A cold frontal boundary moved southeastward across Wisconsin early in the day on 12 January 2007 — an extensive deck of post-frontal stratus cloud covered much of the southern half of the state during the afternoon hours, as seen on the MODIS true color image (above). As cold air advection in the wake of the frontal passage began to cool surface temperatures below freezing, patches of drizzle began to precipitate from the stratus deck; AWIPS imagery of the MODIS Cloud Phase Product (below) indicated that this stratus cloud deck covering southern Wisconsin was composed primarily of supercooled water droplets (blue enhancement = water phase clouds). This scenario of supercooled liquid precipitation falling onto surfaces that have cooled below freezing created icing conditions that prompted the issuance of freezing rain advisories for many of the counties across southern Wisconsin (farther to the south, ice accruals of 1-2 inches were reported across parts of OK, KS, MO, and IL during the 12-14 January period). Regional rawinsonde profiles at 12:00 UTC (6am local time) showed that the arctic air mass was fairly shallow (especially evident on the Minneapolis sounding), but temperatures were below freezing throughout the atmospheric column on both the Minneapolis MN (KMPX) and Green Bay WI (KGRB) soundings; however, the sounding at Davenport IA (KDVN) did reveal two layers of above-freezing air located between the surface and the 700 hPa pressure level.

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During periods when the GOES-12 imager is placed into Rapid Scan Operations (RSO) — as was the case on 05 January 2007 to monitor severe convection over the southeastern US — the coverage of the southern 2/3 of the South American continent is limited to only 1 image every 3 hours (when GOES-12 does a full disk scan). The color-enhanced IR window (IRW) image comparison above shows the difference in South American coverage between GOES-12 (in RSO) and GOES-10 (in routine operations) at 20:25/20:28 UTC, and Java animations of GOES-12 and GOES-10 imagery from that day further demonstrate the value of having the GOES-10 satellite positioned at 60º W longitude to support the Earth Observation Partnership of the Americas (EOPA) project. During the GOES-12 RSO period, which began at 18:30 UTC on that day, the entire South American continent was sampled 3-4 times per hour with GOES-10, allowing southern hemisphere meterologists to monitor the widespread convection and other phenomena that were occurring over that continent. The latest GOES-10 sounder and imager products are available on the CIMSS GOES Realtime Derived Products site.

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GOES-11 visible channel imagery from 05 January 2007 (above) revealed some complex wave structures within the various cloud features that were located over the Baja California region (Java animation): (1) a cold front was surging southward across the northern Gulf of California (near the top center of the images), and the broken cloud deck behind the front exhibited some waves; (2) a packet of stationary waves was seen to the lee of Isla de Cedros (“Cedros Island”, located near the center of the images) — mountains on this island rise to elevations of 1205 m (3949 ft), which were high enough to act as a barrier to the prevailing westerly/northwesterly flow on that day; (3) other wave packets were noted both in the stratocumulus clouds over the open waters of the Pacific Ocean, as well as the clouds located inland over parts of Baja California.

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05 January 2007 was the final day of the GOES-13 Post-Launch NOAA Science Test; following the final image at 09:45 UTC (above), the satellite was placed into on-orbit storage until it is needed to replace one of the other operational GOES. This also marked the final opportunity to view the western hemisphere using imagery from 4 different GOES perspectives (below).

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