Tropical Depression 05W briefly reached tropical storm status overnight on June 5 into June 6, and then weakened back to a depression at 5 a.m. EDT (0900 UTC). Once 05W reached tropical storm status it was named "Ewiniar." NASA's Aqua satellite captured infrared imagery that provided clues that the storm would strengthen.
NASA's Aqua satellite passed over 05W on June 5 at 2:05 a.m. EDT (0605 UTC) and analyzed the storm in infrared light. Infrared light provides temperature data and that's important when trying to understand how strong storms can be. The higher the cloud tops, the colder and the stronger they are.
AIRS data showed coldest cloud top temperatures in thunderstorms flaring east of 05W's center were warming, indicating weakening. Coldest temperatures were as cold as minus 63 degrees Fahrenheit (minus 53 degrees Celsius). Storms with cloud top temperatures that cold have the capability to produce heavy rainfall.
Ewiniar never made landfall on Hainan Island, China as its center stayed just to the east of the island. The storm did make landfall in extreme southwestern Guangdong province. The Joint Typhoon Warning Center or JTWC noted that a clear low level circulation center remains present over the southern portion of the Leizhuo Peninsula.
On June 6 at 5 a.m. EDT, Ewiniar's maximum sustained winds were near 30 knots (34.5 mph/55.5 kph). It was centered near 20.3 degrees north latitude and 110.2 degrees east longitude. It was located approximately 254 nautical miles west-southwest of Hong Kong. It has tracked southwestward at 4 knots.
China's National Meteorological Centre continued to issue blue warning of typhoon at 6:00 a.m. (local time) on June 6. At 5:00 a.m. (local time), this year's No.4 typhoon (tropical storm level) warning extends to June 7. The warning includes Hainan Island, central-northern Guangdong and coastal regions, eastern Guangxi, southern Hunan, southern Jiangxi, western and northern Fujian, and southeastern Zhejiang, for heavy rain. The warning noted "Heavy downpours will batter northern Hainan Island, central-northern Guangdong, and central-western coastal regions. In some regions, heavy rainstorm (250-280mm) will appear. In these regions, there will be severe convective weather like lightning or short-range precipitation (30-50mm)."
There's also a Yellow Warning for rainfall that includes central-eastern South China over the next four days. The warning includes "cumulative rainfall in northern Hainan Island, central and western coastal Guangdong, and southeastern coastal Guangxi will amount to 300 mm. In some regions, there will be severe convective weather like thunderstorm or gale."
Explore further: NASA finds some fragmented strength in Tropical Depression 05W