Severe/Winter Weather Guides
About This Page
The National Weather Service authors Severe and Winter Weather guides annually. The guides serve to educate the public about hazardous weather and how to prepare for severe and winter storms.
 
Winter Guide (Ice Storms of Dec 2000/Pg 2)
 
In the days preceding the ice storms of December, 2000...cold air in Arkansas was shallow (i.e. near the ground)...with warmer air aloft arriving from the southwest. In the days preceding the ice storms of December, 2000...cold air in Arkansas was shallow (i.e. near the ground)...with warmer air aloft arriving from the southwest (as shown to left).

 

The diagram to right shows that temperatures and dewpoints (thin green lines) were below freezing near the ground (1000 mb), but above freezing aloft (950 mb to 725 mb). Precipitation fell as rain (green dots) aloft, but froze on contact with exposed surfaces once it reached the ground. The diagram shows a temperature profile at Little Rock on 12/26/2000.

 

A diagram showing how the depth of cold air determines precipitation types in Arkansas. If high pressure had been a little closer to Arkansas, cold air would have been deeper with snow more likely. Instead, Arkansas was close to the edge of the high...with ice occurring. For a larger graphic, click here.

 

Ice Storms Foreseen?
As mentioned, the depth of the cold air is one factor to consider when forecasting wintry precipitation in Arkansas. Another factor is how much moisture will be available when the cold air arrives. In this case there was a lot of moisture, with shallow cold air...with significant icing the result. Ice Storm Warnings were posted well in advance to allow people to prepare for the expected conditions. For a closer look at what warnings are...as well as watches and advisories...see the next page.

 


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.