Tropical Storm Ivette Develops Unexpectedly

Tropical Storm Ivette developed unexpectedly over the Eastern North Pacific Ocean southwest of Baja California on Monday afternoon. At 5:00 p.m. EDT on Monday the center of Tropical Storm Ivette was located at latitude 17.7°N and longitude 113.9°W which put it about 445 miles (710 km) southwest of the southern tip of Baja California. Ivette was moving toward the west at 2 m.p.h. (3 km/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 1005 mb.

The circulation around former Tropical Depression Ten-E strengthened unexpectedly on Monday afternoon and the National Hurricane Center upgraded the system to Tropical Storm Ivette. An upper level ridge west of Mexico had been producing moderate easterly winds that were blowing across the top of former Tropical Depression Ten-E’s circulation. Those winds were causing moderate vertical wind shear and the shear was blowing the tops off of any thunderstorms that tried to form in the tropical depression. The strengthen of the upper level winds weakened for a few hours on Monday, which caused the vertical wind shear to decrease. New thunderstorms formed in bands in the western half of former Tropical Depression Ten-E. Downdrafts in those thunderstorms transported stronger winds to the surface and the depression strengthened to Tropical Storm Ivette. Tropical storm force were occurring up to 90 miles (145 km) in the northwestern quadrant of Ivette’s circulation. The winds in the other quadrants were blowing at less than tropical storm force.

Tropical Storm Ivette will move through an environment unfavorable for intensification during the next several days. Ivette will move over water where the Sea Surface Temperatures are 27˚C. However, the upper level ridge west of Mexico will continue to cause moderate vertical wind shear. Tropical Storm Ivette is likely to weaken during the next 48 hours, although some fluctuations in intensity could occur if the strength of the upper level winds varies.

Tropical Storm Ivette will move around the southern part of a high pressure system over the Eastern North Pacific Ocean. The high pressure system will steer Ivette slowly toward the west during the next 48 hours. On its anticipated track Tropical Storm Ivette will move a little farther away from Baja California.