GOES R Proving Ground MVFR/IFR Assessment

There was an excellent area of mixed MVFR/IFR clouds across eastern OH, western PA and all of WV that was used to assesses the performance of the GOES R MVFR/IFR satellite product. The GOES R product did an excellent job with the depiction of the area covered by the clouds, but some perceived weakness in the accuracy of showing the appropriate percentage of MVFR and IFR. The series of images below show how the cloud area did not change over about 1 1/2 hours (see 4 vis images), yet the MVFR satellite analysis showed the percentages increasing with time. The obs at this time showed the deck was solid mvfr with a few sites sitting in ifr conditions. This was pretty stable. We were speculating whether this had to do with the increasing visible reflectance with increasing sun angle, or some other underlying element within the algorithm.

















A suggestion would be to reassess the enhancement curve applied to the MVFR/IFR products. Due to the sharp color shift at a specific percentage, it causes your attention to focus (probably too much) on specific areas that aren't significantly different. For example, the "yellow" 74% is not statistically different from the "red" 76%. Yet, the product suggests this is a big jump. We discussed using a curve with more of a gradient, in this case a grey scale from the vis enhancement. This introduced a more natural looking product. It is understood that colors are a very personal thing and this is open to lots of opinions! :)





Steve Davis NWS Milwaukee/Sullivan
Justin Sieglaff CIMSS