Hurricane Teddy rapidly intensifies to a Category 4 storm

September 17th, 2020 |

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (with and without an overlay of GLM Flash Extent Density) [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (with and without an overlay of GLM Flash Extent Density) [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images — with and without an overlay of GLM Flash Extent Density (above) showed Hurricane Teddy as it rapidly intensified (ADT | SATCON ) to a Category 4 storm on 17 September 2020. The coldest cloud-top infrared brightness temperatures were in the -80 to -85ºC range.

Metep-A ASCAT surface scatterometer wind speeds were as high as 74 knots in the northwestern portion  of the eyewall (below).

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

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

Microwave (85 GHz) DMSP-17 (at 1023 UTC), GMI (at 1720 UTC) and DMSP-18 (at 2034 UTC) images from the CIMSS Tropical Cyclones site are shown below.

DMSP-17 SSMI Microwave (85 GHz) image at 1023 UTC [click to enlarge]

DMSP-17 SSMI Microwave (85 GHz) image at 1023 UTC [click to enlarge]

GMI Microwave (85 GHz) image at 1720 UTC [click to enlarge]

GMI Microwave (85 GHz) image at 1720 UTC [click to enlarge]

DMSP-18 SSMI Microwave (85 GHz) image at 2034 UTC [click to enlarge]

DMSP-18 SSMI Microwave (85 GHz) image at 2034 UTC [click to enlarge]

Category 4 Hurricane Laura makes landfall in Louisiana

August 27th, 2020 |

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (with and without an overlay of GLM Flash Extent Density) [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (with and without an overlay of GLM Flash Extent Density) [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images — with and without an overlay of GLM Flash Extent Density (above) showed Category 4 Hurricane Laura as it made landfall near Cameron, Louisiana around 0600 UTC on 27 August 2020. The GLM data showed intermittent lightning activity along the inner eyewall region of the hurricane.

Strong outer convective bands ahead of Laura’s landfall produced isolated tornadoes as it moved onshore (SPC Storm Reports). Peak wind gusts included 116 knots or 133 mph at Lake Charles at 0642 UTC (in addition, Lake Charles reported another peak wind gust of 113 knots or 130 mph at 0703 UTC). Strong winds associated with the northern portion of the eyewall destroyed the Lake Charles radar (YouTube video) — the final reflectivity and velocity images at 0553 UTC (12:53 am CDT) are shown here (the 0.5-degree inbound and outbound radial velocity values were as high as 160-162 mph).


Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0751 UTC (credit William Straka, CIMSS) [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0751 UTC (credit William Straka, CIMSS) [click to enlarge]

A toggle between Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0751 UTC (above) revealed the nighttime glow of lights from Lake Charles (since that city was near the inside edge of the eye of Hurricane Laura at that time) — in other locations across Louisiana and far eastern Texas, the signature of city lights was muted to varying degrees by the storm’s dense cloud cover and precipitation.

The corresponding Suomi NPP ATMS Microwave (88.2 GHz) and MiRS Rainfall Rate images at 0751 UTC (below) depicted the pattern of precipitation that was spreading inland.

Suomi NPP ATMS Microwave (88.2 GHz) and MiRS Rainfall Rate images at 0751 UTC (credit William Straka, CIMSS) [click to enlarge]

Suomi NPP ATMS Microwave (88.2 GHz) and MiRS Rainfall Rate images at 0751 UTC (credit William Straka, CIMSS) [click to enlarge]

DMSP-17 and GMI Microwave (85 GHz) images from the CIMSS Tropical Cyclones site (below) showed the structure of Laura several hours before landfall.

DMSP-17 SSMI Microwave (85 GHz) image at 0054 UTC [click to enlarge]

DMSP-17 SSMI Microwave (85 GHz) image at 0054 UTC [click to enlarge]

GMI Microwave (85 GHz) image at 0255 UTC [click to enlarge]

GMI Microwave (85 GHz) image at 0255 UTC [click to enlarge]

An animation of the MIMIC-TC product during the 26-27 August period (below) showed the deterioration of the eyewall structure after landfall.

MIMIC-TC product during the 26-27 August period [click to enlarge]

MIMIC-TC product during the 26-27 August period [click to enlarge]

Prior to making landfall, Laura had been moving across the warm waters of the Gulf of Mexico — however, it began to encounter an environment characterized by increasingly unfavorable deep-layer wind shear as it approached the Gulf Coast (below) which likely prevented further intensification.

GOES-16 Infrared Window (11.2 µm) images, with an overlay of deep-layer wind shear [click to enlarge]

GOES-16 Infrared Window (11.2 µm) images, with an overlay of deep-layer wind shear [click to enlarge]

Hurricane Genevieve in the East Pacific Ocean

August 18th, 2020 |

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

 1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) displayed the well-defined eye of Category 4 Hurricane Genevieve in the East Pacific Ocean (off the west coast of Mexico) on 18 August 2020. Genevieve underwent a period of rapid intensification during the pre-dawn hours that day (ADT plot).

A GOES-16 Visible image at 1617 UTC (below) includes plots of Metop-A ASCAT scatterometer surface winds — the highest wind was 69 knots just northeast of the storm center.

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

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

Hurricane Douglas moves just north of Hawai’i

July 26th, 2020 |

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed  Category 1 Hurricane Douglas as it moved just north of Hawai’i during the day on 26 July 2020 (the boundary of the Mesoscale Sector was abruptly shifted westward at 1658 UTC). The coldest cloud-top infrared brightness temperatures were around -80ºC.

GOES-17 “Clean” Infrared Window (10.35 µm) images, with analysis of deep layer wind shear at 20 UTC [click to enlarge]

GOES-17 “Clean” Infrared Window (10.35 µm) images, with analysis of deep-layer wind shear at 20 UTC [click to enlarge]

The apparent storm center as seen in satellite imagery was shifted north of the actual surface center location, due to the presence of southerly/southwesterly deep-layer wind shear as shown by a 20 UTC analysis from the CIMSS Tropical Cyclones site (above). This offset was also evident in a comparison of a DMSP-17 SSMIS Microwave (85 GHz) image at 1711 UTC with the analyzed surface position of Douglas at 1800 UTC (below).

DMSP-17 SSMIS Microwave (85 GHz) image at 1711 UTC, with the analyzed surface position of Douglas at 1800 UTC [click to enlarge]

DMSP-17 SSMIS Microwave (85 GHz) image at 1711 UTC, with the analyzed surface position of Douglas at 1800 UTC [click to enlarge]

===== 27 July Update =====

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-17 Visible and Infrared images (above) showed that the low-level circulation became exposed from the deep convection of Douglas a few hours after sunrise on 27 July, as it moved southwestward near the island of Nihoe. An analysis of deep-layer wind shear at 22 UTC (below) indicated the presence of 25-30 knots of southwesterly shear over that area — an unfavorable environment for tropical cyclone intensification/maintenance, in spite of the fact that the storm was moving over favorably-warm water.

GOES-17 “Red” Visible (0.64 µm) images, with analysis of deep layer wind shear at 22 UTC [click to enlarge]

GOES-17 “Red” Visible (0.64 µm) images, with analysis of deep-layer wind shear at 22 UTC [click to enlarge]