Santa’s Christmas Forecast

I’m very busy today preparing for a Christmas-Eve party with my family, but I thought I’d get in a quick Christmas Eve and Christmas Day forecast for the citizens of Western Washington, as well as a quick aviation forecast for tonight so that Santa knows what he’s dealing with as he somehow travels down millions of chimneys across the world in a matter of hours.

We saw some flakes yesterday as a weak low pressure system came in just to our south, giving us moisture and cool northerly flow. Most places saw a slushy inch or less, but some places picked up far more – the South Fork Reservoir of the Tolt River picked up 6 inches, while some places near Bellingham picked up over 4 inches. Snow was highly localized, with lower elevations below 200 feet or so mainly seeing a mix. My house is at 45′ near Lake Washington and we saw a rain/snow mix throughout the day.

The atmosphere has dried out today as this low pressure system has moved to our east and drier, northeasterly flow has moved into the region. Temperatures are in the 30s for most places in the Western Washington lowlands, with low 40s on the coast.

As the satellite image below shows, most of the region is currently experiencing mostly cloudy skies, with a little more clearing further north and significantly clearer conditions along the coast. There are a few isolated areas of precipitation over the Central/Northern Sound at this time, but they are very light and will just bring a light drizzle or rain/snow mix to areas below 500 feet.

Clouds will clear and showers will wilt as the day goes on due to a sharp ridge of high pressure currently offshore moving eastward into our area. Christmas Day looks chilly and dry, with partly cloudy skies and highs in the upper 30s for most folks.

Santa’s Forecast:

I don’t know what elevation Santa and his reindeer like to fly at, but I’m assuming they fly at very low elevations when going through densely-populated areas and delivering presents and fly at several thousand feet when covering large distances such as across the boreal forests of Northern Canada. I doubt they fly at 30,000 feet like airplanes, as his reindeer would have trouble getting an adequate supply of oxygen, and at the middle-levels of the atmosphere, they’d have to deal with clouds, which I’m sure are no fun. Too close to the surface and you have to deal with nighttime radiation fog and a variety of ground-related hazards.

Let’s assume Santa and his reindeer fly at 925 mb (approximately 2,500 feet) when covering large distances, and at 10 meters (33 feet) when traveling between houses in densely populated areas.

Winds look light at 925 mb, with temperatures slightly below freezing. Good for Santa and his reindeer.

Unfortunately, Santa will have to deal with some fog increasing throughout the night, particularly in the south sound. Though this may not be a problem at “cruising altitude,” it may cause some troubles when he’s at lower elevations. Thankfully, rumor has it that the National Weather Service installed one of their new dual-polarization radars on his sled, and this should help him navigate through areas of low visibility.

That’s all for now, got a turkey to baste!

Thanks for reading, and Merry Christmas.
Charlie