Forecast Discussion:

Mild weather has invaded. In the wind chill maps (where actual temperature and wind speeds combine to give you a physiological sensation of colder temperatures) there is an interesting warmer signal down hill from the Rockies with calm air and the compressional heating of the air (darker blues around and east of the Longmont dot – Figure 1 and 2).

The surface front and pressure lines (isobars) are hinting that there is high pressure in the western states (there are a few H’s again- Figure 3). Beautiful stuff!

Figure 1: Wind chill map for the U.S. from Thursday afternoon. From weatherunderground.com
Figure 2: Wind chill map for the Western U.S. states from Thursday afternoon. From weatherunderground.com
Figure 3: The current surface map from Thursday PM and the Weather Channel.

The longer range forecast:

The ridge dominates the west into the weekend. It is holding on strong early Saturday (Figure 4). The meteogram from Weather5280.com (figure 5) shows the trough in Figure 4, off the California coast, moving in later in the weekend creating western CO snows. Some showers may sneak off the mountains to the I-25 corridor… we’ll see as we get closer.

Later next week (7-9 days from now) a bigger temperature drop arrives with increased rain/snow chances (Figure 5). The GFS gives Longmont 4-5 inches of snow (total) over the next 10 days. (Alert: do not place monetary wagers on 10 day forecasts!).

Figure 4: The 500mb forecast upper air analysis for Saturday AM. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.
Figure 5: 10 day meteogram from weather5280.com for DIA.
Figure 6: The forecast accumulated snow map from the GFS and weather5280.com for Colorado, for the next 10 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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