Tropical Storm Arthur forms off the coast of Florida

May 16th, 2020 |

GOES-16

GOES-16 “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) “Clean” Infrared Window (10.35 µm) images, with and without an overlay of GLM Flash Extent Density (above) showed the period leading up to the formation of Tropical Storm Arthur during the evening of 16 May 2020 (at 03 UTC on 17 May) — making it the first tropical cyclone of the season in the Atlantic Basin. There were periods of lightning activity within the elongated cluster of deep convection east of the storm center.

==== 17 May Update =====

GOES-16 "Red" Visible (0.64 µm) images [click to play animation | MP4]

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

During most of the day on 17 May, the low-level circulation center of Arthur was easily seen in 1-minute GOES-16 “Red” Visible (0.64 µm) images (above).

The corresponding GOES-16 Infrared images — with and without an overlay of GLM Flash Extent Density — are shown below.

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

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

===== 18 May Update =====

GOES-16 "Red" Visible (0.64 µm) images [click to play animation | MP4]

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

1-minute GOES-16 Visible images (above) showed that the low-level circulation center of Arthur became exposed during the day on 18 May. The center of Arthur passed very close to the Diamond Shoals buoy just off the coast of North Carolina (wind/pressure plot).

GOES-16  Visible images with plots of Metop ASCAT winds (below) revealed surface winds as high as 37 knots just east of the center of Arthur.

GOES-16 "Red" Visible (0.64 µm) images, with plots of Metop ASCAT winds [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) images, with plots of Metop ASCAT winds [click to play animation | MP4]

Lake Erie mesovortex, and an undular bore over the Dakotas

March 24th, 2020 |

GOES-16

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

Two interesting small-scale features were seen in GOES-16 (GOES-East) imagery on 24 March 2020. First of all, 1-minute Mesoscale Domain Sector “Red” Visible (0.64 µm) images (above) showed a mesovortex that was migrating west-northwestward across Lake Erie during the day. This feature had a diameter of around 10 miles — such a small-scale circulation was not captured by Metop-A ASCAT surface scatterometer data.

During the preceding overnight hours, an early signature of the mesovortex was evident in Suomi NPP VIIRS Shortwave Infrared (3.74 µm) and “Fog product” Brightness Temperature Difference (BTD) images at 0806 UTC (below).

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) and "Fog product" Brightness Temperature Difference (BTD) images [click to enlarge]

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) and “Fog product” Brightness Temperature Difference (BTD) images [click to enlarge]

The second feature of interest was a pre-cold-frontal undular bore that was moving eastward across the Dakotas, as seen in Day Cloud Phase Distinction Red-Green-Blue (RGB) images (below).

GOES-16 Day Cloud Phase Distinction RGB images [click to play animation | MP4]

GOES-16 Day Cloud Phase Distinction RGB images [click to play animation | MP4]

Dorian moves across the Maritime Provinces of Canada

September 8th, 2019 |

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) showed Hurricane Dorian as it briefly intensified from a Category 1 to a Category 2 storm during the morning of 07 September 2019. Later in the day, Dorian transitioned to a post-tropical storm before making landfall over Nova Scotia around 2215 UTC. Due to high amounts of  deep-layer wind shear, the low-level circulation center of Dorian remained exposed while deep convection remained to its north and northeast. The eye of Dorian moved over Buoy 44011, which recorded a wind gust to 82 knots; in western Nova Scotia, winds gusted to 70 knots at Yarmouth.

VIIRS True Color RGB and Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20 [click to enlarge]

VIIRS True Color RGB and Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20 [click to enlarge]

VIIRS True Color RGB and Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20 as visualized using RealEarth (above) revealed a brighter region exhibiting a somewhat hazy appearance within the cloud-free slot southwest of the eye during the 16-17 UTC period. This could have been a signature of diffuse solar reflection off highly-agitated ocean waves — a NHC discussion noted strong Metop-B ASCAT winds of 80 knots or higher in that area around 15 UTC (below).

Metop-B ASCAT winds [click to enlarge]

Metop-B ASCAT winds [click to enlarge]

On the following day, Suomi NPP VIIRS True Color and Infrared  images (below) showed Post-Tropical Cyclone Dorian when its center was over the Gulf of St. Lawrence. Wind gusts included 68 knots at Heath Point, Quebec (CWHP) and 57 knots at Deer Lake, Newfoundland (CYDF).

Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]


Hurricane Barbara in the East Pacific

July 2nd, 2019 |

GOES-17

GOES-17 “Red” Visible (0.64 µm, top) and “Clean” Infrared Window (10.3 µm, bottom) images [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed the eye of Category 4 Hurricane Barbara on 02 July 2019. Mesovortices were briefly seen within the eye in the Visible imagery. Barbara was moving through an environment of low deep-layer wind shear and over warm water, factors favorable for rapid intensification (ADT | SATCON).

DMSP-17 SSMIS Microwave (85 GHz) imagery from the CIMSS Tropical Cyclones site (below) showed a closed eyewall at 1448 UTC.

DMSP-17 SSMIS Microwave (85 GHz) image [click to enlarge]

DMSP-17 SSMIS Microwave (85 GHz) image [click to enlarge]

A 1700 UTC  GOES-17 “Red” Visible image with an overlay of Metop-A ASCAT winds (below) revealed surface scatterometer wind speeds as high as 76 knots just north of the eye.

GOES-17

GOES-17 “Red” Visible (0.64 µm) and Metop-A ASCAT winds [click to enlarge]

===== 03 July Update =====

GOES-17 "Red" Visible (0.64 µm, top) and "Clean" Infrared Window (10.3 µm, bottom) images [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm, top) and “Clean” Infrared Window (10.3 µm, bottom) images [click to play animation | MP4]

Barbara maintained Category 4 intensity on 03 July — and 1-minute GOES-17 Visible and Infrared GOES-17 images (above) provided a better view of mesovortices within the eye.