While post-Tropical Cyclone Debbie continued to bring flooding from the southeastern United States to southeastern Canada on Friday, the next tropical threat from the Atlantic is already looming. Computer models predict that a large tropical wave in the mid-tropical Atlantic will encounter too much wind-sheared dry air to develop on Saturday, but will develop by Sunday and Monday as the wave approaches the Lesser Antilles. will encounter a more favorable development environment.
The tropical wave, which is not yet well organized enough to be awarded an “investment” designation by the National Hurricane Center, was centered several hundred miles west-southwest of the Cape Verde Islands on Friday morning and was heading west at about 15 mph. move. Satellite imagery showed the wave was located just south of a large area of dry air in the Saharan air layer, with the disturbance producing limited severe thunderstorms and only slight rotation. High wind shear of 15-25 knots suppressed wave development, but the waves were in warm waters of 28°C (82°F). Sea surface temperatures in much of the western tropical Atlantic remain 1-2 degrees Celsius (1.8-3.6°F) above average temperatures for early August.
Disturbance trajectory prediction
A strong ridge of high pressure associated with the Azores-Bermuda High will direct the disturbance to the west on Sunday and then more to the west-northwest starting Monday. Along this route, waves will bring heavy rain over the Lesser Antilles starting on Monday, with the epicenter of the disturbance likely to cross the Lesser Antilles on Tuesday. Heavy rain is possible in Puerto Rico, the Dominican Republic, Haiti, the Turks and Caicos Islands and the southeastern Bahamas from Wednesday into Thursday. By then, a trough moving northward may direct the disturbance more to the northwest. It is too early to assess potential threats to the U.S. and Canadian coasts, but the system poses a threat to landfall. Offshore circulation routes are also possible.
Disturbance intensity prediction
The atmosphere is expected to be steadily moist, with mostly moderate wind shear and sea surface temperatures close to historical records. This disturbance has good model support for development before reaching the Lesser Antilles, although it seems unlikely to impact as a hurricane. these islands. If the system moves south, disruptions in circulation through Puerto Rico and the Hispaniola Mountains will slow development, while if the system moves north, it could produce stronger storms.
At 8 a.m. EDT on Friday, the National Hurricane Center's Tropical Weather Outlook gave the two-day and seven-day chances of hurricane development at 0% and 60%, respectively. There are currently no hurricane hunters scheduled to fly into the storm, but hurricane hunters may begin flying into the storm on Monday. The next name on the list of Atlantic storms is Ernesto. Based on data from 1991-2020, the average date of an “E” storm, the fifth naming system for the Atlantic season, is August 22.
Debbie will be worth billions
Former Hurricane Debbie, now a post-tropical cyclone, will end its North American journey on Friday and Saturday, slamming across the northeastern United States and into southeastern Canada. Post-tropical Cyclone Debbie was moving northeast at 35 mph at 11 a.m. ET Friday. Rainfall amounts of 2 to 5 inches, with localized amounts exceeding 6 inches, are expected near Debbie's path, through central and far northern New York, and along the St. Louis in southeastern Ontario and southern Quebec, Canada, including Montreal. Lawrence Valley.
Continued rain is expected Friday, still enough to cause flash flooding in some cases, as far south as the Coastal Carolinas. Severe thunderstorms associated with Debbie affected Washington, D.C. on Friday morning and a tornado warning was issued.
Rainfall from Debbie caused severe flooding on two North Carolina rivers Friday afternoon, including one in South Carolina and one in Georgia. Severe flooding is expected by Monday on three other rivers in North Carolina, two rivers in South Carolina and one river in Florida. Rainfall from Debbie is expected to cause moderate flooding on dozens of rivers in Virginia, Maryland, Pennsylvania, New York and New Jersey. Storm surge combined with high runoff from heavy rains caused moderate flooding along the coast of Annapolis, Maryland, on Friday.
Debbie is expected to join the ranks of billion-dollar U.S. hurricanes — in fact, two Atlantic hurricanes so far this year — Beryl and Debbie — fall into that category. However, the damage caused by Debbie was less than feared, as expected rainfall totals of more than 20 inches failed to materialize, and no state set all-time records for tropical cyclone rainfall. The latest summary of preliminary storm totals includes peaks by state as of 10 a.m. Friday:
Florida: 18.86 inches, Parrish
South Carolina: 18.25 inches, 5.3 miles southeast of Somerville
Georgia: 14.82 inches, 1.4 miles east-southeast of Oliver
Maryland: 6.95 inches, 1 mile south of Damascus
New Jersey: 8.67 inches, 1.7 miles southeast of Pennington
North Carolina: 15.25 inches, king grant
Delaware: 6.57 inches, 5.3 miles north of Newark
Virginia: 7.6 inches, 1.3 miles east-northeast of Everton
West Virginia: 5.98 inches, 12.8 miles south-southwest of Harpers Ferry
Pennsylvania: 5.39 inches, 5 miles north-northwest of Rainsburg
According to Gallagher Re, Debbie's insured losses could be $1-2 billion, with wind-related losses accounting for only a few hundred million of the total. Most of Debbie's losses came from flooding, and only about 10-50% of properties in the hardest-hit areas had flood insurance, so Debbie's total losses (both insured and uninsured) would be well above $1-2 billion .
Over the next few days we will publish in this article the latest information on the unrest threatening the Lesser Antilles.
We help millions of people understand climate change and what to do about it. Help us reach more people like you.
