Blas Strengthens to Cat. 4 Hurricane

Hurricane Blas strengthened rapidly Tuesday to a Category 4 hurricane on the Saffir-Simpson Scale.  At 11:00 p.m. EDT on Thursday the center of Hurricane Blas was located at latitude 14.4°N and longitude 121.7°W which put it about 970 miles (1560 km) west-southwest of the southern tip of Baja California.  Blas was moving toward the west at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 140 m.p.h. (220 km/h) and there were wind gusts to 170 m.p.h. (275 km/h).  The minimum surface pressure was 947 mb.

The Hurricane Intensity Index (HII) for Blas was 28.2.  The Hurricane Size Index (HSI) was 12.2 and the Hurricane Wind Intensity Size Index (HWISI) was 40.4.

The circulation of Hurricane Blas is fairly symmetrical and well organized, although many of the stronger thunderstorms are occurring in the southeastern quadrant.  Blas has a clear eye which is surrounded by a ring of strong thunderstorms.  Those storms generated upper level divergence which pumped out a lot of mass in all directions and allowed the pressure to decrease rapidly on Tuesday.

Hurricane Blas is in an environment that is favorable for strong hurricanes.  It is moving over water where the Sea Surface Temperature is near 29°C.  The winds in the upper levels are light and there is not much vertical wind shear.  Hurricane Blas could get stronger on Wednesday.  However, eyewall replacement cycles sometimes occur in strong hurricanes.  When an eyewall replacement cycle occurs, it can bring an end to a period of intensification.

A ridge of high pressure located north of Blas is steering the hurricane toward the west and that motion is expected to continue for several more days.  Hurricane Blas continues to move farther away from Mexico.