Tropical Depression Five’s remnants continue to linger over Louisiana and Mississippi, and NASA satellite data continues to capture its cloud temperatures and extent. The slow moving remnants and an associated tropical air mass are expected to creep across the Louisiana and Mississippi and into Arkansas for the next couple of days.

Tropical Depression Five’s (TD5) remnants remain over the lower Mississippi valley today and are slowly drifting northeast. Yesterday, NASA satellite imagery observed the bulk of TD5’s precipitation just south of Louisiana, over the Gulf of Mexico. Today, August 18, that precipitation has moved north and is drenching east-central Louisiana and western Mississippi.

A flash flood watch was issued for today and this evening for much of central Mississippi and northeastern Louisiana due to the risk for very heavy rainfall associated with the remnants of tropical depression five. Two to three inches of rainfall and locally higher amounts of greater than five inches will be possible.

Tropical Storm Dianmu Strengthening

Tropical Depression 05W formed east of the island of Ishigakijima, Japan, then strengthened into Tropical Storm Dianmu. Two instruments on Aqua provided an infrared and microwave look at Dianmu and caught signs that the tropical storm was strengthening on its way toward South Korea. The name Dianmu is the name of the goddess of thunder and lightning in Chinese folklore.

Early on August 8, Dianmu formed in the Northwestern Pacific Ocean and by 2100 UTC (5 p.m. EDT) Dianmu had maximum sustained winds near 35 knots (40 mph) and was about 180 miles southwest of Okinawa, Japan. On August 9 at 04:35 UTC (12:35 a.m. EDT), the Atmospheric Infrared Sounder (AIRS) instrument on NASA’s Aqua satellite captured an infrared image of Tropical Storm Dianmu. The AIRS infrared image showed very cold cloud-top temperatures and showed banding of strong thunderstorms around the north, east and south of the center of circulation.

Those cloud tops were so high that they were colder than -63 Fahrenheit. The center of circulation was also clearly visible in the infrared image and appeared as a small circle. At 1500 UTC (11 a.m. EDT), Dianmu’s maximum sustained winds were near 52 mph (45 knots). It was located about 180 nautical miles northwest of Okinawa, Japan. That’s near 29.2 North and 125.3 East.

Dianmu is moving north at 17 mph and creating 18-foot high waves. Forecasters at the Joint Typhoon Warning Center in Pearl Harbor, Hawaii forecast Dianmu to continue on a northward track in the Northwestern Pacific Ocean. A ridge of high pressure sitting east of Japan is causing the storm to track north and it will continue in that direction for the next day. The Joint Typhoon Warning Center expects Dianmu to intensify because upper level winds will diminish.

A visible image of System 97L showing a large area of cloudiness and thunderstorms while local radar showed heavy rainfall in the eastern part of Puerto Rico mid-day on July 20.

UTC (11:15 a.m. EDT) on July 20 showed clouds (and showers and thunderstorms) over the Northern Leeward Islands, the Virgin Islands, Puerto Rico, and Dominican Republic.

The National Hurricane Center noted that showers and thunderstorms have become more concentrated near Puerto Rico and the Virgin Islands during the morning hours of July 20. A flash flood watch is now in effect for all of Puerto Rico, including Culebra and Vieques and for all of the U.S. Virgin Islands through this evening.

Even if System 97L doesn’t develop it will still bring heavy rainfall and gusty winds to the Northern Leeward Islands, The Virgin Islands, Puerto Rico, the Dominican Republic, Haiti, Eastern Cuba, Turks and Caicos Islands, and the Southeastern Bahamas during the next couple of days. The National Hurricane Center gives System 97L a “40 percent chance” of developing into a tropical depression in the next 48 hours.

The  storm known formerly as Tropical Depression 6E, or TD6E, has been downgraded into a remnant low pressure system in the Eastern Pacific Ocean. On July 16 when NASA’s Aqua satellite flew over TD6E, the infrared imagery showed a small area of strong convection in the storm.

The image, captured on July 15 at 2105 UTC 5:05 p.m. EDT was captured when 6E was still a tropical depression. By July 16, 6E was a remnant low pressure area and had maximum sustained winds near 25 knots (28 mph). It was located near 18 North and 111 West hundreds of miles from the southwestern coast of Mexico. 6E was moving west-northwestward near 10 knots (11 mph). The estimated minimum central pressure is 1006 millibars.

On July 16, the National Hurricane Center indicated that scattered moderate isolated strong convection is occurring within 300 nautical miles in the western semicircle. On July 15, NASA infrared imagery showed the strongest convection to the south of the center of circulation.

6E is a large remnant low, about 600 nautical miles in diameter, and is being “stretched” and elongated because of strong vertical wind shear. It’s the wind shear, coupled with dry air and cooler waters (that 6E is moving into) that make strengthening back into a tropical storm very unlikely.

Tropical Storm Conson and the conditions within the storm as it changes in strength on its track through the South China Sea. NASA’s Infrared imagery revealed some strong convection in the storm as it takes a more westerly route toward another landfall.

Tropical Storm Conson on July 14 at 1747 UTC (1:47 p.m. EDT), the Atmospheric Infrared Sounder (AIRS) instrument captured a look at the storm’s cloud-top temperatures. Cloud top temperatures tell scientists how high thunderstorms are and that translates into strength because the higher and colder the cloud tops, the stronger the thunderstorms, and typically more rain falls from them.

Tropical Storm Conson’s thunderstorm cloud-top temperatures revealed 2 large areas of strong convection and icy cold (high, strong thunderstorms) cloud tops that were colder than -63 Fahrenheit. That means there was a lot of energy in Tropical Storm Conson yesterday when the Aqua satellite passed overhead. Animated infrared satellite imagery today, July 15, showed tightly wrapped convective banding around the storm’s center indicating its maintaining intensity.

On July 15 at 0600 UTC (4 a.m. EDT), Tropical Storm Conson’s maximum sustained winds were near 50 knots (57 mph). Conson was located about 290 nautical miles east-southeast of Hainan Island near 16.6 North and 113.3 East. It was moving west near 12 knots (13 mph).

Tropical Storm Conson is in an area of strong northeasterly vertical wind shear, blowing at a speed greater than 30 knots (34 mph). Despite the strong wind shear, the storm is maintaining intensity. However, that wind shear is pushing the strongest convection southwest of Conson’s center.

Typhoon Warning Center are forecasting Conson to keep tracking westward and cross Hainan Island in the next 24-36 hours (mid-day Eastern Time on Friday, July 16). Thereafter, Conson is expected to make landfall in northern Vietnam and dissipate over the weekend.