High Plains leeside cold frontal gravity wave

October 10th, 2019 |

GOES-16 Low-level (7.3 µm, left), Mid-level (6.9 µm, center) and Upper-level (6.2 µm, right) Water Vapor images, with plots of surface wind barbs and gusts in knots [click to play animation | MP4]

GOES-16 Low-level (7.3 µm, left), Mid-level (6.9 µm, center) and Upper-level (6.2 µm, right) Water Vapor images, with plots of surface wind barbs and gusts in knots [click to play animation | MP4]

GOES-16 (GOES-East) Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (above) revealed the classic signature of a leeside cold frontal gravity wave (reference) moving southward across the High Plains on 10 October 2019. Peak wind gusts of 50-60 mph were reported at some sites in eastern Colorado and western Kansas — and impressive drops in surface air temperature accompanied the cold frontal passage.


On the corresponding GOES-16 “Red” Visible (0.64 µm) imagery (below), note the lack of clouds along the western end of the cold front (across the New Mexico / Texas border region).

GOES-16 "Red" Visible (0.64 µm, left), Mid-level Water Vapor (6.9 µm, center) and Upper-level Water Vapor (6.2 µm, right) images, with plots of surface wind barbs and gusts in knots [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm, left), Mid-level Water Vapor (6.9 µm, center) and Upper-level Water Vapor (6.2 µm, right) images, with plots of surface wind barbs and gusts in knots [click to play animation | MP4]

A plot of rawinsonde data from Amarillo, Texas at 12 UTC (below) showed how shallow the cold air was behind the cold front as it first moved southward through the Texas Panhandle.

Plot of rawinsonde data from Amarillo, Texas [click to enlarge]

Plot of 12 UTC rawinsonde data from Amarillo, Texas [click to enlarge]

However, note that GOES-16 Water Vapor weighting functions calculated using 12 UTC rawinsonde data from Amarillo (below) indicated that peak contributions were in the middle troposphere — in the 440-500 hPa pressure range — with no surface radiation contributions at 6.9 µm or 6.2 µm. It was the deep-tropospheric nature of the leeside cold frontal gravity wave that allowed its signature to be sensed by the 6.9 µm and 6.2 µm Water Vapor spectral bands.

GOES-16 Water Vapor weighting functions, calculated using 12 UTC rawinsonde data from Amarillo, Texas [click to enlarge]

GOES-16 Water Vapor weighting functions, calculated using 12 UTC rawinsonde data from Amarillo, Texas [click to enlarge]

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