A slow moving winter storm settled over the northeastern United
States Sunday evening (March 4, 2001), merging one system that brought
plenty of moist air from the Gulf of Mexico with another system that
brought frigid temperatures southward from Canada. Today (March 5)
these merging systems formed a low-pressure trough off the New Jersey
coast, drawing in a new influx of moisture from the Atlantic and
sweeping it inland in a large-scale counter-clockwise pattern, thus
intensifying the strength of the storm. Officials across all New
England states are now braced for what could become a major winter
storm, dumping as much as 2 feet of snow in some areas over the next 48
hours.
This false-color composite image shows the western half of the winter
storm over the northeastern United States. This scene was acquired at
11:46 a.m. EST today (March 5) by the Moderate-resolution Imaging
Spectroradiometer (MODIS), flying aboard NASA's Terra spacecraft, and
processed by the University of Wisconsin-Madison's MODIS direct
broadcast receiving facility. In this scene, there appears to be cold
air moving in from the northwest, as the system as a whole moves toward
the northeast while being fed with moisture and energy from the Atlantic
Ocean. The feature in the top center of the image appears to be a large
jet of moisture wrapping around the back side of the storm system.
At visible wavelengths of light (e.g., 0.66 microns), snow cover is
as bright as clouds and is therefore difficult to distinguish from cloud
cover. However, at near-infrared wavelengths (e.g., 1.6 microns), snow
cover absorbs sunlight and therefore appears much darker than clouds.
This allows MODIS to discriminate between snow cover and clouds very
effectively. In this scene, land surfaces are green, water surfaces are
black, snow cover is red, and clouds are white. Those clouds that
contain a significant fraction of ice and snow particles appear pinkish
and progressively more red the greater the snow and ice content.
Image courtesy Liam Gumley, MODIS Atmosphere Team, University of
Wisconsin-Madison Cooperative Institute for Meteorological Satellite
Studies