CIMSS Satellite Blog

GOES-13 Visible (0.65 µm) Imagery, 1300-2045 UTC on 5 January 2015 [click to animate]

As a low pressure moved away from the coast, and a High pressure system approached from the west (link), cold air swept south along the east coast of the United States and produced light snow/flurries over Tidewater VA and the Outer Banks of North Carolina on Tuesday, 5 January 2016. The animation above, of the GOES-13 Visible Imagery, shows a band of cloudiness originating over the northern Chesapeake Bay that widened as it moved south. By the time it reached southern Virginia, it was producing snow. Conditions over the Outer Banks of North Carolina were very icy, as shown in this Video, courtesy of Sam Walker. The snow closed schools in Dare County. The 1300 UTC observations, below, in a toggle with 2100 UTC observations, showed snow over Tidewater and over extreme eastern North Carolina with strong north-northwest winds. By 2100 UTC, winds had shifted and weakened and snow was not reported. It was still cold however: the sub-freezing high in Norfolk was the first of the winter and the coldest day since late February 2015.

GOES-13 Visible (0.65 µm) Imagery, 1300 and 2045 UTC on 5 January 2015, with surface weather observations and wind barbs [click to enlarge]

The cold air aloft necessary for Bay Effect (or Ocean Effect) snows was present in the 1200 UTC Sounding at Wallops Island, Virginia (Or click to compare Stuve and Skew-T plots from this site). Temperatures 1 km above the surface were at -15.7ºC, with 850-mb temperatures near -10ºC. NOAA’s NAM and the GFS Numerical Models indicated 850-mb temperatures cooler than -10ºC near Chesapeake Bay. That in combination with sea-surface temperatures at +10ºC, at least as forecast (source) or recently observed from satellite (30 December and 27 December) (source) or observed from buoys, easily met the 13ºC temperature difference threshold commonly cited to support lake-effect snows.

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