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Tropical Storm Flossie Takes Aim at Hawaii

By: Dr. Jeff Masters, 3:15 PM GMT on July 28, 2013

In the Central Pacific, Tropical Storm Flossie, a strong tropical storm with 65 mph winds, is headed west at 20 mph towards Hawaii. Satellite images show that Flossie is maintaining a modest area of heavy thunderstorms that are well-organized. The storm is over waters of 25°C, which is about 1°C below the water temperature typically needed to sustain a tropical storm. Flossie peaked in intensity Saturday morning, when the storm had 70 mph winds. As Flossie approaches the Big Island of Hawaii on Monday, these waters will warm to 26°C, but wind shear is expected to be in the moderate range, which should keep Flossie from strengthening. Dry air aloft will likely cause some weakening before landfall Monday morning, and Flossie will likely have top winds of 45 - 55 mph when is passes through the Hawaiian Islands. Flossie's main threat will be heavy rains, with 6 - 10" expected over The Big Island and Maui County, and 4 - 8" in Oahu. Rains of this magnitude are capable of causing dangerous flash flooding and mudslides. Sunday's 11 am EDT wind probability forecast from the Central Pacific Hurricane Center gave Hilo on the Big Island a 33% chance of experiencing sustained tropical storm force winds of 39 mph or greater from Flossie. These odds were 32% for Honolulu and 41% for Kahului.

Figure 1. MODIS satellite image of Tropical Storm Flossie taken at approximately 5 pm EDT Saturday July 27, 2013. At the time, Flossie had top winds near 50 mph. Image credit: NASA.

Tropical storms are uncommon in Hawaii
On average, between four and five tropical cyclones are observed in the Central Pacific every year. This number has ranged from zero, most recently as 1979, to as many as eleven in 1992 and 1994. August is the peak month, followed by July, then September. Tropical storms and hurricanes are uncommon in the Hawaiian Islands. Only eight named storms have impacted Hawaii in the 34 year period 1979–2012, an average of one storm every four years. Since 1949, the Hawaiian Islands received a direct hit from just two hurricanes--Dot in 1959, and Iniki in 1992. Both hit the island of Kauai. Only one tropical storm has hit the islands since 1949--an unnamed 1958 storm that hit the Big Island. A brief summary of the three most significant hurricanes to affect Hawaii in modern times:

September 1992: Hurricane Iniki was the strongest, deadliest, and most damaging hurricane to affect Hawaii since records began. It hit the island of Kauai as a Category 4 on September 11, killing six and causing $2 billion in damage.

November 1982: Hurricane Iwa was one of Hawaii's most damaging hurricanes. Although it was only a Category 1 storm, it passed just miles west of Kauai, moving at a speed of nearly 50 miles per hour (80 km/h). Iwa killed one person and did $250 million in damage, making it the second most damaging hurricane to ever hit Hawaii. All the islands reported some surf damage along their southwest facing shores, and wind damage was widespread on Kauai.

August 1959: Hurricane Dot entered the Central Pacific as a Category 4 hurricane just south of Hawaii, but weakened to a Category 1 storm before making landfall on Kauai. Dot brought sustained winds of 81 mph with gusts to 103 mph to Kilauea Light. Damage was in excess of $6 million. No Dot-related deaths were recorded.

Figure 2. Tracks of all tropical storms and hurricanes to pass within 100 miles of the Hawaiian Islands, 1949 - 2012. During that time span, the Hawaiian Islands received a direct hit from just two hurricanes--Dot in 1959, and Iniki in 1992. Both hit the island of Kauai. One tropical storm also hit, and unnamed 1958 storm that hit the Big Island of Hawaii. Image credit: NOAA/CSC.

Remains of Dorian are worth watching
The remains of Tropical Storm Dorian will be passing just north of northern Lesser Antilles Islands today and just north of Puerto Rico tonight. Satellite images show no signs of a surface circulation, and just a moderate area of heavy thunderstorms associated with the storm. AIr Force hurricane hunter aircraft are on call to investigate Dorian's remains on Sunday afternoon and Monday afternoon, if necessary. In their 8 am EDT Tropical Weather Outlook, NHC gave Dorian's remains a 20% chance of regenerating by Tuesday.

Extreme heat wave in Europe
An extreme heat wave is baking Europe today, and at least five countries have a chance at setting a new all-time national heat record. The most likely candidate is Liechtenstein, where the forecast for Balzers Sunday calls for a high of 95°F. According to wunderground's International Records database maintained by our weather historian, Christopher C. Burt, the current all-time heat record for Liechtenstein is 36°C (96.8°F) set at Vaduz on August 13, 2003.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.