Super Typhoon Meranti

September 12th, 2016

Himawari-8 0.64 µm Visible (top) and 10.4 µm Infrared Window (bottom) images [click to play MP4 animation]

Himawari-8 0.64 µm Visible (top) and 10.4 µm Infrared Window (bottom) images [click to play MP4 animation]

Rapid-scan (2.5-minute interval) Himawari-8 AHI Visible (0.64 µm) and Infrared Window (10.4 µm) images (above; also avialable as a 33 Mbyte animated GIF) showed the pin-hole eye and cold cloud-top IR brightness temperatures (-80º C and colder, violet color enhancement) associated with Super Typhoon Meranti (16W) in the Philippine Sea on 11-12 September 2016. Note that the ABI instrument on GOES-R will provide similar 0.5-km resolution Visible and 2-km resolution Infrared imagery.

Himawari-8 Infrared Window (10.4 µm) image at 1230 UTC on 12 September, with 11 September images of Sea Surface Temperature and Ocean Heat Content [click to enlarge]

Himawari-8 Infrared Window (10.4 µm) image at 1230 UTC on 12 September, with 11 September images of Sea Surface Temperature and Ocean Heat Content [click to enlarge]

As Meranti was intensifying from a Category 4 to a Category 5 storm, it was passing over waters that exhibited both warm Sea Surface Temperatures and high Ocean Heat Content as seen on images from the CIMSS Tropical Cyclones site (above), and was also moving through an environment of very low deep-layer wind shear (below) — all factors that are favorable for tropical cyclone intensification.

Himawari-8 Infrared Window (10.4 µm) images, with satellite-derived 850-200 hPa deep layer wind shear [click to play animation]

Himawari-8 Infrared Window (10.4 µm) images, with satellite-derived 850-200 hPa deep layer wind shear [click to play animation]

Himawari-8 Infrared Window (10.4 µm) images (below; also available as an 89 Mbyte animated GIF) showed Meranti as a Category 5 storm during the nighttime hours on 12 September.

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

A comparison of a Himawari-8 Infrared Window (10.4 µm) image at 1830 UTC and a DMSP-15 SSMIS Microwave (85 GHz) image at 1847 UTC (below) again displayed the very small eye.

Himawari-8 Infrared Window (10.4 µm) and DMSP-15 SSMIS Microwave (85 GHz) images [click to enlarge]

Himawari-8 Infrared Window (10.4 µm) and DMSP-15 SSMIS Microwave (85 GHz) images [click to enlarge]

During the subsequent daytime hours (local time) on 12 September, another comparison of rapid-scan (2.5-minute interval) Himawari-8 Visible (0.64 µm) and Infrared Window (10.4 µm) images (below; also available as a 24 Mbyte animated GIF) continued to show a well-defined eye as Meranti maintained Category 5 intensity (ADT plot). Mesovortices could be seen spinning within the eye on the visible imagery during this time.

Himawari-8 0.64 µm Visible (top) and 10.4 µm Infrared Window (bottom) images [click to play MP4 animation]

Himawari-8 0.64 µm Visible (top) and 10.4 µm Infrared Window (bottom) images [click to play MP4 animation]

===== 13 September Update =====

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

Super Typhoon Meranti went through a secondary round of intensification on 13 September (ADT plot) , with the JTWC estimating maximum sustained winds of 165 knots with gusts to 200 knots at 21 UTC. CIMSS Satellite Consensus (SATCON) plots of wind and pressure indicated that Meranti reached peak intensity near the middle of the day. Himawari-8 Infrared Window (10.4 µm) images (above; also available as a 114 Mbyte animated GIF) continued to display a well-defined eye with an annular storm structure during this period. A faster version of the animated GIF better showed the pronounced trochoidal motion exhibited by the eye of Meranti, as it moved just south of the island of Taiwan.

Himawari-8 Infrared Window (11.45 µm) images [click to enlarge]

Himawari-8 Infrared Window (11.45 µm) images [click to enlarge]

The eye of Meranti passed directly over the small Philippine island of Itbayat, as seen on Himawari-8 Infrared Window (11.45 µm) images viewed using RealEarth (above).

Suomi NPP overflew Meranti around 1730 UTC, just as the eye of the storm was passing over Itbayat. In a toggle between VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) images (below; courtesy of William Straka, SSEC) ample lunar illumination provided a very good “visible image at night” which also included a bright lightning streak emanating from the eastern eyewall of the Category 5 storm. The image pair also shows a good example of the “stadium effect” eye geometry (where the eye diameter at the surface is smaller, and opens to a wider distance with increasing height). A larger-scale view of the entire storm from the Day/Night Band is available here; the corresponding 11.45 µm Infrared image is available here.

Suomi NPP VIIRS Infrared Window (11.45 µm) and Day/Night Band visible (0.70 µm) imagery of Meranti, 1735 UTC on 13 September 2016 [click to enlarge]

Suomi NPP VIIRS Infrared Window (11.45 µm) and Day/Night Band visible (0.70 µm) imagery of Meranti, 1735 UTC on 13 September 2016 [click to enlarge]

DMSP-15 SSMI Microwave (85 GHz) and Himawari-8 Infrared Window (11.45 µm) images [click to enlarge]


DMSP-15 SSMI Microwave (85 GHz) and Himawari-8 Infrared Window (11.45 µm) images [click to enlarge]

In a comparison of DMSP-15 SSMI Microwave (85 GHz) and Himawari-8 Infrared Window (11.45 µm) images around 1830 UTC (above), the appearance of concentric eyewalls on the microwave data suggested that Meranti was preparing to go through an eyewalll replacement cycle, which also signaled that the storm was perhaps near maximum intensity.

This formation of concentric eyewalls was nicely depicted by the MIMIC-TC product (below).

MIMIC-TC product [click to play animation]

MIMIC-TC product [click to play animation]

=====14 September Update =====

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

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


Less than 2 hours prior to landfall (which was around 1905 UTC on 14 September, over Xiamen City in the Fujian Province of China), a toggle between Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1716 UTC (above) still showed well-defined curved banding structures around the center of of the Category 2 typhoon.

Himawari-8 Infrared Window (10.4 µm) images from pre-landfall at 0600 UTC on 14 September to post-landfall at 0600 UTC on 15 September (below; also available as a 47 Mbyte animated GIF) showed that Meranti quickly dissipated as it moved inland over mainland China. The images are centered on Xiamen (station identifier ZSAM); alternate animation versions with the BD grayscale enhancement are available in MP4 and animated GIF format.

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

About 4 hours after landfall, good curved banding structure was still observed in DMSP-18 SSMIS Microwave (85 GHz) imagery at 2314 UTC, while the overall presentation of the storm on Himawari-8 Infrared Window (11.45 µm) imagery began to deteriorate (below).

DMSP-18 SSMIS Microwave (85 GHz) and Himawari-8 Infrared Window (11.45 µm) images [click to enlarge]

DMSP-18 SSMIS Microwave (85 GHz) and Himawari-8 Infrared Window (11.45 µm) images [click to enlarge]

Post-Tropical Cyclone Hermine

September 5th, 2016

GOES-13 Visible (0.63 µm) images, with buoy/ship reports plotted in yellow [click to play animation]

GOES-13 Visible (0.63 µm) images, with buoy/ship reports plotted in yellow [click to play animation]

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.

GOES-13 Visible (0.63 µm) images, with buoy/ship reports plotted in yellow [click to play animation]

GOES-13 Visible (0.63 µm) images, with buoy/ship reports plotted in yellow [click to play animation]

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

GOES-13 Visible (0.63 µm) images, with surface/buoy/ship data plotted in yellow [click to play animation]

GOES-13 Visible (0.63 µm) images, with surface/buoy/ship data plotted in yellow [click to play animation]

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.

GOES-13 Visible (0.63 µm) image at 1600 UTC, with ASCAT winds and surface/buoy/ship reports [click to enlarge]

GOES-13 Visible (0.63 µm) image at 1600 UTC, with ASCAT winds and surface/buoy/ship reports [click to enlarge]

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

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

MIMIC Total Precipitable Water product [click to play animation]

MIMIC Total Precipitable Water product [click to play animation]

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.

 

GOES-14 SRSO-R: Tropical Disturbance near the Caribbean

August 25th, 2016

GOES-14 Visible (0.63 µm) images [click to play animated gif]

GOES-14 Visible (0.63 µm) images [click to play animated gif]

GOES-14 SRSO-R Imagery is being produced over the Greater Antilles on 25 August 2016 to monitor a tropical wave (Invest 99L) that is moving towards Florida and the southeast United States. The visible animation above shows a highly sheared system: a low-level circulation center (LLCC) is evident north of Hispaniola and east of the Turks and Caicos, but strong convection (overshooting tops are readily apparent) is displaced well to the east of the system. There is also considerable convection over Hispaniola.

A 2-panel comparison of GOES-14 Visible and Infrared Window images, below (also available as a large 200 Mbyte animated GIF), provided a slightly closer view of the LLCC feature.

GOES-14 0.63 µm Visible (top) and 10.7 µm Infrared Window (bottom) images [click to play MP4 animation]

GOES-14 0.63 µm Visible (top) and 10.7 µm Infrared Window (bottom) images [click to play MP4 animation]

Wind shear analyses from the CIMSS Tropical Weather site, below, show the surface circulation is within a small ribbon of relatively strong shear. Development chances will increase if the wind shear relaxes. A GOES-13 Visible image with overlays of satellite winds and wind shear is available here.

Wind Shear Analysis, 1200 UTC on 25 August 2016 [click to play animated gif]

Wind Shear Analysis, 1200 UTC on 25 August 2016 [click to enlarge]

Metop-A overflew the system at about 0200 UTC on 25 August (link to orbit path), and winds near Tropical Storm Force cover a wide swath of the southwestern Atlantic. Even if this system does not develop into a Tropical Depression, gusty winds and abundant moisture (see the animation of MIRS Total Precipitable Water from this site, below) herald a weekend when it’s appropriate to pay attention to the weather because of the potential for rain and winds.

Morphed Observations of Total Precipitable Water from MIRS, 0000 UTC 24 August - 1500 UTC 25 August [click to play animated gif]

Morphed Observations of Total Precipitable Water from MIRS, 0000 UTC 24 August – 1500 UTC 25 August [click to play animated gif]

===== 28 August Update =====

GOES-14 0.63 µm Visible (top) and 10.7 µm Infrared Window (bottom) images [click to play MP4 animation]

GOES-14 0.63 µm Visible (top) and 10.7 µm Infrared Window (bottom) images [click to play MP4 animation]

Invest 99L developed into Tropical Depression 09 around 21 UTC on 28 August. A comparison of 1-minute GOES-14 Visible (0.63 µm) and Infrared Window (10.7 µm) images, above (also available as a large 94 Mbyte animated GIF), showed the tropical depression as it moved westward through the Florida Straits.

Bonnie

May 29th, 2016

GOES-13 6.5 µm Water Vapor Infrared images [click to play animation]

GOES-13 6.5 µm Water Vapor Infrared images[click to play animation]

Tropical Depression 2 was upgraded to Tropical Storm Bonnie at 2100 UTC on Saturday 28 May, the second named storm of the 2016 Atlantic Season (Hurricane Alex, which formed in January, was the first named storm). The water vapor animation above shows that Bonnie’s initial spin may be traced to a front associated with an occluded system which crawled through the eastern United States, exiting on about 23 May 2016. It’s not uncommon for vorticity associated with extratropical cyclone fronts to sow the seed of a tropical cyclone, especially early (or late) in the season. In this case, the cold front failed to pass Bermuda, and by 27 May, persistent thunderstorms about halfway between Bermuda and the Bahamas suggested tropical cyclogenesis was underway (GOES-13 visible image animations: 26 May | 27 May).

MIMIC Total Precipitable Water derived from Microwave imagery, 1800 UTC 28 May - 1700 UTC 30 May [click to enlarge]

MIMIC Total Precipitable Water derived from Microwave imagery, 1800 UTC 28 May – 1700 UTC 30 May [click to enlarge]

Total Precipitable Water fields from the microwave MIMIC product, above, show the system was embedded deep within tropical moisture (24-26 May animation). Tropical moisture associated with the storm moved up the east coast of the United States into the mid-Atlantic States with local flooding reported. This longer animation (from 21 through 28 May) shows that persistent westward motion of moisture occurred over the tropical Atlantic well in advance of Bonnie’s formation.

Rapidscat Scatterometer Winds, 1012 UTC on 27 May [click to enlarge]

Rapidscat Scatterometer Winds, 1012 UTC on 27 May [click to enlarge]

The tropical wave that produced Bonnie showed a closed circulation as early as 1012 UTC on 27 May according to Rapidscat scatterometer winds, above, and MODIS Sea Surface Temperatures, below, showed very warm water (with SST values of 80º F) over the Gulf Stream.

MODIS-based Sea Surface Temperatures, 1848 UTC on 27 May [click to enlarge]

MODIS-based Sea Surface Temperatures, 1848 UTC on 27 May [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.70 µm Visible) and Infrared (11.45 µm) Imagery at 0621 UTC on 27 May 2016 [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.70 µm Visible) and Infrared (11.45 µm) Imagery at 0621 UTC on 27 May 2016 [click to enlarge]

Suomi NPP overflew this tropical system at various times during its lifecycle. Shortly after midnight on 27 May 2016, above, strong convection was centered just north of the apparent surface circulation (as inferred by the curved bands of low-level clouds, clouds made visible by moonlight in the night-time VIIRS Day/Night Band visible imagery). Twenty-four hours later, at 0742 UTC on 28 May, below, in a more zoomed-in view, the (then) Tropical Depression Number 2 is supporting strong convection that is obscuring the low-level circulation center.

Suomi NPP VIIRS Day/Night Band (0.70 µm Visible) and Infrared (11.45 µm) Imagery at 0742 UTC on 28 May 2016 [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.70 µm Visible) and Infrared (11.45 µm) Imagery at 0742 UTC on 28 May 2016 [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.70 µm Visible) and Infrared (11.45 µm) Imagery at 0723 UTC on 29 May 2016 [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.70 µm Visible) and Infrared (11.45 µm) Imagery at 0723 UTC on 29 May 2016 [click to enlarge]

Finally, at 0723 UTC on 29 May, (above) after strong wind shear has displaced all convection well north of the center, the low-level circulation of Tropical Storm Bonnie is southeast of the South Carolina Coast. Strong convection is over North Carolina. This shear was noted in the 0300 UTC and 0900 UTC (29 May) Discussions from the National Hurricane Center. The effect of shear is apparent in the two GOES-13 Infrared Images below, from 2045 UTC on 28 May when convection was close to the center, and from 1045 UTC on 29 May, shortly before landfall, when convection was stripped from the center and displaced well to the north.

GOES-13 Infrared (10.7 µm) Imagery at 2045 UTC on 28 May and at 1045 UTC 29 May 2016; the Yellow Arrow points to the low-level circulation center [click to enlarge]

GOES-13 Infrared (10.7 µm) Imagery at 2045 UTC on 28 May and at 1045 UTC 29 May 2016; the Yellow Arrow points to the low-level circulation center [click to enlarge]

Closer views of the sheared system on 28 May can be seen on 1906 UTC VIIRS and 1937 UTC AVHRR Visible and Infrared images, as well as a GOES-13 Visible animation.

===== 01 June Update =====

GOES-13 Visible (0.63 µm) images [click to play MP4 animation]

GOES-13 Visible (0.63 µm) images [click to play MP4 animation]

The remnant circulation of Bonnie moved very slowly northeastward during the 30 May – 01 June period, as seen in GOES-13 Visible (0.63 µm) images covering each of those 3 days (above; also available as a large 95 Mbyte animated GIF). The periodic formation of deep convective clusters continued to produce heavy rainfall over parts of far eastern North and South Carolina.

On the morning of 01 June, an overpass of the Metop-B ASCAT instrument sampled the flow around the low-level circulation center (LLCC) off the coast of North Carolina; several hours later, Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images provided a high-resolution view of the system at 1755 UTC (below). Cloud-top IR brightness temperatures were as cold as -78º C within the small convective cluster located just north of the LLCC.

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images [click to enlarge]