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Hurricane Season in the Atlantic: Invest Area 99L and TS Gaston

Posted On: August 26, 2016 - By: Barbra Lashbrook

Ahh…it is that time of year again, it’s hurricane season for the Atlantic and Pacific Oceans; the blog will focus on the Atlantic hurricane activity that is ongoing. Two to mention that are active right now are the Invest Area 99L and Tropical Storm Gaston. The current status of both Invest Area/Tropical Storm whereabouts can be seen via the National Hurricane Center website.

Monitoring severe tropical weather events from the range of invest areas, tropical depressions, tropical storms to the order of Category 1-5 hurricanes by National Weather Service (NWS) forecasters can be challenging. Whether if the tropical event is occurring during the day or night, NWS forecasters can utilize satellite products and supplemental products to provide the best forecasts for the general public. One of the big challenges for forecasters is monitoring these events during the night-time. A product to consider is the Near-Constant Contrast (NCC), derived from the Day-Night Band (DNB), a sensor on the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument on-board the Suomi-National Polar-orbiting Partnership (Suomi-NPP) satellite. The NCC has the capability of observing night-time light emissions and atmospheric features across the globe, including monitoring tropical storms.

The following animated gifs below highlight the NCC with infrared (IR) satellite imagery in the early morning near 5Z and 6Z, 26 August, 2016 of Invest Area 99L (Figure 1) and Tropical Storm Gaston (Figure 2), respectively.

Invest Area 99L


Figure 1: The Invest Area 99L is currently hovered over Hispaniola in the Caribbean Sea (white circle) and has a 30% chance of formation in the next 48 hours. Within the animation, NCC is shown first depicting the distinct cloud cover of the invest area, and IR shown second showing the brightness temperatures (in degrees Celsius) of the cloud convective tops. If you look closely you can see lightning (horizontal white streaks) embedded in the storm. Cloud cover and city lights are depicted as well.

Tropical Storm Gaston


Figure 2: Tropical Storm Gaston located in the mid-Atlantic Ocean has a chance of becoming a Category One Hurricane within the next 48 hours as well. Within the animation, NCC is shown first depicting the circulation of the tropical storm in the Atlantic, and IR shown second highlighting the brightness temperatures (in degrees Celsius) of the cloud convective tops. Lighting are also seen embedded in the storm while cloud cover and city lights are depicted as well.

Additionally, here are the variety of forecast track model outputs for Invest Area 99L and Tropical Storm Gaston for the next few days.

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