The MIMIC Total Precipitable Water product at 3-hour intervals (below) indicated the presence of TPW values in the 2.0 to 2.5 inch range over parts of the region.Upstream rawinsonde data profiles from Washington Dulles International Airport in northern Virginia (below) showed TPW values of 46.8 mm or 1.83 inches at 12 UTC on 30 July, and 49.2 mm or 1.94 inches at 00 UTC on 31 July (although the later data looks suspect, given the balloon was launched as strong thunderstorms were approaching).
During the subsequent daylight hours, GOES-13 Visible (0.63 µm) images (below) revealed the extent of the valley fog which had formed (the yellow symbols denote stations reporting fog). However, this fog quickly dissipated quickly with strong heating from the July sun.This region frequently experiences such episodes of river valley fog, but they are most common during the Autumn months as nights grow longer and nighttime temperatures get colder. In this late July event, the primary ingredient favoring fog formation was high soil moisture due to recent heavy rainfall (below), much of which occurred on 24 July.
The corresponding GOES-13 Water Vapor (6.5 µm) images (below) perhaps highlighted the transverse banding features a bit better at times, since the weighting function for that spectral band generally peaks in the middle to upper troposphere where the transverse banding cloud features existed.A sequence of Infrared Window images from POES AVHRR (10.8 µm) and Suomi NPP VIIRS (11.45 µm) (below) showed a higher-resolution view of the initial formation of transverse banding during the 0411 to 1008 UTC time period. Shown below are two other types of satellite imagery that can be helpful for identifying the areal extent of transverse banding cloud features: the Suomi NPP VIIRS Day/Night Band (0.7 µm), and the MODIS Cirrus band (1.37 µm). A similar Cirrus band will be part of the ABI instrument on GOES-R.
A sequence of Infrared images from Terra/Aqua MODIS (11.0 µm) and Suomi NPP VIIRS (11.45 µm) (below) showed greater detail in the storm-top temperature structure at various times during the event.
===== 19 July Update =====A comparison of Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images from before the event (09 July) and after the event (12 through 19 July) (above) revealed the large amounts of sediment flowing offshore into the southwestern portion of Lake Superior.
Another comparison of before (09 July) and after (13 through 19 July) true-color RGB images from Terra and Aqua MODIS is shown below.A toggle between a Terra MODIS Visible (0.65 µm) image and the corresponding MODIS Sea Surface Temperature (SST) product on 16 July (below) showed that the SST values in the sediment-rich nearshore waters were significantly warmer (middle 60s F, red enhancement) than those found closer to the center of Lake Superior (middle 40s F, cyan enhancement).