Tropical Storm Sanvu formed over the northern Marianas on Monday.  At 11:00 a.m. EDT on Monday the center of Tropical Storm Sanvu was located at latitude 20.4°N and longitude 146.4°E which put it about 100 miles (160 km) north-northeast of Agrihan.  Sanvu was moving toward the north-northeast at 3 m.p.h.  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 994 mb.

Tropical Storm Sanvu developed when a distinct center of circulation formed within a much larger area of low pressure over the northern Marianas.  The circulation of Sanvu is still in the early stages of consolidation around the center.  Most of the showers and thunderstorms were forming in bands in the southern half of the circulation.  The bands in the northern half of the circulation were weaker.  The showers and thunderstorms south of the center were beginning to generate some upper level divergence which was pumping mass away to the south of the tropical storm.

Tropical Storm Sanvu will be moving through an environment that is somewhat favorable for intensification.  Sanvu will move over water where the Sea Surface Temperature is near 30.5°C.  Sanvu is under the axis of a narrow upper level ridge and the winds over the southern half of the circulation are fairly weak.  There is little vertical wind shear over that part of the tropical storm.  An upper level trough north of the ridge is producing stronger winds over that half of the circulation.  The stronger winds may be responsible for the lack of strong rainbands in the northern half of Sanvu.  The trough is forecast to move east and the shear in that region should decrease.  When the shear decreases Sanvu could intensify at a faster rate and it is forecast to become a typhoon in two or three days.

The trough is currently steering Tropical Storm Sanvu slowly toward the north-northeast.  When the trough moves away to the east a ridge if forecast to steer Sanvu more toward the north.  On its anticipated track Tropical Storm Sanvu will gradually move away from the northern Marianas and the weather should improve in that region.