Tropical Storm Larry has formed in the far eastern Atlantic Ocean. The large-scale view of the tropical Atlantic, shown above, taken from CSPP Geosphere (direct link to the imagery) shows Larry west of Africa. Tropical depression Kate is also apparent, and that storm again has convection near its center as shear there has relaxed. Kate is also moving towards a region with cooler sea surface temperatures.

The animation above shows a brownish color to the True Color imagery, suggestive of dust in the atmosphere, and a Sahara Air Layer analysis from the CIMSS Tropical Website, below, shows a strong signal just north of Larry (click here for the most recent image).

The toggle below shows the Air Mass RGB and low-level water vapor infrared imagery both show a dry signature where the SAL analysis has a strong signature. Note how Tropical Depression Kate is near a signal in the Air Mass RGB — but rather than dry air as in a SAL, this is associated with a Potential Vorticity anomaly, as suggested in this toggle between the Air Mass RGB and a pressure analysis on the 1.5 PVU surface (from the UKMET model).

Larry is forecast to stay south of the dry air, and forecast to become a strong storm (Shear values near the storm are small, based on the 1300 UTC analysis). For more details, refer to the National Hurricane Center.

View only this post Read Less

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).

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.

View only this post Read Less

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 Caldor 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]

View only this post Read Less

The animation above, of GOES-16 Visible (0.64 µm) imagery, shows Tropical Storm Kate at sunrise with convection near the storm center and to its east. (An overnight image from Suomi NPP’s Day Night Band, below, taken from NASA Worldview, also shows convection near the storm center.) As the day progresses, however, the obvious surface circulation moves northward and the convection near the surface collapses.

The shear analysis from the CIMSS Tropical Website, below, shows why the convection is displaced to the east of this storm. Strong westerly shear is present.

View only this post Read Less