Coastal Watches/Warnings and 5-Day Forecast Cone for Storm Center, courtesy the National Weather Service

HAWAII ISLAND – Tropical Depression Nine-E has become Tropical Storm Guillermo, and it is tracking in the direction of Hawaii.

At 11 p.m. HST (2 a.m. PDT) the center of Tropical Storm Guillermo was located near latitude 8.5 North, longitude 126.3 West. Guillermo is moving toward the west-northwest near 15 mph, and forecasters say this motion is expected to continue during the next day or two. Maximum sustained winds are near 40 mph with higher gusts.

The National Hurricane Center says some strengthening is forecast and Guillermo could become a hurricane on Friday.

From the most recent National Weather Service discussion:

The environment of low shear and warm SSTs is quite favorable for strengthening, and Guillermo will likely become a hurricane in about 36 hours. The probability of rapid intensification included in the SHIPS guidance is 32 percent. After 72 hours, both cooler ocean and increasing shear will likely induce gradual weakening. The NHC forecast follows very closely the intensity consensus.

The best estimate of the initial motion is toward the west-northwest or 285 degrees at 13 kt. Guillermo is well embedded within the deep easterly flow south of a moderate subtropical ridge. There is high confidence that this pattern should keep the cyclone on this general track for the next 2 to 3 days, given that the guidance is tightly clustered during that period. After that time, Guillermo will reach the western edge of the ridge and will turn more to the northwest toward a mid-latitude trough. The NHC track forecast is similar to the previous one and is basically on top of the consensus of the ECMWF and the GFS global models. – National Weather Service

Guillermo is the seventh tropical storm of the 2015 eastern north Pacific hurricane season.