Tornado outbreak in Indiana/Ohio

August 24th, 2016

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

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

An outbreak of tornadoes (SPC storm reports) occurred during the afternoon/early evening hours of 24 August 2016 from central Indiana to northwestern Ohio (NWS Indianapolis | NWS Northern Indiana | NWS Cleveland). In terms of forcing mechanisms, while the supercell thunderstorms developed well in advance of a cold frontal boundary (surface analyses), GOES-13 Visible (0.63 µm) images (above) showed a mesoscale convective vortex or MCV moving eastward across northern Illinois which may have played a role in helping to initiate convection. Moisture was also abundant across the region, with Total Precipitable Water (TPW) values as high as 53.1 mm or 2.1 inches on the 1200 UTC Lincoln IL rawinsonde report and 60.7 mm or 2.4 inches just east of the convection developing over central Indiana on the 1941 UTC Aqua MODIS TPW product (below).

Aqua MODIS Visible (0.65 µm) image and Total Precipitable Water product [click to enlarge]

Aqua MODIS Visible (0.65 µm) image and Total Precipitable Water product [click to enlarge]

A closer view of the 1841 UTC Aqua MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images (below) showed the thunderstorm complex over central Indiana just after the time of the first EF2-rated tornado in Montgomery County — the coldest cloud-top infrared brightness temperature was -80º C (violet color enhancement) over the southeastern portion of that county. In addition, an “enhanced-V” cloud top signature was evident over northeastern Clinton County — the next EF3-rated tornado formed just to the northeast in Howard County at 1920 UTC.

Aqua MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Aqua MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images [click to enlarge]

The GOES-13 (GOES-East) satellite had been placed into Rapid Scan Operations (RSO) mode, providing images as frequently as every 5-7 minutes — in the Visible (0.63 µm) images with plots of preliminary SPC storm reports of tornadoes (red) and hail/wind (cyan) shown below (also available as an MP4 animation), numerous overshooting tops can be seen. These overshooting tops were often in the vicinity of the parallax-corrected SPC storm reports (assuming a mean cloud top height of 12 km).

GOES-13 Visible (0.63 µm) images, with SPC storm reports of tornadoes in red and hail/wind in cyan [click to play animation]

GOES-13 Visible (0.63 µm) images, with SPC storm reports of tornadoes in red and hail/wind in cyan [click to play animation]

The corresponding GOES-13 Infrared Window (10.7 µm) images (below; also available as an MP4 animation) revealed cloud-top IR brightness temperatures as cold as -67º C (darker black enhancement) over Indiana at 1845 and 1855 UTC; the location of parallax-corrected preliminary SPC storm reports of tornadoes (white) and hail/wind (cyan) are also plotted on the images.

GOES-13 Infrared Window (10.7 µm) images, with plots of SPC storm reports of tornadoes in white and hail/wind in cyan [click to play animation]

GOES-13 Infrared Window (10.7 µm) images, with plots of SPC storm reports of tornadoes in white and hail/wind in cyan [click to play animation]

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]