Hurricane Lorenzo reaches Category 5 intensity

September 29th, 2019 |

GOES-16 "Clean" Infrared Window (10.35 µm) images [click to play animation | MP4]

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

GOES-16 (GOES-East) “Clean” Infrared Window (10.35 µm) images (above) showed Hurricane Lorenzo during the time it intensified to a Category 5 storm around 0130 UTC on 29 September 2019. A plot of the CIMSS Advanced Dvorak Technique (below) indicated a peak intensity estimate of 143 knots from 0220-0820 UTC.

Plot of the CIMSS Advanced Dvorak Technique (ADT) for Hurricane Lorenzo [click to enlarge]

Plot of the CIMSS Advanced Dvorak Technique (ADT) for Hurricane Lorenzo [click to enlarge]

 


A toggle between NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0425 UTC is shown below.

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images (courtesy of William Straka, CIMSS) [click to enlarge]

GOES-16 Water Vapor images, with contours and streamlines of deep-layer wind shear [click to play animation]

GOES-16 Water Vapor (6.9 µm) images, with contours and streamlines of deep-layer wind shear [click to play animation]

Lorenzo was moving through an environment characterized by low values of deep-layer vertical wind shear (above). In addition, Lorenzo was moving over water having warm Sea Surface Temperatures but only modest Ocean Heat Content (below).

Sea Surface Temperature and Ocean Heat Content on 29 September, with a plot of the track/intensity of Lorenzo [click to enlarge]

Sea Surface Temperature and Ocean Heat Content on 29 September, with a plot of the track/intensity of Lorenzo [click to enlarge]

Hurricane Dorian off the coasts of South Carolina and North Carolina

September 5th, 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 off the coast of South Carolina from 1116-1900 UTC on 05 September 2019. During this period, Dorian weakened from a Category 3 to a Category 2 hurricane — a plot of deep-layer wind shear from the CIMSS Tropical Cyclones site (below) showed that the storm was moving into an environment of increasingly unfavorable shear.

GOES-16 “Clean” Infrared Window (10.35 µm) images, with contours of deep-layer wind shear at 19 UTC [click to enlarge]

GOES-16 “Clean” Infrared Window (10.35 µm) images, with an overlay of deep-layer wind shear at 19 UTC [click to enlarge]

Dorian’s eye passed directly over EDISTO Buoy 41004; a combined plot of wind speed, wind gust, and air pressure is shown below.  Across the region, peak wind gusts were 98 mph and rainfall was as high as 10.19 inches.

Plot of wind speed (blue), wind gust (red) and air pressure (green) for Buoy 41004

Plot of wind speed (blue), wind gust (red) and air pressure (green) for Buoy 41004

A sequence of VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20 as viewed using RealEarth are shown below.

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]

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

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

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

Dorian made landfall on Cape Hatteras, North Carolina around 1235 UTC on 06 September — 1-minute GOES-16 Infrared images (above) showed the eye moving northeastward across the Outer Banks. Peak wind gusts were as high as 110 mph, with rainfall amounts up to 13.74″.

Hurricane Dorian reaches Category 5 intensity

September 1st, 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]

Overlapping 1-minute Mesoscale Domain Sectors provided GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images at 30-second intervals (above) as Hurricane Dorian reached Category 5 intensity just east of Great Abaco Island in the Bahamas during the morning hours on 01 September 2019. West of Dorian, station Identifier MYGF is Freeport on Grand Bahama Island (which stopped reporting at 00 UTC on 01 September, due to evacuation).

As noted in the 15 UTC NHC discussion, the eye of Dorian was exhibiting a pronounced “stadium effect”, with a smaller-diameter surface eye sloping outward with increasing altitude (below).

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images at 1200 UTC [click to enlarge]

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images at 1200 UTC [click to enlarge]

GOES-16 Visible images with and without overlays of GLM Flash Extent Density (below) revealed that lightning activity began to ramp up within the eyewall region after 12 UTC.

GOES-16 “Red” Visible (0.64 µm) images, with and without overlays of GLM Flash Extent Density [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) images, with and without overlays of GLM Flash Extent Density [click to play animation | MP4]

A Mid-Level Wind Shear product (below) showed that Dorian had been moving through an environment of low shear — generally 10 knots or less — during the 00-15 UTC time period on 01 September.

Mid-layer Wind Shear product, 00-15 UTC [click to enlarge]

Mid-layer Wind Shear product, 00-15 UTC [click to enlarge]


As pointed out by NWS Grand Forks (above), portions of the outer cays just east of Great Abaco Island could be seen in GOES-16 Visible imagery through breaks in the low-level clouds within the eye (below).

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]

VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20 as viewed using RealEarth are shown below, as the eye was moving over Great Abaco Island.

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]


After moving slowly westward across Great Abaco Island, Dorian later became the first Category 5 hurricane on record to make landfall on Grand Bahama Island (below). Station identifier MYGF is Grand Bahama International Airport in Freeport, and MYGW is West End Airport.

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

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

===== 02 September Update =====

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

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

Prior to sunrise on 02 September, 1-minute GOES-16 Infrared images (above) showed Dorian moving very slowly — with a forward speed of only 1 mph — across the eastern end of Grand Bahama Island (as it remained at Category 5 intensity).

After sunrise, 1-minute GOES-16 Visible and Infrared images (below) showed that the eye of Dorian was finally beginning to move very slowly northwestward away from Grand Bahama Island. At the end of the animation (15 UTC), Dorian was downgraded slightly to a high-end Category 4 hurricane.

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]

Suomi NPP VIIRS True Color RGB and Infrared images (below) provided a view of Dorian at 1817 UTC.

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]

At 21 UTC, a comparison of MIMIC Total Precipitable Water and DMSP-16 SSMIS Microwave images (below) suggested that a tongue of drier air from the northwest and west was wrapping into the southern and southeastern portion of Dorian’s circulation.

MIMIC Total Precipitable Water and DMSP-16 SSMIS Microwave images at 21 UTC [click to enlarge]

MIMIC Total Precipitable Water and DMSP-16 SSMIS Microwave images at 21 UTC [click to enlarge]

A long animation of GOES-16 Infrared images (below) covers the 1.5-day period from 1200 UTC on 01 September to 2359 UTC on 02 September — and initially includes 30-second images from 1200-1515 UTC on 01 September. Dorian was rated at Category 5 intensity from 1200 UTC on 01 September until 1400 UTC on 02 September. Station identifier MYGF is Grand Bahama International Airport in Freeport.

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

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


Additional satellite imagery and products are available from EUMETSAT.

Hurricane Dorian

August 28th, 2019 |

NOAA-20 Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images, courtesy of William Straka (CIMSS) [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images, courtesy of William Straka (CIMSS) [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images (above) showed cold overshooting tops (darker black infrared enhancement) over the Leeward Islands as well as subtle mesospheric airglow waves propagating southward away from the center of Tropical Storm Dorian at 0606 UTC on 28 August 2019.

In a toggle between GOES-16 (GOES-East) “Clean” Infrared Window (10.35 µm) and DMSP-18 SSMIS Microwave (85 GHz) images from the CIMSS Tropical Cyclones site (below), the Microwave image revealed a convective band that was wrapping around the northern portion of the center of Dorian at 0930 UTC.

GOES-16 "Clean" Infrared Window <em>(10.35 µm)</em> and DMSP-18 SSMIS Microwave <em>(85 GHz)</em> images [click to enlarge]

GOES-16 “Clean” Infrared Window (10.35 µm) and DMSP-18 SSMIS Microwave (85 GHz) images [click to enlarge]

1-minute Mesoscale Domain Sector GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (below) also showed a convective burst wrapping around the eastern and northern edges of the center of Dorian after 15 UTC. The coldest cloud-top infrared brightness temperature associated with that early convective burst was -83ºC.

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]

Dorian was upgraded to a Category 1 Hurricane at 18 UTC. Prior to that time, the tropical cyclone had been moving through an environment of low deep-layer wind shear (below), one factor that is favorable for intensification. Dorian was also passing over water possessing warm sea surface temperatures and modest ocean heat content.

http://cimss.ssec.wisc.edu/goes/blog/wp-content/uploads/2019/08/.gifGOES-16 Infrared Window (10.35 µm) images, with contours of deep-layer wind shear at 19 UTC [click to enlarge]

GOES-16 Infrared Window (10.35 µm) images, with contours of deep-layer wind shear at 19 UTC [click to enlarge]

VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP as viewed using RealEarth are shown below, from around the time when Dorian was upgraded from a Tropical Storm to a Hurricane.

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

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

A comparison of GOES-16 Infrared (at 2330 UTC) and GMI Microwave (at 2341 UTC) images (below) revealed Dorian’s small eye.

GOES-16 Infrared (10.35 µm) and GMI Microwave (85 GHz) images [click to enlarge]

GOES-16 Infrared (10.35 µm) and GMI Microwave (85 GHz) images [click to enlarge]

===== 29 August Update =====

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]

On 29 August, 1-minute GOES-16 Visible and Infrared images (above) showed that periodic convective bursts persisted around the center of Category 1 Hurricane Dorian.

During one of those convective bursts from 1800-1900 UTC, an increase in GOES-16 GLM Flash Extent Density was evident (below).

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

GOES-16 Visible and Infrared images at 1852 UTC with and without an overlay of GLM Flash Extent Density are shown below. At that particular time, the overshooting top infrared brightness temperature reached a minimum value of -82.5C.

GOES-16 “Red” Visible (0.64 µm) image at 1853 UTC, with and without an overlay of GLM Flash Extent Density [click to enlarge]

GOES-16 “Red” Visible (0.64 µm) image at 1852 UTC, with and without an overlay of GLM Flash Extent Density [click to enlarge]

GOES-16 “Clean” Infrared Window (10.35 µm) image at 1853 UTC, with and without an overlay of GLM Flash Extent Density [click to enlarge]

GOES-16 “Clean” Infrared Window (10.35 µm) image at 1852 UTC, with and without an overlay of GLM Flash Extent Density [click to enlarge]

===== 30 August Update =====

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]

The eye of Dorian became more well-defined in 1-minute GOES-16 Visible and Infrared images (above) during the morning hours on 30 August.

A DMSP-17 Microwave (85 GHz) Microwave image at 1141 UTC (below) did not yet show a completely closed eyewall structure at that earlier time.

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

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

Dorian was upgraded to a Category 3 hurricane at 18 UTC — the storm was moving into a narrow corridor of weaker deep-layer wind shear around that time. During the 3 hours leading up to 18 UTC, animations of 1-minute GOES-16 Visible and Infrared imagery — with and without an overlay of GLM Flash Extent Density — are shown below.

GOES-16 “Red” Visible (0.64 µm) images, with and without overlays of GLM Flash Extent Density [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) images, with and without overlays of GLM Flash Extent Density [click to play animation | MP4]

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

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

===== 31 August Update =====

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

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

Overlapping 1-minute GOES-16 Mesoscale Domain Sectors provided imagery at 30-second intervals — Visible and Infrared animations of the Category 4 hurricane from 1430-1900 UTC are shown above and below, respectively. A longer Visible animation from 1100-2259 UTC is available here (courtesy of Pete Pokrandt, AOS).

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

30-second GOES-16 “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]