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Hurricane Season 2011: Don (Gulf of Mexico)
08.05.11
 
Tropical Storm Don drops barely any rain on parched Texas

Texans, including Governor Rick Perry, have been hoping and praying for rain for months to abate the baking heat and break the extreme drought that has gripped almost their entire state. When tropical storm Don formed in the Gulf of Mexico and headed toward Corpus Christi, some Texans thought that their prayers were about to be answered.

Unfortunately, tropical storm Don lost strength as it neared the coast, and its path over land only provided a slight sprinkling of rain to the far southern part of Texas. So the drought and heat continue.

The Goddard Earth Sciences Data and Information Services Center (GES DISC) provides several tools providing views of Don. The GES DISC also provides daily updated images of hydrological conditions in the United States and around the world. Rainfall anomaly images from the Current Conditions Related to Droughts and Floods analysis map page illustrate the severity of the drought in Texas.

It's hard to believe that anyone would hope for a tropical storm or hurricane to hit their state, but in the case of Texas, a slow-moving drenching downpour from a tropical system would seem like an answer to a prayer. In fact, in many southeastern states, rainfall from tropical systems is usually an important provider of rain during the summer months.

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Figure 1. Global merged IR animation showing Tropical Storm Don making landfall along the southeast Texas coast. (This animation was generated with the Hurricane Data Analysis Tool).



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Figure 2. Rainfall accumulation map for Tropical Storm Don, July 29-31, 2011. The visualized data are the 3B42RT data product, from the experimental Near-Real-Time TRMM Multi-Satellite Precipitation Analysis (TMPA-RT)in TOVAS Giovanni.



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Figure 3. 60-day rainfall anomaly in the United States. Dark blue areas (circled by yellow) indicate that less-than-normal rainfall was received during the past 60 days. (This figure was obtained from the Current Conditions Related to Droughts and Floodsanalysis map page.)




July 29, 2011

TRMM image of Tropical Storm Don on July 29, 2011 at 1322 UTC (9:22 a.m. EDT).› View larger image
The TRMM satellite measured rainfall in Tropical Storm Don when it passed over on July 29, 2011 at 1322 UTC (9:22 a.m. EDT). The yellow and green areas indicate moderate rainfall between .78 to 1.57 inches (20 to 40 mm) per hour.
Credit: NASA/SSAI, Hal Pierce
The TRMM satellite precipitation analysis showed where rainfall was down for the month of July.› View larger image
Texas has been suffering from extreme drought this year so Don's rainfall may provide some relief. The TRMM satellite precipitation analysis showed where rainfall was down for the month of July. The yellow-orange areas show a deficit between 5 and 8 inches of rain, which is seen in southeastern Texas. The The analysis used near-real time Multi-satellite Precipitation Analysis (TMPA) data that were constructed by first computing the average rainfall rate over the period and then subtracting the 10-year average rate for the same period.
Credit: NASA/SSAI, Hal Pierce
NASA's TRMM Satellite Watches Don's Rainfall on Texas Approach

The Tropical Rainfall Measuring Mission (TRMM) satellite measured rainfall in Tropical Storm Don when it passed over on July 29, 2011 at 1322 UTC (9:22 a.m. EDT) and noticed a large area of moderate rainfall, falling at a rate between .78 and 1.57 inches (20 to 40 mm) per hour. Credit: NASA/SSAI, Hal Pierce

The image was created at NASA's Goddard Space Flight Center in Greenbelt, Md. by the TRMM team, who combined a rainfall analysis from TRMM's Microwave Imager (TMI) overlaid on a sunlit combination visible/infrared image from TRMM's Visible and InfraRed Scanner (VIRS) instrument, so it took two instruments on TRMM to make one image.

At 2 p.m. EDT on July 29, Tropical Storm Don's maximum sustained winds were near 50 mph (85 kmh). Don's center was near 26.5 North and 95.6 West, about 145 miles (235 km) southeast of Corpus Christi, Texas. Don is moving toward the west-northwest near 15 mph (23 kmh) and expected to continue in that direction for the next day or two. Don's center is expected to make landfall on the Texas coast tonight or early Saturday and then move across southern Texas on Saturday, the National Hurricane Center noted.

The National Weather Service in Texas has noted that showers are already affecting coastal counties at 2 p.m. EDT. The forecast at that time on July 29, noted that "Isolated showers will move onshore and move generally southwest over the coastal counties while producing brief moderate to heavy downpours," for Kenedy county, inland and coastal Willacy county, and inland and coastal Cameron county. For a look at live National Weather Service radar from Brownsville, Texas, visit: http://radar.weather.gov/radar.php?rid=BRO&product=NCR&overlay=11101111&loop=yes.

Text credit: Rob Gutro, NASA's Goddard Space Flight Center, Greenbelt, Md.















Visible image from the GOES-13 satellite, captured at 1402 UTC (10:02 a.m. EDT)› View larger image
This visible image from the GOES-13 satellite, captured at 1402 UTC (10:02 a.m. EDT) shows the fringes of Tropical Storm Don's western edge just brushing coastal Texas.
Credit: NASA/NOAA GOES Project
AIRS infrared image of Tropical Storm Don at 8:17 UTC (4:17 a.m. EDT) on July 29.› View larger image
NASA's Aqua satellite passed over Tropical Storm Don at 8:17 UTC (4:17 a.m. EDT) on July 29. The infrared image revealed a large area of powerful, high thunderstorms with cold cloud tops (purple) surrounding the center where cloud temperatures were colder than -63 Fahrenheit (-52 Celsius).
Credit: NASA JPL, Ed Olsen
TRMM image of Tropical Storm Don on July 28, 2011 at 0609 UTC (1:09 a.m. CDT).› View larger image
The TRMM satellite had a fairly good view of tropical Storm Don when it passed over on July 28, 2011 at 0609 UTC (1:09 a.m. CDT). A red tropical storm symbol shows the position, north of Mexico's Yucatan peninsula, where Don was located at that time. A TRMM rainfall analysis showed Don was dropping moderate to heavy rainfall (red) of up to 2 inches/50 mm per hour in the eastern side of the small storm. The yellow and green areas indicate moderate rainfall between .78 to 1.57 inches (20 to 40 mm) per hour.
Credit: NASA/SSAI, Hal Pierce
Tropical Storm Don Analyzed in 3 NASA Satellite Images

NASA is analyzing Tropical Storm Don from all angles, inside and out, using three different satellites. Don is expected to make landfall in southeastern Texas tonight or early Saturday.

NASA's Aqua satellite passed over Tropical Storm Don at 8:17 UTC (4:17 a.m. EDT) on July 29. The instrument called the Atmospheric Infrared Sounder (AIRS) took the temperature of Don's clouds in an infrared image. AIRS data revealed a large area of powerful, high thunderstorms with cold cloud tops surrounding Don's center where cloud temperatures were colder than -63 Fahrenheit (-52 Celsius). The higher the thunderstorm cloud-top, the colder it is, and the more powerful they are.

When the GOES-13 satellite passed over Don at 1402 UTC (10:02 a.m. EDT) this morning, July 29, it captured a picture that showed the fringe of the tropical storm's western edge was just brushing coastal Texas on its approach to landfall. The GOES-13 satellite is managed by NOAA and keeps an eye on all weather in the eastern half of the U.S. The NASA/NOAA GOES Project at NASA's Goddard Space Flight Center in Greenbelt, Md. created the image that showed the strongest thunderstorms around the center of circulation. In the image, the highest thunderstorms around the storm's center cast small shadows on the lower clouds.

Those high thunderstorms around the center have been dropping heavy rainfall since July 28, when the Tropical Rainfall Measuring Mission satellite (TRMM) passed overhead. TRMM can measure rainfall from its orbit in space and passed over Don at 0609 UTC (1:09 a.m. CDT). At that time, Don's center was north of Mexico's Yucatan peninsula, where Don was located at that time. A TRMM rainfall analysis showed Don was dropping moderate to heavy rainfall of up to 2 inches/50 mm per hour in the eastern side of the small storm. Most of the other rainfall was moderate, falling between .78 to 1.57 inches (20 to 40 mm) per hour.

With NASA and NOAA satellites confirming that Don is bringing heavy rainfall and gusty winds, a tropical storm warning is in effect for the Texas coast from the mouth of the Rio Grande to Matagorda as tropical storm-force conditions are expected within the warning area by late today.

According to NOAA's National Hurricane Center, at 11 a.m. EDT (1500 UTC) on July 29, 2011, Tropical Storm Don's maximum sustained winds were near 50 mph (85 km/h) with higher gusts. Tropical storm force winds extend outward up to 105 miles (165 km) from the center, so Don has expanded to 210 miles, since yesterday when the storm was 180 miles in diameter.

The center of Tropical Storm Don was located near latitude 26.2 North and longitude 94.9 West. Don is moving toward the west-northwest near 14 mph (22 km/h) and is expected to continue moving on that track for the next day or two. The estimated minimum central pressure is 1002 millibars.

So what can residents of southern Texas and northern Mexico expect from Don? According to the National Hurricane Center (NHC), storm surge will make water levels rise as much as 2 feet above ground level, mostly along the immediate coast and to the northeast of where Don's center makes landfall. Regardless, all residents in the warning area can expect rough surf and damaging waves.

The heavy rainfall that NASA's TRMM satellite saw on July 28 within Don will bring 3 to 5 inches in south Texas and extreme northeastern Mexico. The NHC noted that isolated totals to 7 inches are even possible. Residents should also be prepared for the tropical storm-force winds and the possibility of isolated tornadoes over south Texas today and tonight as Don begins making landfall.

Text credit: Rob Gutro, NASA's Goddard Space Flight Center, Greenbelt, Md.



July 28, 2011

image of Tropical Storm Don › View larger image
This infrared image of Tropical Storm Don from the GOES-13 satellite at 1101 UTC (7:01 a.m. EDT) on July 28 shows a small storm that appears somewhat disorganized, near the Yucatan Peninsula of Mexico.
Credit: NASA/NOAA GOES Project
Tropical Storm Don May Bring Drought Relief to South Texas

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."

Text credit: Rob Gutro, NASA's Goddard Space Flight Center, Greenbelt, Md.



July 27, 2011

TRMM data was used to create a 3-D image of Tropical Storm Nock-ten's rainfall and cloud heights on July 26.› View larger image
The Tropical Rainfall Measuring Mission (TRMM) satellite data was used to create a 3-D image of System 90L's rainfall and cloud heights as it passed overhead on July 26 at 1435 UTC (10:35 a.m. EDT). System 90L did have towering convective storms near its center of circulation that extended to heights above 15km (~9.3 miles) with heavy rainfall, falling at 2 inches (50 mm) per hour.
Credit: NASA/SSAI, Hal Pierce
TRMM captured the rainfall rates of System 90L on July 26.› View larger image
TRMM captured the rainfall rates of System 90L on July 26. The heaviest rainfall appears in red, falling at almost 2 inches (50 mm) per hour on the southeastern side of System 90L. The yellow and green areas indicate moderate rainfall between .78 to 1.57 inches (20 to 40 mm) per hour.
Credit: NASA/SSAI, Hal Pierce
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."

Text credit:Rob Gutro/Hal Pierce, NASA Goddard Space Flight Center, Greenbelt, Md./SSAI