In Brief:

Our first cold front is moving in to knock 5F off the temperatures and give the western slopes some rain/thundershowers. We’ll mainly see increased clouds east of the Rockies with a possible sprinkle. A couple of additional cool fronts will lower us to the 70’sF for highs over the weekend with afternoon showers possible. Next week seems dominated by 70’sF weather for highs and better rain chances.

Forecast Discussion:

Our first cool front is on its way and is kicking off showers over the western counties of Colorado (Figure 1). Down slope flow on this side of the mountains will assure that very little water falls from the sky. By Wednesday morning, the front will be draped down the Front Range into the southeastern parts of the state. A bit more moisture will return behind the front (Figure 2).

The Longer Range Forecast:

Later in the week, a deeper trough starts its trek across the nation (Figure 3). This will kick a couple more cool fronts past us, cooling us to the 70’sF for the weekend. The warmth before the weekend will feel a contribution from that same down slope warming/drying we are experiencing today (Figure 4).

Next week, the trough seems to hold on (or get reinforced) and we stay cool with better rain chances returning (Figure 4). The GFS gives the somewhat dry western and southwestern parts of our state the best rainfall over the next 10 days (Figure 5).

Figure 1: SW US current surface map analysis from Tuesday midday from weatherunderground.com
Figure 2: The forecast surface map for Wednesday AM from NCEP.
Figure 3: The 500mb forecast upper air analysis for Friday AM. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.
Figure 4: the graphical forecast for the next 10 days for Longmont, CO from weatherunderground.com
Figure 5: The forecast rainfall totals for the next 10 days from the GFS and weather5280.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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