Updated 2/14/08, 4:45pm – In the end, a pretty typical late winter storm.  A decent bit of moisture in the snow that fell and it is already mostly melted.  🙂  ThorntonWeather.com recorded 2.6 inches of the white stuff which is below the low end of what was originally forecast.  It was a pretty stark contrast though between Wednesday when we reached a high of 69 and  today with a high of only 32 – a difference of 37 degrees in just a single day! 

Updated 2/14/08, 11:25am – The snowstorm is now slowly deteriorating from north to south across the metro area.  Snow will continue to diminish as the storm moves further away.  The Snow and Blowing Snow Advisory remains in effect until 2:00pm.

Updated 2/14/08, 5:20am – Nearly an inch of snow has fallen in Thornton thus far today as the storm hits the metro area.  The storm arrived a bit later than expected as it stalled over northern Colorado but it has intensified considerably just in the last hour and a half or so. 

A Snow and Blowing Snow Advisory remains in effect until 2:00pm today.  It is currently quite windy out there right now with gusts up to 25 mph.  This is blowing the snow considerably decreasing visibility and making small drifts.  Please allow extra time for your commute to work this morning as it is liable to be a rough one. 

Snow will continue this morning and may be heavy at times. Overall snowfall accumulations won’t be quite as bad as originally forecast.  Total accumulations of 3 to 6 inches can be expected before the snow diminishes early this afternoon; Thornton and the north area will be on the lighter side of that range. North winds of 15 to 25 mph with gusts as high as 35 mph east of I-25 will produce areas of blowing and drifting snow. 

For the latest closings, delays and cancellations, please visit 9News’ website. 

Denver and Thornton wrapped on the first month of 2008 dry.  Official measurements at Stapleton and at ThorntonWeather.com recorded only 0.08 inch of precipitation making it the 7th driest January since recordkeeping began in 1872.  This was 0.43 inch below the 0.51 normal, so a pretty big drop.  Only two days had measurable precipitation in the form of snow at Stapleton while in Thornton we recorded four. 

Officially only 3.1 inches of snowfall was recorded near the former Stapleton International Airport and in Thornton we recorded a bit less at 2.8 inches.  This was 4.6 inches below normal for Denver.  Thornton’s seasonal snowfall stood at 26.4 inches at the end of the month (the official Denver measurement was 29.5 inches) which is below the official normal of 33.3 inches for this period. There were no precipitation records set or tied during the month.

In regards to temperature, the normal average for the month is 29.2 degrees which we finished slightly below at 27.9 (28.2 in Thornton).  Illustrating the wide range of temperatures we experience in Colorado, we had a high temperature of 66 degrees on the 27th and a low of -1.7 on the 22nd (Denver recorded 63 and -3 on those days).  All but one day of the month, the 4th, recorded low temperatures below freezing and five days had high temperatures that never got above freezing.  While the month was below normal, it was still warmer than what it was just one year ago in 2007 when the average was 22.8 degrees! 

Some other interesting statistics…  We did have sunshine 79% of the possible time so it was pretty sunny at least.  Wind is of course a fact of life on the plains and we did have 12 days with wind gusts registering over 25mph.  On the 25th of the month we registered the highest gust of the month at 38mph. 

For a day by day log, click here to view our climate log for January 2008.

Much to everyone’s surprise, what was forecast to be not much more than a dusting of snow turned into quite a bit more.  In Thornton from about 6:00pm to 7:00pm we saw 1.5″ fall very quickly with near blizzard conditions for that brief period.  Much of the Denver metro area saw more snow than that, primarily west of I-25 and south of I-70.  Not far from us Broomfield reported 3.4″ and Federal Heights 3″.

Why did this storm offer more than predicted?  Here is what 7News’ meterologists offer:

Computer models had shown little if any snow across Denver.  However, instability in the atmosphere provided enough juice for a convective-type snowfall.  Reports of thundersnow came from southwest Denver near Chatfield State Park as a result of the instability early Wednesday afternoon.

This type of snow is called CSI, Conditional Symmetric Instability. It is generated when enough instability exists in the atmosphere to give snow showers a thunderstorm-type development.  With help from upslope flow, these snow events can dump a lot of snow in a short period of time.  While these events don’t last more than a few hours in most cases, snowfall rates as high as 2 to 3 inches can amount to excessive accumulation.

For the foreseeable future we expect to stay pretty dry.  Our next chance for snow comes Monday and into Tuesday.  No predictions yet on amounts of snow as it is too far out and the models aren’t consistent yet.  Until then, temperatures should be pretty seasonable.