Leslie brushing Bermuda, heading for Newfoundland

It's a wet, windy day on Bermuda today, where Tropical Storm Leslie is bringing high winds and heavy rain as the storm's core passes 120 miles (200 km) east of the island. At the Saint David's weather station on the east end of the island, Leslie brought sustained winds of 39 mph, gusting to 54 mph, at 12:30 pm AST today. Bermuda radar shows a large area of heavy rain from Leslie is over the island, and these rains will continue through most of the afternoon, and the Bermuda airport is closed until 4 pm AST. Satellite loops show that Leslie is a large storm with a huge eye 60 miles (100 km) in diameter, but the storm does not have an eyewall.


Figure 1. Radar image of Tropical Storm Leslie from the Bermuda radar, taken at 12:43 AST.

Forecast for Leslie
As Leslie continues to move north over warmer water, the storm should be able to build an eyewall and become a Category 1 hurricane. The strong trough of low pressure pulling Leslie to the north will bring Leslie very close to Newfoundland, Canada by Tuesday. At that time, Leslie should be weakening due to cooler waters and increased wind shear, and is likely to be a tropical storm. Heavy rain will be the main threat to Newfoundland. The latest 11 am EDT NHC wind probability forecast calls for a 36% chance that Leslie will be a Category 1 or stronger hurricane Tuesday morning at 8 am EDT, when the storm will be near Newfoundland. Even if the core of Leslie misses Newfoundland, the island will still likely experience tropical storm-force winds, since 39+ mph winds are expected to extend outward from its center 160 miles to its northwest on Tuesday. Large swells from Leslie continue to pound the entire Eastern Seaboard, and are creating beach erosion and dangerous rip currents.


Figure 2. Tropical Storm Leslie as seen by NOAA's F-16 polar orbiting satellite at 9:20 am EDT Sunday September 9, 2012. At the time, Leslie had top winds of 60 mph. Bermuda is the yellow triangle at the left of the image. Image credit: NOAA/RAMMB.

Hurricane Michael weakens to Category 1
Hurricane Michael has weakened to a Category 1 storm with 90 mph winds, out over the open mid-Atlantic Ocean. Satellite loops show that Michael is still an impressive storm with a well-developed eye. None of the models show that Michael will threaten any land areas during the coming five days, and Michael will likely die at sea over cold waters east of Newfoundland in 3 - 4 days.


Figure 3. Hurricane Michael as seen by NASA's Terra satellite at 9:40 am EDT Sunday September 9, 2012. At the time, Michael was a Category 1 hurricane with 90 mph winds. Image credit: NOAA/RAMMB.

91L off the coast of Africa
A tropical wave that emerged off the coast of Africa on Friday (Invest 91L) is 250 miles west of the Cape Verde Islands, and is headed west-northwest at 10 - 15 mph. The disturbance is large with plenty of spin, but has limited heavy thunderstorm activity due to dry air. Most of the reliable computer models are predicting that 91L will develop into a tropical depression by Wednesday. In their 8 am EDT Tropical Weather Outlook, NHC gave 91L a 40% chance of developing into a tropical depression by Tuesday morning. Our two most reliable models, the GFS and ECMWF, predict that 91L will pass at least 500 miles to the northeast of the Lesser Antilles Islands late this week, on a track that would likely keep this storm far out at sea away from any land areas.

Jeff Masters