Hail damage to Delta Flight 1889 over Nebraska

August 7th, 2015 |

GOES-13 Sounder Lifted Indices [click to play animation]

GOES-13 Sounder Lifted Indices [click to play animation]

Hail associated with a line of rapidly developing thunderstorms near the borders of Kansas, Nebraska and Colorado heavily damaged Delta Flight 1889 bound from Boston to Salt Lake City, forcing an emergency landing in Denver (media report). An excellent blog post on the radar presentation of the system is here. What did the satellite data show? GOES Sounder Derived Product Image (DPI) values of Lifted Index (LI), above, (realtime images available here) showed instability over the High Plains of Colorado throughout the day. At 2000 UTC, for example, values greater than -8º C prevailed (subsequent cloud development prevented the retrieval of LI values using the Sounder). GOES Sounder DPI of Convective Available Potential Energy (CAPE), below, (realtime images available here) also indicated strong destabilization during the late afternoon (1600, 1800 and 2000 UTC are shown in the animation). The 08 August/00 UTC rawinsonde report from North Platte, Nebraska had LI and CAPE values of -5ºC and 1592 J/kg, respectively.

GOES Sounder Convective Available Potential Energy (CAPE), 1600 - 2000 UTC 7 August 2015  [click to enlarge]

GOES Sounder Convective Available Potential Energy (CAPE), 1600 – 2000 UTC 7 August 2015 [click to enlarge]

LAP (Legacy Atmospheric Profiles) from GOES-13 (from here) also showed strong instability in between extensive cloud cover: the imagery at 1600 UTC on 7 August for CAPE and LI is shown below.

GOES-13 LAP estimates of Lifted Index (LI) and Convective Available Potential Energy (CAPE), 1600 UTC 7 August 2015  [click to enlarge]

GOES-13 LAP estimates of Lifted Index (LI) and Convective Available Potential Energy (CAPE), 1600 UTC 7 August 2015 [click to enlarge]

Given the instability present, rapid thunderstorm development should not surprise (the region was under a Severe Thunderstorm Watch, and a Mesoscale Convective Discussion had been issued specifically mentioning the possibility of severe hail). The visible animation from GOES-13, below, from 1900 UTC on 7 August through 0145 UTC on 8 August, showed rapid convective growth, and the damaging convective cell is quite apparent growing northward over northwestern Kansas at the end of the animation.

GOES-13 Visible imagery (0.63 µm) 1900 UTC 7 August - 0145 UTC 8 August [click to animate]

GOES-13 Visible imagery (0.63 µm) 1900 UTC 7 August – 0145 UTC 8 August [click to animate]

A slower animation of GOES-13 visible images from 0045-0130 UTC is shown below.

GOES-13 Visible imagery (0.63 µm) 0045 UTC 8 August - 0130 UTC 8 August [click to animate]

GOES-13 Visible imagery (0.63 µm) 0045 UTC 7 August – 0130 UTC 8 August [click to animate]

GOES-15 Visible imagery (0.63 µm) 1900 UTC 7 August - 0145 UTC 8 August [click to animate]

GOES-15 Visible imagery (0.63 µm) 1900 UTC 7 August – 0145 UTC 8 August [click to animate]

GOES-15 also viewed the rapid development of convection. The animation from 1900 UTC on 7 August 2015 through 0145 UTC on 8 August is shown above; the animation from 0000 UTC through 0145 UTC is shown below. Convective development over northwest Kansas was racing northward.

GOES-15 Visible imagery (0.62 µm) 1900 UTC 7 August - 0145 UTC 8 August [click to enlarge]

GOES-15 Visible imagery (0.62 µm) 0000 UTC 8 August – 0145 UTC 8 August [click to enlarge]

GOES-13 Infrared (10.7 µm) brightness temperatures confirmed the quick growth of the convection. The animation below showed strong cooling starting around 0115 UTC in extreme northwest Kansas. Coldest brightness temperatures at 0100 UTC (200.2 K or -73ºC) dropped to 196.2 K (-77ºC) at 0115 UTC, then to 194.0 K (-79ºC) at 0130 UTC, 192.8 (-80.4ºC) at 0145 and 192.2 K (about -81ºC!) at 0200 UTC. The rocking animation at bottom testifies to how quickly the developing convection was able to close the gap in convection through which the aircraft was attempting to fly.

GOES-13 Infrared imagery (10.7 µm) 0015 UTC 8 August - 0215 UTC 8 August [click to animate]

GOES-13 Infrared imagery (10.7 µm) 0015 UTC 8 August – 0215 UTC 8 August [click to animate]

Rocking animation of GOES-13 Infrared imagery (10.7 µm) 0015 UTC 8 August - 0215 UTC 8 August [click to enlarge]

Rocking animation of GOES-13 Infrared imagery (10.7 µm) 0015 UTC 8 August – 0215 UTC 8 August [click to enlarge]

The side-by-side comparisons shown below of GOES-15 (left) and GOES-13 (right) 10.7 µm Infrared and 0.63 µm Visible images also help to demonstrate the value of more frequent images for monitoring the rapid development of such features. GOES-15 was in Rapid Scan Operations (RSO) mode, providing up to 10 images every hour (at :00, :11, :15, :22, :30, :41, :45, :52, :55, and :57), while GOES-13 was in Routine Scan mode, providing up to 4 images every hour (at :00, :15, :30. and :45). Unfortunately, there were 30-minute gaps in both GOES-15 (between 0030 and 0100 UTC) and GOES-13 (between 0015 and 0045 UTC) during the time that the new line of thunderstorms began to rapidly build northward across far northwestern Kansas, between the 2 pre-existing areas of thunderstorm activity.

GOES-15 (left) and GOES-13 (right) 10.7 µm Infrared images [click to play animation]

GOES-15 (left) and GOES-13 (right) 10.7 µm Infrared images [click to play animation]

GOES-15 (left) and GOES-13 (right) 0.63 µm Visible images [click to play animation]

GOES-15 (left) and GOES-13 (right) 0.63 µm Visible images [click to play animation]

In addition to the animated GIFs, MP4 versions of the Infrared and Visible images are available here and here.

The flight positions of Delta 1889 are superimposed on a composite animation of GOES-13 Infrared (10.7 µm)and Goodland, Kansas radar reflectivity, below (courtesy of Rick Kohrs, SSEC).

Delta Flight 1889 position, GOES-13 Infrared images, and Goodland, Kansas radar reflectivity [click to play QuickTime movie]

Delta Flight 1889 position, GOES-13 Infrared images, and Goodland, Kansas radar reflectivity [click to play QuickTime movie]

Typhoon Soudelor approaches Taiwan

August 7th, 2015 |
COMS-1 10.8 µm Infrared imagery (click to play animation)

COMS-1 10.8µm Infrared imagery (click to play animation)

Imagery from the Korean COMS-1 satellite, above, shows Category 3 Typhoon Soudelor approaching the island of Taiwan. The eye appearance becomes ragged at the end of the animation, suggesting entrainment of dry air into the center of the Typhoon. Although Sea Surface Temperatures are warm (image taken from here), strengthening before landfall is not forecast. Life-threatening flooding is likely as the circulation and moisture associated with Soudelor interact with the high terrain on the island of Taiwan (Total Precipitable Water animation from MIMIC).

Suomi NPP overflew Soudelor during the morning of the 7th (1709 UTC on 6 August), and the half-moon illumination allowed the VIIRS Day/Night Band to show impressive outflow in the northern semi-circle of the storm; the 11.45 µm Infrared image, however, shows few cold cloud tops just to the north of the eye.

Suomi NPP VIIRS Day/Night Band Visible  (0.70 µm) and Infrared (11.45 µm)  images, 1709 UTC 6 August 2015 (click to enlarge)

Suomi NPP VIIRS Day/Night Band Visible (0.70 µm) and Infrared (11.45 µm) images, 1709 UTC 6 August 2015 (click to enlarge)

A closer view of the eye of Typhoon Soudelor is shown below.

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

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

The 16-channel animation from Himawari-8 AHI, below, at half-hour time steps from 0000 through 1230 UTC on 7 August, shows plain evidence of dry air at mid-levels increasing with time, first northeast of the storm and later west of the storm (especially in the ‘water vapor’ channels: 6.2 µm, 6.9 µm and 7.3 µm).

All 16 Himawari-8 AHI channels, 0000-1230 UTC on 7 August, wavelengths as indicated (click to animate)

All 16 Himawari-8 AHI channels, 0000-1230 UTC on 7 August, wavelengths as indicated (click to animate)

About 5 hours prior to landfall on Taiwan, a nighttime comparison of Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared (11.45 µm) images at 1653 UTC on 07 August (00:53 AM on 08 August, Taiwan time) is shown below. The images showed a ragged eye structure, but a well-defined spiral band wrapping around the northern semicircle of the typhoon.

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

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

According to The Weather Channel, the highest reported gust in Taiwan was 64.0 meters per second (143 mph) at 5 a.m. Taiwan time on 08 August at Su-ao, Yilan County. However, the Central Weather Bureau deleted all wind data for this site, so the accuracy may be in question. The next-highest gust was 58.5 meters per second (131 mph) on the island of Pengjiayu, northeast of mainland Taiwan. The highest reported rainfall total was 1329.0 millimeters (52.32 inches) at Taipingshan, Datong Township, Yilan County, Taiwan, during the 72-hour period from 06 August through 08 August.

Ice in Hudson Bay, Canada

August 7th, 2015 |

GOES-13 visible (0.63 µm) images [click to play animation]

GOES-13 visible (0.63 µm) images [click to play animation]

GOES-13 visible (0.63 µm) images (above; click image to play animation; also available as an MP4 movie file) revealed a large amount of ice remaining in southern and eastern portions of Hudson Bay, Canada on 07 August 2015. The ice can be seen “sloshing” back and forth during the day as winds and/or water currents moved it around.

The discrimination of ice vs supercooled water droplet clouds can be made by comparing Terra MODIS true-color and false-color Red/Green/Blue (RGB) images at 1611 UTC (below). On the false-color image, ice (and glaciated clouds with a high concentration of ice crystals at cloud top) appeared as darker shades of red, in contrast to supercooled water droplet clouds which appeared as varying shades of white to cyan.

Terra MODIS true-color and false-color images [click to enlarge]

Terra MODIS true-color and false-color images [click to enlarge]

A Suomi NPP VIIRS true-color image as visualized using the SSEC RealEarth web map server (below) showed the ice at 1800 UTC; even greater detail can be seen in this zoomed-in version of the image.

Suomi NPP VIIRS true-color image [click to enlarge]

Suomi NPP VIIRS true-color image [click to enlarge]


Maps from from the Canadian Ice Service (below) indicated that the concentration of this thick first-year ice (dark green) was still as high as 9/10ths to 10/10ths (red) on 07 August; on 03 August, the ice concentration departure from normal was as high as +9/10ths to +10/10ths (dark blue) in some locations.

Hudson Bay ice concentration [click to enlarge]

Hudson Bay ice concentration [click to enlarge]

Hudson Bay ice stage [click to enlarge]

Hudson Bay ice stage [click to enlarge]

Hudson Bay ice concentration departure from normal [click to enlarge]

Hudson Bay ice concentration departure from normal [click to enlarge]