November 21 Snow
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Posted November 23, 2007

Category: Weather

It is snowing today!! It is snowing while I write this. The snow started just before midnight on Tuesday November 20. It has been progressively getting heavier. I'm thinking there will be a couple of inches or more by the time it is done. The moisture is limited but the dynamics are so strong that a nice snow is guaranteed.

From midnight to 1 am the snowflakes have been gradually getting bigger. The surface air has now been moistened up (wet-bulbed out). There is now moderate snow coming down and it is accumulating! The ground is turning white! If it keeps snowing like this there will be a couple of inches by morning. It is interesting how much brighter it is outside at night due to the surface snow cover (high albedo, reflective). I'm playing some Christmas music and watching the snow fall.

It is 2 am and the snow is lightening. I will go to bed soon. I should wake up to about 2 inches on the ground. I will get some pictures and post them at the bottom of this page.

Below are the model images preceding the event showing forecasted precipitation, the intense vort max over Colorado (a classic example of positive vorticity advection) and the subfreezing temperatures. Also below is the Tuesday afternoon temperatures and a cold air damming example. Radar images during the snow event are also shown.







Here are the Tuesday afternoon temperatures (with Haby drawn mountains). Notice the cold air damming along the front range. The temperatures at this time where warmer in the mountains since the denser cold air was trapped at the lower elevations. As the layer of cold air thickens it will eventually get cold in the mountains also.


Here are the conditions during the snow event on Early Wednesday. Snow time! * * *




Below is the midnight radar showing the snow band setting up.


Here are the photo results of the snow. The snow melted on the concrete since the ground was warm but it accumulated real good on the grass. The first two are snow at my apartment. The next is snow on the truck. The fourth is snow at a local park.