GOES-16 Mid-level Water Vapor (6.9 µm) images [click to play animation | MP4]

GOES-16 (GOES-East) Mid-level Water Vapor (6.9 µm) images (above) showed Hurricane Larry as it made landfall in Newfoundland at 0345 UTC on 11 September 2021 (causing wind gusts to 73 knots at Cape Race and 78 knots at St. Johns) — maintained hurricane intensity until 1500 UTC over the Labrador Sea — then was quickly absorbed by a large extratropical low as it progressed toward the southeast coast of Greenland on 12 September. Along the coast of Greenland, the merged remnants of Larry caused wind gusts to 63 knots at Narsarsuaq and 88 knots at Kulusuk.

Surface analyses during this period (source) are shown below.

Surface analyses [click to enlarge | MP4]

A VIIRS True Color RGB image from Suomi NPP as viewed using RealEarth (below) showed clouds associated with Post-Tropical Cyclone Larry at 1530 UTC on 11 September, when the system was centered at 54.0 N latitude, 48.2 W latitude over the Labrador Sea.

VIIRS True Color RGB image from Suomi NPP at 1530 UTC on 11 September [click to enlarge]

VIIRS True Color RGB images from Suomi NPP on 12 September (below) show the merged remnants of Larry as the large extratropical low was off the southeast coast of Greenland.

VIIRS True Color RGB images from Suomi NPP on 12 September [click to enlarge]

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JMA Himawari-8 Infrared Window (10.4 µm) images [click to play animation | MP4]

2.5-minute rapid scan JMA Himawari-8 Infrared Window (10.4 µm) images (above) displayed Typhoon Chanthu as it regained Category 5 intensity for a period of over 24 hours (track) as it moved north-northwestward between the Philippines and Taiwan during 10-11 September 2021. 

A VIIRS Infrared Window (11.45 µm) image from NOAA-20 as viewed using RealEarth (below) showed Chanthu around 17 UTC on 10 September.

VIIRS Infrared Window (11.45 µm) image from NOAA-20 [click to enlarge]

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The early afternoon NOAA-20 overpass over the Great Lakes saw mostly clear skies, allowing for an accurate measurement — from satellite — of the lake surface temperatures, scaled in the image above to be between 55º and 75º F. Western Lake Erie has the warmest temperatures (peaking just below 75º, but a warm plume also exists in southern Lake Michigan. The zoomed-in image below shows Buoy observations in/around the lakes; buoy observations were very close to satellite measurements.

True Color and ACSPO SST imagery are available for AWIPS via an LDM feed from CIMSS. True-Color imagery is also available at the VIIRS Today website.

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The animation above (created using Geo2Grid) with a 3-h time step shows the approach of a mid-latitute shortwave trough (that produced large hail over Wisconsin on Tuesday 7 September; SPC Storm Reports) to Hurricane Larry over the tropical Atlantic. The Potential Vorticity anomaly associated with the mid-latitude trough (moving from the western Great Lakes on the 8th to the east coast on the 10th) appears as red/orange in the RGB imagery, and by 1200 UTC on the 10th, the anomaly sits over the eastern United States with Larry to its east. The RGB at 1200 UTC on the 10th shows orange/red hues to the south and east of the the hurricane center; in that region, however, the orange colors do not signify upper level potential vorticity anomalies, but rather dry air in the mid-tropopshere.

The correlation between red/orange values in the RGB and large values of potential vorticity in the upper troposphere with the feature in the midwest United States is confirmed by the overlay below that shows a pressure analysis on the 1.5 Potential Vorticity Unit (PVU) surface. The UKMET Office model data shows pressure values below 500 mb.

NUCAPS (NOAA-Unique Combined Atmospheric Processing System) profiles yield information about the thermal structure of the atmosphere, and also measure ozone concentration. Gridded values from the profiles, shown below (from this url) show a low tropopause and enhanced ozone (both suggestive of a tropopause fold/stratospheric intrusion) over the eastern US at 0647 UTC on 10 September (and also at 1812 UTC on 10 September).

For more information on Larry, refer to the webpages of the National Hurricane Center.

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