Note: Matthew was upgraded to a Hurricane at 1800 UTC on 29 September. See the National Hurricane Center Website for the latest information.The area of disturbed weather that has been moving across the tropical Atlantic for the past week, shown above in six-hour steps using visible (0.63 µm) imagery during the day and shortwave infrared (3.9 µm) imagery at night, has developed into a strong tropical storm, named Matthew, as it moves through the Windward Islands. Matthew is embedded with the rich moisture source of the Intertropical Convergence Zone, as shown in the animation below of MIRS Total Precipitable Water, taken from this source. Matthew is also heading towards a region rich in moisture — it appears that dry air should not influence Matthew’s evolution in the near term. Matthew’s predicted course into the Caribbean is over very warm water with high heat content (below, imagery from the CIMSS Tropical Weather site). Wind shear over the storm is low, with larger values to the west; the region of high shear in advance of Matthew has been preceding the storm for the past 72 hours and it is forecast to continue its retreat from Matthew. The forecast from the National Hurricane Center is for slow strengthening. Late in the afternoon on the 28th, GOES-13 detected cloud tops cooler than -80º C associated with some of the overshooting tops (the purple enhancement). Overshooting tops can be detected automatically and shown at this website.
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Suomi NPP overflew the eastern Caribbean early on 29 September, and the Day Night Band imagery, below, (from RealEarth) shows Matthew west of the Windward Islands. A lone lightning strike is visible in the convective clouds. There appears in this very low light image to be a low-level circulation exposed to the west of the deep clouds, suggesting a sheared storm.
A GOES-13 Visible Image animation from just after sunrise shows a the circulation center exposed to the west of the deep convection.
NOAA-19 overflew Matthew at about 1900 UTC on 29 September 2016, shortly after the storm was upgraded to a Hurricane, and visible imagery from that pass (data courtesy of the AOML Direct Broadcast antenna) shows far less evidence of a sheared storm. The Central Dense Overcast is above the surface circulation.