With the evolution of an upper trough and associated strong upper-level jet, active weather was expected to occur across the central US on Monday, March 6, 2017. Given this, two GOES-East (GOES-13) rapid scan mode requests were made. SPC made a request to cover the Enhanced risk for Severe Weather (below right), while WFO Pueblo made a request to cover the widespread high fire danger (below left). Given these requests, both non-operational GOES-16 mesoscale sectors were shifted west from their default locations to cover the severe and fire weather threats (below middle).
Strong surface winds, low relative humidities and dry fuels led to widespread critical to extreme fire weather conditions across the southern Plains. The 2-hr (~10 AM to Noon) loop of 1-min satellite imagery below shows the rapid ignition and movement of a wildfire from the Oklahoma Panhandle northeast into Kansas (Fig 1). The 3.9 um shortwave IR channel depicts the progress of the fire hotspot, while the 0.47 um visible channel shows the evolution of the smoke plume, including pyrocumulus clouds. It is vital that fire crews are alerted to the presence of new wildfires as soon as possible. NWS forecasters being able to detect new fire starts in GOES-16 imagery as they occur, and track their evolution in real-time, is a major help. In addition to the improved temporal resolution, the increased spatial resolution allows hotpots to be detected even sooner than with current GOES.
A wind shift occurred between 2230 UTC and 2330 UTC. By utilizing the 1-min GOES-16 imagery, forecasters could track the approach of the wind shift in real-time. Here we are looking at the 2.25 um Near-IR band, which is less sensitive to cooler fires than 3.9 um, but more sensitive to very hot fires. The smoke is also apparent in 2.25 um during the day. At night in the lack of solar reflectance, the scene will appear dark with the exception of the heat from the fire.
GOES-16 can continue to be used to track wildfire hotspots after dark. The 3.9 um channel is most sensitive to the heat of a fire, followed by 2.25 um and then 1.61 um. Hotspots viewed in the two Near-IR channels, however, will contrast well with the non-reflective background, making them easy to detect. Additionally, the 1.61 um channel has a spatial resolution of 1 km resolution compared to 2 km for the two other fire detecting channels. Below is a 3-panel comparing the three channels for the fires in Oklahoma and Kansas. The 1.61 um and 2.25 um displays use the same color table/range.
When strong flow is present over the Colorado Rockies, interesting cloud features are often observed. The 1-min 0.64 um visible imagery provided a unique view of a localized gravity wave feature over the northern Sangre de Cristo mountain range. This was likely in an area of relative strong atmospheric stability, trapping the wave as flow intensified over the mountains.
Severe convection developed quickly across the western edge of the SPC risk zone. Below is an animation of an image combination known as a “sandwich product”. This is simply transparent 10.4 um IR channel overlaid on 0.64 um visible channel. With this combination, one is getting the benefit of the higher resolution in the visible imagery, and the benefit of the temperature information from the IR imagery. One can clearly see the evolution of overshooting tops, and the rapid expansion of the storm anvils.
Bill Line, NWS/PUB
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