Land breeze convergence cloud band in Lake Michigan

September 23rd, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with hourly plots of surface and buoy reports [click to play animation | MP4]

GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed a narrow cloud band that had developed in Lake Michigan in response to land breeze induced convergence on the morning of 23 September 2018. With inland temperatures cooling overnight into the 30s and 40s F (the coldest in both Wisconsin and Michigan was 29ªF) and lake water temperatures of 64ºF (at the North Michigan buoy 45002) to 69ºF (at the South Michigan buoy 45007), a well-defined nocturnal land breeze was established along the western and eastern shorelines of the lake.

Nighttime VIIRS Day/Night Band (0.7 µm) images from Suomi NPP at 0743 UTC and NOAA-20 at 0832 UTC (below) showed that the cloud band had not yet formed at those times.

VIIRS Day/Night Band (0.7 µm) images from Suomi NPP at 0743 UTC and NOAA-20 at 0832 UTC [click to enlarge]

VIIRS Day/Night Band (0.7 µm) images from Suomi NPP at 0743 UTC and NOAA-20 at 0832 UTC [click to enlarge]

The Terra and Aqua MODIS Sea Surface Temperature product (below) confirmed that mid-lake water temperatures were generally in the middle to upper 60s F (green to light yellow enhancement) across the entire length of Lake Michigan.

Terra/Aqua MODIS Sea Surface Temperature product [click to enlarge]

Terra/Aqua MODIS Sea Surface Temperature product [click to enlarge]

An examination of the MODIS SST product with overlays of RTMA surface winds (below) showed that there was no clear signature in the model wind field of enhanced convergence either before or after the mid-lake cloud band had formed.

Terra/Aqua MODIS Sea Surface Temperature product, with RTMA surface winds [click to enlarge]

Terra/Aqua MODIS Sea Surface Temperature product, with RTMA surface winds [click to enlarge]

However, an overpass of the Metop-A satellite at 1559 UTC provided ASCAT surface scatterometer winds that did a better job than the RTMA at highlighting the mid-lake convergence that was helping to sustain the cloud band (below). This example underscores the value that satellite-derived winds can have over even high resolution models.

Terra MODIS Sea Surface Temperature product, with RTMA surface winds and Metop ASCAT winds [click to enlarge]

Terra MODIS Sea Surface Temperature product, with RTMA surface winds and Metop ASCAT winds [click to enlarge]

Hurricane Florence makes landfall in North Carolina

September 14th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with hourly plots of surface wind gusts in knots [click to play MP4 animation]

Hurricane Florence made landfall near Wrightsville Beach, North Carolina at 1115 UTC (7:15 am EDT) with estimated maximum winds of 78 knots (90 mph) and a minimum central pressure estimate of 958 hPa (28.29″). Overlapping GOES-16 (GOES-East) Mesoscale Domain Sectors provided images every 30 seconds — “Red” Visible (0.64 µm) images (above) and “Clean” Infrared Window (10.3 µm) images (below) showed the storm as it slowly moved inland after sunrise. A peak wind gust of 105 mph was recorded at Wilmington NC (which is located at the center of the GOES-16 images); in northeastern North Carolina, winds gusted to 105 mph at Fort Macon and 112 mph at the New River Inlet Buoy.

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with hourly plots of wind gusts [click to play MP4 animation]

The MIMIC Total Precipitable Water product (below) showed abundant moisture associated with Florence moving inland during the 48-hour period ending at 23 UTC on 14 September.

MIMIC Total Precipitable Water product [click to play animation | MP4]

MIMIC Total Precipitable Water product [click to play animation | MP4]

Toggles between Visible and Infrared Window images from Terra/Aqua MODIS and Suomi NPP VIIRS are shown below.

Terra MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Terra MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images at 1620 UTC [click to enlarge]

Aqua MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Aqua MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images at 1801 UTC [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images at 1835 UTC [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images at 1835 UTC [click to enlarge]

Over the western Atlantic Ocean, strong winds associated with Florence created large waves which induced upwelling of colder water from below the ocean surface, as seen in Ocean Heat Content data (below).

Ocean Heat Content data from 14 September [click to enlarge]

Ocean Heat Content data from 14 September [click to enlarge]

Hurricane Florence off the coast of North Carolina

September 13th, 2018 |

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

A toggle between NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images (above) showed Category 2 Hurricane Florence off the coast of North Carolina at 0646 UTC on 13 September 2018. GCOM AMSR2 Microwave (89 GHz), Convective Rain Rate and Surface Rain Rate (below) indicated that the southern and southeastern portions of the eye and eyewall had become fragmented. (VIIRS and AMSR2 imagery courtesy of William Straka, CIMSS)

GCOM AMSR2 Microwave (89 GHz), Convective Rain Rate and Surface Rain Rate [click to enlarge]

GCOM AMSR2 Microwave (89 GHz), Convective Rain Rate and Surface Rain Rate [click to enlarge]

In a toggle between DMSP-17 SSMIS Microwave (85 GHz) and GOES-16 Infrared Window (10.3 µm) images from the CIMSS Tropical Cyclones site (below), microwave imagery revealed the very large internal core of the hurricane at 1216 UTC.

DMSP-17 SSMIS Microwave (85 GHz) and GOES-16 Infrared Window (10.3 µm) images [click to enlarge]

DMSP-17 SSMIS Microwave (85 GHz) and GOES-16 Infrared Window (10.3 µm) images [click to enlarge]

The Metop-A satellite passed over the western edge of Florence, with ASCAT sensing surface winds as high as 66 knots along the western edge of the storm core (below).

GOES-16

GOES-16 “Red” Visible (0.64 µm) image at 1427 UTC, with plots of buoy reports and Metop-A ASCAT surface scatterometer winds [click to enlarge]

Comparisons of Visible and Infrared Window images from Terra MODIS (1538 UTC), NOAA-20 VIIRS (1804 UTC) and Suomi NPP VIIRS (1854 UTC) are shown below.

Terra MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images at 1538 UTC [click to enlarge]

Terra MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images at 1538 UTC [click to enlarge]

NOAA-20 VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images at 1804 UTC [click to enlarge]

NOAA-20 VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images at 1804 UTC [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images at 1854 UTC [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images at 1854 UTC [click to enlarge]

As Florence approached the coast, it moved over Gulf Stream waters as warm as 82-85ºF, as seen in a comparison of 12 September MODIS Sea Surface Temperature product and 13 September MODIS Visible images (below).

12 September Terra MODIS Sea Surface Temperature product and 13 September Terra MODIS Visible (0.65 µm) image [click to enlarge]

12 September Terra MODIS Sea Surface Temperature product and 13 September Terra MODIS Visible (0.65 µm) image [click to enlarge]

The strong winds associated with Florence created large waves which induced upwelling of colder water from below the ocean surface:


Overlapping GOES-16 (GOES-East) Mesoscale Domain Sectors were providing images every 30 seconds; “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) animations are shown below. Note that a secondary eyewall began to form following a convective burst which developed southwest of the eye around 1920 UTC (Visible | Infrared) — and as the new eyewall convection quickly wrapped around to the north, Cape Lookout, North Carolina (Buoy CLKN7) recorded a peak wind speed of 73 knots at 20 UTC and 21 UTC.

GOES-16

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

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

The large pattern of upper-tropospheric outflow was quite apparent on GOES-16 Near-Infrared “Cirrus” (1.37 µm) images (below) — spanning a distance of approximately 1000 miles.

GOES-16 Near-Infrared "Cirrus" (1.37 µm) images [click to play MP4 animation]

GOES-16 Near-Infrared “Cirrus” (1.37 µm) images [click to play MP4 animation]

Hurricane Florence continues to approach the southeastern US

September 11th, 2018 |

GOES-16

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

Hurricane Florence maintained Category 4 intensity on the morning of 11 September 2018 — and 1-minute (initially 30-second, until 1345 UTC) Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) and “Clean” Infrared Window (10.3 µm) images (below) showed improving eye structure after the tropical cyclone completed an eyewall replacement cycle during the preceding nighttime hours (MIMIC TC). A distinct pattern of transverse banding was also evident within the northern semicircle of Florence on Infrared imagery.

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

DMSP-18 SSMIS Microwave (85 GHz) imagery from the CIMSS Tropical Cyclones site (below) showed a large eye at 1015 UTC, and also at 1103 UTC.

DMSP-18 SSMIS Microwave (85 GHz) and GOES-16

DMSP-18 SSMIS Microwave (85 GHz) and GOES-16 “Clean” Infrared Window (10.3 µm) images at 1015 UTC [click to enlarge]

GOES-16 Upper-level Water Vapor (6.2 µm) images with Derived Motion Winds (below) revealed that a well-defined high altitude outflow channel had developed northwest of Florence, helping the storm to maintain its intensity.

GOES-16 Upper-level Water Vapor (6.2 µm) images, with Derived Motion Winds [click to play MP4 animation]

GOES-16 Upper-level Water Vapor (6.2 µm) images, with Derived Motion Winds [click to play MP4 animation]

1-minute GOES-16 True Color Red-Green-Blue (RGB) images (courtesy of Kathy Strabala, CIMSS; details) are shown below. A larger-scale RGB animation beginning at sunrise is available here (courtesy of Rick Kohrs, SSEC).

GOES-16 natural color RGB images [click to play MP4 animation]

1-minute GOES-16 True Color RGB images, 1330-1440 UTC [click to play MP4 animation]

Taking a closer look at the center of Florence later in the day, 1-minute GOES-16 data (below) showed mesovortices within the eye on Visible imagery, along with a narrow radial band of colder (darker red) cloud-top infrared brightness temperatures about 30-50 miles from the inner edge of the eyewall.

GOES-16

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

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

===== 12 September Update =====

Florence remained at Category 4 intensity early in the day as it continued its northwestward motion toward the southeast coast of the US on 12 September. A 20-hour period of 1-minute GOES-16 Infrared images (from 0000-2015 UTC) is shown below.

1-minute GOES-16

1-minute GOES-16 “Clean” Infrared Window (10.3 µm) images, from 0000-2015 UTC [click to play MP4 animation]

Nighttime toggles between VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20 are shown below (courtesy of William Straka, CIMSS). Bright lightning-illuminated cloud areas can be seen on the DNB images distant to the north and northwest of the storm center; with minimal illumination from the Moon (which was in the Waxing Crescent phase, at only 10% of Full), Florence was illuminated primarily via airglow. On the Infrared images, a coarse pattern of transverse banding was evident along the far southern and western periphery of the storm.

Suomi NPP VIIRS Day/Night Band and Infrared Window images [click to enlarge]

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

NOAA-20 VIIRS Day/Night Band and Infrared Window images [click to enlarge]

NOOA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

A sequence of Terra/Aqua MODIS and Suomi NPP VIIRS Infrared images (below) showed dramatic changes in the cold central dense overcast (CDO) of Florence between 02 and 18 UTC.

Infrared Window images from Terra MODIS (11.0 µm) and Suomi NPP VIIRS (11.45 µm) [click to enlarge]

Infrared Window images from Terra MODIS (11.0 µm) and Suomi NPP VIIRS (11.45 µm) [click to enlarge]

During the morning hours, 1-minute GOES-16 Visible and Infrared images (below) once again displayed a distinct eye and eyewall structure, with surface mesovortices evident within the eye. A curious linear standing wave — extending radially outward to the northeast of the storm center — developed from about 13-15 UTC (best seen on Infrared images).

GOES-16

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

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

ASCAT surface scatterometer winds from Metop-A (below) were as strong as 76 knots just northeast of the eye at 1450 UTC.

GOES-16

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

A stereoscopic animation using GOES-16 and GOES-17 imagery is shown below — to view in three dimensions, cross your eyes until 3 equal images are apparent, then focus on the image in the center. *Note: GOES-17 images shown here are preliminary and non-operational*

Stereoscopic animation using GOES-16 and GOES-17

Stereoscopic animation using GOES-16 and GOES-17 “Red” Visible (0.64 µm) imagery [click to play animation]

During the afternoon hours, GOES-16 Visible and Infrared images (below) showed that the eye presentation  was beginning to deteriorate as Florence weakened to Category 3 intensity by 21 UTC.

GOES-16

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

GOES-16

GOES-16 “Clean” Infrared Window {10.3 µm) images [click to play MP4 animation]

The MIMIC Total Precipitable Water product (below) indicated that high TPW values associated with Florence began to move inland along the US East Coast by the end of the day.

MIMIC Total Precipitable Water product [click to enlarge]

MIMIC Total Precipitable Water product [click to enlarge]