Cranston Fire pyrocumulonimbus

July 25th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, left) and Shortwave Infrared (3.9 µm, right) images, with hourly plots of surface reports [click to play animation | MP4]

GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (above) showed the smoke and pyrocumulus clouds as well as the thermal anomaly or “hot spot” (red pixels) associated with the Cranston Fire — located in the center of the images — which started southwest of Palm Springs, California (KPSP) around 1852 UTC or 11:52 am PDT on 25 July 2018. The large areas of red seen on the Shortwave Infrared images early in the animation were signatures of very hot sandy soil surfaces of the southern California deserts. Note the very warm air temperatures seen across the region; Palm Springs had an afternoon high of 116ºF, and Thermal KTRM had a high of 119ºF (farther inland, Death Valley had a high of 127ºF).

A slightly different view — with the fire located in the lower left corner, southwest of KPSP — using GOES-16 “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.3 µm) images (below) revealed that the fire actually produced 3 distinct pulses of pyroCumulonimbus (pyroCb) cloud, where the 10.3 µm cloud-top infrared brightness temperature reached or exceeded the -40ºC threshold (lime green enhancement). Three specific times that these separate pyroCb clouds were evident were 2102 UTC, 2147 UTC and 2312 UTC.

GOES-16 "Red" Visible (0.64 µm, left), Shortwave Infrared (3.9 µm, center) and "Clean" Infrared Window (10.3) images, with 4-letter airport identifiers plotted in yellow [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm, left), Shortwave Infrared (3.9 µm, center) and “Clean” Infrared Window (10.3 µm, right) images, with 4-letter airport identifiers plotted in yellow [click to play animation | MP4]

Another view of the pyroCb pulses was provided by a 4-panel view of GOES-16 “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.3 µm) and Cloud Top Phase (below). The coldest 10.3 µm cloud-top infrared brightness temperatures were -55ºC as the primary pyroCb anvil drifted northeastward toward the California/Nevada border.

GOES-16 "Red" Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), "Clean" Infrared Window (10.3 µm, bottom left) and Cloud Top Phase (bottom right) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), “Clean” Infrared Window (10.3 µm, bottom left) and Cloud Top Phase (bottom right) images [click to play animation | MP4]

There was also substantial lightning observed with these pyroCb clouds:


Below is a timelapse video of the first 8 hours of the fire, which shows the pyroCb evolution at the end.

Timelapse of Cranston Fire [click to play YouTube video]

Timelapse of Cranston Fire [click to play YouTube video]

===== 26 July Update =====

GOES-16 "Red" Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), "Clean" Infrared Window (10.3 µm, bottom left) and Fire Temperature (bottom right) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), “Clean” Infrared Window (10.3 µm, bottom left) and Fire Temperature (bottom right) images [click to play animation | MP4]

Another pyroCb was produced by the Cranston Fire on 26 July, as shown by GOES-16 “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.3 µm) and Fire Temperature images (above). Similar to the previous day, there appeared to be 2 pulses of pyroCb formation — with cloud-top infrared brightness temperatures cooling to -44ºC. Pyrocumulus from the smaller Ribbon Fire (just southeast of the Cranston Fire) could also be seen.

Fog/stratus along the New England coast

July 24th, 2018 |

GOES-16 Total Precipitable Water product [click to play animation | MP4]

GOES-16 Total Precipitable Water product [click to play animation | MP4]

The GOES-16 (GOES-East) Total Precipitable Water product (above) showed a northerly/northwesterly flow of tropical moisture toward New England during the day on 24 July 2018, with TPW values in the 1.0 to 1.6 inch range moving toward the region. As this moist air moved over relatively cool water — as indicated by Aqua MODIS Sea Surface Temperature values generally in the 60s F on the previous day (below) — areas of marine boundary layer fog/stratus developed.

Aqua MODIS Sea Surface Temperature product from 23 July [click to enlarge]

Aqua MODIS Sea Surface Temperature product from 23 July [click to enlarge]

1-minue Mesoscale Domain Sector GOES-16 “Red” Visible (0.64 µm) images (below) revealed interesting patterns in the resulting marine layer fog/stratus — for example, bow shock waves along the eastern edges of Nantucket Island and Cape Cod, and narrow clear swaths to the lee of some of the smaller islands off the coast of Maine.

GOES-16

GOES-16 “Red” Visible (0.64 µm) images [click to play MP4 animation]

Wildfires in Greece

July 24th, 2018 |

Suomi NPP VIIRS Shortwave Infrared (3.75 µm), Near-Infrared (1.61 and 2.25 µm) and Day/Night Band (0.7 µm) images [click to enlarge]

Suomi NPP VIIRS Shortwave Infrared (3.75 µm), Near-Infrared (1.61 and 2.25 µm) and Day/Night Band (0.7 µm) images [click to enlarge]

Suomi NPP VIIRS Shortwave Infrared (3.75 µm), Near-Infrared (1.61 and 2.25 µm) and Day/Night Band (0.7 µm) images (above) showed thermal signatures and the bright glow of wildfires in the Athens, Greece area at 0005 UTC or 3:05 am local time on 24 July 2018. The 2 largest fires were burning in the vicinity of Kineta and Mati.

Similar images from an overpass of the NOAA-20 satellite 50 minutes later are shown below.

NOAA-20 Shortwave Infrared (3.75 µm), Near-Infrared (1.61 and 2.25 µm) and Day/Night Band (0.7 µm) images [click to enlarge]

NOAA-20 Shortwave Infrared (3.75 µm), Near-Infrared (1.61 and 2.25 µm) and Day/Night Band (0.7 µm) images [click to enlarge]

Over 70 deaths have resulted from these fast-moving wildfires, which were driven by strong winds (below).

Time series of surface observations at Athens, Greece [click to enlarge]

Time series of surface observations at Athens, Greece [click to enlarge]

VIIRS images courtesy of William Straka, CIMSS.

Cloud-top “warm trench” infrared signature over Colorado

July 22nd, 2018 |

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with plots of surface reports [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.3 µm) images (above) revealed a well-defined “warm trench” signature (ring of brighter red enhancement) surrounding the cold overshooting top (cluster of pixels enhanced as black to lighter shades of gray) of a thunderstorm in far eastern Colorado during the nighttime hours on 22 July 2018. This warm trench appears to be a ring of compensating subsidence immediately surrounding the vigorous overshooting top; the cold/warm (overshooting_top/warm_trench) “delta-T” on the 0412 UTC image was 16.4ºC (-85.5ºC / -67.1ºC). Just to the south, at 0453 UTC there was a northerly peak wind gust to 45 knots or 52 mph at KITR (Burlington Colorado: plot | text) as the updraft supporting the overshooting top collapsed — but no other SPC storm reports were seen in that area.

A 250-meter resolution Terra MODIS Infrared Window (11.0 µm) imageat 0402 UTC (below) with a slightly different color enhancement showed similar delta-T values (-81ºC/-67ºC) with the overshooting top / warm trench. The diameter of the warm trench was approximately 30-40 miles.

Terra MODIS Infrared Window (11.0 µm) image, with plots of surface reports [click to enlarge]

Terra MODIS Infrared Window (11.0 µm) image, with plots of surface reports [click to enlarge]

A plot of 00 UTC rawinsonde data from North Platte, Nebraska (below) showed a tropopause temperature of -73ºC at an altitude of 15.7 km or 51,500 feet — so the much colder infrared brightness temperatures seen on GOES and MODIS imagery were indicative of a very robust overshooting top that penetrated the tropopause a significant distance.

Plot of 00 UTC rawinsonde data from North Platte, Nebraska [click to enlarge]

Plot of 00 UTC rawinsonde data from North Platte, Nebraska [click to enlarge]

The GOES-16 Cloud Top Height product at 0412 UTC (below) indicated values of 54,000 ft / 49,000 ft for the cold overshooting top / warm trench features — however, note that the resolution of this infrared-derived product is 10 km (and the accuracy is within 1500 feet).

GOES-16 Cloud Top Height derived product at 0412 UTC [click to enlarge]

GOES-16 Cloud Top Height derived product at 0412 UTC [click to enlarge]

Another interesting (and yet-to-be-explained) feature was an arc of warming cloud-top infrared brightness temperatures that was seen propagating southwestward toward the overshooting top / warm trench signature. A larger-scale view (below) showed this wave feature moving from southwestern Nebraska at around 02 UTC to southern Colorado/Kansas by 10 UTC.

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with 11.2 µm infrared Derived Motion Winds [click to play animation | MP4]

This cloud-top wave feature was also apparent on GOES-16 Upper-level Water Vapor (6.2 µm) images (below) — at times the wave was tracked by Derived Motion Winds at speeds of 20-30 knots (0252 UTC | 0337 UTC | 0922 UTC). According to rawinsonde data from Dodge City, Kansas (plot | data) as well as North Platte, winds with a northerly to easterly component were only found at altitudes of 20 km or higher!

GOES-16 Upper-level Water Vapor (6.2 µm) images, with 6.2 µm water vapor Derived Motion Winds [click to play animation | MP4]

GOES-16 Upper-level Water Vapor (6.2 µm) images, with 6.2 µm water vapor Derived Motion Winds [click to play animation | MP4]

Special thanks to NWS Grand Rapids forecasters Brett Borchardt and TJ Turnage for bringing this case to our attention!