Severe Tropical Storm Kompasu moved westward just north of the island of Luzon in the Philippines on 11 October. The Himawari-8 Target Sector clean window infrared (Band 13, 10.4 µm) imagery, above, from 0232 – 1502 UTC (Imagery courtesy JMA; imagery available here), shows deep convection becoming more organized as the storm center moved.

Moderate wind shear that had been affecting Kompasu slowly relaxed in the 24 hours before the storm moved north of Luzon, as shown in the wind shear tendency map shown below (imagery obtained from this link at the CIMSS Tropical Website). Shear over/around the storm has been relaxing.

Computed shear (imagery also taken from the CIMSS Tropical Website) is shown in the animation above. Wind shear for both animations above is defined here. A relatively small area of favorable wind shear was near the storm center as Kompasu became better organized in the band 13 imagery above.

Scatterometry imagery, below, from various satellite platforms at this site, tracked the system’s motion from 0100 to 1130 UTC on 11 October, as it moved north of Luzon.

Kompasu is forecast to move due west across the South China Sea in the next days, affecting the island of Hainan on the 13th before 1200 UTC. (Forecast, from JTWC; Here is a similar plot from JMA). Wind shear is not forecast to relax further in the next days so significant stregthening is not forecast.

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GOES-16 “Red” Visible (0.64 µm) images, with SPC Storm Reports plotted in red [click to play animation | MP4]

1–minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) include time-matched plots of SPC Storm Reports produced by supercell thunderstorms that moved eastward across Oklahoma and Texas late in the day on 10 October 2021. These storms developed along and ahead of a strong cold front — and in Texas the hazy signature of post-frontal blowing dust was evident immediately behind the western edge of the convective cloud line.

GOES-16 “Clean” Infrared Window (10.35 µm) images (below) revealed pulsing overshooting tops that exhibited infrared brightness temperatures in the -70 to -75ºC range (shades of white embedded within dark black pixels).

GOES-16 “Clean” Infrared Window (10.35 µm) images, with SPC Storm Reports plotted in cyan [click to play animation | MP4]

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GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 (GOES-East) True Color RGB images created using Geo2Grid (above) showed the south-southeastward drift of an ash-laden volcanic cloud from Cumbre Vieja on La Palma in the Canary Islands on 09 October 2021. Since this most recent ongoing eruptive period began on 19 September, intermittent periods of volcanic clouds with an elevated ash content have been observed — and on this day, the darker tan to light brown appearance was an indication that higher ash concentrations were likely.     

In the corresponding GOES-16 Ash RGB  images (below), increasing shades of pink — which suggest a higher ash content — became apparent within a semi-circular volcanic cloud element after 1100 UTC.  

GOES-16 Ash RGB images [click to play animation | MP4]

A NOAA-20 VIIRS True Color image as viewed using RealEarth (below) also showed the darker tan to light brown shades of the ash-laden volcanic cloud.

NOAA-20 VIIRS True Color RGB image [click to enlarge]

GOES-16 retrieved products from the NOAA/CIMSS Volcanic Cloud Monitoring site (below) indicated that the more distinct pulse of ash-laden volcanic cloud had a maximum height in the 5-6 km range, and was composed of ash particles having an effective radius 10 µm and smaller. 

GOES-16 Ash Probability [click to play animation | MP4]

GOES-16 Ash Loading [click to play animation | MP4]

GOES-16 Ash Height [click to play animation | MP4]

GOES-16 Ash Effective Radius [click to play animation | MP4]

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GOES-17 Visible (0.64 µm, center), Shortwave Infrared (3.9 µm, center) and Infrared Window (10.35 µm, bottom) images [click to play animation | MP4]

The KNP Complex wildfire continued to burn in central California on 04 October 2021, producing a pair of pyrocumulonimbus or pyroCb clouds — one during the atypical late morning hours (beginning around 1530 UTC, or 11:30 am PDT) and the other during the more typical late afternoon hours (beginning around 2130 UTC, or 5:30 PM PDT). 1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed the pyroCB clouds, fire thermal anomalies or “hot spots” (clusters of red pixels) and cold cloud-top infrared brightness temperatures, respectively. The minimum 10.35 µm temperatures were near -60ºC. Note the relatively warm (darker gray) appearance of the pyroCb clouds in the 3.9 µm images — this is a characteristic signature of pyroCb cloud tops, driven by the smoke-induced shift toward smaller ice particles (which act as more efficient reflectors of incoming solar radiation, contributing to the warmer 3.9 µm brightness temperatures). Note: beginning at 1700 UTC, overlapping GOES-17 Mesoscale Sectors provided imagery at 30-second intervals.

1-minute GOES-17 True Color RGB images created using Geo2Grid (below) showed the first pyroCb cloud as it continued to move northeastward across the California/Nevada border, and then the second pyroCb cloud as it moved northwestward. The change in direction of motion was influenced by the approach of an offshore closed low from the west (250 hPa analysis: 12 UTC | 00 UTC). 

GOES-17 True Color RGB images [click to play animation | MP4]

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