Tropical Storm Noru formed southeast of Japan on Thursday.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Noru was located at latitude 28.3°N and longitude 157.0°E which put it about 1145 miles (1850 km) east-southeast of Tokyo, Japan.  Noru was moving toward the northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 40 m.p.h. (64 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1003 mb.

Tropical Storm Noru had a complicated development.  Noru began as a cold front that became stationary southeast of Japan.  The front stalled over water where the Sea Surface Temperature (SST) was near 30°C.  Transfers of internal energy from the ocean to the atmosphere warmed the air and the temperature difference between the two sides of the front gradually diminished.  A surface low pressure system developed along the dissipating front.  An upper level low initially near the front caused strong vertical wind shear over the surface low.  The wind shear kept blowing the tops off thunderstorms that started to develop near the surface low.  Eventually, the upper low moved far enough to the northwest of the surface low for the vertical wind shear to decrease and thunderstorms were able to develop near the surface low.  The low gradually began to exhibit tropical characteristics and the Japan Meteorological Agency designated the system as Tropical Storm Noru.

The circulation of Tropical Storm Noru is still not well organized.  Although there is a definite center of circulation at the surface most of the showers and thunderstorms are forming in bands in the eastern half of the circulation.  There are few showers and thunderstorms in the western half of the circulation.  Thunderstorms on the eastern side of Noru are generating some upper level divergence which is pumping mass away to the east of the tropical storm.

Tropical Storm Noru is an environment that is somewhat favorable for intensification.  Noru is moving over water where the SST is near 30°C.  However, the upper low northwest of Noru and an upper level ridge near Noru are generating moderate vertical wind shear.  The wind shear may be part of the reason for the asymmetrical distribution of thunderstorms.  Tropical Storm Noru is likely to intensify but the vertical wind shear will slow the rate of intensification.

A subtropical ridge to the north of Noru is steering the tropical storm toward the northwest.  The northwesterly motion is expected to continue for another day or two.  The steering currents are expected to weaken in 36 to 48 hours an Noru could meander southeast of Japan during the weekend.