After an extended period when drier air and wind shear inhibited the organizational processes in Tropical Storm Vance, it has intensified rapidly in recent hours and it is now a hurricane.  At 10:00 a.m. EST on Sunday the center of Hurricane Vance was located at latitude 11.9°N and longitude 107.5°W which put it about 535 miles south-southwest of Manzanillo, Mexico.  Vance was moving toward the northwest at 15 m.p.h.  The maximum sustained wind speed was 80 m.p.h. and the minimum surface pressure was 990 mb.

Vance is moving around the western end of a ridge of high pressure over Mexico.  A large upper level trough west of California will begin to affect Vance as it moves farther north.  The trough is expected to turn Vance toward the northeast early next week.  The track forecast becomes more challenging for the period when Vance could be approaching the coast of Mexico.  Much of the guidance from the numerical models suggests that the upper level winds could be strong enough to separate the upper portion of Vance’s circulation from the lower level rotation.  If that happens, then the middle and upper portions of the circulation could be transported across Mexico, while the surface low gets left behind and meanders southeast of Baja California.

Vance is over water where the Sea Surface Temperature is near 29°C and the upper level winds are relatively light.  So, the period of rapid intensification could continue for another 12-24 hours.  When the upper level trough approaches Vance from the northwest on Monday, the wind shear will increase and Vance will start to weaken and it could weaken quickly.  Even if the low level center of Vance does not make landfall, moisture in the middle and upper portions of the circulation could enhance precipitation over Mexico next week.