Transverse banding: a signature of potential turbulence

July 20th, 2016

GOES-13 Infrared Window (10.7 um) images, pilot reports of turbulence, Turbulence AIRMET boundaries [click to play animation]

GOES-13 Infrared Window (10.7 um) images, pilot reports of turbulence, Turbulence AIRMET boundaries [click to play animation]

GOES-13 (GOES-East) Infrared Window (10.7 µm) images (above) showed the formation of tendrils of transverse banding along the northern semicircle of  decaying mesoscale convective systems as they moved eastward across Nebraska and Iowa on 19 July 2016. Pilot reports of turbulence are plotted on the images, along with Turbulence AIRMET polygons issued at 0800 UTC and 1400 UTC. Most of the pilot reports of turbulence were in the Light to Moderate category, although there was one report of Moderate to Severe intensity at 1612 UTC over eastern Iowa.

The corresponding GOES-13 Water Vapor (6.5 µm) images (below) perhaps highlighted the transverse banding features a bit better at times, since the weighting function for that spectral band generally peaks in the middle to upper troposphere where the transverse banding cloud features existed.

GOES-13 Water Vapor (6.5 um) images, pilot reports of turbulence, Turbulence AIRMET boundaries [click to play animation]

GOES-13 Water Vapor (6.5 um) images, pilot reports of turbulence, Turbulence AIRMET boundaries [click to play animation]

A sequence of Infrared Window images from POES AVHRR (10.8 µm) and Suomi NPP VIIRS (11.45 µm) (below) showed a higher-resolution view of the initial formation of transverse banding during the 0411 to 1008 UTC time period.

Infrared Window images from POES AVHRR (10.8 µm) and Suomi NPP VIIRS (11.45 µm) [click to enlarge]

Infrared Window images from POES AVHRR (10.8 µm) and Suomi NPP VIIRS (11.45 µm) [click to enlarge]

Shown below are two other types of satellite imagery that can be helpful for identifying the areal extent of transverse banding cloud features: the Suomi NPP VIIRS Day/Night Band (0.7 µm), and the MODIS Cirrus band (1.37 µm). A similar Cirrus band will be part of the ABI instrument on GOES-R.

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

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

Terra MODIS Infrared Window (11.0 µm) and Cirrus (1.37 µm) images [click to enlarge]

Terra MODIS Infrared Window (11.0 µm) and Cirrus (1.37 µm) images [click to enlarge]

Severe thunderstorms and heavy rainfall/flooding in the Upper Midwest

July 12th, 2016

GOES-13 Infrared Window (10.7 µm) images, with SPC storm reports [click to play animation]

GOES-13 Infrared Window (10.7 µm) images, with SPC storm reports [click to play animation]

GOES-13 Infrared Window (10.7 µm) images (above; also available as an MP4 movie file) showed a series of mesoscale convective systems that moved across northeastern Minnesota, northwestern Wisconsin and the Upper Peninsula of Michigan during the 11 July12 July 2016 period. Some of these storms produced tornadoes, large hail, and damaging winds (SPC storm reports) in addition to heavy rainfall, with as much as 9.00 inches in Minnesota and 9.80 inches in Wisconsin (NWS Duluth storm summary). Several highways were closed due to flooding and/or washout, including a portion of Interstate 35 in Minnesota (interstates and highways are plotted in violet on the images).

A sequence of Infrared images from Terra/Aqua MODIS (11.0 µm) and Suomi NPP VIIRS (11.45 µm) (below) showed greater detail in the storm-top temperature structure at various times during the event.

Infrared images from Terra/Aqua MODIS (11.0 µm) and Suomi NPP VIIRS (11.45 µm) [click to play animation]

Infrared images from Terra/Aqua MODIS (11.0 µm) and Suomi NPP VIIRS (11.45 µm) [click to play animation]

===== 19 July Update =====

Comparison of before (09 July) and after (12 July through 19 July) Suomi NPP VIIRS true-color images [click to enlarge]

Comparison of before (09 July) and after (12 July through 19 July) Suomi NPP VIIRS true-color images [click to enlarge]

A comparison of Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images from before the event (09 July) and after the event (12 through 19 July) (above) revealed the large amounts of sediment flowing offshore into the southwestern portion of Lake Superior.

Another comparison of before (09 July) and after (13 through 19 July) true-color RGB images from Terra and Aqua MODIS is shown below.

Comparison of before (09 July) and after (13 through 19 July) Terra/Aqua MODIS true-color images [click to enlarge]

Comparison of before (09 July) and after (13 July through 19 July) Terra/Aqua MODIS true-color images [click to enlarge]

A toggle between a Terra MODIS Visible (0.65 µm) image and the corresponding MODIS Sea Surface Temperature (SST) product on 16 July (below) showed that the SST values in the sediment-rich nearshore waters were significantly warmer (middle 60s F, red enhancement) than those found closer to the center of Lake Superior (middle 40s F, cyan enhancement).

Terra MODIS Visible (0.65 µm) image and Sea Surface Temperature product [click to enlarge]

Terra MODIS Visible (0.65 µm) image and Sea Surface Temperature product [click to enlarge]

Mesoscale Convective System in the Upper Midwest

July 6th, 2016

GOES-13 Infrared Window (10.7 um) images, with SPC storm reports [click to play animation]

GOES-13 Infrared Window (10.7 µm) images, with SPC storm reports [click to play animation]

GOES-13 (GOES-East) 4-km resolution Infrared Window (10.7 µm) images (above) showed the development of a large Mesoscale Convective System (MCS) which produced tornadoes, large hail, and damaging winds (SPC storm reports | NWS La Crosse summary) as it propagated southeastward across the Upper Midwest during the evening and overnight hours of 05 July06 July 2016.

A sequence of 1-km resolution Terra/Aqua MODIS (11.0 µm), 1-km resolution POES AVHRR (12.0 µm) and 375-meter resolution Suomi NPP VIIRS (11.45 µm) Infrared images (below) showed better details of such features as overshooting tops, some of which exhibited IR brightness temperature values as cold as -78º C on MODIS, -81º C on AVHRR and -86º C on VIIRS.

Infrared MODIS (11.0 um), AVHRR (12.0 um) and VIIRS (11.45 um) images, with SPC storm reports [click to play animation]

Infrared MODIS (11.0 µm), AVHRR (12.0 µm) and VIIRS (11.45 µm) images, with SPC storm reports [click to play animation]

A comparison of Suomi NPP VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) images at 0852 UTC or 3:52 am local time (below) showed the MCS as its core was centered over northern Illinois. Note how the tall, dense cloud mass blocked the view of nearly all city lights over a large area — including the normally very large and very bright lights of the Chicago metroplex. With almost no illumination from the Moon (which was in its Waxing Crescent phase, at 1% of Full), only the faint light of airglow helped to illuminate some cloud features over the northern portion of the satellite scene. In addition, numerous bright white streaks were seen in the Day/Night Band image along the leading (southern) edge of the MCS, due to cloud illumination from intense lightning activity; one lone lightning streak was evident in Wisconsin, whose intensity was bright enough to saturate the Day/Night Band detectors (hence the long “post-saturation recovery” streak as the sensor continued scanning toward the southeast).

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

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

A few hours earlier at 0339 UTC, the CLAVR-x POES AVHRR Cloud Top Height product (below) showed areas with height values of 16-17 km (lighter cyan color enhancement) — the large amount of water and ice particles contained within such tall clouds was therefore able to effectively block the view of city lights on the VIIRS Day/Night Band image. Note that a Cloud Top Height product will be available from the ABI instrument on GOES-R.

POES AVHRR Cloud Top Height product and Infrared (12.0 um) image [click to enlarge]

POES AVHRR Cloud Top Height product and Infrared (12.0 µm) image [click to enlarge]

Localized heavy rainfall and flooding in south-central Wisconsin

June 15th, 2016

GOES-13 Infrared Window (10.7 µm) images [click to play animation]

GOES-13 Infrared Window (10.7 µm) images [click to play animation]

GOES-13 Infrared Window (10.7 µm) images (above) showed the development of several rounds of deep convection which moved over parts of southern Wisconsin during the 14 June15 June 2016 period; these storms were responsible for heavy rainfall at some locations (NWS Milwaukee summary). As mentioned in a WPC Mesoscale Precipitation Discussion, some of these storms were focused along the nose of a low-level jet that was helping to push a warm frontal boundary (surface analyses) through the region. Moisture was also abundant south of the warm front, with a total precipitable water value of 55.1 mm (2.17 inches) seen in rawinsonde data from Davenport IA.

Landsat-8 false-color image [click to enlarge]

Landsat-8 false-color image [click to enlarge]

A timely cloud-free overpass of the Landsat-8 satellite on the morning of 15 June provided a 30-meter resolution false-color image as viewed using RealEarth (above), which showed areas of flooding — water appears as darker shades of blue — in the Black Earth area of western Dane County in southern Wisconsin. A before/after comparison of Landsat-8 images processed using an equation to highlight water as blue (below, courtesy of Shane Hubbard, SSEC/CIMSS) revealed the areas of inundation due to the 14-15 June thunderstorms.

Landsat-8 derived water change, 30 May vs 15 June 2016 [click to enlarge]

Landsat-8 derived water change, 30 May vs 15 June 2016 [click to enlarge]

Aerial footage from a drone flight (below) showed vivid images of the flooding along Black Earth Creek.

YouTube video from drone flight near Black Earth, Wisconsin [click to play]

YouTube video from drone flight near Black Earth, Wisconsin [click to play]