Tropical Storm “Calvin” impacting Hawaii

Tropical Storm “Calvin” formed on July 12, 2023, as the 3^rd named storm of the 2023 Pacific hurricane season. The system is now passing south of the Big Island, Hawaii while weakening, but still bringing heavy to excessive rains, life-threatening surf in exposed areas, and strong winds.

• Calvin has almost completed its passage south of Hawaii County. Expect periods of flash flooding, dangerous surf and damaging winds, NHC said. The system will continue to weaken as it moves westward to the south of the other Hawaiian Islands today and tonight, bringing the potential for some peripheral impacts.

As of 15:00 UTC on July 19, 2023, the center of Tropical Storm “Calvin” was located 175 km (170 miles) SW of Hilo and 405 km (250 miles) SSE of Honolulu, Hawaii. Calvin’s minimum central pressure at the time was 1 006 hPa.

The system had maximum sustained winds of 75 km/h (45 mph) and was moving W at 31 km/h (20 mph). This general motion is expected to continue through Thursday, July 20.

A Tropical Storm Warning has been in effect for Hawaii County since July 17. The National Hurricane Center (NHC) advises interests elsewhere in Hawaii to monitor the progress of Calvin.

“Although the center of Calvin is passing south of the Big Island, much of the island remains within the 34 kt (63 km/h; 39 mph) radius, and impacts from strong winds, heavy rainfall, and high surf are occurring,” NHC forecaster Powel said at 15:00 UTC on July 19 (05:00 HST).

“The forecast calls for Calvin to finish its passage south of the Big Island this morning, then continue moving westward away from the main island chain as a weakening tropical storm. Vertical shear affecting the tropical cyclone is expected to be moderate today, then strong by tonight. The strong shear should result in weakening to post-tropical/remnant low status late Thursday night.”

On July 18, Governor Josh Green of Hawaii declared a state of emergency in response to escalating conditions, and a team from the Federal Emergency Management Agency (FEMA) was dispatched to the state to aid with precautionary measures.

From the afternoon of July 18, all state parks on the Big Island, including most parts of Hawaiʻi Volcanoes National Park, were closed. Public schools across the state were also closed for the entire day on July 19.

In response to the emergency, Hawaiian Airlines extended an offer to its passengers to reschedule flights between Hilo and Kona scheduled for July 19 and 20 without any additional charges. To accommodate residents and tourists, eight emergency shelters were established throughout the county starting from July 18.

A Flash Flood WARNING was issued until 19:15 UTC (09:15 a.m. HST Wednesday, July 19) for the Big Island with heavy rain falling over Ka ‘u district, Hawaii EMA said. Wood Valley Road is closed for flooding, and Hawaii Belt Road near Punaluu also may flood, the agency added.

The National Weather Service reported three-hour rainfall totals of up to 50 mm (2 inches) in some places.

Hawaii Island Mayor Mitch Roth is urging people to stay off the roads if possible.

“This may not be a full on hurricane, but it is coming close enough to our island that we are concerned for flooding and other kinds of things,” he said.

References:

¹ Tropical Storm Calvin Advisory Number 32 – NWS Central Pacific Hurricane Center Honolulu HI – EP032023 – 500 AM HST Wed Jul 19 2023

² Flash flood warning issued for Hawaii Island as Tropical Storm Calvin drenches state – Hawaii News Now – July 19, 2023

Featured image: Tropical Storm “Calvin” at 03:40 UTC on July 19, 2023. Credit: NOAA/GOES-18, RAMMB/CIRA, The Watchers