In Brief:

If it wasn’t for the cold fronts coming this weekend, this would be a very boring discussion. In advance of that, we’ll see above average temperatures and a small chance of an afternoon thunderstorm. The main front arrives mid-afternoon Saturday with a better chance of showers/thunderstorms.

Sunday is cool with slowly clearing clouds. We remain just below 80F for much of next week with some afternoon rain chances.

Forecast Discussion:

Today (Thursday) will see very low chances of afternoon storms (more in the southern mountains again – Figure 1). We end the week with above average high temperatures (mid 80’sF). The first surge of cool air comes in Friday afternoon (blue line – Figure 2) with a slightly better chance of showers. We are cooled 10F on Saturday.

The Longer Range Forecast:

The next front comes in Saturday afternoon (with the big peak in rain chances – not marked by an added graphic- Figure 2) and we cool another 10F going into Sunday.

This double shot of cool air is coming in thanks to a big trough north of the state (Figure 3). Rain amounts over the next 5 days (the green line in Figure 2 – and painted out in Figure 4) show Longmont getting minimal rain totals, but lucky folks in the mountains and out on the eastern plains will break 1 inch of water.

There isn’t any severe weather on the near horizon either. Any storm can be dangerous with local flooding, lightning, and a blast of strong winds. Respect the storms, especially if you are up in the mountains!

Figure 1: The forecast surface map for Thursday night from NCEP.
Figure 2: the graphical forecast for the next 10 days for Longmont, CO from weatherunderground.com
Figure 3: The 500mb forecast upper air analysis for Sunday AM. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.
Figure 4: the forecast accumulated precipitation map from the GFS and weather5280.com for Colorado,over the next 5 days.
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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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