MONDAY 5 PM UPDATE: Karen has been downgraded to a tropical depression, according to the 5 pm advisory from the National Hurricane Center. Hurricane hunters found a broad low-level area of low pressure, but the former tropical storm lacked a well-defined center and wind speeds have been reduced to 35 mph or less.
The presence of strong winds aloft and pockets of dry air surrounding Tropical Depression Karen make it questionable whether the system will even maintain tropical characteristics before reaching the island of Puerto Rico. However, tropical storm warnings continue for the island because only a small increase in strength could bring tropical storm conditions to the region. Tropical Depression Karen is still officially forecast to move north of the Greater Antilles later in the week, slow down, and potentially intensify again.
The original version of the story, as published midday Monday, continues below.
Tropical Storm Karen, the season’s 11th named storm is barely hanging on as a tropical storm as of midday Monday. It may have an opportunity to restrengthen in a few days when the environment surrounding it is expected to become more favorable.
Forecaster Dan Brown at the National Hurricane Center said that “...the Air Force Reserve reconnaissance aircraft that has been investigating Karen has had difficulty finding a closed surface circulation.” He added that moderate to strong wind shear is expected to remain over Karen for another 24 hours, which could cause Karen to weaken a tropical wave.
Even if Karen continues its weakening trend, forecasters say gusty winds and tropical storm force winds are likely in squalls over Puerto Rico and the Virgin Islands on Tuesday.
Nearly all of the global models are indicating much lighter wind shear and moist air in the Atlantic waters north of Puerto Rico where Karen (or its remnant) is likely to be later this week — an environment that is more conducive for a strengthening tropical storm. It is unclear whether Karen’s structure will be in a position to take advantage of the more favorable setup.
Not only are there questions as to whether Karen will survive the hostile environment in the Caribbean, but there is considerable uncertainty in its future path. Karen is forecast to move toward the north, and be located between the Bahamas and Bermuda Wednesday and Thursday. A ridge of high pressure that is causing the unusually warm weather over our area is forecast to build over the western Atlantic Ocean late this week into the upcoming weekend. This ridge may act as a “block” to Karen’s northward motion, causing it to stall. Some models are also suggesting that Tropical Storm Jerry may not move rapidly out-to-sea as previously anticipated. If it does not, Jerry may also have a say in the steering pattern for Karen, which would complicate the forecast further.
The season’s 12th named storm, Tropical Storm Lorenzo, was classified by the National Hurricane Center as of 11 AM Monday. Lorenzo is currently forecast to become a hurricane on Wednesday and be just shy of major hurricane strength on Friday. The forecast cone keeps the tropical storm over the open waters of the Atlantic through Saturday, with no threat to any land areas through that time.