Even though the South Sandwich Islands are near the limb of the GOES-16 (GOES-East) view, Near-Infrared “Cloud Particle Size” (2.24 µm) images (above) were able to display a long volcanic plume (brighter shades of white) originating from Mount Michael on Saunders Island during the daylight hours on 12 March 2020. In addition, smaller/shorter volcanic plumes could also be seen originating from a few of the smaller islands just to the north of Saunders Island. The volcanic plumes were more reflective (brighter white) because they were comprised of smaller droplets compared to the expansive stratus/stratocumulus clouds over the South Atlantic Ocean.

The smaller cloud particles of the volcanic plume were also more efficient reflectors of incoming solar radiation, thus appearing warmer (darker shades of gray) in GOES-16 Shortwave Infrared (3.9 µm) images (below).

2 days later, southerly/southwesterly winds interacting with the rugged terrain of the islands created von Kármán vortex streets downwind (north-northeast) of some of the islands (especially Montagu Island, the largest of the South Sandwich chain) — VIIRS True Color Red-Green-Blue (RGB) images from NOAA-20 and Suomi NPP  as visualized using RealEarth (below) provided a detailed view of these vortices.

In spite of the lower spatial resolution and large satellite viewing angle, the von Karman vortices could also be seen in GOES-16 “Red” Visible (0.64 µm) images (below).

 

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images along with 5-minute Fire Power and Fire Temperature products (which are components of the GOES Fire Detection and Characterization Algorithm (SHyMet | ATBD) showed the rapid northeastward run (as fast as 103 feet per minute) of the 13,000 acre “Beaver Fire” (also known as the “412 Fire”) in the Oklahoma Panhandle on 07 March 2020. An elevated thermal signature on Shortwave Infrared imagery first began to appear southwest of Beaver, OK around 1546 UTC  — and 3.9 µm infrared brightness temperatures eventually peaked around 139ºC. Maximum Fire Power and Fire Temperature values exceeded 3100 MW and 2900 K, respectively. Fire Warnings were issued, with residents of Beaver and Forgan being advised to evacuate as the fire rapidly approached. In Visible imagery, the dark signature of a long, narrow vegetation burn scar was evident — and pyrocumulus clouds were seen developing over the fire.

@NWSDodgeCity @NWSAmarillo photos taken at 4:49 4:53 and 4:55 PM about 4 miles N of the KS-OK State line. Best view of the pyroCu I’ve had. pic.twitter.com/j2nQyGqd6a

— C W (@wilscale) March 7, 2020

Extreme fire behavior was aided by anomalously-strong winds across the southern Plains. The peak wind gust at Beaver, Oklahoma was 46 mph; south of the fire, surface winds were gusting to 43 mph at Perryton (in far the northern Texas Panhandle), and west of the fire winds gusted to 42 mph at Guymon (in the Oklahoma Panhandle). A large-scale animation of 1-minute GOES-16 Visible images from the AOS site (below) indicated that the smoke plume was transported northeastward across Kansas and eventually moved over south-central Nebraska. Smoke reduced the surface visibility to 6 miles at Dodge City as it moved across southwestern Kansas.

Shortwave Infrared images from MODIS (3.7 µm) and VIIRS (3.74 µm) (below) displayed three snapshots of the 10-15 mile long thermal anomaly (elongated cluster of black pixels) associated with the wildfire.

===== 08 March Update =====

During the subsequent overnight hours, a comparison of NOAA-20 VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images at 0857 UTC or 3:57 am local time (above) revealed the dark southwest-to-northeast oriented burn scar, with isolated small fires still burning along the northwestern periphery of the burn scar. Note: the NOAA-20 images are incorrectly labelled as Suomi NPP.

===== 09 March Update =====

A toggle between a GOES-16 Land Surface Temperature product and the corresponding Visible image (above) showed the fire burn scar at 2101 UTC on 09 March. Land Surface Temperature values were 10ºF warmer within the burn scar (middle 80s F, shades of yellow to orange) compared to areas immediately adjacent to the burn feature.

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GOES-17 (GOES-West) Mid-level Water Vapor (6.9 µm) and Air Mass RGB images (above) depicted a rapidly intensifying Storm Force low (surface analyses) moving from the North Pacific Ocean toward the Alaska Panhandle on 04 March 2020. A comparison of GOES-17 Mid-level Water Vapor and Air Mass RGB images with NAM40 PV1.5 pressure (below) showed that the Dynamic Tropopause — taken to be the pressure of the Potential Vorticity 1.5 surface — had descended to the 650 hPa pressure level in the vicinity of the low at 1200 UTC. The deeper red hues on Air Mass RGB imagery also indicated the presence of ozone-rich stratospheric air within the atmospheric column as the tropopause lowered in the vicinity of the rapidly-deepening low pressure.

1-minute Mesoscale Domain Sector GOES-17 “Red” Visible (0.64 µm) images (below) revealed mesovortices within the core of the large low pressure system.

===== 05 March Update =====

On the following day, GOES-17 “Clean” Infrared Window (10.35 µm) mages (above) showed clouds associated with the Storm Force low as it moved slowly northward near the coast of the Alaska Panhandle (surface analyses). The storm prompted a wide variety of advisories, including a High Wind Warning for the Juneau area and a Blizzard Warning for the Skagway area.

Strong arctic outflow event ongoing across the N Panhandle. Gale and storm force winds + freezing spray in many of the northern marine areas. Blizzard warning for Klondike Highway, and High wind warning for downtown Juneau and Douglas. #akwx pic.twitter.com/rEPlhPeKBc

— NWS Juneau (@NWSJuneau) March 5, 2020

GOES-17 True Color Red-Green-Blue (RGB) images created using Geo2Grid (below) revealed several plumes of airborne glacial silt drifting over the Gulf of Alaska, lofted by a strong offshore gap winds. A ship near Prince William Sound reported blowing dust at 18 UTC. Also seen in the images was the northwestward drift of ice into Cook Inlet and Turnagain Arm as high tide approached.

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When GOES-15 stopped sending data, IFR Probability fields based on GOES-15 ceased being sent over LDM to users. CIMSS is now sending GOES-17 IFR Probability fields (shown in a toggle above with the Night Fog Brightness Temperature Difference field) via the EXP LDM feed from CIMSS.  Particular strengths of IFR Probability fields include giving a useful low cloud signal below high clouds (as over the western Olympic Peninsula in Washington) and differentiating between elevated stratus and fog, as in the northern Willamette Valley in Oregon.

Note that the Brightness Temperature Difference field shows artifacts related to GOES-17’s poorly-functioning Loop Heat Pipe.  Those artifacts are rapidly diminish day-to-day in early March as GOES-17 enters eclipse season.  Blog posts that discuss GOES-17 IFR Probability are available <a href=”https://fusedfog.ssec.wisc.edu/?cat=36″>here</a>.

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