the National Hurricane Center (NHC).
TRMM's Precipitation Radar (PR) data indicated that a convective tower within this area of disturbed weather reached to heights of over 15 kilometers (~9.3 miles). A convective or "hot tower" is a tall cumulonimbus cloud that breaks into the tropopause. In the tropics, that layer is usually about 9.3 miles above sea level. They are called "hot towers" because of the large amount of latent heat they release as water vapor.
The showers and thunderstorms associated with System 90L appear a lot more organized today, July 27, near the Yucatan Channel. The National Hurricane Center noted that radar from Mexico indicates a circulation could be forming some 50 miles northeast of Cancun this morning.
TRMM captured the rainfall rates of System 90L and noticed that the heaviest rainfall (falling at almost 2 inches (50 mm) per hour) was on the southeastern side of the storm. Most of the precipitation falling was moderate, falling between .78 to 1.57 inches (20 to 40 mm) per hour.
NHC said that "a Tropical depression could develop later today."
Rob Gutro/Hal Pierce, NASA Goddard Space Flight Center
, Greenbelt, Md./SSAI