14 April 2012 - Sounder Airmass RGB

Well, it's not quite the Spring Experiment yet, but we did have a significant severe weather event over the plains this past weekend that I figured would be a good opportunity to capture some of the GOES-R Proving Ground products that we receive at the Storm Prediction Center and Hazardous Weather Testbed. We will start with the GOES Sounder Airmass RGB that is provided to us by CIRA and NASA SPoRT. RGB simply stands for Red-Green-Blue, which is a composite image created by combining three separate channels or channel differences into one image. This technique helps us identify specific features in the atmosphere without the use of complex derived products. The airmass RGB is a combination of thermal infrared, water vapor and ozone channels that help us identify regions of warm and moist versus cold and dry airmasses, spin in the atmosphere and jet streaks. The airmass RGB has been used extensively over Europe using the Meteosat Second Generation satellite, which has similar spectral channels to what will be available on the GOES-R Advanced Baseline Imager (ABI). Current GOES imagers do not contain the spectral bands necessary to generate this product, but we are able to simulate the RGB using the GOES sounder, which does have some similar channels to the ABI. Unfortunately this data only arrives once hourly from the sounder, but when GOES-R is launched, we will be able to create this product every 5 minutes over the continental US.
Below is a time-series of the SPC's outlooks from day 7 up until the event on Saturday 14 April 2012 from the SPC Facebook page. You can see clearly that the SPC had a good handle on the threat a week in advance and that the threat area depicted on day 1 well outlined the events that occurred in NE, KS, OK and IA. Preliminary storm reports from the SPC website indicate 135 tornado reports (likely will end up being about 75 individual tornadoes following official surveys) occurred during this event, with what appears to be several long tracks across OK and KS.

If we take a look at the sounder airmass RGB product at 12 UTC on 14 April 2012 (top image below), we can see a strong center of circulation over CA/AZ/UT/NV with indications of a significantly lowered tropopause, associated jet streaks and high PV (red hues) within the circulation and extending along the Pacific coast up into Canada. This can be confirmed by overlaying the tropopause pressure from the RUC analysis (middle image below) or the the 500 mb heights and vorticity (bottom image below).

If we move forward to 15 UTC (image below), just prior to initiation in KS, we can begin to see evidence of a moisture boundary (blue-to-green hue gradient) setting up along a line extending from NW KS near the KS/NE border down into the OK panhandle and down into west TX. Initiation in southern KS and down through the OK panhandle into TX would occur along a dryline located in this area, which is likely what the airmass RGB is picking up at this time.

Moving forward to 02 (top image below), 03 (middle image below) and 04 UTC (bottom image below) on 15 April 2012, the moisture gradient feature really begins to tighten up and better define itself as the dryline continued to evolve and the Pacific cold front approached, initiating a line of storms extending into central TX.