Tropical Storm Barbra To Become Hurricane: Will Hawaii See Impacts?

Tropical Storm Barbra has developed in the eastern Pacific and will become a hurricane later today (Monday). TS Barbra is well south of Mexico (see Fig. 1), and currently has maximum sustained winds of 65mph (as of Monday morning) and is rapidly moving W at 21mph. The W to WNW motion is expected to continue thanks to a ridge to the north of the storm (see Fig. 2).

Fig. 1: TS Barbra’s current position

Fig. 2: Current upper-level features creating steering pattern for Barbra

Barbara is expected to intensify over the next week. The storm is currently over anomalously warm waters (see Fig. 3) and will move into an environment with minimal environmental shear (see Fig. 4). This should allow Barbra to quickly intensify. The National Hurricane Center calls for Barbra to become a Category 3 hurricane by Tuesday (see Fig. 5) before a gradual weakening trend occurs.

Fig. 3: Current SST anomalies

Fig. 4: Current wind shear over eastern Pacific

Fig. 5: NHC’s forecast track for Barbra

The weakening trend will be gradual and Barbra is expected to remain a hurricane as it moves west towards Hawaii. It is still too early to determine if Barbra will impact Hawaii. Current guidance does indicate Barbra will be close to the islands in about two weeks. Latest European ensembles spaghetti plots indicate Barbra will track south of the big island (see Fig. 6).

Fig. 6: Barbra’s spaghetti plots

However, a few members of the spaghetti plot do indicate a farther north track near the big island. Track uncertainty this far out makes it hard to forecast direct impacts on Hawaii but it is something that needs to be monitored closely. Steering patterns appear to guide Barbara towards the islands due to ridging north of the storm (see Fig. 7) , the environmental shear while not ideal will be low enough for Barbra to at least maintain Tropical Storm status (see Fig. 8) and sea-surface temperatures are anomalously warm near Hawaii (see Fig. 3).

Fig. 7: Upper-level features steering Barbra west during the second week of July

Fig. 8: Environmental wind shear during the second week of July

Regardless of direct impacts, the islands can expect a gradual increase in wave heights by the end of the first week of July with significantly larger waves entering week 2 of July (see Fig. 9).

Fig. 9: Wave height for Hawaii during the second week of July

Whether impacts may eventually reach Hawaii after next weekend will depend on the storm’s exact track. Many uncertainties exist so keep checking back for updates.