What in the world is a Fire Weather Watch and why is the D.C. area under one?
It isn't often the D.C. area is put under a Fire Weather Watch. It probably happens about 2 to 3 times per year. It is issued when conditions are expected to be favorable for the spread of wildfires in the next 12 to 72 hours. It usually precedes a Red Flag Warning which means that extreme fire conditions are possible due to not only the current weather but also the weather that has been around the region the previous week or two. As Reagan National Airport has only received 0.58 inches of precipitation in February that makes it nearly an inch and a half below normal for the month.
- Fire Weather Watch Map
You can see by the map above that the counties are mainly located to the north of D.C., corresponding with the locales that didn't receive any snow last weekend. Low soil moisture is always something to look at when forecasting for fire weather conditions, as are the winds.
A cold front will push through the area tomorrow but it appears it will be a mainly dry frontal passage with only up to a tenth of an inch of rain likely. It's the winds that will really gear up in the afternoon hours tomorrow that would help in the aid and spread of any wildfires that develop. Winds are forecast to gust to nearly 50 mph by tomorrow afternoon. They are also expected to be westerly, which because of the mountains to our west acts to remove even more moisture out of the air due to compression. Relative humidity values are only expected to be in the 25 to 30 percent range. The combination of these factors explains why the National Weather Service in Sterling, VA issued the watch.
Similar conditions existed last February 19th, which happened to be one of the busiest days in the Prince George's County Fire/EMS Department History.
- Wind forecast for tomorrow afternoon
Above is the wind forecast from windfinder.com which I just happened to stumble upon. Pretty neat. Anyways, by the afternoon, winds should be sustained around 20mph with much higher gusts. Bring those sunglasses to shield the eyes if you're headed outdoors!
Here's a few great sources from the government that are all about fire weather. First is the Fire Weather website which is still experimental but has a ton of great links on it. The second shows active fire areas around the country from the National Interagency Fire Center.
Wildfires can and do happen. Not just in Southern California either. Here's some proof. Do what Smokey says.