9am Update:

Weak up slope flow associated with the front and shortwave creating snow in the mountains (again) has formed freezing fog and very light snow along I-25. This looks like it will clear around noon. There are no watches or warnings associated with this weather situation. Just don’t slip!

End 9am update.

A very small amount of snow made it to I-25 in Larimer county (not shown) Saturday night, but nothing hit Boulder county. We remain dry today with some warming with a ridge overhead and down-slope flow from the ongoing snow showers on the Western Slopes (Figure 1).

We warm to the 50’s for the middle of the week (Figure 2), then start a good cool down (more on that in the longer range forecast). The GFS (Figure 3) has us completely dry through Thursday AM.

The longer range forecast:

By Friday, after some Thursday PM shower chances, the cool down and change begins (Figure 2 and 3). What starts to occur is an overall trough pattern settling into the west with short wave after short wave moving over the state embedded in the northern branch of the jet stream (Figure 4). Thursday night’s showers are kicked off by the short wave drawn over western Colorado in Figure 4.

After Saturday – there are daily snow chances with high temperatures only rising to the lower 30’s F most days (Figure 2 and 3). The overall trough, with shortwaves, keeps us cool and moist even up to next Tuesday (Figure 5).

Change is coming after Valentines Day. I’ll try to add a heart to the graphical forecast when used this week.

Figure 1: The forecast surface map for Monday PM. From NCEP.
Figure 3: the graphical forecast for the next 10 days for Longmont, CO from weatherunderground.com
Figure 3: 10 day meteogram from weather5280.com for DIA.
Figure 4: The 500mb forecast upper air analysis for Thursday PM from the GFS and tropicaltidbits.com. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.
Figure 5: The 500mb forecast upper air analysis for Tuesday early AM from the GFS and tropicaltidbits.com. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.
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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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