Decker Fire in Colorado

October 2nd, 2019 |

GOES-16 “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (above) showed the afternoon/evening smoke plume and the persistent thermal anomaly (cluster of hot pixels) associated with the Decker Fire burning just southwest of Salida, Colorado on 02 October 2019.

A closer view of the fire was provided by a 4-panel comparison of GOES-16 Shortwave Infrared, Fire Power, Fire Temperature and Fire Area products (below). More information on these GOES Fire Detection and Characterization Algorithm (FDCA) products can be found here. Windy conditions on this day —  with sustained speeds of 20-30 mph and gusts to 46 mph — promoted rapid fire growth during the afternoon hours.

GOES-16 Shortwave Infrared (3.9 µm), Fire Power, Fire Temperature and Fire Area [click to play animation | MP4]

GOES-16 Shortwave Infrared (3.9 µm), Fire Power, Fire Temperature and Fire Area [click to play animation | MP4]

A sequence of VIIRS True Color Red-Green-Blue (RGB) and Infrared Window images from Suomi NPP and NOAA-20 as viewed using RealEarth (below) showed the smoke plume and the fire’s thermal anomaly (cluster of dark black pixels).

VIIRS True Color RGB and Infrared Window (11.45 um) images from Suomi NPP and NOAA-20 [click to enlarge]

VIIRS True Color RGB and Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20 [click to enlarge]

A time series of surface observation data from the Salida Airport (identifier KANK, located just northwest of the fire) revealed southwesterly winds gusting to 20-29 knots as the dew point dropped to the -1 to -11ºF range — creating Relative Humidity values as low as 4% — during the afternoon hours (below).

Time series of surface observation data from Salida, Colorado [click to enlarge]

Time series of surface observation data from Salida, Colorado [click to enlarge]

===== 03 October Update =====

GOES-17 “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

The Decker Fire continued to burn on 03 October, as seen using 1-minute Mesoscale Domain Sector GOES-17 “Red” Visible and Shortwave Infrared images (above). Although surface winds were still gusting as high as 30 knots at Salida, additional boundary layer moisture (dew points were in the 20s F) helped to slow the rate of fire growth compared to the previous day. The southeasterly winds transported some low-altitude smoke toward Salida, reducing the visibility to 5-7 miles at times (below).

Time series of surface observation data from Salida, Colorado [click to enlarge]

Time series of surface observation data from Salida, Colorado [click to enlarge]

A comparison of GOES-16 (GOES-East) and GOES-17 (GOES-West) Shortwave Infrared images with topography (below) demonstrated the effect of large satellite viewing angles on apparent fire location in areas of rugged terrain — note the offset in the position of the Decker Fire thermal anomaly between the 2 satellites (the viewing angle of the fire from each satellite is about 53 degrees).

GOES-16 and GOES-17 Shortwave Infrared (3.9 µm) images, with topography [click to play animation | MP4]

GOES-16 and GOES-17 Shortwave Infrared (3.9 µm) images, with topography (highways are plotted in cyan) [click to play animation | MP4]

Eruption of Popocatépetl in Mexico

October 2nd, 2019 |

GOES-16

GOES-16 “Red” Visible (0.64 µm), Split Window (10.3 – 12.3 µm), Ash RGB, Dust RGB and SO2 RGB images [click to play animation | MP4]

A sequence of GOES-16 (GOES-East) “Red” Visible (0.64 µm), Split Window (10.3 – 12.3 µm), Ash RGB, Dust RGB and SO2 RGB images (above) revealed signatures of volcanic plumes from an eruption of Popocatépetl on 02 October 2019. According to the Volcanic Ash Advisory issued at 1323 UTC (below), the longer plume moving westward — which was clearly seen in the Visible imagery — extended to an altitude of 21,000 feet. The second volcanic plume moving northwestward — which exhibited subtle signatures in the Split Window and RGB images — extended to an altitude of 24,000 feet. Although neither the Split Window nor the RGB images showed strong volcanic cloud signatures, taken together they helped to confirm the presence and transport of the 2 separate plumes.

GOES-16 Split Window image with the text of the 1323 UTC Volcanic Ash Advisory [click to enlarge]

GOES-16 Split Window (10.3 – 12.3 µm) image showing the text of the 1323 UTC Volcanic Ash Advisory [click to enlarge]

The radiometrically-retrieved Volcanic Ash Height product from the NOAA/CIMSS Volcanic Cloud Monitoring site indicated a maximum height in the 5-7 km range for the westward-moving plume (below).

GOES-16 Volcanic Ash Height product [click to play animation | MP4]

GOES-16 Volcanic Ash Height product [click to play animation | MP4]

Fresh snow cover in Montana and Alberta

September 30th, 2019 |

GOES-16 Day Cloud Phase Distinction RGB images [click to play animation | MP4]

GOES-16 Day Cloud Phase Distinction RGB images [click to play animation | MP4]

Through breaks in the cloud cover, GOES-16 (GOES-East) Day Cloud Phase Distinction Red-Green-Blue (RGB) images on 30 September 2019 (above) showed the bright green signature of fresh snow cover across northern Montana and southern Alberta in the wake of a record-setting snowfall event that occurred during the previous 2-3 days (NWS Great Falls summary). Note that the surface air temperatures over the areas of fresh snow cover only rose into the upper 20s and low 30s F, in contrast to 40s F in adjacent areas with minimal or no snow cover — in fact, many locations set daily record low maximum temperatures.


GOES-16 Mid-level Water Vapor (6.9 µm) images from 0001 UTC on 28 September to 0901 UTC on 30 September (below) covered the duration of the winter storm — the circulation of an anomalously-deep mid-tropospheric low over the Pacific Northwest was evident, in addition to a long fetch of middle/high-level moisture from the southwestern US toward Montana. Another notable feature included widespread mountain waves over Colorado beginning on 29 September, which eventually extended downwind over western Nebraska/Kansas; Colorado had a peak wind gust of 81 mph during this event (WPC storm summary).

GOES-16 Mid-level Water Vapor images, with hourly plots of precipitation type [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images, with hourly plots of precipitation type [click to play animation | MP4]

===== 01 October Update =====

GOES-16 Day Cloud Phase Distinction and Day Snow-Fog RGB images [click to play animation | MP4]

GOES-16 Day Cloud Phase Distinction and Day Snow-Fog RGB images [click to play animation | MP4]

With less cloud cover on 01 October, a comparison of GOES-16 Day Cloud Phase Distinction and Day Snow-Fog RGB images (above) provided a better view of the areal coverage of snow cover. Note that while the Day Cloud Phase Distinction RGB (snow=green) produces “sharper” imagery — since it uses the higher spatial resolution of the 0.64 µm Visible data — the Day Snow-Fog RGB (snow=red) does a better job at highlighting thin supercooled cloud features (shades of white) over snow cover.  The combination of fresh snow cover, light winds and minimal cloudiness allowed Cut Bank to record the coldest official temperature in the US at +1ºF (although a couple of sites unofficially dropped below 0ºF).

In a toggle between GOES-16 Day Cloud Phase Distinction RGB and Topography images (below), note the darker blue gaps in snow cover in Montana and Alberta – with easterly/northeasterly winds during the snow event (Cut Bank | Havre | Great Falls), those areas experienced downslope flow which warmed the boundary layer air and minimized snow accumulation.

GOES-16 Day Cloud Phase Distinction RGB and Topography images [click to enlarge]

GOES-16 Day Cloud Phase Distinction RGB and Topography images [click to enlarge]

Hurricane Lorenzo in the Atlantic Ocean

September 26th, 2019 |

 

GOES-16 “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-16 (GOES-East) “Clean” Infrared Window (10.35 µm) images (above) showed Hurricane Lorenzo as it rapidly intensified from a Category 2 storm at 00 UTC to a Category 4 storm by 15 UTC (ADT | SATCON) on 26 September 2019.

A toggle between VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20 as viewed using RealEarth (below) provided a detailed view of the eye and eyewall region of Lorenzo at 1542 UTC and 1632 UTC. On the Suomi NPP Infrared image, note the transverse banding northwest of the eye, and a small packet of gravity waves southwest of the eye.

VIIRS True Color RGB and Infrared Window<em> (11.45 µm)</em> images from Suomi NPP and NOAA-20 [click to enlarge]

VIIRS True Color RGB and Infrared Window (11.45 µm) images from Suomi NPP (at 1542 UTC) and NOAA-20 (at 1632 UTC) [click to enlarge]

A DMSP-18 SSMIS Microwave (85 GHz) image from the CIMSS Tropical Cyclones site (below) revealed a well-defined eyewall wrapping around the southern, eastern and northern periphery of the eye.

DMSP-18 SSMIS Microwave (85 GHz) image at 1941 UTC [click to enlarge]

DMSP-18 SSMIS Microwave (85 GHz) image at 1941 UTC [click to enlarge]