The GOES-16 Total Precipitable Water product (above) highlighted the northward surge of monsoon moisture across portions of the Southwest US on 25 July 2019. TPW values as high as 2.0-2.1 inches were seen over the California/Arizona border early in the day, and also over far southeastern California and southwestern Arizona later in the day. The TPW value of 1.56 inches as derived from 12 UTC Las Vegas rawinsonde data was a record maximum for 25 July (below), and the TPW value of 1.76 inches at Phoenix was above the 90th percentile of the climatological average for the date.

Overlapping GOES-17 (GOES-West) Mesoscale Domain Sectors provided imagery at 30-second intervals from 1445-2100 UTC — and “Red” Visible (0.64 µm) images (below) showed the development of thunderstorms across the region during that period. Many of these storms produced heavy rainfall, prompting the issuance of numerous Flash Flood Warnings in California, Nevada and Arizona (with a Dust Storm Advisory being issued due to thunderstorm outflow in Arizona).

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Solar heating of the ABI instruments (on both GOES-16 and GOES-17) occurs at night around the Equinoxes. As the ABI points down to the Earth to observe the atmosphere and surface, sunlight falls on the ABI, warming it, and the Loop Heat Pipe that is not operating at capacity on GOES-17 does not circulate enough heat to radiators for dissipation to space. So, the temperature of the ABI increases during part of the night, reaches a maximum, and then decreases (as the solar illumination of the ABI decreases).

The change in temperature means that calibration looks at the Internal Calibration Target (ICT) within the ABI that occur regularly will quickly become invalid because of the changing temperature of the ABI. The images below show the temperature of the Focal Plane within the GOES-17 ABI in mid-June, in mid-July and in late July. For the best calibration, the focal plane temperatures would be steady. They are not. Note that the y-axis values are different in the plots. More significant warming is present in the latest plot and those peak values will steadily increase until Eclipse Season starts in late August. This blog post shows the effects of the warming in mid-April of this year. Predictive Calibration accounts for the change in the temperatures in between calibration looks and was implemented in the GOES-17 Ground Station at 1721 UTC on 25 July 2019. The beneficial effects of Predictive Calibration are shown in the figure (courtesy Mat Gunshor, CIMSS) above for ABI band 12; large warm and cold biases have been mitigated. ABI band 8 (6.2 µm) shows similar improvements.

The image above, (reproduced from this blog post and originally from here) shows the predicted focal plane maximum each day over the course of the year. It also shows at which temperature each band will marginally saturate, meaning that the effects of the warming ABI start to become noticeable.

The animation below shows the GOES-17 ABI Band 12 ‘Ozone Band’ (at 9.6 µm) that, according to the figure above is one of the first (along with Bands 10 — 7.34 µm — and 16 — 13.3 µm) to show the effects of the warming focal plane. Brightness temperatures warm before 1300 UTC and cool after 1300 UTC, and the amount of noise/stripeyness in the imagery increases  (This is most apparent at the northern edge of these 5-minute PACUS images).  These are all manifestations of the warming and cooling focal plane temperatures.

One week later, on 25 July 2019, below, the effects of the heating because the Loop Heat Pipe and radiator are not working at capacity are even more evident. The imagery exhibits a warm bias before 1300 UTC and a cold bias after 1300 UTC and the stripeyness of the image increases. Predictive calibration will mitigate the warm and cold bias.

Comparisons between individual bands from GOES-16 and GOES-17 for Full Disk and CONUS/PACUS views (in both cases in regions between the subsatellite points to minimize the effects of view angle) are available at this link, or also through this link.

======== ADDED, After Predictive Calibration was turned on ============The animation below shows GOES-17 ABI Band 12 for the same time period as above, 0836-1511 UTC, but for the day after Predictive Calibration was implemented. You no longer see changes in observed brightness temperature that result from the warming focal plane temperatures. There is still some striping; this is associated with detector saturation and that striping will become more obvious in the next week and will lead to missing data. Predictive Calibration will not mitigate the issue of missing or striped data due to saturated sensors. Predictive Calibration is designed to mitigate warm biases before saturation, and cold biases after saturation.

The animation below (click to animate) shows both 25 July (left, before Predictive Calibration) and 26 July (right, after Predictive Calibration).

You can view a short video on this topic here.

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed the development and propagation of a Mesoscale Convective System (MCS) that produced hail up to 3.0 inches in diameter in Minnesota and wind gusts to 84 mph and a few tornadoes in Wisconsin (SPC Storm Reports | NWS Twin Cities | MN DNR | NWS Green Bay) on 19 July 2019. Numerous overshooting tops and widespread storm-top gravity waves were evident in the imagery, along with a few Above-Anvil Cirrus Plume features extending northeastward from some of the overshooting tops around sunset. Also notable were the inflow feeder bands that were streaming northward into the southern flank of the MCS across Minnesota.

A comparison of GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (below) revealed cloud-top infrared brightness temperatures as cold as -86ºC over northwestern Wisconsin.

As the MCS persisted into the subsequent nighttime hours, GOES-16 Infrared images (below) showed the large canopy of cold cloud tops, with infrared brightness temperatures of -80ºC or colder (violet pixels).  Some of the embedded storms exhibited well-defined Enhanced-V storm top signatures (for example, at 2219 UTC).

===== 22 July Update =====

A comparison of Terra MODIS True Color Red-Green-Blue (RGB) images from 11 July and 22 July (above) showed the subtle NW-SE oriented swath of downed trees across northeastern Wisconsin. A 14 July vs 22 July comparison as viewed using RealEarth is shown below — the swath extended from approximately Pickerel to Mountain.

In 22 July Terra MODIS images displayed using AWIPS (below), the swath of downed trees was brighter (more reflective) in the Near-Infrared “Snow/Ice” (1.61 µm), warmer (darker shades of orange to red) in the Shortwave Infrared (3.7 µm) and Land Surface Temperature, and lighter shades of green in the Normalized Difference Vegetation Index.

The swath of downed trees was also seen in GOES-16 Normalized Difference Vegetation Index images (below), showing up as a darker shade of green with that product’s default enhancement.

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A sequence of GOES-16 (GOES-East) Ash, SO2 and CIMSS Natural Color Red-Green-Blue (RGB) images (above) showed the volcanic cloud following an eruption of Ubinas in southern Peru on 19 July 2019. The volcanic plume was rich in both ash and SO2.

A plot of surface data from La Paz, Bolivia (below) indicated that the visibility dropped to 3 miles around 16 UTC as the volcanic cloud was drifting over that area (located about 150 miles downwind of Ubinas).

Terra MODIS Ash Probability, Ash Loading, Ash Height and Ash Effective Radius from the NOAA/CIMSS Volcanic Cloud Monitoring site (below) confirmed the high amounts of ash loading (of generally small ash particles) — with maximum radiometrically-retrieved Ash Height values in the 18-20 km range.

GOES-16 retrieved Ash Height values (below) were in general agreement with those obtained using the higher-resolution MODIS data.

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