by David Murphy
A stationary front is shown on a weather map as line of alternating red and blue, with both pointed blue pips and curved red pips on either side. The stationary front marks a line of little movement between a cool air mass and a warm air mass. Stationary fronts usually form after a cold front has pushed south or east as far as the force of the flow behind it will allow and stalls. Often, these stalled fronts linger for a full day, or perhaps several days, before lifting back to the north as a warm front, returning warmer air to the region where the cold front originally invaded.
A stationary front can be a very tricky feature to anticipate, because computer models often have a hard time determining exactly where the front will stall. A difference of even 50 to 100 miles can dramatically change a forecast. If the front is too far south, temperatures will be much cooler than anticipated. Conversely, if the front stalls too for to the north, it will be unexpectedly warm. Cloud cover and precipitation forecasts can also bust , or go wrong easily with these fronts.
You can now understand why I often refer to stationary fronts as my least favorite weather feature. Often, when forecasting the a stationary front's movement, I will leave a lot of room for temperature and sky cover variations, depending on the front's actual movement.
In our region, these troublesome fronts tend to be most common in spring and fall.