Forecast Discussion:

Closer the cold comes, step by step by step. Sunday PM, the leading edge of the very cold air has made it into Wyoming and the Dakotas (those poor people – Figure 1). We will see the typical pre-storm warmth with westerly down-slope winds (gusty at times) and compression heating. The cold air begins to slide in later Tuesday with almost 24 hours of snow on Wednesday (Figure 2).

The longer range forecast:

By Wednesday (Figure 3) air that is around 25°F below normal is sliding into Denver. This will feel like quite a shock after our mild week. The weatherunderground model has 1-3 inches of snowfall. The GFS model (Figure 4) gives us 1-2 inches. The NAM has us at about 2-3 inches (though it is hard to read in Figure 5). Those are too far off of most of this winter’s storms and all models agree that a trough takes over for the ridge in the west and we stay below normal to normal, temperature-wise, for the rest of the 10 day window.  Yes, get the coats ready again.

Figure 1: The forecast temperature departure from normal map from the GFS and weather5280.com for Colorado, Sunday evening.
Figure 2: the graphical forecast for the next 10 days for Longmont, CO from weatherunderground.com
Figure 3: The forecast temperature departure from normal map from the GFS and weather5280.com for Colorado, Wednesday evening.
Figure 4: the forecast accumulated snow map from the GFS and weather5280.com for Colorado, through Thursday AM.
Figure 5: The forecast accumulated snow map from the NAM and tropicaltidbits.com for Colorado, through Thursday morning.
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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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