Skies cleared late on the 26th with no precipitation on the 27th or 28th. 0.07 A strong 1040 mb surface high was located over southern Saskatchewan and Manitoba on the evening of November 28. The surface weather analyses at 00Z and 03Z on November 29 showed slight pressure increases, with 3-hour pressure changes of less than 1.0 mb. Surface pressure gradients over south-central and southeast Montana were rather weak with a tendency for an upslope east to northeast wind. Naturally, visible imagery is only available during daylight hours.
Infrared imagery is a poor choice for night viewing because low clouds and fog are hard to detect.
This is because low clouds and fog have a similar radiating temperature as the underlying land. The imagery is reduced by subtracting the 3.9 u brightness temperatures from those at 10.7 u . High clouds appear dark in this imagery since much of the sensed energy comes from the ground, and the 3.9 u channel response to warm sub-pixel temperatures is greater than that at 10.7 u . This is true even though the emissivity of an ice cloud is about the same as at the 3.9 u and 10.7 u . Additionally, putting these images in animation, fog and low clouds would be easily observed since the higher ice clouds would show more rapid movement.