The early morning area forecast discussion issued by the National Weather service office at State College, Pennsylvania mentioned that river valley fog was being detected by the MODIS fog/stratus product:
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
526 AM EDT FRI SEP 16 2011.SYNOPSIS...
A LARGE HIGH PRESSURE SYSTEM OVER THE GREAT LAKES WILL BUILD SLOWLY EAST TO NEW ENGLAND BY SUNDAY AND MONDAY. A DYING COLD FRONT WILL LIKELY PUSH INTO THE REGION LATE MONDAY OR TUESDAY. A DIGGING TROF AND ASSOCIATED SLOW MOVING COLD FRONT COULD AFFECT THE REGION BY LATE NEXT WEEK..NEAR TERM /UNTIL 6 PM THIS EVENING/... EARLY AM MODIS 11-3.7UM IMAGERY SHOWING DENDRITIC PATTERN OF FOG IN THE DEEP RIVER VALLEYS OF THE ALLEGHENY MTNS.
A comparison of AWIPS images of the 1-km resolution MODIS fog/stratus product with the corresponding 4-km resolution GOES-13 fog/stratus product (above) demonstrated the advantage of higher spatial resolution for detecting such small-scale features. A subtle fog signal was beginning to show up at this time in the GOES-13 fog/stratus product image, but it was difficult to tell whether it was due to noise or actual fog features.
About an hour and 15 minutes later, a similar comparison using a 1-km resolution POES AVHRR fog/stratus image and the corresponding 4-km resolution GOES-13 fog/stratus product image (below) showed that while the fog signal had become better defined by this time on the GOES-13 image, the POES AVHRR image again showed the river valley fog features with much greater clarity.