MODIS true color (Bands 1/4/3) and false color (Bands 7/2/1) RGB images

A comparison of 250-meter resolution MODIS Red/Green/Blue (RGB) true color (using Bands 1/4/3) and false color (using Bands 7/2/1) images from the SSEC MODIS Today site (above) showed the main portion of the surface oil slick in the northern Gulf of Mexico on 24 May 2010. This was Day 34 following the deadly explosion on the offshore oil rig Deepwater Horizon, and the damaged underwater wellhead continued to discharge more than 5,000 barrels of oil per day.

A day later, MODIS true color and false color images from 25 May 2010 (below) continued to exhibit a distinct signature of the surface oil slick.

MODIS true color (using Bands 1/4/3) and false color (using bands 7/2/1) images

View only this post Read Less

GOES-13 visible images + lower-tropospheric atmospheric motion vectors

An animation of GOES-13 visible images from the CIMSS Tropical Cyclones site (above) showed the development of a discrete low-level cyclonic circulation associated with the first Atlantic Basin tropical cyclone “Invest” of the season on 23 May 2010. An overlay of lower-tropospheric atmospheric motion vectors (along with a handful of ship reports) also showed a broad cyclonic circulation around this developing cloud feature.

GOES-13 IR images (below) showed that there were some large clusters of cold-topped convection located off to the northeast, but this deep convection did not appear to be directly related to the developing low-level cyclonic circulation seen on visible imagery.

GOES-13 IR images

GOES-13 water vapor imagery with an overlay of deep layer (850-200 hPa) wind shear (below) showed 2 factors present that were unfavorable for the rapid intensification of Invest 90L: very dry air aloft moving in from the west, along with increasing values of wind shear — however, model guidance suggested that there was a small chance that this system could eventually develop into a subtropical cyclone.

GOES-13 water vapor images + deep layer wind shear

View only this post Read Less

POES AVHRR 11.0 µm IR image + SPC storm reports

AWIPS images of the 1-km resolution POES AVHRR 11.0 µm IR channel data (above) showed a detailed view of the severe thunderstorm that produced a very large and violent “wedge” tornado that was responsible for EF4 damage in northeastern South Dakota on 22 May 2010. The coldest IR brightness temperature on the image was -77º C. An overlay of the corresponding SPC storm reports is also shown; this storm also produced hail up to 1.75 inch in diameter.

A comparison of the AVHRR IR image with the corresponding 0.63 µm visible channel image (below) revealed a large storm top plume that appeared to be spreading out northeastward from one of the overshooting tops located near the South Dakota / North Dakota border.

POES AVHRR 11.0 µm IR and 0.63 µm visible channel images

View only this post Read Less

AVHRR 12.0 µm IR + SPC tornado/hail reports + cloud-to-ground lightning

An AWIPS image of the 1-km resolution POES AVHRR 12.0 µm IR channel data (above) displayed a classic and well-defined example of an “Enhanced-V” storm top signature over the northern Texas Panhandle region on 18 May 2010. Overlays of SPC storm reports and cloud-to-ground (CG) lightning strikes near the time of the image showed that this severe thunderstorm was producing hail as large as 2.75 inch in diameter, as well as a couple of tornadoes — and there were a large number of CG strikes within the Enhanced-V signature. The coldest cloud top IR brightness temperature was -74º C.

The corresponding 4-km resolution GOES-13 10.7 µm IR image (below) did exhibit an Enhanced-V signature, but the details were not as well-defined at the coarser spatial resolution. The coldest cloud top IR brightness temperatures were also about 10º C warmer on the GOES-13 image.

GOES-13 10.7 µm IR image

As part of the GOES-R Proving Ground activities to support the SPC Hazardous Weather Testbed, an Overshooting Top product is being generated by CIMSS. A 24-hour composite of the Overshooting Top (OT) hits is shown below, with a number of OT hits seen across the northern Texas panhandle.

GOES-13 Overshooting Tops product

View only this post Read Less