Caldor Fire approaches South Lake Tahoe

August 31st, 2021 |
Suomi NPP and NOAA-20 (as indicated) VIIRS Day Night Band visible (0.7 µm) imagery, 11-31 August 2021 (Click to enlarge). Sacramento CA is at the western edge of the imagery, and Reno NV is along the northern boundary.

Day Night Band imagery collected from the VIIRS-Today website, above, shows night-time snapshots of the Caldor Fire (discussed previously here, here and here on this blog) as it formed and moved towards Lake Tahoe in August 2021. On 31 August, the last day of the animation, the fire was close enough to the city of South Lake Tahoe that evacuation orders for that town have been issued.

The longer animation, below, shows the evolution of the Caldor Fire and the Dixie Fire complex as well (and is an update to this blog post).

Suomi NPP and NOAA-20 (as indicated) Day Night Band Imagery, 9 July – 31 August 2021 (Click to enlarge)

VIIRS imagery can also be used to outline burn scars from the fire. The ‘False Color’ RGB image below, from 30 August 2021 (from this url at VIIRS Today), depicts just how large the burn scar (the brownish region in the imagery) from the Dixie Fire is.

NOAA-20 False Color imagery from 30 August 2021 (Click to enlarge)

Smoke plumes continue from Northern California wildfires

August 30th, 2021 |

GOES-17 True Color RGB images [click image to play animation | MP4]

GOES-17 (GOES-West) True Color RGB images created using Geo2Grid (above) showed the diurnal variation of smoke from the Dixie Fire and the Calfor Fire in Northern California on 30 August 2021. Early in the day, smoke from the previous day of fire activity that had settled into valleys was apparent — however, 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 once again. Occasional brighter-white pyrocumulus clouds were produced over the hottest portion of the larger fires.

===== 31 August Update =====

GOES-17 True Color RGB images [click image to play animation | MP4]

GOES-17 (GOES-West) True Color RGB images created using Geo2Grid (above) showed the diurnal variation of smoke from the Dixie Fire, Caldor Fire and Tamarack Fire in Northern California on 31 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 once again. Occasional brighter-white pyrocumulus clouds were produced by the larger, hotter fires.

In a toggle between Suomi NPP VIIRS True Color RGB and False Color RGB images (below), recent fire burn scars appear as darker shades of reddish-brown while currently active and hot fires appear as brighter shades of pink in the False Color image. 

Suomi NPP VIIRS True Color RGB and False Color RGB images [click to enlarge]

Suomi NPP VIIRS False Color RGB images 5 days apart — 26 August and 31 August — (below) revealed changes in fire burn scar size and active fire locations across that region.

Suomi NPP VIIRS False Color RGB images on 26 August and 31 August [click to enlarge]

A closer view of Suomi NPP VIIRS True Color RGB and False Color RGB mages centered on the Caldor Fire (below) showed that a large active fire was located just a few miles south of South Lake Tahoe, California. 

Suomi NPP VIIRS True Color RGB and False Color .RGB images [click to enlarge]

 

Northern California fires

August 26th, 2021 |

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.

A three panel animation on 08/26/21 at 08:56Z showing the VIIRS I04 band over northern California, the I04 band with fires labeled, and the VIIRS day-night band.

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.

The HRRR 8-hr forecast for vertically integrated smoke for 08/26/21 at 1500Z.

Smoke from wildfires in Northern California

August 25th, 2021 |

GOES-17 True Color RGB images [click to play animation | MP4]

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.

GOES-17 True Color RGB images [click to play animation | MP4]

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.

Suomi NPP VIIRS True Color RGB and False Color RGB images [click to enlarge]