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97L to spread heavy rains in Lesser Antilles; major flooding in North Carolina

By: Dr. Jeff Masters, 3:42 PM GMT on October 02, 2010

A large region of disturbed weather (Invest 97L), centered about 400 miles east of the northern Lesser Antilles Islands, is headed west-northwest at about 15 mph and will bring heavy rain showers and gusty winds to the northern Lesser Antilles Islands today and Sunday. These showers can be seen approaching the islands on Martinique radar this morning. Wind shear is a moderate 10 - 20 knots over 97L, and the waters beneath are very warm, 29°C, but recent satellite imagery shows that 97L's heavy thunderstorms are limited and not well organized. A pass from the Windsat satellite at 5:51am EDT showed a moderate wind shift associated with 97L, but nothing close to a closed circulation. Top winds were around 30 - 35 mph. The SHIPS model predicts that wind shear over 97L will rise to the high range, 20 - 30 knots, today through Monday, then decline. The ECMWF model is the only model currently showing significant development 97L in the next seven days. The model predicts 97L will be near Puerto Rico on Monday, the Dominican Republic on Tuesday, and Haiti on Wednesday, with the storm developing into a tropical depression on Wednesday just north of Haiti, then moving northwards through the Turks and Caicos Islands and out to sea on Thursday. NHC is giving 97L a 20% chance of developing into a tropical depression by Monday, and has not tasked the Hurricane Hunters to fly into the storm over the next two days. 97L will move at about 10 mph through the islands on Sunday through Wednesday, bringing the potential for an extended 3-day period of heavy rains for the islands in its path. Even if 97L does not develop into a tropical depression, its slow motion may result in life-threatening flash flooding and mudslides in Puerto Rico, the Dominican Republic, Haiti, and eastern Cuba as it moves past.

Figure 1. Morning satellite image of Invest 97L.

Major flooding in northeastern North Carolina
Major flooding continues in northeastern North Carolina, where the Cashie River in Windsor is 5.4 feet over flood stage. North Carolina has been deluged by more than twenty inches of rain in some regions over the past week, due to tropical moisture streaming northwards in advance of Tropical Storm Nicole. Wilmington, NC set records this week for the heaviest 3-day, 4-day, and 5-day rainfall events in city history, and the month of September ended up as the second rainiest month ever recorded in the city. A remarkable 22.54" of rain fell on Wilmington during the 5-day period Sunday through Thursday. The previous record was 19.06", set in September 1999 during Hurricane Floyd. Fortunately, eastern North Carolina was under moderate drought conditions prior to this week's rainfall onslaught, with just 0.18" of rain falling during the first 25 days of September. Representatives from Portlight.org are on their way to the hardest-hit areas of North Carolina to beginning identifying needs in the wake of the flooding. Portlight expects to perform the first deployment of their new relief trailer within the next few days and send a truck loaded with water, food and personal hygiene supplies. You can follow their progress via the live webcam on the Portlight truck.

Our new Weather Extreme blogger, Christopher C. Burt, has posted a comparison of the maximum rainfall totals in each state affected by Hurricane Floyd of 1999, and this weeks extreme rainfall event, which he dubs "Super-Rainstorm Nicole." The two storms were very similar in the amount of rain they dumped, and we are very fortunate that moderate drought conditions preceded the arrival of this week's storm, or else billions in damage would have resulted.

Figure 2. Rainfall for the 7-day period ending at 8am EDT this morning shows the remarkable accumulations that fell in association with the tropical moisture ahead of Tropical Storm Nicole. Image credit: NOAA.

Elsewhere in the tropics
Disturbed weather has diminished in the Central Caribbean, where the remnants of Tropical Storm Nicole are no longer kicking up significant thunderstorm activity. Several of the models are predicting the formation of a tropical depression in the Mid-Atlantic 6 - 8 days from now, in a location that would not be of any danger to land areas.

Next update
I'll have an update Sunday morning.

Jeff Masters
Flooding Bristol Vermont
Flooding Bristol Vermont
Too Wet To Harvest Today
Too Wet To Harvest Today
Heavy rain and high winds for 2 days caused flash flooding in many areas of New York State

Flood Hurricane

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.