Large-scale blowing dust event

April 10th, 2019 |

GOES-16 Split Window (10.3-12.3 µm) images [click to play animation | MP4]

GOES-16 Split Window (10.3-12.3 µm) images [click to play animation | MP4]

Strong winds — gusting as high as 77 mph in New Mexico and 88 mph in Texas — associated with a rapidly-intensifying midlatitude cyclone generated large plumes of blowing dust (originating from southeastern Arizona,southern New Mexico, northern Mexico and western Texas) on 10 April 2019. GOES-16 (GOES-East) Split Window (10.3-12.3 µm) images (above) helped to highlight the areas of blowing dust, which initially developed along and behind a cold front after 15 UTC.

GOES-16 Split Window (10.3-12.3 µm) images, with hourly plots of surface winds and gusts [click to play animation | MP4]

GOES-16 Split Window (10.3-12.3 µm) images, with hourly plots of surface wind barbs and gusts [click to play animation | MP4]

GOES-16 Split Window images with hourly plots of surface wind barbs and gusts (above) showed the distribution of strong winds across the region, while plots of the surface visibility (below) showed decreases to 1/4 mile at Deming, New Mexico, 1/2 mile at Lubbock, Texas and 4 miles at Altus, Oklahoma.

GOES-16 Split Window (10.3-12.3 µm) images, with hourly plots of surface visibility [click to play animation | MP4]

GOES-16 Split Window (10.3-12.3 µm) images, with hourly plots of surface visibility [click to play animation | MP4]

GOES-16 True Color Red-Green-Blue (RGB) images (below; courtesy of Rick Kohrs, SSEC) depicted the blowing dust as shades of tan to light brown. Willcox Playa was the source of the dust plume coming from southeastern Arizona. Note that the dust plume emanating from White Sands, New Mexico was lighter in appearance compared to the other tan/brown-colored areas of blowing dust — this is due to the white gypsum sand that comprises the surface of White Sands National Monument.

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 True Color RGB images [click to play animation | MP4]

250-meter resolution MODIS True Color RGB images from the MODIS Today site (below) provided a more detailed view of the plume streaming northeastward from its White Sands source. On the later Aqua image, dense tan-colored areas of blowing dust had developed below the thin higher-altitude veil of brighter gypsum aerosols that had earlier been lofted from White Sands.

MODIS True Color RGB images from Terra and Aqua [click to enlarge]

MODIS True Color RGB images from Terra and Aqua [click to enlarge]

A NOAA-20 True Color RGB image viewed using RealEarth is shown below. 19 UTC surface observations at 3 sites near White Sands included Las Cruces KLRU (visibility 3 miles, wind gusting to 46 knots), Alamogordo KALM (visibility 3 miles, wind gusting to 43 knots) and Ruidoso KSRR (visibility 5 miles, wind gusting to 55 knots). The strong winds and dense areas of blowing dust reducing surface visibility not only impacted ground transportation but also posed a hazard to aviation.

NOAA-20 True Color RGB image at 1928 UTC [click to enlarge]

NOAA-20 True Color RGB image at 1928 UTC [click to enlarge]

===== 11 April Update =====

In a larger-scale view of GOES-16 Split Window images (below), the yellow dust signature could be followed during the subsequent overnight hours and into the following day on 11 April, as the aerosols were being transported northeastward across the Upper Midwest. There were widespread reports and photos of dust residue on vehicles and tan/brown-colored snow in parts of Nebraska, Iowa, Minnesota and Wisconsin.

GOES-16 Split Window (10.3-12.3 µm) images [click to play animation | MP4]

GOES-16 Split Window (10.3-12.3 µm) images [click to play animation | MP4]

IDEA forward trajectories (below) — initialized from a cluster of elevated Aura OMI Aerosol Index points over Mexico, New Mexico and Texas — passed directly over areas of model-derived precipitation across the Upper Midwest, providing further support of precipitation scavenging of dust aerosols. Interestingly, a similar event of long range dust transport occurred on 10-11 April 2008.

IDEA forward trajectories initialized from a cluster of elevated Aqua MODIS Aerosol Optical Depth points over NM/TX [click to play animation]

IDEA forward trajectories initialized from a cluster of elevated Aqua MODIS Aerosol Optical Depth points over NM/TX [click to play animation]

HYSPLIT model 24-hour forward trajectories initialized at 3 locations — El Paso, Lubbock and Amarillo in Texas — showed a few of the likely dust transport pathways toward the Upper Midwest at 3 different levels (below).

HYSPLIT model forward trajectories initialized at El Paso, Lubbock and Amarillo, Texas [click to enlarge]

HYSPLIT model 24-hour forward trajectories initialized at El Paso, Lubbock and Amarillo, Texas [click to enlarge]

GOES-16 True Color RGB images from the AOS site (below) showed that some clouds across the Upper Midwest exhibited a subtle light brown hue at times.

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 True Color RGB images [click to play animation | MP4]

===== 12 April Update =====

GOES-16 Split Window (10.3-12.3 µm) images [click to play animation | MP4]

GOES-16 Split Window (10.3-12.3 µm) images [click to play animation | MP4]

GOES-16 Split Window (10.3-12.3 µm) images (above) showed that the yellow signature of dust aerosols aloft had wrapped all the way around the southern and eastern sectors of the occluded low on 12 April.

Ground-based lidar at the University of Wisconsin – Madison confirmed the presence of elevated levels of aerosol loading between the surface and 6 km.

Lidar aerosol class [click to enlarge]

Lidar aerosol class [click to enlarge]

Fires in the Plains

April 8th, 2019 |

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

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

GOES-16 (GOES-East) Shortwave Infrared (3.9 µm) images and the corresponding GOES-16 Fire Temperature product (above) showed the thermal signatures of widespread fires across the Great Plains (primarily in the Flint Hills of Kansas and Oklahoma) on 08 April 2019. Although fairly small and often relatively brief, some of these fires become quite hot — exhibiting Fire Temperature values as high as 2762 K (or 4512ºF) southwest of Cottonwood, Kansas at 2011 UTC. These fires were typical Springtime prescribed burns and agricultural fields being cleared for planting.

One fire southwest of Salina, Kansas began to exhibit a prominent 3.9 µm thermal anomaly after 22 UTC, attaining a peak infrared brightness temperature of 95.6ºC (or 204ºF); a closer view of that fire is shown using GOES-16 Shortwave Infrared images along with Fire Temperature, Fire Area and Fire Power products (below). Note that during much of the time (for example, at 2221 UTC) there were no Fire Temperature, Fire Area or Fire Power values processed for the hottest 3.9 µm fire pixel — this is because the fire was producing a thick smoke plume, and the smoke-filled (on Visible imagery) hot pixel was flagged by the GOES Fire Detection and Characterization Algorithm (FDCA) Cloud Mask as a “cloudy pixel”. Beginning in May 2019, an updated algorithm will begin to produce the Fire Power parameter for all types of fire pixel (Processed fire, Saturated fire, Cloud-contaminated fire, and High/Medium/Low-probability fires), but the Fire Temperature and Fire Size parameters will only be available for the Processed fire category.

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

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

A sequence of MODIS and VIIRS Shortwave Infrared (3.7 µm) images from the Aqua, Suomi NPP and NOAA-20 satellites (below) showed a more detailed view of the fire thermal signatures (black to yellow to red enhancement) during the 1.5 hours between 1822 and 2001 UTC.

Sequence of MODIS and VIIRS Shortwave Infrared (3.7 µm) images from 1822-2001 UTC [click to enlarge]

Sequence of MODIS and VIIRS Shortwave Infrared (3.7 µm) images from 1822-2001 UTC [click to enlarge]

Most of the small fires did not produce particularly large smoke plumes, but the density of the fires led to a rather large pall of smoke over the region as seen in GOES-16 “Red” Visible (0.64 µm) images (below). Note the smoke plume emanating from the fire southwest of Salina, Kansas (as previously discussed). Most of the smoke was dispersed above the boundary layer — but the surface visibility was reduced by smoke at sites such as Coffeyville, Chanute and Eureka in southeastern Kansas and Bartlesville in northeastern Oklahoma.

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

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

===== 09 April Update ====

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images [click to enlarge]

As some of the larger fires in southern Kansas continued burning into the night, their thermal signature could be seen in NOAA-20 VIIRS Shortwave Infrared (3.74 µm) image (darker gray to black pixels), along with their bright glow in the corresponding VIIRS Day/Night Band (0.7 µm) image at 0818 UTC or 3:18 am CDT (above). Note: the NOAA-20 images are incorrectly labeled as Suomi NPP.

Hurricane Force low off the US East Coast

April 2nd, 2019 |

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

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

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed a cluster of deep convection just to the north of the center of a rapidly-intensifying midlatitude cyclone (surface analyses) off the coast of North Carolina on 02 April 2019. In addition, convection was later seen developing along the north-south cloud band marking the leading edge of the cyclone’s cold front. The rapid deepening of this hurricane force low easily met the criteria of a bomb cyclone — its central pressure dropped 20 hPa in just 12 hours (from 1004 hPa at 18 UTC on 02 April to 984 hPa at 06 UTC on 03 April).

The primary convective cluster began to exhibit a large amount of lightning after 1830 UTC, as seen in plots of GOES-16 GLM Groups (below). To the east of this intensifying convection, one ship report at 18 UTC included winds from the east at 50 knots — in addition, a moderate to heavy shower of hail was being reported and their surface visibility was restricted to 1.25 miles (18 UTC surface analysis).

GOES-16 "Red" Visible (0.64 µm) images, with GLM Groups and surface wind gusts plotted in red [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) images, with GLM Groups and surface wind gusts plotted in red [click to play animation | MP4

There were several factors pointing to the development of a sting jet with this storm, as discussed here and here. GOES-16 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (below) revealed distinct areas of warming/drying (darker shades of yellow to orange) that possibly highlighted rapidly-descending air associated with a sting jet (for example, on the 1946 UTC images).

GOES-16 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images [click to play animation | MP4]

GOES-16 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images [click to play animation | MP4]

After 23 UTC, GOES-16 “Clean” Infrared Window (10.3 µm) images (below) portrayed the formation of a large eye-like feature indicative of a warm seclusion (00 UTC surface analysis). Lightning activity remained very high during that time.

GOES-16 "Clean" Infrared Window (10.3 µm) images [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play animation | MP4]


A comparison between 1-km resolution Terra MODIS Infrared Window (11.0 µm) imagery at 0237 UTC with an Aqua MODIS Sea Surface Temperature product at 1755 UTC on the following afternoon (below) showed that the storm intensified and formed the large eye-like feature over the northern portion of the axis of warmest Gulf Stream water (where SST values were in the 70-76ºF range).

Terra and Aqua MODIS Infrared Window (11.0 µm) images from 0237 UTC and 0649 UTC, along with the Aqua MODIS Sea Surface Temperature product at 1755 UTC [click to enlarge]

Terra MODIS Infrared Window (11.0 µm) image at 0237 UTC, along with the 1755 UTC Aqua MODIS Sea Surface Temperature product [click to enlarge]

With a nighttime overpass of the NOAA-20 satellite at 0651 UTC, the eye-like feature was apparent in VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) images (below). Although the Moon was in the Waning Crescent phase (at only 8% of Full), that illumination with the aid of airglow was sufficient to provide a useful “visible image at night” using the Day/Night Band; a streak of bright pixels was due to intense lightning activity within a line of thunderstorms just ahead of the cold front. Note: the NOAA-20 images are incorrectly labeled as Suomi NPP.

NOAA-20 VIIRS Infrared Window (11.45 µµ) and Day/Night Band (0.7 µm) images [click to enlarge]

NOAA-20 VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) images, with an overlay of the 06 UTC surface analysis [click to enlarge]

Tornado outbreak in Alabama and Georgia

March 3rd, 2019 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with SPC storm reports plotted in red [click to play animation | MP4]

An outbreak of severe thunderstorms occurred during the afternoon hours of 03 March 2019, which produced large hail, damaging winds and tornadoes (SPC storm reports). 1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed the development of numerous thunderstorms along and ahead of an advancing cold front (surface analyses); many of those storms exhibited well-defined overshooting tops. Tornado track summaries for Alabama and Georgia are available from NWS Birmingham and NWS Atlanta.

The corresponding GOES-16 “Clean” Infrared Window (10.3 µm) images are shown below. Cloud-top infrared brightness temperatures cooled to around -70ºC (darker black enhancement) with many of the stronger storms — judging from rawinsonde data from Birmingham, Alabama (at 12 UTC) and Peachtree City, Georgia (at 18 UTC), this roughly corresponded to an air parcel rising significantly past the tropopause to an altitude of at least 15 km.

GOES-16 "Clean" Infrared Window (10.3 µm) images, with SPC storm reports plotted in red [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.3 µm) images, with SPC storm reports plotted in cyan [click to play animation | MP4]

An area which included western Lee County (located in far eastern Alabama, adjacent to the Georgia border) was highlighted by a SPC MCD that was issued at 1900 UTC. Beginning about an hour later, 2 large tornadoes producing EF2 to EF4 damage moved across southern Lee County — initially beginning around 2000 UTC, then again beginning around 2050 UTC — and the formation of prominent overshooting tops was evident in GOES-16 Visible and Infrared imagery (below). Station identifier KAUO in Lee County is the Auburn-Opelika Airport. (side note: later, around 2204 UTC, the Weedon Field Airport KEUF METAR site to the south of Lee County was directly hit by a separate EF2 tornado, and rendered inoperative)

GOES-16 "Clean" Infrared Window (10.3 µm) images, with SPC storm reports plotted in cyan [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm, left) and “Clean” Infrared Window (10.3 µm, right) images, with SPC storm reports plotted in red/cyan — Lee County, Alabama is outlined in solid blue, with other affected counties in dashed blue [click to play animation | MP4]

In a plot of the GOES-16 “Clean” Infrared Window coldest brightness temperature for the EF4-tornado storm’s overshooting top as it moved from Macon/Lee Counties in Alabama to Muscogee/Harris/Talbot Counties in Georgia (below), 3 distinct periods of cooling/warming occurred — with the warming indicative of a temporary collapse of the overshooting top pulse. The first (and largest-magnitude) cold/warm pulse (-70.3ºC to -65.6ºC) occurred from 1953-1959 UTC — just prior to the beginning of the Beauregard-Smiths Station EF4 Tornado at 2000 UTC. A second cold/warm pulse (-70.8ºC to -66.9ºC) occurred from 2006-2012 UTC, with a third (-70.0ºC to -66.0ºC) from 2015-2022 UTC. At 2029 UTC the long-track tornado then crossed into Muscogee County in Georgia, producing EF3 damage.

Plot of the coldest GOES-16

Plot of the coldest GOES-16 “Clean” Infrared Window (10.3 µm) overshooting top brightness temperatures, 2040-2115 UTC [click to enlarge]

The NOAA/CIMSS ProbSevere product (below) displayed a high tornado probability for the cells that approached Lee County, as discussed by the Hazardous Weather Testbed. The ProbSevere model incorporates GOES-derived Normalized vertical growth rate and Cloud-top glaciation rate as 2 of its predictors.

MRMS MergedReflectivity composite, with countours of the ProbSevere parameter [click for link to HWT blog post]

MRMS MergedReflectivity composite, with countours of the ProbSevere parameter [click for link to HWT blog post]

A comparison of Aqua MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images along with the Total Precipitable Water derived product at 1836 UTC (below) showed that a few large thunderstorms had begun to develop by that time; TPW values were as high as 43 mm (1.7 inches) over far southwestern Georgia.

Aqua MODIS Visible (0.65 µm), Infrared Window (11.0 µm) and Total Precipitable Water images at 1836 UTC [click to enlarge]

Aqua MODIS Visible (0.65 µm), Infrared Window (11.0 µm) and Total Precipitable Water images at 1836 UTC [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image, with plots of available NUCAPS soundings [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image, with plots of available NUCAPS soundings [click to enlarge]

An overpass of the Suomi NPP satellite around 1850 UTC provided NUCAPS soundings in non-cloudy areas (above). One of the Good quality (green) NUCAPS soundings in the pre-storm environment was located over southwestern Georgia (circled in magenta) — it showed a Most Unstable CAPE value of 1264 J/kg, with a Lifted Index value of -4 (below).

NUCAPS sounding over southwestern Georgia [click to enlarge]

NUCAPS sounding over southwestern Georgia [click to enlarge]

The GOES-16 All Sky CAPE product (below) showed a trend of destabilization across southern Alabama and southern Georgia during the 5 hours leading up to the fatal tornadoes in Lee County AL.

GOES-16 All Sky CAPE product [click to play animation]

GOES-16 All Sky CAPE product [click to play animation]

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

Comparison between Terra MODIS True Color and False Color RGB images on 24 February and 05 March 2019 [click to enlarge]

Comparison between Terra MODIS True Color and False Color RGB images on 24 February and 05 March 2019 [click to enlarge]

A toggle between before/after (24 February / 05 March 2019) Terra MODIS True Color and False Color Red-Green-Blue (RGB) images from the MODIS Today site (above) showed subtle evidence of portions of a tornado damage path — presumably that of the EF4 tornado that began in/near Lee County, Alabama and ended in far western Georgia. Click an additional time on the image to view at full magnification.

Sentinel-2 True Color images (below) provided a higher-resolution view of the tornado damage path. Imagery courtesy of Sentinel Hub.

Sentinel-2 True Color RGB images from 24 February and 06 March [click to enlarge]

Sentinel-2 True Color RGB images from 24 February and 06 March [click to enlarge]