Tropical storm warning flags flew from Guadeloupe to Puerto Rico ahead of Potential Tropical Cyclone 5 on Monday. Tropical Storm Ernesto will strengthen near Puerto Rico and the Virgin Islands early Wednesday. By later this week, Future Ernesto could become an intensified hurricane that could threaten Bermuda and possibly Canada's southeastern coastal provinces.
As of 11 a.m. ET Monday, PTC 5 is a large but unorganized tropical wave with widespread showers and thunderstorms (convection) but without the organized central circulation needed to form a tropical depression. With maximum sustained winds estimated at 35 mph, PTC 5 is located approximately 435 miles east-southeast of Antigua, moving due west-north at 26 mph. By early Monday afternoon, convection is beginning to form around a potential low-level center, which could eventually make PTC 5 a tropical depression or tropical storm by Monday night.
PTC 5/Ernesto-to-be Forecast
Once convection around PTC 5 manages to consolidate around a centralized center, conditions will be favorable for development this week. By midweek, wind shear should remain light to moderate (mainly 5-10 knots) and the system is in a fairly humid atmosphere, with moderate relative humidity around 65%. Large areas of dry air extending to the north and east may hinder development at times, but as the drying effects become organized and intensified, PTC 5 appears to be able to largely insulate this effect. Over the next few days, sea surface temperatures were nearly 1 degree Celsius (2 degrees Fahrenheit) above average along the path of PTC 5. As the National Hurricane Center forecast shows, intensity models are very consistent that PTC 5 will become Tropical Storm Ernesto on Tuesday.
Some uncertainty will continue regarding the details of Ernesto's short-term action until the low-level center consolidates, but strong guidance from highs over Bermuda-Azores gives confidence in an overall west-northwest track . Future Ernesto is expected to track over the northern Leeward Islands on Tuesday and over or near Puerto Rico and/or the Virgin Islands on Tuesday night or early Wednesday. In addition to high winds that could knock down trees and branches and cause power outages, the main threat will be heavy rainfall, with localized totals expected to reach 6 inches in the northeastern Leeward Islands and near or exceed 10 inches in Puerto Rico, and the risk of flash flooding and mudslides.
Once clear of the islands, the system is expected to turn north and accelerate across the open northwest Atlantic during the second half of the week as it feels the effects of a broad upper-level trough extending south from far east Canada. NHC officials predict the system will reach hurricane strength Wednesday night and Category 2 hurricane strength on Friday and Saturday, possibly approaching Bermuda. As shown in Figure 1 above, there is close agreement between the operational and ensemble models on this projected northward trajectory, with future Ernesto appearing to remain in the eastern United States. Far southeast Canada could be affected in about a week.
Status Check: Are we still facing a hyperactive Atlantic season?
While the 2024 Atlantic hurricane season is expected to be wild, the pace of named storms currently lags well behind 2005 (Tropical Storm Irene formed on August 7) and 2020 (Tropical Storm Josephine formed on August 7 13th) and other landmark years.
However, that doesn't mean we've had a quiet season so far. As of August 12, the accumulated cyclone energy in the Atlantic this year was approximately three times the average for that day (40.7 vs. 13.2). Of course, this is largely due to the long-standing Category 5 Hurricane Beryl. That ratio may be even more skewed in a few days once we see how Ernesto performs in the future.
In the latest update released on August 6, Colorado State University forecasters slightly lowered their forecast for named storms from 25 to 23 as dry air largely suppresses development in the Atlantic Ocean in mid-to-late July . Even so, the organization still expects 12 hurricanes and six major hurricanes, saying forecast confidence in August is above average. The result will make 2024 one of the busiest seasons ever.
Keep in mind that the 2005 season spawned 17 named storms after August 15, including 11 hurricanes and 5 major hurricanes. After August 15, the 2020 hurricane season was also very productive, producing 19 named storms, 12 hurricanes, and 7 major hurricanes. So if the past is prologue, hurricane season still has a long way to go to track and prepare for.
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