Blowing dust in northeastern Arkansas

April 12th, 2016

GOES-13 Visible (0.63 um) images [click to play animation]

GOES-13 Visible (0.63 um) images [click to play animation]

Strong southwesterly winds (gusting as high as 39 knots or 45 mph) created areas of blowing dust that reduced visibility to near zero and caused 2 incidents of multiple-vehicle accidents (NWS Local Storm Reports) near Portia in northeastern Arkansas on 10 April 2016. GOES-13 (GOES-East) Visible (0.63 um) images (above) showed the faint hazy signature of a few narrow plumes of blowing dust moving northeastward, one of which moved across Lawrence County and between Portia (denoted by the red * symbol) and Walnut Ridge (station identifier KARG). The blowing dust plumes are perhaps a bit easier to see on these images without county outlines and highways, though they are still somewhat difficult to identify with the patches of thin cirrus and contrails drifting from west to east overhead. Video of the conditions on the ground can be seen here.

Time series plots of surface data for Walnut Ridge (KARG) located just to the northeast and Newport (KM19) located farther to the south-southwest are shown below. Surface reports indicated that the visibility was reduced to less than 1 mile at 1756 UTC at Newport, and less than 3 miles at 1735 UTC at Walnut Ridge.

Time series plot of surface data for Walnut Ridge, Arkansas [click to enlarge]

Time series plot of surface data for Walnut Ridge, Arkansas [click to enlarge]

Time series plot of surface data for Newport, Arkansas [click to enlarge]

Time series plot of surface data for Newport, Arkansas [click to enlarge]

On the previous day, a comparison of the 1849 UTC Aqua MODIS Visible (0.65 µm) image and the corresponding Normalized Difference Vegetation Index (NDVI) product (below) showed that there were many areas upwind (to the southwest of) Portia and Walnut Ridge — in both southern Lawrence and northern Jackson counties — that exhibited low NDVI values (tan color enhancement), indicative of recently-plowed and/or unplanted agricultural fields within that part of the Mississippi Alluvial Plain. It is possible that field plowing activities on that windy day may have been the catalyst for the some of the  blowing dust plumes.

Aqua MODIS Visible (0.65 um) and Normalized Difference Vegetation Index (NDVI) product [click to enlarge]

Aqua MODIS Visible (0.65 um) and Normalized Difference Vegetation Index (NDVI) product [click to enlarge]

Similarly, a comparison of the 1849 UTC Aqua MODIS NDVI and Land Surface Temperature (LST) products (below) showed that the land surface in areas with less vegetation were warming up more quickly, with some LST values in excess of 90º F (darker red enhancement).

Aqua MODIS Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature products [click to enlarge]

Aqua MODIS Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature products [click to enlarge]

Large grass fire in Oklahoma and Kansas

March 23rd, 2016

GOES-13 Shortwave Infrared (3.9 µm) images, with surface reports [click to play animation]

GOES-13 Shortwave Infrared (3.9 µm) images, with surface reports [click to play animation]

A grass fire (now referred to as the “Anderson Creek fire”) was first reported in western Woods County, Oklahoma around 2245 UTC or 5:45 PM local time on 22 March 2016. “Hot spot” signatures (yellow to red to black pixels) on GOES-13 Shortwave Infrared (3.9 µm) images (above) showed that the fire proceeded to make a very fast run to the north during the overnight hours, crossing over the Kansas border into Comanche and Barber Counties. The fire eventually jumped Highway 160  — which runs west-to-east across the northern portion of those 2 counties (highways are plotted in violet) — forcing it to be closed for several hours. As of the afternoon of 23 March, the fire was reported to have burned at least 72,000 acres; on that evening, the mayor of Medicine Lodge, Kansas (station identifier KP28) called for a voluntary evacuation as the fire began to approach the edge of the town. Note that GOES-13 (GOES-East) had been placed into Rapid Scan Operations (RSO) mode specifically to monitor the extremely critical fire risk, and was providing images as frequently as every 5-7 minutes.

A nighttime comparison of Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images at 0823 UTC or 3:23 AM local time (below) showed the hot spots and the bright glow of the large and very hot fire.

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

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

A sequence of Shortwave Infrared images from POES AVHRR, Terra/Aqua MODIS, and Suomi NPP VIIRS (below) provided higher-resolution snapshots of the rapid northward progression of the fire during the overnight hours (aided by strong southerly winds), followed by an east/northeastward expansion during the subsequent daylight hours (driven by a switch to strong southwesterly winds after the passage of a dryline).

POES AVHRR (3.7 µm), Terra/Aqua MODIS (3.7 µm), and Suomi NPP VIIRS (3.74 µm) Shortwave Infrared images [click to enlarge]

POES AVHRR (3.7 µm), Terra/Aqua MODIS (3.7 µm), and Suomi NPP VIIRS (3.74 µm) Shortwave Infrared images [click to enlarge]

GOES-13 Visible (0.63 µm) images (below) revealed a large increase in smoke produced by the fire during the day on 23 March. This smoke was drawn cyclonically northeastward then northward around the circulation of a storm system that was deepening over western Kansas. Afternoon wind gusts were as high as 61 mph in Newton, Kansas. Downstream of the fire source region, smoke reduced the surface visibility to 4 miles at Hutchinson, Kansas (station identifier KHUT) at 21 UTC or 4 PM local time, and Wichita (station identifier KICT) reported a visibility of 1.75 miles at 00 UTC or 7 PM local time; ash falling from the smoke aloft caused the surface air quality in Wichita to briefly deteriorate to unhealthy levels.

GOES-13 Visible (0.63 µm) images, with surface reports [click to play animation]

GOES-13 Visible (0.63 µm) images, with surface reports [click to play animation]

In the early afternoon at 1748 UTC or 12:48 PM local time, a pilot report near the northern flank of the fire (below) indicated that the tops of the smoke towers were already rising to altitudes of 8000 to 11000 feet above ground level.

GOES-13 Visible (0.63 µm) image, with surface reports and a pilot report of smoke altitude [click to enlarge]

GOES-13 Visible (0.63 µm) image, with surface reports and a pilot report of smoke altitude [click to enlarge]

It is of interest to note that a similar (albeit smaller) grass fire spread rapidly northward from Oklahoma into Kansas, one county to the west and about one month earlier: the Buffalo fire. That event had the benefit of Super Rapid Scan Operations of GOES-14, which provided imagery at 1-minute intervals. The ABI instrument on the GOES-R satellite will be capable of providing 1-minute images over 2 pre-defined mesoscale sectors.

===== 24 March Update =====

Anderson Creek Fire perimeter map [click to enlarge]

Anderson Creek Fire perimeter map [click to enlarge]

A map of the Anderson Creek Fire perimeter (above) was issued by the Oklahoma Forestry Services at 1642 UTC or 11:42 AM local time. At that time, an estimated 397,420 acres (621 square miles) had been burned — which makes it the largest wildfire on record for the state of Kansas.

A comparison of Suomi NPP VIIRS true-color and false-color Red/Green/Blue (RGB) images from the SSEC RealEarth site (below) showed the extent of the burn scar, with smoke plumes drifting south-southeastward from 2 small areas of fires that were still actively burning at 2106 UTC or 4:06 PM local time. As discussed above, it can be seen that the fire crossed (and forced the closure of) US Highway 160 between Coldwater and Medicine lodge, and came very close to the town of Medicine Lodge.

Suomi NPP VIIRS true-color and false-color images [click to enlarge]

Suomi NPP VIIRS true-color and false-color images [click to enlarge]

===== 25 March Update =====

Suomi NPP VIIRS Day/Night Band (0.7 µm) image [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image [click to enlarge]

With ample illumination from the Moon (in the Waning Gibbous phase, at 98% of Full), the contrast between the dark Anderson Creek fire burn scar and the lighter surrounding grassland was very apparent on a Suomi NPP VIIRS Day/Night Band (0.7 µm) image at 0742 UTC or 2:42 AM local time. This example demonstrates the “visible image at night” capability of the VIIRS Day/Night Band.

GOES-14 SRSO-R: Return flow of Gulf of Mexico moisture in eastern Texas; blowing dust and a wildfire in western Texas

February 1st, 2016

GOES-14 Visible (0.63 µm) images, with surface observations [click to play MP4 animation]

GOES-14 Visible (0.63 µm) images, with surface observations [click to play MP4 animation]

Day 1 of the 01-25 February 2016 test period of GOES-14 Super Rapid Scan Operations for GOES-R (SRSO-R) revealed some interesting features across the state of Texas. During the morning hours, the northward “return flow” of moisture from the Gulf of Mexico could be seen in the form of widespread fog and low stratus across the eastern part of the state on 1-minute interval GOES-14 Visible (0.63 µm) images (above; also available as a large 83 Mbyte animated GIF). Surface reports showed that dew point temperatures were as high as the 60s F along and just inland of the coast. GOES-13 derived products such as the MVFR Probability, LIFR Probability, and Low Cloud Thickness (FLS product training) showed the northward motion of the fog and low stratus during the preceding overnight hours.

During the afternoon hours, GOES-14 Visible (0.63 µm) images (below; also available as a large 91 Mbyte animated GIF) revealed the hazy signature of areas of blowing dust across southwest Texas, both ahead of and also in the wake of a cold frontal passage (surface analyses). Much of the blowing dust ahead of the cold front originated from dry lake beds in northern Mexico, which was then transported northeastward across Texas by strong southwesterly winds (an enhanced visible MP4 animation which shows the blowing dust better is available here). Blowing dust along and behind the cold front restricted the surface visibility to 1.0 miles at Big Spring (KBPG) and 2.5 miles at Midland (KMAF). Also note that early in the animation — beginning at 1800 UTC — there were small convective bands moving northeastward over the El Paso area, which produced light to moderate accumulating snow that reduced surface visibility to 1.0 miles at El Paso and Biggs Army Air Field (KBIF), and 2.0 miles at Ciudad Juarez, Mexico (MMCS).

GOES-14 Visible (0.63 µm) images, with surface reports [click to play MP4 animation]

GOES-14 Visible (0.63 µm) images, with surface reports [click to play MP4 animation]

GOES-14 Shortwave Infrared (3.9 µm) images (below; also available as a large 52 Mbyte animated GIF) showed the “hot spot” signature (darker black to red pixels) associated with a large grass fire which developed in the Big Bend National Park area, beginning around 2300 UTC. The hot spot was seen to diminish not long after the arrival of cooler air (lighter shades of gray) behind the cold front. Surface air temperatures were quite warm in Texas ahead of the cold front, with daytime highs of 91º F at Del Rio (KDRT)  and 95º F — the highest temperature recorded for the day in the lower 48 states — farther to the southeast at Cotulla.

GOES-14 Shortwave Infrared (3.9 µm) images [click to play MP4 animation]

GOES-14 Shortwave Infrared (3.9 µm) images [click to play MP4 animation]

GOES-14 Water Vapor (6.5 µm) images (below; also available as a large 57 Mbyte animated GIF) showed a broad ascending belt of moisture curving cyclonically over central and eastern Colorado, where moderate snow and significant accumulations were occurring at a number of locations.

GOES-14 Water Vapor (6.5 µm) images, with surface weather symbols [click to play MP4 animation]

GOES-14 Water Vapor (6.5 µm) images, with surface weather symbols [click to play MP4 animation]

A blog post discussing this ascending belt of moisture in more detail can be found here; a YouTube animation of GOES-14 Infrared Window (10.7 µm) images is available here.

===== 02 February Update =====

GOES-14 Shortwave Infrared (3.9 µm) images [click to play MP4 animation]

GOES-14 Shortwave Infrared (3.9 µm) images [click to play MP4 animation]

During the subsequent overnight  hours, an undular bore developed along and just ahead of the advancing cold front, as seen in GOES-14 Shortwave Infrared (3.9 µm) images (below; also available as a large 107 Mbyte animated GIF). A detailed view of the undular bore was also captured at 0859 UTC (3:59 AM local time) on Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images (below).

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Smog and poor air quality in Beijing, China

November 30th, 2015

Suomi NPP VIIRS true-color images [click to play animation]

Suomi NPP VIIRS true-color images [click to play animation]

The sequence of 5 daily Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images shown above are centered on Beijing in northeastern China — these images (viewed using RealEarth) showed the transition from the Beijing area being sunny and snow-covered on 26 November to enshrouded in dense smog on 30 November 2015. The smog exhibited a distinct gray-colored appearance, in contrast to the brighter white clouds and snow cover. Much of this smog was driven by the burning of coal, both on a local level and by regional power plants (as discussed in this Capital Weather Gang blog post).

The corresponding daily time series plots of surface weather data at Beijing Capital International Airport (below) revealed that the surface visibility remained below 1.0 statute miles for extended periods. Although not indicated on the 26 November plot, the surface visibility began at 19 statute miles on that day, before the wind speeds became 4 knots or less beginning at 10 UTC and the visibility eventually began to decrease.

Daily time series plots of Beijing surface data [click to play animation]

Daily time series plots of Beijing surface data [click to play animation]