Matthew Plods Along… (H. Michael Mogil, CCM, CBM, DMS)
The overall picture of the future of powerful Hurricane Matthew remains little changed since yesterday. Following a cyclonic loop and a slow course adjustment to the northwest, Matthew is still just moving at a five-mile per hour forward speed. Over the next five days, Matthew is expected to make relatively slow progress as he plods northwestward and then northward. He should be near the latitude of West Palm Beach, FL by early this Friday (Oct. 7, 2016) morning. Earlier computer model runs placed Matthew as far north as the Carolinas by this time.
This provides important information about the forecastability of these storms. While the National Hurricane Center (NHC) has made substantial gains in its ability to forecast where storms like Matthew will go, center errors are still around 175 miles at day 4 (96 hour forecast) and 230 miles at day 5 (120 hours forecast). Errors in intensity are comparably as large or greater.
Early this Sunday morning, Matthew, will his 150-mile per hour sustained winds (Category 4 on the Saffir-Simpson wind scale) was located at 13.9 degrees North latitude and 74.1 degrees West longitude or about 345 miles south-southwest of Port Au Prince, Haiti. Central pressure was 27.76 inches of mercury or about nine percent below average atmospheric pressure. The lower the central pressure in a hurricane, typically, the stronger the hurricane’s wind field.
Hurricane-force winds currently extend outward up to 25 miles, and tropical-storm-force winds extend outward up to 205 miles, from Matthew’s center.
Fig. 1 shows current hurricane and tropical storm watches, warnings and advisories associated with Matthew. According to NHC, a warning is typically issued 36 hours before the anticipated first occurrence of tropical-storm- force winds, conditions that make outside preparations difficult or dangerous. A Tropical Storm or Hurricane Watch means that tropical storm or hurricane conditions, respectively, are possible within the watch area.
While Matthew’s winds will likely produce significant structural damage and down trees and power lines, the greater danger may well lie in Matthew’s rainfall potential. Given the slow storm movement, strong winds, and mountainous terrain in his path, total rain accumulations across Haiti should be in the range of 15 to 25 inches, with possible isolated maximum amounts of 40 inches. The risk of flash flooding and mudslides is high. Matthew is also expected to produce total rain accumulations of 10 to 20 inches over eastern Jamaica, the Dominican Republic and eastern Cuba, with possible isolated maximum amounts of 25 inches.
The combination of a dangerous storm surge and large and destructive waves could raise water levels by as much as seven to 11 feet along the south coast of Haiti and somewhat lesser amounts in other coastal areas within the hurricane and tropical storm watch and warnings areas.
Some fluctuations in intensity are possible during the next couple of days due to eye wall replacement cycles, interaction with land, and other factors. But, forecasters expect Matthew to remain a powerful hurricane through Monday night.
Matthew will be close enough to the southeast U.S. coast well into the week. Hence, people along the eastern seaboard from the Carolinas southward should stay abreast of Matthew and his expected track, until the storm has safely passed their latitude. People in other East Coast locations should monitor the storm as Matthew’s impacts may affect these locations by next weekend.
Our correspondent team here at the Global Weather and Climate Center will be posting the latest information and explanations about the storm and about hurricanes, in general.
© 2016 H. Michael Mogil
Originally posted 10/2/16