The 2021 northern California wild fire season is still active. It is difficult to see smoke using the VIIRS SNPP day night band (0.7 micron) at night, but there are visible bright spots of the Caldor Fire near Lake Tahoe. The VIIRS I04 (3.74 micron) band shows bright spots of hot fires in northern California. Names of fires were taken from the CAL FIRE website here.

For smoke forecasts, the NOAA Earth System Research Laboratories Global Systems Division runs the High-Resolution Rapid Refresh (HRRR) Smoke modeling system, which can be viewed here. Dynamics and physics come from the HRRR experimental model and fire emission information is from real-time satellite observations from VIIRS which is flown aboard NOAA-20 and Suomi-NPP.

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GOES-17 (GOES-West) True Color RGB images created using Geo2Grid (above) showed the diurnal variation of smoke from the Dixie Fire, Beckwourth Complex, Caldor Fire and Tamarack Fire in Northern California on 25 August 2021. Early in the day, smoke from the previous day of fire activity that had settled into valleys was evident — but as daytime heating continued, this valley smoke was ventilated and mixed to higher altitudes, with new smoke plumes eventually developing as the fire activity ramped up again. Occasional pyrocumulus clouds were produced by the larger, hotter fires.

===== 26 August Update =====

In GOES-17 True Color RGB images on 26 August (below), less cloudiness allowed a clearer view of the smoke from these wildfires.

In a toggle between Suomi NPP VIIRS True Color RGB and False Color RGB images (below), the large wildfire burn scars appear as shades of reddish-brown in the False Color image (these VIIRS images were downloaded and processed by the SSEC/CIMSS Direct Broadcast ground station). At that time, dense smoke from the Caldor Fire was restricting surface visibility to 3/4 mile at South Lake Tahoe, California.

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Synthetic Aperture Radar (SAR) winds over the northwest Pacific, above, derived from Radar Constellation Mission (RCM) Satellite #2, shows a narrow ribbon of strong winds (>30 knots) stretching from 50 N, 138 W towards 53 N, 140 W. What kind of cloud imagery is associated with this wind feature?

Near-sunrise visible imagery from GOES-17, below, shows a narrow band of low-level clouds aligned with the region of stronger winds. This does not appear to be a deep feature: cloud shadows are much larger along the eastern edge of the visible image, which region is east of the SAR domain shown above.

A zoomed-out 10.3 µm infrared image, below, documents how subtle the cloud feature associated with the strong winds is. Blue arrows point to the region of strong winds.

SAR Winds are available from a variety of different satellites at this link.

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GOES-16 (GOES-East) Shortwave Infrared (3.9 µm) images (above) showed rapid growth of the thermal anomaly — cluster of hot pixels, red enhancement — associated with the Greenwood Fire in northeast Minnesota on 23 August 2021. With gusty winds in the wake of a frontal passage, the fire exhibited extreme behavior on this day, growing in size from 8862 acres to 19,493 acres. Vegetation was near a historic level of dryness, due to ongoing drought conditions. 

GOES-16 True Color RGB images created using Geo2Grid (below) displayed the dense smoke plume from the Greenwood Fire (as well as other plumes from wildfires farther to the north in Minnesota and Ontario) as they moved eastward.

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