Hurricane Florence continues to approach the southeastern US

September 11th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images [click to play MP4 animation]

Hurricane Florence maintained Category 4 intensity on the morning of 11 September 2018 — and 1-minute (initially 30-second, until 1345 UTC) Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) and “Clean” Infrared Window (10.3 µm) images (below) showed improving eye structure after the tropical cyclone completed an eyewall replacement cycle during the preceding nighttime hours (MIMIC TC). A distinct pattern of transverse banding was also evident within the northern semicircle of Florence on Infrared imagery.

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

DMSP-18 SSMIS Microwave (85 GHz) imagery from the CIMSS Tropical Cyclones site (below) showed a large eye at 1015 UTC, and also at 1103 UTC.

DMSP-18 SSMIS Microwave (85 GHz) and GOES-16

DMSP-18 SSMIS Microwave (85 GHz) and GOES-16 “Clean” Infrared Window (10.3 µm) images at 1015 UTC [click to enlarge]

GOES-16 Upper-level Water Vapor (6.2 µm) images with Derived Motion Winds (below) revealed that a well-defined high altitude outflow channel had developed northwest of Florence, helping the storm to maintain its intensity.

GOES-16 Upper-level Water Vapor (6.2 µm) images, with Derived Motion Winds [click to play MP4 animation]

GOES-16 Upper-level Water Vapor (6.2 µm) images, with Derived Motion Winds [click to play MP4 animation]

1-minute GOES-16 True Color Red-Green-Blue (RGB) images (courtesy of Kathy Strabala, CIMSS; details) are shown below. A larger-scale RGB animation beginning at sunrise is available here (courtesy of Rick Kohrs, SSEC).

GOES-16 natural color RGB images [click to play MP4 animation]

1-minute GOES-16 True Color RGB images, 1330-1440 UTC [click to play MP4 animation]

Taking a closer look at the center of Florence later in the day, 1-minute GOES-16 data (below) showed mesovortices within the eye on Visible imagery, along with a narrow radial band of colder (darker red) cloud-top infrared brightness temperatures about 30-50 miles from the inner edge of the eyewall.

GOES-16

GOES-16 “Red” Viisible (0.64 µm) images [click to play MP4 animation]

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

===== 12 September Update =====

Florence remained at Category 4 intensity early in the day as it continued its northwestward motion toward the southeast coast of the US on 12 September. A 20-hour period of 1-minute GOES-16 Infrared images (from 0000-2015 UTC) is shown below.

1-minute GOES-16

1-minute GOES-16 “Clean” Infrared Window (10.3 µm) images, from 0000-2015 UTC [click to play MP4 animation]

Nighttime toggles between VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20 are shown below (courtesy of William Straka, CIMSS). Bright lightning-illuminated cloud areas can be seen on the DNB images distant to the north and northwest of the storm center; with minimal illumination from the Moon (which was in the Waxing Crescent phase, at only 10% of Full), Florence was illuminated primarily via airglow. On the Infrared images, a coarse pattern of transverse banding was evident along the far southern and western periphery of the storm.

Suomi NPP VIIRS Day/Night Band and Infrared Window images [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 VIIRS Day/Night Band and Infrared Window images [click to enlarge]

NOOA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

A sequence of Terra/Aqua MODIS and Suomi NPP VIIRS Infrared images (below) showed dramatic changes in the cold central dense overcast (CDO) of Florence between 02 and 18 UTC.

Infrared Window images from Terra MODIS (11.0 µm) and Suomi NPP VIIRS (11.45 µm) [click to enlarge]

Infrared Window images from Terra MODIS (11.0 µm) and Suomi NPP VIIRS (11.45 µm) [click to enlarge]

During the morning hours, 1-minute GOES-16 Visible and Infrared images (below) once again displayed a distinct eye and eyewall structure, with surface mesovortices evident within the eye. A curious linear standing wave — extending radially outward to the northeast of the storm center — developed from about 13-15 UTC (best seen on Infrared images).

GOES-16

GOES-16 “Red” Visible (0.64 µm) images [click to play MP4 animation]

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

ASCAT surface scatterometer winds from Metop-A (below) were as strong as 76 knots just northeast of the eye at 1450 UTC.

GOES-16

GOES-16 “Red” Visible (0.64 µm) image with Metop-A ASCAT surface scatterometer winds [click to enlarge]

A stereoscopic animation using GOES-16 and GOES-17 imagery is shown below — to view in three dimensions, cross your eyes until 3 equal images are apparent, then focus on the image in the center. *Note: GOES-17 images shown here are preliminary and non-operational*

Stereoscopic animation using GOES-16 and GOES-17

Stereoscopic animation using GOES-16 and GOES-17 “Red” Visible (0.64 µm) imagery [click to play animation]

During the afternoon hours, GOES-16 Visible and Infrared images (below) showed that the eye presentation  was beginning to deteriorate as Florence weakened to Category 3 intensity by 21 UTC.

GOES-16

GOES-16 “Red” Visible (0.64 µm) images [click to play MP4 animation]

GOES-16

GOES-16 “Clean” Infrared Window {10.3 µm) images [click to play MP4 animation]

The MIMIC Total Precipitable Water product (below) indicated that high TPW values associated with Florence began to move inland along the US East Coast by the end of the day.

MIMIC Total Precipitable Water product [click to enlarge]

MIMIC Total Precipitable Water product [click to enlarge]

Hurricane Florence

September 9th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) iimages [click to play MP4 animation]

After previously weakening from a Category 4 hurricane (on 04 September) to a tropical storm on 07 September (track/intensity), Florence re-intensified to become a Category 1 hurricane at 15 UTC on 09 September 2018. 1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.63 µm) are shown above, with the corresponding “Clean” Infrared Window (10.3 µm) images shown below. An eye structure appeared for brief intervals during the day, but was often masked by cloud debris from a series of convective bursts within the surrounding eyewall.

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

GPM GMI Microwave (85 GHz) image at 1811 UTC [click to enlarge]

GPM GMI Microwave (85 GHz) image at 1811 UTC [click to enlarge]

GPM GMI (above) and DMSP-16 SSMIS (below) Microwave (85 GHz) images from the CIMSS Tropical Cyclones site revealed that the eye was still partially open at 1811 UTC and 1945 UTC.

DMSP-16 SSMIS Microwave (85 GHz) image at 1845 UTC [click to enlarge]

DMSP-16 SSMIS Microwave (85 GHz) image at 1845 UTC [click to enlarge]

===== 10 September Update =====

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with GLM Group lightning [click to enlarge]

GOES-16 GLM lightning Groups (aggregates of GLM lightning Events) are plotted on “Red” Visible (0.64 µm) images (above) and “Clean” Infrared Window (10.3 µm) images (below), courtesy of Dave Santek, SSEC.

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with GLM Group lightning [click to enlarge]

Overlapping GOES-16 and GOES-17 Mesoscale Domain Sectors were positioned over Hurricane Florence beginning at 1200 UTC (providing imagery at 30-second intervals) — Visible animations are shown below.

* GOES-17 images shown here are preliminary and non-operational *

GOES-16

GOES-16 “Red” Visible (0.64 µm) images [click to play MP4 animation]

GOES-17

GOES-17 “Red” Visible (0.64 µm) images [click to play MP4 animation]

Longer animations of 30-second GOES-16 Visible and Infrared images viewed using AWIPS (below) provided a better view of  the mesovortices within the eye. Florence rapidly intensified (ADT | SATCON) to a Category 4 hurricane during this period.

GOES-16

GOES-16 “Red” Visible (0.64 µm) images [click to play MP4 animation]

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

One particularly large mesovortex rotated around the eastern edge of the eye after 2100 UTC, significantly eroding the eyewall (below).

GOES-16

GOES-16 “Red” Visible (0.64 µm) images [click to play MP4 animation]

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

Later in the early evening hours, GOES-16 Infrared imagery (below) showed an area of pronounced cloud-top warming and a thinning of cloud material just south of the eyewall, as Florence began to undergo an eyewall replacement cycle.

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

Suomi NPP views of Ernesto and Florence

August 5th, 2012 |
Tropical Storm Ernesto as seen by VIIRS Day-Night Band on Suomi/NPP

Tropical Storm Ernesto as seen by VIIRS Day-Night Band on Suomi/NPP

Tropical Storm Florence as seen by VIIRS Day-Night Band on Suomi/NPP

Tropical Storm Florence as seen by VIIRS Day-Night Band on Suomi/NPP

The Day-Night Band from VIIRS on the Suomi/NPP has been giving excellent imagery of Tropical Storms Ernesto and Florence over the weekend. The views are especially crisp because of the near fullness of the moon. For example, the sheared nature of Ernesto (top) is evident, and the overshooting tops in Florence are distinct. Infrared imagery at the same times show the extreme height (and coldness) of the overshooting tops in both Ernesto and Florence.

Suomi/NPP Visible and Infrared Imagery of Tropical Storm Ernesto

Suomi/NPP Visible and Infrared Imagery of Tropical Storm Ernesto

The Day-Night Band (DNB) has a nadir resolution of approximately 800 m. Visible resolution in daytime is 400 m, and toggle from 1739 UTC on 4 August between visible and infrared imagery (both with native 400-m resolution) shows very cold overshooting tops (temperatures as cold as -91 C) and evidence of gravity waves propagating outward from the overshoots. Details on the different VIIRS bands are available here.

Hurricane Florence: high winds along the US east coast

September 11th, 2006 |

CIMSS low-level steering flow products

Hurricane Florence passed very near Bermuda on 11 Sep (IR image | water vapor image), with a peak wind gust of 111 mph reported on the island. The radius of high winds associated with Florence was rather large, and the tight pressure gradient between the tropical cyclone and a large area of high pressure over southeastern Canada (above) was creating strong winds that prompted the issuance of high surf and other marine warnings/advisories along much of the US east coast. GOES-12 low-level visible winds (below) indicated the extent of the strong winds along the western periphery of Florence, with several targets having speeds of 34 knots or greater (bold green or cyan wind barbs on this closer view) a considerable distance from the storm center.

GOES-12 low-level visible winds