GOES-R IFR Probability fields computed using GOES-15 are periodically — once or twice per night — showing unusual behavior, as documented in the short animation above. The 0730 UTC shows a greatly expanded region of modest IFR Probability values compared to 0715 UTC; at 0745 UTC, fields return to ‘normal’. This aberrant behavior does not occur during the day, nor does it occur every night, nor at specific times. This intermittent type of error makes it difficult to determine and exact cause, but it appears to be related to GOES-15 3.9 µm emissivity. That field is missing when the erroneous fields are produced. This could be an issue of timing — that is, the algorithm requests the field before it is created.
CIMSS scientists are actively working to determine the underlying cause of this error.
======================== Added August 4 2015 =======================
Tweaks to the processing flow at CIMSS at the end of July appear to have fixed this problem, as it has not occurred in August.