Alisal Fire in Southern California

October 12th, 2021 |

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

GOES-17 (GOES-West) True Color RGB images created using Geo2Grid (above) showed the transport of smoke from the Alisal Fire in Southern California on 12 October 2021. The dashed line in the images is Highway 101 — a portion of which was closed, as the wind-driven fire raced toward the coast. Late in the day some low-altitude smoke began to move eastward along the coast, eventually reducing the surface visibility to 6 miles at Santa Barbara.

During the preceding overnight hours (at 0916 UTC or 2:16 am PDT), a comparison of Suomi-NPP VIIRS Shortwave Infrared and Day/Night Band images (below) revealed the thermal signature and nighttime glow of the fire. The VIIRS imagery was downloaded and processed via the SSEC/CIMSS Direct Broadcast ground station.

Suomi-NPP VIIRS Shortwave Infrared (3.74 µm) and Day/Night Band (0.7 µm) images [click to enlarge]

The Suomi-NPP overpass time of the fire region was actually 0926 UTC — and a time-matched comparison of Shortwave Infrared images from GOES-17 and Suomi-NPP (below) demonstrated that the superior spatial resolution of VIIRS instrument (~375 meters, vs ~2 km for the ABI on GOES-17) provided a more accurate depiction of the areal coverage of the fire.

Shortwave Infrared images from Suomi-NPP (3.74 µm) and GOES-17 (3.9 µm) [click to enlarge]

===== 13 October Update =====

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

On 13 October, GOES-17 True Color RGB images (above) showed that as offshore wind speeds relaxed, a shift to onshore flow recirculated some of the smoke inland — with smoke briefly reducing the surface visibility to 1.5 miles at Santa Barbara airport (below). Farther to the south, residual smoke from the previous day of burning was also evident, with some of it traveling as far as Isla Guadalupe (Guadalupe Island) nearly 400 miles away.

Time series of surface observation data from Santa Barbara Municipal Airport [click to enlarge]

Cyclone Shaheen-Gulab makes landfall in Oman

October 3rd, 2021 |

US Space Force EWS-G1 Infrared Window (10.7 µm) images [click to play animation | MP4]

US Space Force EWS-G1 (formerly GOES-13) Infrared Window (10.7 µm) images (above) showed
Hurricane Shaheen-Gulab weakening to a Tropical Storm shortly after it made a rare landfall along the coast of Oman on 03 October 2021. The storm exhibited an eye at times as it was a Category 1 Hurricane over the Gulf of Oman. This was likely the first tropical cyclone to make landfall along that coastal portion of Oman since 1890 (Wikipedia).

Meteosat-8 Infrared images, with contours of deep-layer wind shear from the CIMSS Tropical Cyclones site (below) indicated that the storm was moving through an environment of low shear.

Meteosat-8 Infrared images, with contours of deep-layer wind shear [click to enlarge]

Suomi-NPP VIIRS True Color RGB and infrared Window (11.45 µm) images viewed using RealEarth (below) showed the Category 1 Hurricane at 0927 UTC.

Suomi-NPP VIIRS True Color RGB and infrared Window (11.45 µm) images at 0927 UTC [click to enlarge]

Kilauea is active again

October 1st, 2021 |
GOES-17 Shortwave Infrared, 0126 – 1156 UTC on 1 October 2021 (Click to enlarge)

GOES-17 Shortwave Infrared imagery, above, shows the hot-spot associated with the latest eruptive phase of the Halema’uma’u Crater on Kilauea’s southern slope. (Click here for webcams).

The Day Night band from VIIRS on board Suomi NPP and NOAA-20 show the light source from the eruption as well, as shown in the toggle below (imagery from the Honolulu Direct Broadcast site, here)

VIIRS Day Night Band imagery from Suomi NPP (1111 UTC) and NOAA-20 (1200 UTC), 1 October 2021 (Click to enlarge)

The NOAA/CIMSS Volcanic Cloud Monitoring Web Portal (i.e., VOLCAT — link) include a Kilauea sector under the Washington DC VAAC tab; an imagery example is here.

FDCA — the Fire Detection and Characterization Algorithm — should have a signal here but does not. The landcover dataset used for the product is missing Hawaii. Fires aren’t looked for when land does not exist, even if its absence is in error. NOAA/NESDIS Scientists and their partners at CIMSS are working to correct this oversight.

Pyrocumulonimbus cloud over northern Paraguay

September 29th, 2021 |

GOES-16 Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, center) and Infrared Window (10.35 µm, bottom) images [click to play animation | MP4]

Fires burning in far northern Paraguay on 29 September 2021 created a pyrocumulonimbus or pyroCb cloud — GOES-16 (GOES-East) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed the pyroCB cloud, fire thermal anomalies or “hot spots” (clusters of red pixels) and cold cloud-top infrared brightness temperatures, respectively. The minimum 10.35 µm temperature was -47.6ºC at 1840 UTC. Note the relatively warm (darker gray) appearance of the pyroCb cloud in the 3.9 µm images — this is a characteristic signature of pyroCb cloud tops, driven by the smoke-induced shift toward smaller ice particles (which act as more efficient reflectors of incoming solar radiation).

A Suomi-NPP VIIRS Infrared Window (11.45 µm) image at 1751 UTC as viewed using RealEarth (below) revealed cloud-top infrared brightness temperatures in the -60s C (shades of red). Surface temperatures at nearby sites had reached 38ºC (100ºF) by 18 UTC. 

Suomi-NPP VIIRS Infrared Window (11.45 µm) image at 1751 UTC [click to enlarge]

South American pyrocumulonimbus clouds are fairly uncommon — since the first documented case in 2018, only 7 other pyroCbs have been identified over that continent. 

Thanks to Mike Fromm, NRL, for alerting us to this latest pyroCb case. Additional information is available from