Tropical Storm Flossie, a rare tropical cyclone in the central Pacific Ocean, is pushing into Hawaii and expected to make landfall later today (July 29, 2013). Flossie will gradually weaken as it approaches an area of dry air and wind shear. Although ocean temperatures are expected to warm gradually as the storm approaches Hawaii, the overall environment will not be favorable for strengthening this storm. Still, Flossie is bringing heavy rain, gusty winds near 40-50 miles per hour, and dangerous surf to Hawaii. If Flossie hits the Big Island as a tropical storm, it will be the first tropical storm to strike Hawaii directly since 1958.
Based on the latest satellite appearance of Flossie (as of July 29 at 7 a.m. CDT or 1200 UTC), it looks as if the system is gradually weakening as it is encountering dry air and some wind shear as it approaches the Hawaiian Islands. The appearance of the storm on satellite is not very impressive, and I give it a good shot of weakening into a tropical depression as it pushes into Hawaii later this afternoon. While the weather will decline today, I am not expecting major problems for parts of Hawaii. You will see heavy rain and gusty winds, but significant wind damage is unlikely. Flossie will produce rip currents and dangerous surf for Hawaii as it continues to push to the west. The heavy rains could result into mudslides and flash flooding, which are the primary concerns associated with this storm.
How unusual is it for a tropical storm to hit Hawaii?
Hawaii rarely sees tropical cyclones directly affecting the region. The last time a tropical storm struck Hawaii directly was back in 1958. There have been hurricanes and tropical depressions that have impacted Hawaii after 1958, but not from a direct hit by a tropical storm. The last major tropical cyclone to affect Hawaii was Category 4 Hurricane Iniki in 1992, which was the most damaging hurricane to strike the Hawaiian Islands in recorded history. A large majority of the tropical systems that have affected Hawaii never actually made a direct landfall on one of the islands. As you can see in the image above, direct tropical cyclone hits are a rare occurrence.
Statistically, the majority of tropical cyclones that form in the central Pacific Ocean occur in the month of August. However, July is the second-most-active month with a total around 42 storms. Based of climatology, now is the peak of the central Pacific hurricane season.
Bottom line: Tropical Storm Flossie is weakening as it approaches Hawaii’s Big Island, and it will hit the state later this afternoon/evening (July 29, 2013). Heavy rains, mudslides, and flash flooding are the primary concerns associated with this storm as it continues to push to the west. If Flossie hits the Big Island as a tropical storm, it will be the first time Hawaii has had a direct hit from a tropical storm since 1958.
Matt Daniel is weekend Meteorologist for 13WMAZ (CBS) in Macon, Georgia, and founder of the blog Athens GA Weather. He's a self-described "big weather and music geek" and has produced weather content for CNN, MSN Weather and EarthSky. He has a passion for helping to keep people safe when severe weather strikes and says if you don't have a NOAA Weather Radio ... you should get one.