Extreme Weather News

GPM Observes Tropical Cyclone Dahlia In Southwest Indian Ocean

Yesterday tropical Cyclone Dahlia became the first tropical cyclone of the 2017-2018 Southwest Indian Ocean season. Today, Dahlia was moving toward the southeast and was passing to the south of the Indonesian islands of Java and Sumatra with wind speeds of about 35 kts (40.3 mph). Tropical cyclone Dahlia was passing over the warm ocean waters (28-29 degrees Celsius) of the Indian Ocean.

 GPM Observes Tropical Cyclone Dahlia In Southwest Indian Ocean

On November 29, 2017 at 1731 UTC NASA's GPM Core Observatory satellite passed above forming tropical cyclone Dahlia. Data collected by GPM's Microwave Imager (GMI) and Dual-Frequency Precipitation Radar (DPR) instruments revealed the locations of heavy rainfall around the tropical cyclone. GPM's GMI found that rain was falling at rates greater than 76 mm (~3 inches) per hour in powerful storms around Dahlia's center of circulation. GPM's radar (DPR Ku Band) measured precipitation in a swath (shown in lighter shades) that passed to the west of the heavy rainfall occurring near the center of the tropical cyclone. GPM's radar scanned bands northwest of the Dahlia's center where rain was dropping at a rate of 60 mm (2.4 inches) per hour.

 GPM Observes Tropical Cyclone Dahlia In Southwest Indian Ocean

GPM's radar (DPR Ku Band) provided data used in this 3-D topographic view of precipitation near the forming tropical cyclone. These probes by DPR showed that storm tops west of the Dahlia's center were stetching to heights of almost 12 km (7.4 miles).

Tropical Storm Dahlia

The Indonesia Meteorology, Climatology, and Geophysics Agency (BMKG) warned that tropical cyclone Dahlia may cause flooding and landslides in susceptible areas.

Landslide potential map for Tropical Storm Dahlia

The landslide potential map shown above is based on rainfall estimates from near real-time Multi-satellite Precipitation Analysis (TMPA) data. These TMPA products have been automatically calculated and displayed for over a decade on the TRMM web site at Goddard Space Flight Center. This map shows that heavy rainfall during the past week resulted in an area of potential landslides on the slopes of southern Java.

The Joint Typhoon Warning Center (JTWC) predicts that tropical cyclone Dahlia will initially intensify to tropical storm force as it moves over the Indian Ocean toward northwestern Australia. Dahlia is then expected to encounter cooler waters and weaken to a tropical depression before approaching the northwestern Australia coast on about December 5, 2017.

  • Images and caption by Hal Pierce (SSAI/NASA GSFC)