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1-minute imagery to monitor deep convection for flooding potential across American Samoa

By Scott Bachmeier •

1-minute Mesoscale Domain Sector GOES-18 (GOES-West) “Clean” Infrared Window (10.3 µm) images (above) displayed areas of convection that moved across American Samoa on 01 June 2024 (1-minute imagery was requested by NWS Pago Pago to monitor the approach of thunderstorms, since they had issued a Flood Watch for the islands — and they lack radar coverage). Although there was a... Read More

1-minute GOES-18 “Clean” Infrared Window (10.3 µm) images, from 0127 UTC on 01 June to 0059 UTC on 02 June; NSTU denotes the location of Pago Pago, American Samoa [click to play MP4 animation]

1-minute Mesoscale Domain Sector GOES-18 (GOES-West) “Clean” Infrared Window (10.3 µm) images (above) displayed areas of convection that moved across American Samoa on 01 June 2024 (1-minute imagery was requested by NWS Pago Pago to monitor the approach of thunderstorms, since they had issued a Flood Watch for the islands — and they lack radar coverage). Although there was a break in the convective activity midway through the period, Pago Pago did receive heavy rainfall from thunderstorms that began to arrive just as the 1-minute imagery was ending (decoded surface observations | METARs); those thunderstorms produced 0.62 inch of rainfall in 3 hours and 0.94 inch of rainfall in 6 hours (plot of surface report data).

A GOES-18 Infrared image showing a cold (-77.71ºC) thunderstorm overshooting top (not far to the west of American Samoa) at 0039 UTC on 02 June (below) included a cursor sample of the associated GOES-18 Cloud Top Height (50750 ft) and Rain Rate (1.90 in/hr) derived products at that location.

GOES-18 “Clean” Infrared Window (10.3 µm) image showing a cold thunderstorm overshooting top west of American Samoa at 0039 UTC on 02 June, which includes a cursor sample of the associated GOES-18 Cloud Top Height (blue) and Rain Rate (red) derived products [click to enlarge]

During a break in widespread cloud coverage across the region, the 10-minute GOES-18 Total Precipitable Water (TPW) derived product (in cloud-free regions) (below) showed a NW-to-SE oriented corridor of TPW values in the 2.0 to 2.2 inch range (lighter shades of violet) across the Samoan Islands.

1-minute GOES-18 “Clean” Infrared Window (10.3 µm) images combined with the 10-minute Total Precipitable Water derived product (in cloud-free regions), from 1859 UTC on 01 June to 0000 UTC on 02 June; NSTU denotes the location of Pago Pago, American Samoa [click to play animated GIF | MP4]

However, the GOES-18 derived Total Precipitable Water values were less than the 2.62 inches obtained using rawinsonde data from Pago Pago, American Samoa at 0000 UTC on 02 June (below).

Plot of rawinsonde data from Pago Pago, American Samoa at 0000 UTC on 02 June [click to enlarge]

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Wildfire in British Columbia produces 2 pyrocumulonimbus clouds

By Scott Bachmeier •

10-minute Full Disk sector GOES-18 (GOES-West) Day Land Cloud Fire RGB, Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.3 µm) and “Red” Visible (0.64 µm) images with an overlay of the Fire Mask derived product (a component of the GOES Fire Detection and Characterization Algorithm FDCA) (above) displayed signatures of a wildfire in far northeastern British Columbia, which produced... Read More

GOES-18 Day Land Cloud Fire RGB (top left), Shortwave Infrared (3.9 µm, top right), “Clean” Infrared Window (10.3 µm, bottom left) and “Red” Visible (0.64 µm) images with an overlay of the Fire Mask derived product (bottom right), from 1900 UTC on 29 May to 0200 UTC on 30 May [click to play animated GIF | MP4]

10-minute Full Disk sector GOES-18 (GOES-West) Day Land Cloud Fire RGB, Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.3 µm) and “Red” Visible (0.64 µm) images with an overlay of the Fire Mask derived product (a component of the GOES Fire Detection and Characterization Algorithm FDCA) (above) displayed signatures of a wildfire in far northeastern British Columbia, which produced 2 pyrocumulonimbus (pyroCb) clouds — exhibiting cloud-top infrared brightness temperatures in the -40s to -50s C, denoted by shades of blue to red in the 10.3 µm images — late in the day on 29 May 2024 (Canada’s first pyroCb clouds of their 2024 wildfire season were observed on 13 May).

A similar animation that includes GOES-18 Visible images with an overlay of the Fire Power derived product — another component of the FDCA — is shown below.

GOES-18 Day Land Cloud Fire RGB (top left), Shortwave Infrared (3.9 µm, top right), “Clean” Infrared Window (10.3 µm, bottom left) and “Red” Visible (0.64 µm) images with an overlay of the Fire Power derived product (bottom right), from 1900 UTC on 29 May to 0200 UTC on 30 May [click to play animated GIF | MP4]

GOES-18 True Color RGB images from the CSPP GeoSphere site (below) displayed several plumes of low-altitude wildfire smoke, followed by the explosive development of the 2 high-altitude pyroCb clouds (which then drifted to the northwest).

GOES-18 True Color RGB images, from 1800 UTC on 29 May to 0200 UTC on 30 May [click to play MP4 animation]

The coldest 10.3 µm infrared brightness temperature sensed for each of the 2 pyroCb clouds was -52ºC. According to rawinsonde data from nearby Fort Nelson, BC (CYYE), this represented a pressure level of 307 hPa or an altitude around 8.9 km (below).

Plot of rawinsonde data from Fort Nelson, BC at 0000 UTC on 30 May [click to enlarge]

This wildfire burned very hot, exhibiting a peak 3.9 µm shortwave infrared brightness temperature of 137.88ºC (which is the saturation temperature of GOES-18 ABI Band 7 detectors) — at 2250 UTC (below).

Cursor sampling of the GOES-18 Day Land Cloud Fire RGB (top left), Shortwave Infrared (3.9 µm, top right), “Clean” Infrared Window (10.3 µm, bottom left) and “Red” Visible (0.64 µm) image with an overlay of the Fire Power derived product (bottom right) at 2250 UTC on 29 May [click to enlarge]

The GOES-18 Fire Power value reached 6057.70 MW at 2310 UTC (below) — values over 6000 MW are only seen with very hot fires.

Cursor sampling of the GOES-18 Day Land Cloud Fire RGB (top left), Shortwave Infrared (3.9 µm, top right), “Clean” Infrared Window (10.3 µm, bottom left) and “Red” Visible (0.64 µm) image with an overlay of the Fire Power derived product (bottom right) at 2310 UTC on 29 May [click to enlarge]

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Hail swath across the Texas Panhandle Plains

By Scott Bachmeier •

GOES-16 (GOES-East) Nighttime Microphysics RGB images (above) showed a thunderstorm that moved southeast from the New Mexico / Texas border across the southern Texas Panhandle Plains on 29 May 2024. A narrow northwest-to-southeast oriented hail swath produced by this storm  — from south of Clovis, New Mexico (KCVN) to south of Lubbock,... Read More

GOES-16 Nighttime Microphysics RGB images [click to play animated GIF | MP4]

GOES-16 (GOES-East) Nighttime Microphysics RGB images (above) showed a thunderstorm that moved southeast from the New Mexico / Texas border across the southern Texas Panhandle Plains on 29 May 2024. A narrow northwest-to-southeast oriented hail swath produced by this storm  — from south of Clovis, New Mexico (KCVN) to south of Lubbock, Texas (KLBB) — showed up as pale shades of beige.

GOES-16 “Clean” Infrared Window (10.3 µm) images, with and without an overlay of the Land Surface Temperature derived product (in cloud-free areas) [click to play animated GIF | MP4]

GOES-16 “Clean” Infrared Window (10.3 µm) images with/without an overlay of the hourly Land Surface Temperature (LST) derived product (in cloud-free areas) (above) indicated that the LST within the hail swath was as much as 10-12ºF cooler than adjacent bare ground (even after sunrise). A cursor sample of LST values within and immediately adjacent to the hail swath at 1401 UTC is shown below.

Cursor sample of Land Surface Temperature values (ºF) within and immediately adjacent to the hail swath at 1401 UTC [click to enlarge]

In a comparison of GOES-16 Infrared, Infrared + Land Surface Temperature, Day Land Cloud RGB and CIMSS Natural Color RGB images at 1401 UTC (below) note that the hail swath signature was not evident in the CIMSS Natural Color RGB image.

GOES-16 Infrared, Infrared + Land Surface Temperature, Day Land Cloud RGB and CIMSS Natural Color RGB images at 1401 UTC [click to enlarge]

Hat tip to NWS Midland and NWS Lubbock for pointing out this interesting feature!

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Severe thunderstorms across the southern and central Plains

By Scott Bachmeier •

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) widespread showed thunderstorms that produced tornadoes (resulting in a number of fatalities), large hail (up to 3.5 inches in diameter in Oklahoma) and damaging winds as high as 78 mph in Kansas (SPC Storm Reports) across the southern and central Plains during the daytime hours... Read More

GOES-16 Visible images + SPC Storm Reports

1-minute GOES-16 “Red” Visible (0.64 µm) images with time-matched SPC Storm Reports plotted in red [click to play animated GIF | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) widespread showed thunderstorms that produced tornadoes (resulting in a number of fatalities), large hail (up to 3.5 inches in diameter in Oklahoma) and damaging winds as high as 78 mph in Kansas (SPC Storm Reports) across the southern and central Plains during the daytime hours on 25 May 2024. Pulses of overshooting tops were apparent in the Visible imagery.

In the corresponding 1-minute GOES-16 “Clean” Infrared Window (10.3 µm) images (below), the coldest overshooting top infrared brightness temperatures were in the -70 to -79ºC range (shades of black to white).

1-minute GOES-16 “Clean” Infrared Window (10.3 µm) images with time-matched SPC Storm Reports plotted in cyan [click to play animated GIF | MP4]

In a closer view of a deadly supercell thunderstorm that was moving across North Texas, 1-miinute GOES-16 Infrared images (below) showed pulses of overshooting tops exhibiting cloud-top infrared brightness temperatures of -80ºC or colder (violet pixels) as it produced tornadoes (one of which produced fatalities at Valley View, Texas around 0346 UTC), hail to 3.00″ in diameter and damaging winds to 70 mph.

1-minute GOES-16 “Clean” Infrared Window (10.3 µm) images with time-matched SPC Storm Reports plotted in cyan [click to play animated GIF | MP4]

In addition, a closer view of another deadly tornado-producing supercell thunderstorm (below) similarly showed numerous pulses of overshooting tops as it moved across northeast Oklahoma (including the communities of Claremore and Pryor) and continued across northwest Arkansas (where it produced several more fatalities).

1-minute GOES-16 “Clean” Infrared Window (10.3 µm) images with time-matched SPC Storm Reports plotted in cyan [click to play animated GIF | MP4]

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