Hold the left mouse button down as you drag the slider above the image (or use the arrow buttons) to fade between the 17:43 UTC MODIS 6.7 micrometer IR ("water vapor") image and the corresponding GOES-08 and GOES-10 water vapor images at 17:45 UTC on 14 March 2002. All 3 images have been re-mapped onto a common Lambert Conformal projection. To zoom, click on the "Zoom" button, and then click the "hand" cursor on the image where you want to center the zoom.

As noted in the mid-day SPC Mesoscale Discussion, strong forcing for upward vertical motion in the left exit region of a mid-upper level jet streak moving across Kansas into south-central Nebraska was helping to enhance winter precipitation across parts of northcentral Nebraska (radar composite). Heavy snow (with some convective enhancement) then moved into southeastern South Dakota and southwestern Minnesota as the jet streak continued northeastward towards the Great Lakes region -- accumulations were as high as 19 inches in South Dakota, 21 inches in Minnesota, and 20 inches in Wisconsin.

The higher spatial resolution of the MODIS water vapor channel data (1 km, versus 4x8 km for GOES) allowed better detection of the axis of this jet streak feature crossing the Kansas/Nebraska border. Brightness temperatures were generally 2-6 C warmer across this scene on the MODIS data (especially in the region of the dry slot associated with the axis of the jet streak), in part because the weighting function peaks lower in the atmosphere for the MODIS water vapor channel than it does for the GOES-08/GOES-10 water vapor channel. The more extreme viewing angle from GOES (zenith angles near 50 degrees) also contributes to the colder brightness temperatures compared to MODIS.