Low relative humidities and strong wind gusts combined with very dry fuels resulted in the rapid development and growth of wildfires in southern California overnight on 12/2 – 12/3 2020. In fact, widespread wind gusts greater than 60 mph were reported, with a peak gust of 95 mph measured at Big Black Mountain. GOES-West 3.9 um imagery captured the wildfire development and evolution through the evening (Fig 1). The display also includes surface observations, which captured very nearby wind gusts to 46 knots. RAP RH analysis indicated widespread humidities below 15%, with values dipping as low as 5% near the wildfires.
VIIRS Day Night Band Near Constant Contrast Imagery, available in AWIPS, also captured the glow associated with the southern California Wildfires as they developed (Fig 2). Raising the “Max” value in the colormap range for NCC considerably (in this case to 30), allows the bright glow of the wildfires to stand out against the less bright city lights. During this evening, there were two passes of SNPP and one pass of NOAA-20 over this location, allowing for three images within a ~ 1 hour and 40 minute timespan. The VIIRS imagery is compared with a GOES-West SWIR image, exemplifying the significant amount of detail added from 750 m VIIRS DNB over 2 km (at nadir) ABI SWIR. The glow from the wildfires appears as very light gray to white, while city lights are a medium gray, in this example.
Bill Line, NESDIS and CIRA