Weather Arriving from all Directions

Air masses are coming together in the middle of the country. Follow the changes while practicing your decoding of station model plots of local weather. We will start with this weather map from Sunday evening, February 20, 2022, at 10:00 p.m. CST and update with later maps as the storm develops.

This is a very interesting map because the weather is very busy. Behind a cold front dropping south into the north central U.S., temperatures drop off quickly from the 50s over southern Iowa to below zero in southern Canada. Check the station model format on our home page and decode the temperatures. Watch for rain, freezing rain and snow to develop over the central U.S. during the next 24 to 48 hours. We will follow it here so you can practice your decoding skills while following a storm. Pick a few cities and follow their weather.

A broad area of low pressure is located over the Intermountain Region (Utah, Nevada) to the central Plains (Nebraska, Kansas). Southerly winds are blowing from the Gulf Coast north to Kansas and Nebraska and northeast to the lower Great Lakes. Notice the north and northeasterly winds over the Northern Plains (Montana to the Upper Great Lakes. There is a general counter-clockwise air motion over the central Rockies west to Utah as mild Pacific air spreads across that area and southerly winds move north from the Gulf. At the same time cold air is spreading southwestward toward the low pressure from the upper Great Lakes to the Northern Plains. This combination is the counter-clockwise flow spreading toward the area of low pressure in the central Rockies.

Map plotted using Digital Atmosphere available at www.weathergraphics.com

The dashed red lines are isotherms (lines of constant temperature). They are closest together in the cold air. In the warmer air temperatures increase to the mid 60s toward the Gulf coast. Each dashed red line (isotherm) represents a 2-degree F change in temperature. Isobars are the solid black lines of equal pressure. The wind speeds tend to be stronger where the isobars are close together and weaker where the isobars are farther apart.

You will need to know the station model format which can be found on our home page in order to decode the observations. Start by looking at the temperatures at different weather stations and also the wind and the air pressure readings. When you look at this map imagine that the air is coming together from all directions over the central Rockies. That is what is happening. More on this tomorrow.