True color imagery from the CSPP Geosphere site, shown above (click here for a direct link to the animation), depicts the sudden appearance and equally sudden ending of a small fire on the Texas Gulf Coast in Jefferson County, east-northeast of Houston.

The Fire Temperature RGB also shows the quick development (and cessation) of the fire; this RGB is a good situational awareness tool, as it shows an obvious color change (related to the increase in emissions of shortwave radation) when the fire initiates.

GOES-R has derived products that quantify aspects of the detected fire, as shown in the four-panel image below from 1731 UTC, near the time when the fire was most intense. Note the contributions of the red and green components of the RGB, from the 3.9 µm and 2.25 µm channels, respectively, on GOES-16, have maximized in the center pixel, so that pixel is yellow in the RGB (red + green in an RGB yields yellow); had the 1.61 µm emissions been stronger (that is, had the fire been hotter), the pixel would look whiter. The Fire Products (Area, Temperature, Power) are most useful as data assimilated into models that might simulate the evolution of the fire, or the distribution of smoke.

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The Fire Temperature RGB is one of the few RGB products in AWIPS that has a gamma adjustment. A gamma adjustment alters how the ranges of input values (in this case, 3.9 µm brightness temperatures) are displayed. For the Fire Temperature RGB, the warmest parts of the 3.9 µm brightness temperatures occupy proportionally more of the display space in the RGB, and the cooler parts of the RGB (where fire is unlikely, yet information is still needed!) occupy less.

AWIPS allows a gamma adjustment to be altered (using the ‘Composite Options’ window). The toggle below compares the default RGB to one in which the Band 7 Gamma adjustment has been changed to Gamma = 1, resulting in a very red image (because cooler brightness temperatures — that are not that relevant to the detection of fire — are more emphasized).

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Note: AWIPS users might note that the default Gamma of the RGB is 2.5, but the Quick Guide shows the Gamma to be 0.4 (that is, 1/2.5)! This may be a source of confusion. This website shows a Gamma modification of 1/Gamma — and if Gamma is 0.4, that exponent becomes 2.5, which is what AWIPS shows.

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A multi-week “parade of storms” over the Pacific Ocean featuring a persistent atmospheric river pattern and numerous winter storms pounding the U.S. west coast has resulted in record snowpack in the Sierra Nevadas with water equivalency at 205% of normal for mid-January in the northern Sierras, 255% central, and 293% of normal for the southern Sierras. (Data relayed via NWS Sacramento from the California DWR) A break in the cloud cover on Tuesday January 17th enabled satellite views of the record snowpack and visual confirmation of the rising reservoirs.

Ground water is also replenishing making dents in the multi-year drought impacting the western United States.

Compare the weekly Drought Monitor maps (December 27th through January 17th) to see weekly improvements. Note how areas of Exceptional and Extreme drought conditions in California are eradicated during this time period.

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) displayed the small eye-like feature associated with a warm seclusion that developed about 200 miles southeast of the New Jersey coast on 15 January 2023. Areas of deep convection around the periphery of the seclusion occasionally exhibited cloud-top infrared brightness temperatures around -50ºC.

During the preceding nighttime hours, a comparison of Suomi-NPP VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) images valid at 0718 UTC (below) provided a view of the cyclone as it was beginning to transition to its occluded phase — and the Sea Surface Temperature derived product indicated that water temperatures in the general vicinity were in the upper 60s to low 70s F (suggesting that the system was very near the axis of the Gulf Stream). One isolated bright lightning streak was seen in the Day/Night Band image, associated with a thunderstorm located near the warm front (which exhibited a cloud-top infrared brightness temperature of -56ºC).

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1-minute GOES-16 (GOES-East) Mesoscale Domain Sector “Red” Visible (0.64 µm) images (above) included time-matched (+/- 3 minutes) plots of SPC Storm Reports — which showed severe thunderstorms that moved east-northeastward across parts of the Deep South and Ohio Valley on 12 January 2023.

1-minute GOES-16 “Clean” Infrared Window (10.3 µm) images (below) indicated that the coldest pulsing overshooting tops associated many of the storms exhibited infrared brightness temperatures around -70ºC range (darker black enhancement). These thunderstorms produced numerous tornadoes (with multiple fatalities in Alabama and Georgia), hail up to 1.75 inches in diameter in Mississippi and Alabama, and damaging winds up to 67 mph in Alabama.

In a toggle between NOAA-20 (mislabeled as NPP) VIIRS Infrared Window (11.45 µm) and Near-Infrared (1.61 µm) images valid at 1843 UTC (below), the thunderstorm located over Autauga County, Alabama (where at least 7 fatalities occurred) appeared to exhibit a subtle Above-Anvil Cirrus Plume or AACP (reference | VISIT training) — along with a pronounced cold / warm (-71ºC / -50ºC) cloud-top infrared brightness temperature couplet. According to NWS Birmingham, this was the same tornado-producing thunderstorm that produced extensive damage in Selma (located just to the southwest, in adjacent Dallas County) about 30 minutes earlier.

A toggle between Infrared Window images from NOAA-20 VIIRS (11.45 µm) and GOES-16 ABI (10.3 µm) valid at 1843 UTC (below) revealed the parallax displacement of thunderstorm cloud-top features that is inherent in geostationary imagery (which is dependent on latitude, storm top height and the resulting satellite viewing angle). In this case, there was a north-northwestward parallax offset of about 4 miles (6.4 km) for the Autauga County AACP feature; according to 1200 UTC Birmingham rawinsonde data (source), the -71ºC overshooting top sensed by VIIRS was roughly equivalent to a Most Unstable air parcel altitude near 12.5 km. For a higher-altitude storm top of 15.2 km over Alabama, the GOES-16 parallax offset would be around 13.5 km.

In addition, the cold / warm storm-top thermal couplet sensed by GOES-16 was -65ºC / -55ºC; the multispectral Cloud Top Temperature derived product values were only about 0.7ºC colder.

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