Kenanga (Southern Indian Ocean)

December 20, 2018 – Seeing Double: Tropical Cyclone Kenanga Same Strength as Other Storm

The Southern Indian Ocean is seeing double. Tropical Cyclone Kenanga was one of two storms at Category 2 hurricane strength in the Southern Indian Ocean on Dec. 20. Kenanga was sporting an eye on visible imagery from NASA-NOAA’s Suomi NPP satellite, and so was Tropical Cyclone Cilida, located west of Kenanga.

Suomi NPP image of Kenanga
On Dec. 20, the VIIRS instrument aboard NASA-NOAA’s Suomi NPP satellite captured a visible image of Tropical Cyclone Kenanga in the Southern Indian Ocean. Kenaga is located east of Tropical Cyclone Cilida. Credit: NASA Worldview, Earth Observing System Data and Information System (EOSDIS)

On Dec. 20, 2018 the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard NASA-NOAA’s Suomi NPP satellite showed a powerful thunderstorms circling Kenanga’s eye.

The Joint Typhoon Warning Center or JTWC noted that after the Suomi NPP image was taken, infrared imagery showed the loss of the eye and the erosion of the eyewall (powerful thunderstorms circling the open center).

Kenanga and Cilida are both Category 2 hurricanes on the Saffir-Simpson Hurricane Wind Scale, and both have maximum sustained winds near 90 knots (103.6 mph/166.7 kph) on Dec. 20 at 10 a.m. EDT (1500 UTC). Strongest storms appeared northwest of the eye.

Kenanga was located near 16.6 degrees south latitude and 81.2 degrees east longitude, approximately 773 nautical miles southeast of Diego Garcia. Kenanga was moving west.

The JTWC forecast calls for Kenanga to steadily weaken, and that will continue under the ongoing influence of moderate to strong vertical wind shear and passage over cooler water. The storm is expected to dissipate below 35 knots (40 mph/74 kph) in 5 days.

By Rob Gutro
NASA’s Goddard Space Flight Center

Walaka (Central Pacific Ocean) 2018

Oct. 05, 2018 -NASA Finds Walaka Weakened, Now a Tropical Storm

NASA’s Aqua satellite passed over the Central Pacific Ocean and obtained infrared data on Walaka, now weakened to a tropical storm with limited thunderstorm development.

hurricane in blue with green data center
At 5:40 a.m. EDT (0940 UTC) on Oct. 5, the MODIS instrument aboard NASA’s Aqua satellite looked at Tropical Storm Walaka in infrared light. MODIS found coldest cloud tops (yellow) in a small area near the center had temperatures near minus 63 degrees Fahrenheit (minus 53 degrees Celsius). Credit: NASA/NRL

Infrared satellite data at 5:40 a.m. EDT (0940 UTC) on Oct. 5, the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA’s Aqua satellite revealed strongest storms with the coldest cloud top temperatures in a small area around Walaka’s center. MODIS found coldest cloud tops had temperatures near minus 63 degrees Fahrenheit (minus 53 degrees Celsius). NASA research has found that cloud top temperatures that cold have the capability to generate heavy rainfall.

At 5 a.m. EDT (0900 UTC) on Friday, Oct. 5, the center of Tropical Storm Walaka was located near latitude 30.6 degrees north and longitude 168.3 degrees west. Walaka is about 480 miles (770 km) north-northwest of the French Frigate Shoals. Walaka is moving toward the north-northwest near 6 mph (9 kph). A turn toward the north is expected tonight, followed by an acceleration toward the northeast Friday through Saturday. Maximum sustained winds are near 70 mph (110 kph) with higher gusts.  Some weakening is forecast during the next 48 hours.

The Central Pacific Hurricane Center or CPHC said Walaka will be over cool sea surface temperatures through the remainder of its journey across the Pacific, with vertical wind shear expected to increase substantially Friday night and Saturday, Oct. 6. Steady weakening is forecast during the next 48 hours, and Walaka is expected to become a post-tropical low by Saturday evening.

CPHC noted that ocean swells generated by Walaka will continue to affect portions of the Papahanaumokuakea Marine National Monument and the main Hawaiian Islands tonight, Oct. 5.

For updated forecasts, visit:  http://www.prh.noaa.gov/cphc

Rob Gutro
NASA’ Goddard Space Flight Center

Leslie (Atlantic Ocean) 2018

NASA’s Aqua satellite passed over the Central Atlantic Ocean and obtained infrared data on Leslie, now weakened to a large tropical storm.

The National Hurricane Center or NHC said that Leslie remains a large tropical storm, with tropical-storm-force winds extending outward up to 290 miles (465 km) from the center. Because of the size and strength of Tropical Storm Leslie, waves from Leslie are expected to increase along the coasts of Atlantic Canada and New England today, Oct. 5.

Satellite data on Leslie
At 1:40 a.m. EDT (0540 UTC) on Oct. 5, the MODIS instrument aboard NASA’s Aqua satellite revealed strongest storms with the coldest cloud top temperatures (yellow) northwest of Leslie’s center with temperatures near minus 63 degrees Fahrenheit (minus 53 degrees Celsius). Credit: NASA/NRL

At 1:40 a.m. EDT (0540 UTC) on Oct. 5, the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA’s Aqua satellite revealed strongest storms with the coldest cloud top temperatures northwest of Leslie’s center. MODIS found coldest cloud tops had temperatures near minus 63 degrees Fahrenheit (minus 53 degrees Celsius). NASA research has found that cloud top temperatures that cold have the capability to generate heavy rainfall.

At 5 a.m. EDT (0900 UTC), the center of Tropical Storm Leslie was located near 35.9 degrees north latitude and 58.3 degrees west longitude. Leslie is moving toward the north-northwest near 14 mph (22 kph). A slower northward motion is expected to occur today, but Leslie will make a sharp turn toward the east and east-southeast over the weekend.

Maximum sustained winds are near 65 mph (100 kph) with higher gusts.  Little change in strength is forecast during the next several days.

NHC cautioned, “Large swells generated by Leslie will continue to affect portions of the southeastern coast of the United States, Bermuda, the Bahamas, and the Greater and Lesser Antilles during the next few days. Swells are expected to increase near the coasts of New England and Atlantic Canada today.”

For updated forecasts, visit: www.nhc.noaa.gov

Rob Gutro
NASA’ Goddard Space Flight Center