Former Tropical Storm Krosa strengthened to a typhoon over the Western North Pacific Ocean north of the Marianas on Sunday.  At 11:00 a.m. EDT on Sunday the center of Typhoon Krosa was located at latitude 23.3°N and longitude 145.4°E which put the center about 270 miles (435 km) north of Agrihan.  Krosa was moving toward the north-northeast at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 971 mb.

Former Tropical Storm Krosa strengthened to a typhoon north of the Marianas on Sunday.  The inner end of a rainband wrapped around the northern and western sides of the center of Typhoon Krosa.  Other bands of showers and thunderstorms were revolving around the center of Krosa’s circulation.  Storms near the center of Krosa generated upper level divergence that pumped mass away from the typhoon.  The removal of mass caused the surface pressure to decrease.

The circulation around Typhoon Krosa became more symmetrical on Sunday.  Winds to typhoon force extended out 45 miles (75 km) from the center of Krosa’s circulation.  Winds to tropical storm force extended out 195 miles (315 km) from the center of Typhoon Krosa.

Tropical Storm Krosa will move through and environment somewhat favorable for intensification during the next 24 hours.  Krosa will move over water where the Sea Surface Temperatures are near 28°C.  It will move under the eastern side of an upper level low centered southeast of Japan.  The upper level low will produce southerly winds that will blow toward the top of Krosa’s circulation.  Those winds will cause some vertical wind shear. The vertical wind shear will inhibit intensification, but the wind shear may not be enough to prevent intensification. Typhoon Krosa could intensify during the next 24 hours.

Typhoon Krosa will move around the western end of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Krosa toward the north during the next 24 hours. On its anticipated track, the center of Typhoon Krosa will pass east of Iwo To.

Elsewhere over the Western North Pacific Ocean, former Tropical Storm Co-may strengthened back to a tropical storm near Okinawa.  At 11:00 a.m. EDT on Sunday the center of Tropical Storm Co-may was located at latitude 26.8°N and longitude 127.6°E which put the center about 15 miles (25 km) northeast of Okinawa.  Co-may was moving toward the west at 16 m.p.h. (26 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 986 mb.