By: Civicane49 , 23. март 2012, 05:15 GMT
Roughly two weeks ago, the "supercell" thunderstorm had generated both a rare tornado and hail in Kaneohe and Kailua, which both are in the windward side of Oahu. Earlier today, the Honolulu National Weather Service office in coordination with the State Climate Extremes Committee has found that one of the hailstones, from the March 9th storm, broke a new hail size record. The large hailstone was first reported by a windward resident in the Aikahi Neighborhood on the same day. In addition, there were many reports of hail of 2 to 3 inches in diameter across Windward Oahu. According to the Honolulu NWS, the final measurement of the hailstone’s length, width, and height were 4.25 inches, 2 inches, and 2.25 inches respectively. This hailstone broke the previous state record which was an inch in length, according to the hail report records that date back to 1950 in Hawaii.
The March 9th storm had also generated an EF-0 tornado with winds of 60-70 mph, on the Fujita scale, and made a path of 1.5 miles from Lanikai to Enchanted Lakes on Oahu, according to the weather service. The weak tornado was originally a waterspout that formed offshore and moved into Lanikai Beach in the early morning. Once the waterspout has moved over land from water, it becomes a tornado. The twister has left some damage in that area, including damaged roofs, knocked down fences, and uprooted plants. However, there were no reports of injury. On average, Hawaii experiences one tornado about every one year. In other parts of the state, the heavy rains from the storm have brought flooding and landslides.
Figure 1. A 4.25-inch hailstone is shown in the image. This grapefruit-size hail was from a severe thunderstorm on March 9th in Hawaii. The ruler shows that this hailstone is measured 4.25 inches long, making a new state hail size record. That is one gnarly looking! Image courtesy: NOAA.
Is hail rare in Hawaii?
The hailstone’s size from a penny to quarter has been reported in Hawaii only eight times since records began. However, there was no report of hail larger than an inch in diameter. The conditions producing a hailstone more than an inch in diameter in Hawaii is very rare. Golf ball-size hail or larger can only be produced in intense thunderstorms called supercells. Supercells require warm, moist air to rise into increasingly colder, drier air, in addition to winds changing direction and increasing height off the ground with increasing speed. This combined condition is extremely rare in Hawaii.
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