(BIVN) – A Hurricane Watch has been issued for Hawaiʻi County, as Tropical Storm Nolo has formed, 310 miles south of South Point.
As of 11 a.m. on Wednesday, Nolo was moving toward the west-northwest near 6 mph, with a sharp turn to the north expected on Thursday. On the forecast track, the Nolo is expected to approach the Big Island of Hawaii on Friday and Saturday, as it strengthens into a hurricane.
Nolo could become a major hurricane by the weekend.
A Hurricane Watch is typically issued 48 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous.
Governor Josh Green and John Bravender, the Warning Coordination Meteorologist with the National Weather Service, gave an update on the approaching storm system. Note the news conference was held at 10 a.m., one hour before the system officially became tropical Storm Nolo, and before the Hurricane Watch was issued.
From the Central Pacific Hurricane Center discussion at 11 a.m. HST:
The system has continued to become better organized this morning, with tighter curved banding features noted on satellite imagery. The low-level circulation remains on the southeastern side of most of the deep convection. Satellite estimates are rising, and the bulk of the values now show this at or above 35 kt. The initial intensity is set to 35 kt, marking the formation of a tropical storm.
Nolo is moving west-northwestward at about 5 kt. There is no change to the synoptic reasoning with a ridge located to the northeast of Hawaii forecast to weaken and push eastward as a mid-latitude trough deepens over the northwestern Hawaiian islands. This pattern is likely to the cause Nolo to slow down tonight and then turn north-northeastward by tomorrow with some increase in forward speed. The trough is forecast to move westward this weekend as the ridge rebuilds north of Hawaii, which should force a sharp leftward turn while the cyclone is close to the Big Island. It really depends on how far northeast Nolo gets before the ridge rebuilds, with the solutions that gain the most latitude in the next few days generally getting closest to Hawaii. Although there has been a small southward shift in the overall guidance on this cycle, there is still a large spread approaching 250 n mi from north-to-south by the weekend. The new forecast is nudged south on this advisory, but it should be considered low confidence.
The current disorganized structure would seem to promote only slow strengthening during the next day or so under otherwise favorable environmental conditions. However, the system is likely to develop an inner core on Thursday, which could support rapid intensification given very warm waters, low shear and high mid-level moisture values. Intensity guidance is a little higher than the last cycle, and the NHC forecast is raised slightly from day 3 and beyond, showing a major hurricane near and west of Hawaii.
Key Messages:
1. Tropical Storm Nolo is expected to strengthen into a hurricane on Thursday as it moves northward, potentially making its closest approach to the Big Island of Hawaii on Saturday. A Hurricane Watch is now in effect for the Big Island, and residents there should follow advice given by local officials, including evacuating if told to do so.
2. The time to prepare for significant heavy rain and flooding impacts on the Big Island is now, as heavy rain becomes more likely by Thursday and Friday. Periods of heavy rain are likely to continue across the Big Island and Maui through the weekend. Life-threatening, catastrophic flooding and mudslides are possible, especially in areas of steep terrain across the Big Island and Maui. Across the remainder of Hawaii, lesser rainfall totals are expected, with isolated flooding possible.
3. Large and damaging waves are possible along the coast of the Big Island into the weekend.
4. Interests elsewhere in Hawaii should closely monitor the latest forecast updates and ensure that they have their preparedness plan in place.
