A GOES-12 imager “decontamination procedure” was performed on 02 July 2007, where certain internal optical components were heated in an attempt to drive off contaminants that had been accumulating for several years. One obvious problem associated with this internal contamination was a “rollover” of warm 3.9µm IR brightness temperatures, such that they were incorrectly displayed as very cold temperatures. This problem made it impossible to determine the hottest brightness temperatures associated with areas of intense fire activity (see recent examples from the Lake Tahoe, Lake Okeechobee, New Jersey, and Georgia fires).

Two sequences of daily GOES-12 3.9µm IR images show regions of sun glint off the Pacific coast of Mexico at 20:45 UTC (above), and also off the coast of Washington / British Columbia at 03:45 UTC (below). Prior to the decontamination procedure at 12:34 UTC on 02 July, portions of the sun glint that should have exhibited very warm IR brightness temperatures (black enhancement) were instead displayed as very cold areas (yellow enhancement); following the decontamination, the regions of daily sun glint were correctly displayed as having warm IR brightness temperatures, indicating that the procedure was successful.

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An AWIPS image of the MODIS sea surface temperature (SST) product on 06 July 2007 (above) showed a nice view of the complex structure of the water temperatures on that relatively cloud-free day over the western Great Lakes– the MODIS product indicated that SST values were as warm as 81.5º F (red enhancement) in western Lake Erie, and as cold as 35.6º F (dark blue enhancement) in western Lake Superior. Of particular interest was the north-to-south oriented plume of warmer SSTs across west-central Lake Michigan (70-75º F, yellow to orange enhancement).

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Unusually hot conditions developed across parts of the Desert Southwest during the first week of July 2007 — daily maximum temperatures on 05 July included 127º F (53º C) at Death Valley, California, 122º F (50º C) at several locations within the Lake Mead/Lake Mohave basin region of Nevada/Arizona, 120º F (49º C) at Needles, California, and 116º F (47º C) at Las Vegas, Nevada (1º F shy of their all-time record high temperature). Following such hot daytime temperatures, a nighttime AWIPS image of the MODIS 11.0µm InfraRed (IR) channel (above) showed that nocturnal temperatures remained rather warm — IR brightness temperatures at 09:22 UTC (2:22 AM local time) were still 30º C / 86º F or warmer (orange to red enhancement) over a good deal of the Death Valley and Lake Mead/Lake Mohave basin regions. In fact, the official cooperative weather observation site at Death Valley (DEVC1) reported an overnight minimum temperature of 95º F (35º C), while a nearby mesonet site at Death Valley National Park (CQ162) only dropped to 105º F (41º C) at 7:00 AM local time (14:00 UTC).

An AWIPS comparison of MODIS IR, GOES imager IR, and GOES Sounder Skin Temperature (above) revealed brightness temperatures in the lowest elevations of Death Valley were still as warm as 86-96º F (30-36º C) at 09 UTC. In addition, an AWIPS image of the MODIS sea surface temperature product (below) indicated that water temperatures were as warm as 87-89º F (31-32º C) (dark red enhancement) in portions of Lake Mead and Lake Mohave.

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The large “Angora wildfire” began to burn just south of Lake Tahoe in California sometime after 21:00 UTC (1:00 PM local time) on 24 June 2007, eventually destroying 254 homes and burning 3100 acres. Images of the 3.9µm InfraRed (IR) and visible channels from GOES-12 (above; Java animation) and GOES-11 (below; Java animation) revealed a large “hot spot” (black pixels) associated with this fire, as well as a long smoke plume that spread quickly northeastward during the afternoon hours. Dark IR “hot spots” were first evident on GOES-12 imagery at 21:32 UTC and on GOES-11 imagery at 21:41 UTC, with a “processed fire” (red pixel) showing up on the GOES-11 Wildfire ABBA product at 22:00 UTC. Note that the hot fire saturated the 3.9µm detectors on GOES-12, causing the temperature to “roll over” and be falsely displayed as very cold (white) pixels. The saturation temperature of the GOES-11 3.9µm detectors (338.8º K / 66º C / 150º F) was reached as early as 22:30 UTC (2:30 PM local time).

The majority of the smoke was transported rapidly northeastward between Reno, Nevada (KRNO) and Fallon, Nevada (KNFL) by strong winds aloft; however, GOES-12 visible imagery indicated that some smoke at lower altitudes was curving southward away from the main plume and moving toward Fallon (and areas south of Fallon) after about 00:00 UTC on 25 June. The surface meteorogram from Fallon (below) indicates that surface visibility there dropped from 10 miles to 6 miles around 02 UTC as this smoke began to move into the area.

The fire continued to burn for several days; a Terra MODIS true color image from 26 June (below) shows a smaller smoke plume that was continuing to drift northward across the lake.

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