UPDATE: 8:25 p.m.

Tropical Storm Nolo was churning with 300 miles from South Point and is expected to grow into hurricane Thursday as it moves on a track similar to that of Hurricane Lala, which devastated Hawaii island in August.

At about 8 p.m., Nolo was maintaining its maximum sustained wind speed of 45 mph about 295 miles south of South Point and 475 miles south-southeast of Honolulu. Nolo was moving west-northwest at 7 mph but the Central Pacific Hurricane Center said it is expected to turn north overnight. Tropical storm-force winds of 39 mph or more extend up to 80 miles from Nolo’s center.

A hurricane watch remains in effect for Hawaii island, while a flood watch covers both the Big Island and Maui County.

“A sharp turn to the north and north-northeast is expected late tonight through Thursday, with this motion continuing through the end of the week,” the 8 p.m. CPHC update said, “On the forecast track, the system is expected to approach the Big Island of Hawaii on Friday and Saturday. … Nolo is forecast to become a hurricane by Thursday night and could become a major hurricane by the weekend.”

“Interests elsewhere in the Hawaiian islands should closely monitor the progress of this system,” forecasters said.

CPHC issued the following warnings about the approaching storm:

>> Wind: Hurricane conditions are possible in the watch area starting as early as Friday night.

>> Rain: Tropical Storm Nolo will produce rainfall totals of 15 to 20 inches across the Big Island with maximum amounts of 35 inches. This rainfall may produce catastrophic life-threatening flooding and mudslides, especially in areas of steep terrain. Rainfall totals of 5 to 10 inches with maximum amounts of 20 inches are expected across Maui. Life-threatening flooding and mudslides possible across Maui, especially in areas of high terrain. Across the remainder of the Hawaiian islands, rainfall totals of 1 to 3 inches with maximum amounts of 6 inches are expected with isolated flooding possible”

>> Storm surge: The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. On Hawaii island, the water could reach 1 to 3 feet above ground somewhere if the peak surge occurs at the time of high tide. The deepest water will occur along the immediate coast near and to the right of the landfall location, where the surge will be accompanied by large and dangerous waves. Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances.

>> Surf: Swells generated by Nolo are expected to reach exposed east and south shores of the Big Island by Friday, spreading west and building through the weekend. These swells are likely to cause life-threatening surf and rip current conditions

5 p.m.

A hurricane watch remains in effect for Hawaii County as Tropical Storm Nolo holds steady and is forecast to turn northward tonight, potentially making its closest approach to Hawaii island on Saturday, according to the Central Pacific Hurricane Center.

As of 5 p.m. today, Nolo was located about 295 miles south of South Point and about 475 miles south-southeast of Honolulu. Nolo was carrying maximum sustained winds of 45 mph with higher gusts and moving west-northwest at 6 mph. Nolo is still forecast to make a sharp turn to the north and north-northeast later tonight and continue in the motion through the end of the week.

Hawaii County will open four shelters this evening as the system is expected to approach Hawaii island Friday and Saturday. Nolo is forecast to become a hurricane by Thursday night and transform into a major hurricane by this weekend.

“A weakening subtropical ridge to the north should allow Nolo to slow down and turn northward tonight into Thursday, followed by a north-northeastward motion as an upper-level trough deepens northwest of the Hawaiian Islands,” according to the forecast.

Nolo is forecast to bring significant heavy rainfall and potential flooding to Hawaii island. Heavy rainfall is likely to continue over Hawaii island and Maui through this weekend.

“Life-threatening, catastrophic flooding and mudslides are possible, especially in areas of steep terrain across the Big Island and Maui,” according to the forecast. “Across the remainder of Hawaii, lesser rainfall totals are expected, with isolated flooding possible.”

Tropical-storm-force winds extend outward up to 80 miles from the center.

2 p.m.

Tropical Storm Nolo strengthened slightly as a hurricane watch remains in effect for Hawaii County.

As of 2 p.m. today, Nolo was located about 305 miles south of South Point and about 485 miles south-southeast of Honolulu. Nolo was carrying increased maximum sustained winds of 45 mph and moving west at 9 mph. Nolo is expected to continue in this general motion tonight before turning sharply to the north and north-northeast on Thursday, continuing in this motion until the end of the week.

On the forecast track, the system is expected to approach Hawaii island on Friday and Saturday. Nolo is forecast to become a hurricane Thursday and a major hurricane by this weekend.

“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,” according to the forecast. “Periods of heavy rain are likely to continue across the Big Island and Maui through the weekend.”

Tropical-storm-force winds extend outward up to 35 miles.

11 a.m.

Tropical Depression Fifteen-E officially strengthened into Tropical Storm Nolo this morning, prompting weather officials to issue a hurricane watch for the Big Island and surrounding waters as the storm tracks toward the main Hawaiian islands.

As of 11 a.m., Nolo was centered about 310 miles south of South Point on the Big Island and 500 miles south-southeast of Honolulu, according to the Central Pacific Hurricane Center. Moving west-northwest at 6 mph with maximum sustained winds of 40 mph, the storm is forecast to turn north and north-northeast Thursday, making its closest approach to the Big Island on Friday and Saturday.

Nolo is expected to reach hurricane intensity Thursday and could become a major hurricane by the weekend, according to the CPHC.

“A hurricane watch means that hurricane conditions are possible within the watch area,” the CPHC said in a bulletin.

“A watch is typically issued 48 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous.”

“Efforts to protect life and property should now be rigorously underway,” the National Weather Service in Honolulu said in a bulletin for Hawaii County, noting the potential for life-threatening winds, coastal surge and catastrophic rainfall.

A flood watch remains in effect through Saturday afternoon for Hawaii island, Maui, Lanai, Molokai and Kahoolawe. Rainfall totals of up to 15 to 20 inches — with localized maximums up to 35 inches — are expected across the Big Island, bringing a high threat of life-threatening flash flooding and mudslides in steep terrain. Maui could see 5 to 10 inches of rain with peak amounts up to 20 inches, while 1 to 3 inches with isolated higher amounts are forecast for the rest of the state.

A hurricane watch is in effect for Big Island coastal waters and the Alenuihaha Channel starting Friday morning, where winds of 30 to 50 knots, gusts to 65 knots and seas of 12 to 17 feet are expected. Small craft advisories remain active through Friday morning across the typically windy waters around Maui County and Hawaii island.

Coastal areas on Hawaii island could experience localized storm surge inundation of 1 to 3 feet above ground in low-lying areas starting early Friday, accompanied by dangerous surf and rip currents spreading westward through the weekend.

Residents and visitors on islands besides the Big Island are advised to closely monitor Nolo’s progress as the storm develops.

EARLIER COVERAGE

Tropical Depression Fifteen-E has reformed southeast of Hawaii and is expected to grow into a major hurricane by this weekend as it moves slowly near or over the Big Island.

At 5 a.m. today, the storm system was about 320 miles south-southeast of Hilo and 525 miles south-southeast of Honolulu with 35 mph maximum sustained winds and moving west-northwest at 6 mph, according to the Central Pacific Hurricane Center.

Forecasters said a sharp turn to the north and north-northeast is expected on Thursday and continue through the end of the week. ”On the forecast track, the system is expected to approach the Big Island of Hawaii on Friday and Saturday. … The system is expected to become a tropical storm later today, with further strengthening to a hurricane likely on Thursday and possibly a major hurricane by this weekend.”

When it forms into a tropical storm, it will be given the name Nolo.

“Interests in the Hawaiian islands should closely monitor the progress of this system. A hurricane or tropical storm watch will likely be required for a portion of the state later today,” forecasters said.

The latest five-day forecast map has the storm system growing into a hurricane by Thursday evening and becoming a possible Category 3 storm with 115 mph winds just southeast of the Big Island by early Saturday as it moves just south of the island. The so-called cone of uncertainty includes Hawaii island, meaning that there is a chance of a direct hit.

A flood watch for Hawaii island and Maui County is in effect from noon today through Saturday afternoon, according to the National Weather Service. A hurricane warning is in effect through Friday for the Hawaiian offshore waters beyond 40 nautical miles out to 240 nautical miles, including the portion of the Papahanaumokuakea Marine National Monument east of French Frigate Shoals. Seas are expected to climb to 8 to 12 feet by Thursday.

A small craft advisory is also in effect until 6 a.m. Friday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel and Big Island leeward and southeast waters, with the NWS warning of northeast winds up to 30 knots, gusts to 40 knots and seas of 7 to 12 feet. Forecasters said the advisory area may expand as the storm approaches and cautioned inexperienced mariners, especially those in smaller vessels, to avoid the water.

CPHC listed the following potential hazards from Nolo:

>> Wind: There is an increasing risk of wind impacts in the Hawaiian islands regardless of the exact track of this system.

>> Rain: Tropical Depression Fifteen-E will produce rainfall totals of 15 to 20 inches across the Big Island with maximum amounts of 35 inches. This rainfall may produce catastrophic life-threatening flooding and mudslides, especially in areas of steep terrain. Rainfall totals of 5 to 10 inches with maximum amounts of 20 inches expected across Maui. Life-threatening flooding and mudslides possible across Maui, especially in areas of high terrain, Across the remainder of the Hawaiian Islands, rainfall totals of 1 to 3 inches, with maximum amounts of 6 inches, are expected with isolated flooding possible.

>> Surf: Swells generated by Tropical Depression Fifteen-E are expected to reach the east and south-facing shores of the Big Island on Friday, spreading westward and building through the weekend. These swells are likely to cause life-threatening surf and rip current conditions.

“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,” CPHC forecasters said. “Periods of heavy rain are likely to continue across the Big Island and Maui through the weekend.”

Tropical Depression Fifteen-E originally formed in the East Pacific last week but dissipated. The remnants of the system moved into the Central Pacific and reformed into a tropical depression overnight.

The National Hurricane Center in Miami is also monitoring two East Pacific hurricanes that are not expected to approach Hawaii or the Central Pacific.

Hurricane Polo, which peaked as a monster Category 5 cyclone with 180 mph maximum sustained winds on Tuesday, was weakening today as it moves slowly just off Mexico’s west coast.

Polo was within 200 miles off Mexico’s southwestern coast this morning with 150 mph maximum sustained winds moving northwest at 5 mph. The storm is expected to skirt the coast over the next five days and bring heavy rain and high surf to Mexico.

Polo intensified from a tropical storm into a Category 5 hurricane within 24 hours. It became the second-most intense hurricane on record, based on central pressure, in the eastern Pacific Ocean, trailing Hurricane Patricia in 2015, the New York Times reported.

Further west, Hurricane Odalys with 75 mph maximum sustained winds was 1,265 miles west-southwest of the southern tip of Baja California this morning and moving east-northeast at 8 mph. Odalys is expected to weaken into a remnant low by Monday as it moves closer to Baja.