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<br />VII. In Situ and Remote Sensing Observation of the Mesohigh Arc <br />Cloud <br /> <br />A mesoscale cluster of cumulonimbus clouds 45 km wide developed on <br /> <br />August 19, 1977, at 1900 g.m.t. 125 km northeast of Goodland, <br />Kansas. This cluster produced a distinct mesohigh arc cloud in a <br />field of cumulus clouds at 2030 g.m.t. In regions where sufficient <br /> <br />instability and moisture exist, a series of clouds formed along the <br /> <br />leading edge of the mesoscale cold front. These clouds were seen on <br />satellite imagery as a distinct arc. The arc generally moved <br /> <br />radially outward from the generating cumulonimbus clouds. <br /> <br />The arc cloud in this case moved southwestward from the cloud <br />cluster with a mean speed of 7 ms-1, while the cloud cluster moved <br />southward at 6 ms-1. This relatively weak arc cloud had a cord <br />length of nearly 95 km and a duration of more than 4 h (see figure 8). <br />Note the clear region behind the arc cloud associated with a cold <br /> <br />moist stable air produced by the thunderstorm downdraft and the <br />local cloud environment's compensating subsidence. Several large <br />cumulus congestus clouds developed along the arc; however, the dry <br /> <br />subsidence associated with the synoptic scale high pressure in <br />Nebraska suppressed further development of clouds along the arc. <br /> <br />The formation and development of the mesohigh and its associated arc <br />cloud was also observed with the Bureau of Reclamation's 5.4-cm <br /> <br />10 <br />