GOES-13 (GOES-East) Visible (0.63 µm) images showed that the circulation of Post-Tropical Cyclone Hermine (NHC discussions) persisted off the US East Coast on 04 September (above; also available as an MP4 animation) and on 05 September 2016 (below; also available as an MP4 animation). On 04 September, the Royal Caribbean cruise ship Anthem of the Seas sustained some minor damage as it encountered strong winds and high waves in the northeastern quadrant of the storm (ship location | satellite images) while sailing from New Jersey to Bermuda.  Also of particular interest were the pair of mesovortices seen rotating around the main circulation center of the storm on 05 September. The GOES-13 satellite had remained in Rapid Scan Operations (RSO) mode during this period, providing images as frequently as every 5-7 minutes.

===== 06 September Update =====

On 06 September, the circulation of Post-Tropical Cyclone Hermine continued to move very slowly westward toward the Northeast US coast as it gradually weakened (above; also available as an MP4 animation). A 1600 UTC GOES-13 Visible image with plots of Metop ASCAT winds along with surface/buoy/ship reports is shown below — the maximum ASCAT surface scatterometer wind speeds were 33 knots in the western semicircle of the storm.

As of 18 UTC, all coastal Tropical Storm Warnings were discontinued by the National Hurricane Center (final advisory).

===== 07 September Update =====

An animation of hourly MIMIC Total Precipitable Water (TPW) product images covering the 04-07 September period {above) showed that the remnant circulation of what was formerly Post-Tropical Cyclone Hermine still contained relatively high values of TPW (in the 50-60 mm or 2.0-2.4 inch range) as it edged closer to the coast on 07 September.

 

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Hermine was upgraded to a Hurricane over the Gulf of Mexico around 20 UTC on 01 September 2016. GOES-13 (GOES-East) Visible (0.63 µm) images (above) showed improvement in the appearance of curved banding structures around the eye late in the day. The GOES-13 satellite had been placed into Rapid Scan Operations (RSO) mode, providing images as frequently as every 5-7 minutes. Note that Hurricane Hermine developed from Tropical Invest 99L, which was sampled by 1-minute GOES-14 imagery beginning on 25 August; unfortunately, the 1-minute Super Rapid Scan Operations for GOES-R (SRSO-R) test period ended at 1115 UTC on 29 August (however, imaging of the evolution of Tropical Depression 9 to Hurricane Hermine continued at 15-minute intervals).

The corresponding GOES-13 Infrared Window (10.7 µm) images (below) revealed the eventual formation of a distinct eye, with bursts of convection exhibiting cloud-top IR brightness temperatures in the -75º to -80º C range (shades of white to violet pixels) in the western and southern semicircles of the eyewall region. Hermine became the first hurricane to make landfall in Florida since Wilma in 2005.

A Suomi NPP VIIRS true-color Red/Green/Blue (RGB) image visualized using RealEarth (below) provided a detailed view of the curved banding around the western and southern portion of the eye.

A comparison of DMSP-17 SSMIS Microwave (85 GHz) and GOES-13 Infrared Window (10.7 µm) images around 2315 UTC (below) depicted a much larger eye presentation on microwave vs infrared — the microwave image showed the curved banding structure around an eye that was still not well-organized.

While Hermine passed over waters exhibiting warm Sea Surface Temperature values in the eastern Gulf of Mexico, the Ocean Heat Content values were only modest (below).

The high values of Total Precipitable Water (TPW) associated with Hermine were evident on hourly composites of morphed TPW from MIRS sensors (below). Rainfall amounts exceeded 22 inches in Florida (WPC storm summary)

===== Post-landfall Update, 02 September ===== 

Suomi-NPP overflew Hermine shortly after 0700 UTC on 02 September, after its 0530 UTC landfall near St. Mars FL. The toggle below shows the VIIRS 0.7 µm Day/Night Band and the 11.45 µm Infrared Window imagery. Both show the asymmetric nature of the storm. Rain and clouds extend quite a distance to the south and east of the storm, but not far to the west. The infrared imagery shows cold cloud tops surrounding the storm center southeast of Tallahassee, with very cold cloud tops also over Tampa FL and near Savannah GA with bands associated with the storm. Cloud detail is missing in the Day/Night Band image because of the lack of lunar illumination — a New Moon occurred early on 01 September — however, high-altitude mesospheric airglow waves (references: 1 | 2 | 3) can be seen off the east coast of Florida and Georgia, excited by Hermine’s bands of strong thunderstorms.

A toggle between before-landfall (0319 UTC Terra MODIS) and after-landfall (0814 UTC POES AVHRR) Infrared images, below, shows the expected trend of warming cloud-top IR brightness temperatures and a consolidation into a more compact storm circulation.

===== 03 September Update =====

A toggle between Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0707 UTC on 03 September (above; courtesy of William Straka, SSEC) showed that Hermine — still being classified as a Tropical Storm — continued to produce mesospheric airglow waves as it moved off the East Coast of the US. Numerous bright white streaks were also evident on the Day/Night Band image, due to cloud illumination from intense lightning activity.

During the following daylight hours of 03 September, GOES-13 (GOES-East) Visible (0.63 µm) images (below: also available as an MP4 animation) showed the circulation of post-tropical cyclone Hermine. In eastern North Carolina, winds gusts as high as 80 mph were recorded, with rainfall amounts as great as 8.54 inches (NWS Newport/Morehead City); the storm also produced a few tornadoes (SPC Storm Reports). In southeastern Virginia, winds gusted to 73 mph (NWS Wakefield). A few of the heavier rainfall amounts for individual states are listed here.

A Suomi NPP VIIRS true-color image visualized using RealEarth (below) showed the clouds associated with Hermine at 1827 UTC.

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Swampy conditions near the meandering Innoko River, a tributary to the Yukon River in Alaska, have been diagnosed by the JPSS River Flood Product near the Innoko’s mouth on the Yukon. (August has been very wet over parts of Alaska) A timely Landsat-8 overpass, in clear skies, on 30 August 2016 allows for excellent validation of the Flood Product. The animation above (using Images from RealEarth) cycles between the Google Maps terrain and satellite views of the region, the JPSS Flood Product (developed by a group led by Sanmei Li at George Mason University, which product uses reflective channels on JPSS (I01, I02, and I03, 0.64 µm, 0.86 µm and 1.61 µm, respectively) and I05, the 11.45 µm channel) and the Landsat-8 False Color overpass. Diagnosed floods in the JPSS Product are distinctly captured in the Landsat-8 False Color product.

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The hourly water vapor animation above over the Atlantic Basin shows the evolution of a strong tropical wave that moved through the Greater Antilles during the week of 23-29 August 2016. (GOES-14 viewed this system on 25 August and 28 August). There are many areas of convection, including Hurricane Gaston, which storm enters the domain from the east. Gaston is no threat to land, however.

Of more interest to the United States are Tropical Depression #8, a small system just southeast of Cape Hatteras, represented as a circular cluster of thunderstorms at the end of the animation, and Tropical Depression #9 near western Cuba. (Click here for an annotated water vapor imagery identifying the storms) Tropical Depression #9 has emerged from the system discussed here. Interests along the coast of North Carolina and Virginia should pay close attention to forecasts on Tropical Depression #8, and those on the Gulf Coast from Louisiana eastward should monitor Tropical Depression #9. For the latest information, see the webpages of the National Hurricane Center.

MIMIC Total Precipitable Water, below, for the 72 hours ending at 1800 UTC on 29 August (from this site), shows that Tropical Depression #8 and Hurricane Gaston, are near regions of dry air that might influence their evolution. In contrast, Tropical Depression #9 is embedded within an atmosphere rich in moisture.

The next two names for tropical cyclones in the Atlantic are Hermine and Ian.

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