No shortage of satellite meteorology topics today over the Upper Midwest and Great Lakes regions! A look at the GOES-12 visible channel animation (below, left) reveals the following features: (1) fingers of morning fog in the river valleys of southwestern Wisconsin, (2) areas of smoke aloft from wildfires burning in Canada and the Pacific Northwest, and (3) afternoon lake breeze boundaries that acted as a focus for thunderstorm development in both Wisconsin and lower Michigan.

(1) As we have noted previously, these narrow fog features are often not detected using the 4 km resolution GOES fog/stratus product, but the 1 km resolution MODIS fog/stratus product (with observations overlaid) is able to resolve the river valley fog in southwestern Wisconsin.

(2) While the smoke signature is subtle on the GOES-East (GOES-12) visible imagery, we can take advantage of a more favorable forward scattering geometry using the GOES-West (GOES-11) satellite to better see the areal extent of the smoke early in the day (GOES-11 animation). The smoke is also depicted as a large plume of high MODIS aerosol optical depth (AOD) extending from southern Canada to the Upper Midwest (below, right). In addition, the thick smoke contributed to a colorful sunset (and sunrise) here in Madison (photo 1 | photo 2).

(3) Narrow pockets of instability were noted on the GOES sounder lifted index (LI) derived product (values of -7 to -8 F), in the vicinity of the lake breeze boundaries in both Wisconsin and Michigan; hail up to 1 inch in diameter was reported from the afternoon lake breeze convection in Wisconsin and Michigan.

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Tropical depression #6 in the Atlantic Basin strengthened into Tropical Storm Florence today (IR image); forecasters at the National Hurricane Center utlized a CIMSS AMSU estimate of 1003 mb central pressure and 42 knot peak wind (below, left) to aid in their intensity estimate of the large developing tropical cyclone. The CIMSS satellite-derived IR/water vapor winds product (below, right) showed the presence of a large subtropical ridge located over the North Atlantic Ocean to the northwest of Florence — this ridge will likely be an important steering mechanism in the coming days as Florence continues to intensify and move toward the US East Coast.

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Wildfire activity persisted across parts of the Northwest US today, with GOES-11 Wildfire ABBA indicating a number of active fires in WA, ID, and MT (below, left). The smoke from these fires became rather thick from eastern Washington to western Montana, as seen by the widespread haziness in the MODIS true color imagery (below, right). Not surprisingly, the IDEA products portrayed very high MODIS aerosol optical depth (AOD) values over that region, and the smoke was having an impact on surface air quality across portions of the Pacific Northwest.

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Subtropical moisture associated with weakening Hurricane John began to spread northward into the desert southwest, which was well depicted on AWIPS imagery of the GOES sounder total precipitable water (PW) derived product (below, left). This surge of moisture (QuickTime animation) prompted the Storm Prediction Center (SPC) to issue a Mesoscale Convective Discussion concerning heavy rainfall over the lower deserts of southern California and Arizona (below, right). GOES sounder and MODIS PW values compared favorably well, and at one point (08 UTC) the GOES sounder PW derived product indicated an isolated value of 61 mm (2.4 inches) over Arizona. Surface dew point temperatures reached the 60s and 70s F at some sites in the lower deserts, and rainfall from thunderstorms that subseqently developed was responsible for some flash flooding in parts of California and Arizona.

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