Forecast Discussion:

Our front has pushed through around 5 pm and by tomorrow morning is draped just a bit further south of us, but is still in Colorado (Figure 1). This is being powered by a (positively tilted) trough sliding by over the next day and a half. After the front and up to 11 pm Tuesday, rain showers will be very widely scattered (Figure 3- the HRRR). The weatherunderground.com model has a fairly low chance of precipitation through 6 pm Wednesday with temperatures probably too warm for snow (Figure 4).

The GFS give us a bit of rain (nearby) – Figure 5. The small amounts of snow are as close as Lyons and Boulder – but still it isn’t much (Figure 6).

The longer range forecast:

From Figure 4, we climb to the mid 70’s F at the end of the week before the next trough moves in (Figure 7 – the red line to our west again). It won’t be moving quickly and another trough lurks out in the Pacific – so we cool down and have pretty good rain chances Saturday pm through Tuesday and beyond.

Figure 1: The forecast surface map for Wednesday AM from NCEP.
Figure 2: The 500mb forecast upper air analysis for Wednesday morning. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.
Figure 3: the HRRR precipitation prediction up to 11pm Tuesday from weather5280.com
Figure 4: the graphical forecast for the next 10 days for Longmont, CO from weatherunderground.com
Figure 5: the forecast accumulated precipitation map from the GFS and weather5280.com for Colorado, over the next 2 days.
Figure 6: the forecast accumulated snowfall map from the GFS and weather5280.com for Colorado, over the next 2 days.
Figure 7: The 500mb forecast upper air analysis for Saturday evening. 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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