Tropical Storm Arlene

April 20th, 2017 |

GOES-16 Visible (0.64 um, left) and Infrared Window (10.3 um, right) images [click to play animation]

GOES-16 Visible (0.64 um, left) and Infrared Window (10.3 um, right) images, with hourly ship reports when available [click to play animation]

** The GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing. **

A comparison of GOES-16 Visible (0.64 um) and Infrared Window (10.3 um) images (above) showed the development of Tropical Storm Arlene in the Atlantic Ocean on 20 April 2017.  Arlene has been one of only two tropical storms to be observed in the Atlantic Basin during the month of April in the satellite era.

A DMSP-15 SSMI Microwave (85 GHz) image from the CIMSS Tropical Cyclones site (below) revealed the formative stage of a convective ring around the core of Arlene at 1654 UTC.

DMSP-15 SSMI Microwave (85 GHz) image [click to enlarge]

9below DMSP-15 SSMI Microwave (85 GHz) image [click to enlarge]

The MIMIC Total Precipitable Water product (below) showed that Tropical Depression 1 / Arlene was embedded within a plume of modest TPW (30-40 mm) which was wrapping into a large mid-latitude cyclone to the west.

MIMIC Total Precipitable Water product, with surface analyses [click to play animation]

MIMIC Total Precipitable Water product, with surface analyses [click to play animation]

Cyclone Debbie makes landfall in Queensland, Australia

March 28th, 2017 |

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

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

Cyclone Debbie formed in the Coral Sea on 22 March 2017, and eventually intensified to a Category 3 storm (ADT | SATCON) as it moved southward toward Australia. Himawari-8 Visible (0.64 µm) and Infrared Window (10.4 µm) images (above) showed the eye of Debbie as it was making landfall in Queensland, near Prosperpine (YBPN).

Landsat-8 false-color, with Himawari-8 Visible (0.64 µm) and Infrared Window (10.4 µm) images [click to enlarge]

Landsat-8 false-color, with Himawari-8 Visible (0.64 µm) and Infrared Window (10.4 µm) images [click to enlarge]

The Landsat-8 satellite made an overpass of the eye at 2358 UTC (above), as a large convective burst had developed within the northern semicircle of the eyewall (which was also evident in the corresponding Himawari-8 Visible and Infrared Window images viewed using RealEarth).

Himawari-8 Infrared Window (10.4 µm) and GMI Microwave (85 GHZ) Images around 1430 UTC on 27 March [click to enlarge]

Himawari-8 Infrared Window (10.4 µm) and GMI Microwave (85 GHZ) Images around 1430 UTC on 27 March [click to enlarge]

Debbie was undergoing an eyewall replacement cycle as the storm center approached the coast — this was evident in Microwave (85 GHz) images from GMI at 1425 (above) and SSMIS at 2017 UTC (below) from the CIMSS Tropical Cyclones site.

Himawari-8 Infrared Window (10.4 µm) and DMSP-18 SSMIS Microwave (85 GHz) images around 2017 UTC on 27 March [click to enlarge]

Himawari-8 Infrared Window (10.4 µm) and DMSP-18 SSMIS Microwave (85 GHz) images around 2017 UTC on 27 March [click to enlarge]

The MIMIC Total Precipitable Water product (below; also available as an MP4 animation) showed copious tropical moisture associated with Cyclone Debbie, which led to rainfall accumulations as high as 780 mm (30.7 inches) — with rainfall rates up to 200 mm (7.9 inches) per hour — and record flooding along the coast from Brisbane to Lismore.

MIMIC Total Precipitable Water product [click to play animation]

MIMIC Total Precipitable Water product [click to play animation]

 

 

 

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 |
ascatwinds_1433utc_21nov2016

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]