Forecast discussion:

Another sprinkle moved through on Saturday, but it wasn’t much. Now the real first warm-up of the year gets underway. From Sunday afternoon, high pressure is sitting in place over our state (Figure 1). By Monday morning, a strong ridge is moving in from the west (Figure 2). By Tuesday afternoon we could be almost 25°F above normal (Figure 3). Tuesday’s high will probably break 80°F for the first time in forever.

The longer range forecast:

Still looking at Figure 4, the next day, Wednesday, a front moves in during the morning and we have about 18 hours of a really good chance of rain. Ground temperatures will be high and we will just be cooling to freezing at the end of the main precipitation event – so snow, if it occurs, it won’t stick around much.

This storm system is caused by a strong short wave moving in with a closed-off low over Utah Wednesday AM (Figure 5). Our 10 day snow totals for the state look like a foot in the higher mountains, but maybe a trace/coating down around Longmont (Figure 6). For rainfall, weatherunderground.com gives us about 1/4th of an inch (Figure 4) while the GFS gives us 1/2 to 3/4th of an inch. Sorry if you were hoping for snow, but it is leaving the forecast (though there is still a lot of disagreement among the models for what happens Thursday on – so I’m not focusing on that longer long range forecast yet).

Figure 1: The forecast surface map for Sunday PM from NCEP.
Figure 2: The 500mb forecast upper air analysis for Monday morning next week. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.
Figure 3: The forecast temperature departure from normal map from the GFS and weather5280.com for Colorado, Tuesday PM.
Figure 4: the graphical forecast for the next 10 days for Longmont, CO from weatherunderground.com
Figure 5: The 500mb forecast upper air analysis for Wednesday morning next week. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.
Figure 6: the forecast accumulated snowfall map from the GFS and weather5280.com for Colorado, over the next 10 days.
Figure 7: the forecast accumulated precipitation map from the GFS and weather5280.com for Colorado, over 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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