Super Typhoon Nock-Ten strikes the Philippines

December 25th, 2016

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]

Rapid-scan (2.5-minute interval) 2-km resolution Himawari-8 Infrared Window (11.45 µm) images (above; also available as a 173 Mbyte animated GIF) showed Category 4 Super Typhoon Nock-Ten making landfall in the Philippines on 25 December 2016. Nock-Ten became the strongest typhoon on record (SATCON | ADT | source) in the Philippines so late in the year:

A 375-meter resolution Suomi NPP VIIRS Infrared Window (11.45 µm) image at 1724 UTC on 24 December (below; courtesy of William Straka, SSEC) was acquired just before the beginning of the Himawari-8 animations above; note the presence of cloud-top gravity waves propagating southeastward away from the eye of Nock-Ten, in addition to prominent larger-scale transverse banding farther out within the eastern semicircle of the storm.

Suomi NPP VIIRS Infrared Window (11.45 µm) image [click to enlarge]

Suomi NPP VIIRS Infrared Window (11.45 µm) image [click to enlarge]

Hurricane Otto

November 22nd, 2016

GOES-13 Infrared Window (10.7 um) images [click to enlarge]

GOES-13 Infrared Window (10.7 um) images [click to enlarge]

As a follow-up to the previous Otto blog post, GOES-13 Infrared Window (10.7 um) images (above) showed Otto around the time that it became the latest hurricane on record to form in the Caribbean Sea on 22 November 2016 (NHC advisory).

A comparison of GOES-13 Visible (0.63 um) and Infrared Window (10.7 um) images (below) revealed multiple convective bursts during the day, some of which exhibited IR brightness temperatures of -80º C and colder (violet enhancement). Because of Otto’s central dense overcast, no eye was apparent in the GOES-13 imagery; even on a DMSP-16 SSMIS Microwave (85 GHz) image at 2049 UTC the eyewall was not fully closed.

GOES-13 0.63 um Visible (top) and 10.7 um Infrared Window (bottom) images [click to animate]

GOES-13 0.63 um Visible (top) and 10.7 um Infrared Window (bottom) images [click to animate]

===== 24 November Update =====

GOES-13 Infrared Window (10.7 µm) images, with hourly surface reports [click to play MP4 animation]

GOES-13 Infrared Window (10.7 µm) images, with hourly surface reports [click to play MP4 animation]

As Otto slowly approached the coast of southern Nicaragua on 24 November, it rapidly intensified (SATCON plot) to a Category 2 hurricane. GOES-13 Infrared Window (10.7 µm) images (above; also available as a 36 Mbyte animated GIF) and Visible (0.63 µm) images (below; also available as a 18 Mbyte animated GIF) showed the development of an eye just offshore, which rapidly filled as the storm moved inland after 17 UTC on 24 November and began to interact with the terrain. After crossing Nicaragua and Costa Rica, an eye was once again discernible around 02 UTC on 15 November (as Otto emerged over the Pacific Ocean).

 

GOES-13 Visible (0.63 µm) images, with hourly surface reports [click to play MP4 animation]

GOES-13 Visible (0.63 µm) images, with hourly surface reports [click to play MP4 animation]

Before the formation of an eye, a Suomi NPP VIIRS Infrared Window (11.45 µm) image at 0639 UTC (below; courtesy of William Straka, SSEC) showed the presence of cloud-top gravity waves propagating westward along the Nicaragua/Costa Rica border; these waves were likely a response to deep convective bursts offshore near the center of Otto.

Suomi NPP VIIRS Infrared Window (11.45 µm) image [click to enlarge]

Suomi NPP VIIRS Infrared Window (11.45 µm) image [click to enlarge]

A comparison of DMSP-17 SSMIS Microwave (85 GHz) and GOES-13 Infrared Window (10.7 µm) images around 1115 UTC on 24 November (below) revealed a much larger (albeit not completely closed) eye signature using the microwave data.

DMSP-17 SSMIS Microwave (85 GHz) and GOES-13 Infrared Window (10.7 µm) images around 1145 UTC [click to enlarge]

DMSP-17 SSMIS Microwave (85 GHz) and GOES-13 Infrared Window (10.7 µm) images around 1145 UTC [click to enlarge]

Otto became the southernmost landfalling hurricane on record for Central America. It was also the strongest hurricane on record for so late in the season within the Atlantic basin.

DMSP-18 SSMIS Microwave (85 GHz) image [click to enlarge]

DMSP-18 SSMIS Microwave (85 GHz) image [click to enlarge]

A DMSP-18 SSMIS Microwave (85 GHz) image at 0043 UTC on 25 November (above) showed that the eye of Otto was still well-defined as it began to move into northern Costa Rica (making this the first hurricane or tropical storm on record for that country). The eye structure could be tracked on MIMIC-TC imagery (below) as it moved inland from the Atlantic Ocean, across far southern Nicaragua and far northern Costa Rica, and eventually emerged over the Pacific Ocean after about 03 UTC on 25 November.

Morphed MIMIC-TC imagery, 24-25 November [click to enlarge]

Morphed MIMIC-TC imagery, 24-25 November [click to enlarge]

===== 26 November Update =====

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

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

As Tropical Storm Otto was weakening during its west-southwestward motion over Pacific Ocean waters with low Ocean Heat Content, nighttime images of Suomi NPP VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) data at 0744 UTC on 26 November (above; courtesy of William Straka, SSEC) displayed shorter-wavelength cloud-top gravity waves on the Infrared image and longer-wavelength mesospheric airglow waves (reference) on the Day/Night Band image (all of which were propagating west-southwestward away from the deep convective cluster near the center of Otto). Bright lightning streaks were also seen on the Day/Night Band image.

More facts on the historic aspects of Otto are available from The Weather Channel and Weather Underground; see the National Hurricane Center and the CIMSS Tropical Cyclones websites for the latest information on this storm.

Late-season Tropical Storm Otto in the southwest Caribbean Sea

November 21st, 2016
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Metop-A Scatterometer winds at 1430 UTC and GOES-13 10.7 µm Brightness Temperature (Click to enlarge)

A late-season tropical depression has formed in the southwestern Caribbean Sea. The morning Metop-A pass on 21 November 2016 allowed ASCAT scatterometer winds to be sampled over the system: rain-flagged values near tropical storm force were present as shown above. A similar image (from this site) is available here, and also here (from this site).

GOES-13 Infrared (10.7 µm) Brightness Temperatures (Click to animate)

Infrared (10.7 µm) imagery from GOES-13, above, from 1315 through 1715 UTC on 21 November, shows periodic deep convection over the Depression; the grey regions in the deepest convection over the system correspond to brightness temperatures colder than -75 C. The environment surrounding this system, shown below, is marginally favorable for strengthening; sea-surface temperatures are warm, although the oceanic heat content suggests the warmth does not extend through a deep column of water. Wind shear over the storm is modest (but far stronger north of the storm). (Imagery below is from this site). The system is forecast to become a tropical storm within the next 24 hours.

Sea-surface temperatures, Oceanic Heat Content and Wind Shear (Click to enlarge)

Update: Otto was named a tropical storm at 2100 UTC 21 November; GOES-13 Visible (0.63 µm) Imagery is shown below. Numerous tropical overshooting tops can be seen during the course of the day.

GOES-13 Visible (0.63 µm) Imagery on 21 November 2016 (Click to animate)

MIMIC Total Precipitable Water fields, below, show that Otto emerged from a region of persistent deep moisture over the southwestern Caribbean Sea that has been contracting as the storm formed. This region of moisture was focused along the intersection of a stalled and decaying Atlantic frontal zone and the Pacific monsoon trough (hourly animation).

MIMIC Total Precipitable Water fields at 2100 UTC on 17,18,19,20 and 21 November (Click to enlarge)

DMSP-16 Microwave (85 GHz) imagery, below, showed evidence of a closed eye associated with Otto at 2132 UTC.

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

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

Hurricane Nicole

October 13th, 2016

Track of Nicole, from 12 UTC on 04 October to 12 UTC on 13 October [click to enlarge]

Track of Nicole, from 12 UTC on 04 October to 12 UTC on 13 October [click to enlarge]

From its inception as a highly-sheared Tropical Storm on 04 October, Nicole moved in an erratic path with small intensity fluctuations for 8 days (above); then a period of intensification began on 12 October, with the storm reaching Category 4 intensity southwest of Bermuda at 03 UTC on 13 October. With ample illumination from the Moon (which was in the Waxing Gibbous phase, at 90% of full) Nicole exhibited a well-defined eye on Suomi NPP VIIRS Day/Night Band (0.7 µm) imagery at 0615 UTC, with cold cloud-top temperatures surrounding the eye on the corresponding VIIRS Infrared Window (11.45 µm) image (below).

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]

As Nicole approached Bermuda, increasing deep-layer wind shear began to impact the storm and weaken it to a Category 3 — and DMSP-17 Microwave (85 GHz) data showed that the eye had become open to the south (below).

DMSP-17 SSMIS Microwave (85 GHz) and GOES-13 Infrared Window (10.7 µm) images [click to enlarge]

DMSP-17 SSMIS Microwave (85 GHz) and GOES-13 Infrared Window (10.7 µm) images [click to enlarge]

The passage of Nicole over Bermuda is shown on GOES-13 Visible (0.63 µm) and Infrared Window (10.7 µm) images spanning the period 1037-1555 UTC (below).

GOES-13 Visible (0.63 µm) and Infrared Window (10.7 µm) images [click to play animation]

GOES-13 Visible (0.63 µm) and Infrared Window (10.7 µm) images [click to play animation]

As the eye of Nicole passed over Bermuda around 13 UTC, the staff at the Bermuda Weather Service were able to successfully launch a rawinsonde balloon, which reported data as high as the 202 hPa pressure level or 12.2 km altitude — much higher than their previous launch attempts at 06 and 12 UTC (below). The Total Precipitable Water (TPW) value derived from that 15 UTC sounding was 72.5 mm or 2.85 inches, which was in general agreement with that displayed by the MIMIC TPW product. Note that the eye of Nicole did not appear to be directly over Bermuda on the 1300 UTC GOES-13 images — this is due to a combination of parallax and the fact that the eye had a significant southwest-to-northeast tilt with height.

Bermuda rawinsonde reports from 00, 06, 12 and 15 UTC on 13 October [click to enlarge]

Bermuda rawinsonde reports from 00, 06, 12 and 15 UTC on 13 October [click to enlarge]

A sequence of Infrared images from POES and Metop AVHRR (12.0 µm) and Terra MODIS (11.0 µm) during the period 1016 to 1513 UTC is shown below.

POES and Metop AVHRR, and Terra MODIS infrared images [click to enlarge]

POES and Metop AVHRR, and Terra MODIS infrared images [click to enlarge]