As April begins, thoughts of warm weather and spring come to mind. However, wacky weather has been known to strike the Washington area in this month. While the month is getting off to a cold start with temperature 2 degrees below average, rain is needed to curb the 2 inch precipitation deficit. Speaking of rainfall deficit, this is also the month where warmer winds combined with low relative humidity and a quickly drying ground (when precipitation is scarce) can lead to wildfire danger.
Already on Wednesday, a Red Flag Warning was posted for the region due to the combination of these factors. Due to the delayed start of the growing season compliments of the recent cold spell, the sun is able to penetrate the forest floor and dry the top soil out quickly. When the wind blows strongly across the ground and dries the air and soil, forest fire danger quickly becomes a problem. Low relative humidity is exasperated by lack of vegetation because leaves and such give off water vapor (evapotranspiration) and act as a humidifier in the summer. This will be a problem during dry, windy periods in April as the leaves, grasses and plant life get a late start this year.
Besides the winds, April can bring excessive heat, numbing cold, spring deluges and flooding as well as late-season robin snow. Here’s a look at the extreme weather in Washington during the month of April.
In addition, it’s important to keep in mind the sun will get higher in the sky. As a matter of fact, the sun angle is comparable to that seen in August. Just because temperatures may be cool, the higher sun angle can equate to sunburn in a short period of time, especially those who are fair-skinned.
The image below shows how the sun angle compares to other times of the year. The April sun angle is the same as the August sun angle and the May sun similar to the July sun angle, etc. (Note the horizontal arrows showing this).
The official Climate Prediction Center forecast calls for a good probability of warmer than average temperatures in the East. Click here for the details.