Tropical Storm Darby Intensifies as Hurricane Celia Weakens

Tropical Storm Darby intensified on Tuesday as it moved in the trail of weakening Hurricane Celia.  At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Darby was located at latitude 15.4°N and longitude 110.4°W which put it about 520 miles (835 km) south of the southern tip of Baja California.  Darby was moving toward the west at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 1000 mb.

Farther west Hurricane Celia continued to weaken slowly on Tuesday.  At 11:00 p.m. EDT on Tuesday the center of Hurricane Celia was located at latitude 18.0°N and longitude 110.4°W which put it about 1360 miles (2190 km) west of the southern tip of Baja California.  Celia was moving toward the northwest at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 986 mb.

More thunderstorms developed near the center of Tropical Storm Darby on Tuesday.  However, most of the stronger thunderstorms were southwest of the center of circulation.  An upper level ridge near the west coast of Mexico was producing northeasterly winds which are blowing over the top of the tropical storm.  The vertical wind shear caused the asymmetric distribution of convection.  Despite the vertical wind shear the circulation in the lower levels was well developed.

Tropical Storm Darby is over water where the Sea Surface Temperature is near 30°C and Darby is expected to intensify into a hurricane.

Hurricane Celia is moving over water where the Sea Surface Temperature is near 25°C.  Since the hurricane is extracting less energy from the ocean, the thunderstorms are not as tall and Celia is slowly weakening.  The hurricane is in an area where the vertical wind shear is minimal and so the weakening trend is likely to occur at a slower rate than normal.

A subtropical ridge north of the Celia and Darby is steering the two tropical storms toward the west and that general motion is expected to continue for the next few days.