In Brief:

After 15 snow flakes fell in town this afternoon (Monday) we enter a very normal, dry (boring) stretch of weather. The models are in a lot of disagreement over what will come next; the weatherunderground and GEM models drop good snow on Longmont Saturday into Sunday. The GFS and NAM do not.

Forecast Discussion:

All is quiet on the western front – well the front that is fading out to our west (Figure 1). High pressure will dominate the weather story for the week. I did see flakes falling between me and my cell phone at lunchtime, but the clouds were thin and the sun was shining. The radar didn’t show precipitation falling. Tuesday is very close to seasonably cool with just a few clouds now and then.

The Longer Range Forecast:

The rest of the week is that same story – mild and cool (Figure 2). The **slow** melt will continue. I finally got the last chunks of ice of my driveway proper, but the street out front is still an icy lumpy mess.

Looking at next weekend the GEM and weatherunderground models – they are sniffing out at least a few, to a number of inches of snow (Figure 2). Still, the GFS says nothing significant will fall in town (Figure 3). It puts all the action up in the mountains.

The Fantasy Far-Out Christmas Forecast:

I’m always rooting for White Christmas. Just looking quickly at the GFS; it has some snow falling in places around the state overnight Saturday into Sunday December 21-22 (Figure 4). It has us locked under a strong (cold) high pressure center for Christmas Eve and Day (not shown). This could certainly change a LOT between now and then. It is good news that there is some type of storm in the area within a few days of Christmas showing up in the models. That hints that a large ridge won’t be ruling the roost entirely by the end of the month. More later!

Figure 1: the current surface analysis map from Monday PM and the weather channel.
Figure 2: the graphical forecast for the next 10 days for Longmont, CO from
Figure 3: 10:1 (snow to liquid) snowfall totals through through NEXT Tuesday midnight/morning from the GFS and weather5280com for Colorado made Monday noon.
Figure 4: The 6 hour precipitation type forecast for midnight/morning Sunday Dec 22 from the GFS.
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John Ensworth works from Longmont as the Principle Investigator for the NASA Science Mission Directorate Earth and space science education product review through the IGES (The Institute for Global Environmental Strategies – . He is in his 14th year running this review. He is an astronomer (from the 2nd grade onward) and became a meteorologist (in the 5th grade) when a thunderstorm in Arizona rained on his telescope when the weather service had only forecasted a 10% chance of rain. He has college degrees in physics and astronomy and climatology and a graduate degree in meteorology and earth science. He lectures at the Little Thompson Observatory in Berthoud, the Estes Park Memorial Observatory in Estes Park, and for a number of online universities. He built and runs a backyard observatory near Pace and 17th in northeast Longmont where he has lived for 8 years with his wife, daughter, son, and two cats. Invitations to open house nights at this observatory, LTO, and EPMO will be posted with future discussions when they are scheduled. Forecasting severe weather and snow amounts via text lead to this column. He began texting friends about the weather right after the September 2013 flood. The readers of this column will, hopefully, keep him honest in what he ‘thought’ he had forecasted for ‘the most recent’ storm.

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