Forecast Discussion:

Our last storm came in a couple of waves.  Thursday into Friday, Denver saw some significant snow (Figure 1) ranging from just a trace in the northern reaches to over 3 inches in the south (up slope flow on to the Palmer Divide).  At the same time, Boulder county received almost nothing (Figure 2).  Larmier county only registered a trace in a couple of stations (no figure, too boring).

Friday into Saturday, the blizzard cranked up out on far northeastern Plains.  I did a quick-and-dirty analysis of the snowfall depth and places out there there saw 4-7 inches of snow (Figure 3). Winds were very strong as well (hence the blizzard). Trees were felled across Limon, for example, with 70+mph wind gusts.

The low departs and a ridge approaches (Figure 4) warming us up this weekend and allowing winds to die down. We approach 80F again on Monday with the ridge of Figure 4 overhead.

 

Figure 1: The CoCoRaHS snowfall 24 hour snowfall reports up to 7am Friday for the Denver Metro.
Figure 2: The CoCoRaHS snowfall 24 hour snowfall reports up to 7am Friday for Boulder County.
Figure 3: The CoCoRaHS snowfall 24 hour snowfall reports up to 7am Saturday for Colorado. Sloppy rough contours added for a big picture glance.
Figure 4: The 500mb forecast map from the GFS for Monday AM. Longmont is the pink dot, red lines are troughs, blue lines are ridges.

The longer range forecast:

Right on the heels of this ridge is a trough that will blow through on Tuesday dropping temperatures briefly and giving us another windy day (Figure 5).  It is too early to know if there will be an elevated fire danger (but one must be careful with conditions as they are).

Our next big storm moves in on Friday into the weekend (Figure 6). The low height center digs much further south than the low height centers of the storms in Figure 4 and 5.  It should move through slower and create more instability over the state. As a hint of what might be coming, the 8 day GFS total snowfall map up through next Saturday paints Longmont with 8″ of snow and puts a foot to two feet of snow up in the nearby mountains and across southern Wyoming and to the east (Figure 7).  We will have to watch this all week to see if it holds in, or fizzles out of, the forecast.

Figure 5: The 500mb forecast map from the GFS for Tuesday AM. Longmont is the pink dot, red lines are troughs, blue lines are ridges.
Figure 6: The 500mb forecast map from the GFS for Friday AM. Longmont is the pink dot, red lines are troughs, blue lines are ridges.
Figure 7: The GFS total snowfall between Saturday AM and next Saturday AM from tropicaltidbits.com
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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 – www.strategies.org) . 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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