Lake-effect clouds

September 8th, 2006 |

Cold air was streaming southwestward across Lake Superior, behind a strong Canadian cold front (temperatures the following morning dropped to 19 F at Embarrass MN and 28 F at Hayward WI). On the MODIS true color image (below, left), the appearance of the cloud bands that formed over the lake closely resembled “lake-effect snow bands” that often form in the winter (due to the large temperature difference between the relatively warm water surface and the cold arctic air). While the air behind this particular front wasn’t cold enough for lake-effect snow, there were some areas of lake-effect rain and drizzle in the UP of Michigan and in northern Wisconsin. Once we get into the winter months, MODIS products such as the Cloud Phase and the Cloud Top Temperature (below, right) will be helpful for determining whether snow or freezing rain/drizzle will be the likely precipitation type over a given region. In this case, the MODIS Cloud Phase product indicated thatwater phase clouds (blue enhancement) covered most of Lake Superior (MODIS IR and Cloud Top Temperature values were several degrees below freezing, so it was likely supercooled water droplets these clouds); farther to the south, over northern Wisconsin and the UP, a band of more intense rain showers and thunderstorms (with some cloud to ground lightning strikes) was depicted as ice phase clouds (pink enhancement), with corresponding IR and cloud top temperature values colder than -30 C (dark blue enhancement on the MODIS CTT and IR images).

Note to AWIPS users: Jordan Gerth made a modification to the MODIS Cloud Phase product, to allow AWIPS cursor display of the actual phase category (along with a phase label in the color bar).

MODIS true color image

AWIPS MODIS products

One Response to “Lake-effect clouds”

  1. jordang says:

    For National Weather Service sites interested in this MODIS Cloud Phase Upgrade or the MODIS in AWIPS project in general, visit the project web site at http://cimss.ssec.wisc.edu/~jordang/awips-modis/ We hope to have some training available for the MODIS Cloud Phase imagery in the coming weeks.

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