96L Over Leeward Islands Not Expected to Develop

November 13, 2018, 4:38 PM EST

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Above: Visible GOES-16 satellite image of 96L at 11 am EST Tuesday, November 13, 2018. The system was being sheared by strong upper-level winds out of the west that were creating about 35 knots of wind shear. Image credit: RAMMB/CSU/CIRA.

A strong tropical wave (96L) was bringing heavy rains and gusty winds to the Leeward and Virgin Islands on Tuesday afternoon, but was very disorganized, and is no longer expected to become the Atlantic’s next tropical depression.

Satellite images on Tuesday afternoon showed that 96L had a moderate-sized area of heavy thunderstorms that were very poorly organized. The system was headed west to west-northwest at about 15 mph, and was under high wind shear of 35 knots, which was inhibiting development. Water temperatures were plenty warm for development, near 29°C (84°F).

96L radar
Figure 1. Long-range radar from San Juan, Puerto Rico of 96L at 11:12 am EST November 13, 2018. Heavy rain showers were affecting the Leeward and Virgin Islands, and were approaching Puerto Rico.

Forecast for 96L

The 12Z Tuesday run of the SHIPS model predicted that shear would slowly fall over the next few days, and become moderately high, near 20 knots, by Thursday. Water temperatures will remain warm, favoring development. However, 96L has poor model support for development. None of our top models for predicting tropical cyclone genesis, the GFS, European and UKMET, predicted development as of their latest runs available at noon EST Tuesday. The system is expected to move west to west-northwest at 5 - 15 mph through Thursday, bringing heavy rains of 1 – 3” to the Leeward Islands, Virgin Islands, Puerto Rico, and Hispaniola. No flash flood watches or warnings were posted for Puerto Rico or the Virgin Islands as of noon EST Tuesday.

By Thursday, 96L will be near the Turks and Caicos Islands and Dominican Republic, and may begin turning to the northwest and then north in response to a trough of low pressure passing to its north. Wind shear will increase significantly on Friday and Saturday, to 30 – 40 knots, putting an end to any further development of 96L. In their 1 pm EST Tuesday Tropical Weather Outlook, NHC gave 96L 2-day and 5-day odds of development of 10% and 20%, respectively. This will be our last post on 96L unless a significant increase in the chances of development occurs.

Tropical Cyclone Gaja heads for southeast India

A slowly organizing tropical storm is expected to make landfall on the far southeast coast of India on Friday local time, possibly at hurricane strength. Tropical Cyclone Gaja was located about 370 miles east of Chennai, India, at 12Z (7 am EST) Tuesday, according to the Joint Typhoon Warning Center. Top sustained winds were 40 mph. Gaja is embedded in a moist environment and traveling over very warm waters (sea surface temperatures of around 29°C or 84°F). However, wind shear of up to 20 knots (23 mph) is impeding Gaja’s organization. The shear is expected to lessen only slightly as Gaja approaches the Indian coast. JTWC brings Gaja onshore roughly 100 miles south of Chennai late Thursday local time as a tropical storm, as does the Indian Meteorological Department (see PDF). Several models bring Gaja onto land as no more than a weak tropical storm, while the high-resolution HWRF model insists that Gaja could vault well beyond hurricane strength just before landfall.

Infrared image of Tropical Cyclone Gaja as of 1600Z (11 am EST) Tuesday, November 13, 2018
Figure 2. Infrared image of disheveled Tropical Cyclone Gaja as of 1600Z (11 am EST) Tuesday, November 13, 2018. Image credit: RAMMB/CSU/CIRA.

Gaja’s heaviest rains will likely stay south of Chennai, a massive and notoriously flood-prone city where more than 250 people were killed by flooding in November-December 2015. Late autumn is normally the wettest time of the year in this part of the country because of the northeast monsoon, the flip side of the summer southwest monsoon that drenches the bulk of India. Another tropical disturbance could bring considerably more rain to southeast India late next week.

Bob Henson wrote the Gaja section of this post.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.

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Dr. Jeff Masters

Dr. Jeff Masters co-founded Weather Underground in 1995 while working on his Ph.D. in air pollution meteorology at the University of Michigan. He worked for the NOAA Hurricane Hunters from 1986-1990 as a flight meteorologist.

emailweatherman.masters@gmail.com

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