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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... Read More
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]
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,... Read More
NOAA-20 True-Color imagery over the Great Lakes, along with ACSPO SST values derived from VIIRS data, 1806 UTC on 10 September 2021 (Click to enlarge)
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.
NOAA-20 SSTs along with Buoy observations, 1800 UTC on 10 September 2021 (Click to enlarge)
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.
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... Read More
GOES-16 Airmass RGB, 0000 UTC on 8 September through 1200 UTC on 10 September 2021 (Click to enlarge)
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.
GOES-16 Airmass RGB (2100 UTC 9 September, 1200 UTC 12 September) and UKMET Model Simulation of 1.5 PVU Pressure values (0000 and 1200 UTC on 10 September), Click to enlarge
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).
NOAA-20 gridded NUCAPS estimates of Tropopause Height, and of Ozone anomalies, 0647 UTC, 10 September 2021 (Click to enlarge)
GOES-17 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), “Clean” Infrared Window (10.35 µm, bottom left), and Fire Temperature RGB (bottom right) [click to play animation | MP4]
1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.35 µm) and Fire Temperature RGB images (above) revealed that the Cougar Peak Fire in southern Oregon produced a pair of pyrocumulonimbus (pyroCb) clouds— denoted by cloud-top 10.35 µm infrared brightness temperatures of -40ºC or colder (with the coldest being -64.9ºC at 0047 UTC) — late in the day on09 September 2021. The maximum surface 3.9 µm brightness temperature sensed with this fire was 138.7ºC — which is the saturation temperature for the ABI Band 7 detectors. Since it was exhibiting extreme fire behavior during this time, evacuation orders were being increased for the immediate area.
5-minute GOES-17 True Color RGB images created using Geo2Grid(below) showed a larger-scale view of the 2 pyroCb clouds. Also apparent were smoke-filled clouds — characterized by shades of tan to light brown — from fires in northern California, which were drifting north-northeastward across southern Oregon and the Cougar Peak Fire.
GOES-17 True Color RGB images [click to play animation | MP4]
