NASA and NOAA satellite finds wind shear pushing center of Tropical Storm Isaac

NASA-NOAA's Suomi nuclear plant satellite provided an infrared survey of tropical storm Isaac that revealed that its circulation center had been displaced from most of the clouds and precipitation. This indicates that wind shear affects the storm.

What is the vertical wind shear?

In general, wind shear is a measure of how wind speed and direction change with altitude. To understand how this affects a tropical cyclone or hurricane, think of a tropical cyclone as a series of vertically stacked tires, all rotating. Going up off the ground, each tire represents the rotation from the center of the storm to a higher level in the atmosphere. The different levels of turning wind at the center of the tropical cyclones must be stacked on top of each other to reinforce each other. If there are higher winds that push some of the tires upwards, this affects the balance and rotation of the tires below. This is what happens when the vertical shear of the wind pushes against a storm. It pushes the center and weakens (or wobbles) the rotation of all the tires.

Satellite data reveal

The National Hurricane Center or NHC noted that "satellite imagery indicates that Isaac remains a poorly organized tropical cyclone, with the low-lying center being mainly exposed in the early morning." Isaac is struck by a strong shear of the vertical wind.

At 13:54 EDT (0554 UTC) on September 13, the VIIRS (Visible Infrared Imaging Radiometer) instrument aboard NASA-NOAA's Suomi satellite analyzed tropical storm Isaac with infrared light. VIIRS found a smaller zone of cooler cloud top temperatures off center compared to minus 70 degrees Fahrenheit (minus 56.6 degrees Celsius).

NASA research has shown that maximum cloud temperatures, as cold or cold as 70F / 56.6C, can generate heavy precipitation.

At 0800 EDT (1200 UTC), the Eastern Caribbean radiosonde data and NOAA Hurricane Hunter aircraft data indicate that Isaac's circulation is relatively weak and weak. It is quite possible that Isaac will degenerate into a tropical wave the next day or two because of the persistent effects of strong wind shear.

Warnings and watches on September 13th

A tropical storm warning is in effect for Martinique, Dominica and Guadeloupe. Tropical Storm Watch is in effect for Antigua, Barbuda, Montserrat, St. Kitts and Nevis, Saba and St. Eustatius, St. Martin and St. Martin.

The statistics of Isaac on September 13, 2018

At 8:00 am EDT (1200 UTC), the center of tropical storm Isaac was located near 15.2 degrees north latitude and 60.9 degrees west longitude. Isaac moves faster westward near 33 km / h. This general movement is expected to continue today with a decrease in speed on the Caribbean Sea. Maximum sustained winds remain near 75 km / h (75 km / h) with higher gusts. Few force changes are expected in the next few hours as Isaac crosses the Leeward Islands. A gradual weakening is expected after Isaac crosses the eastern Caribbean.

Anticipated precipitation in the Leeward and Windward Islands

NHC said tropical storm Isaac is expected to produce total rainfall amounts of 2 to 4 inches with isolated amounts of up to 6 inches across Martinique, Dominica and Guadeloupe, especially on high ground. Rainfall of 0.5 to 1.5 inches with isolated amounts of 3 inches is expected in Puerto Rico and the southern US Virgin Islands. This rain can cause dangerous floods.

The prediction path of Isaac

NHC said on the forecast trail that Isaac would have to cross the center of the Lesser Antilles and enter the eastern Caribbean Sea later in the day, then cross the eastern and central Caribbean Sea throughout the weekend. .

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NASA finds a wind shear pushing the center of Tropical Storm Isaac