Forecast Discussion:

Mild nice-ness continues today. Mountain snows continue today. Figure 1 shows a minor upper level ripple rolling past Colorado to the south keeping the snow-train blowing in the mountains and on the Western Slopes (and rain in New Mexico). We will just get breezes and clouds in NE Colorado. We warm up, a lot, right before the next storm with southwest winds and down-slope flow on tomorrow/Tuesday (Figure 2).

The longer range forecast:

The big news and the big question this week is concerning the next big storm (animation in Figure 3). Somewhere, not far to the east of us, or up into the foothills and over our town, heavy snow, winds to hurricane force/speed, incredible low pressure, and heavy amounts of rain will fall. This will be a very major winter/spring storm for Colorado, Nebraska, Kansas, Texas, and Oklahoma that some people will talk about for years. But will it be us?

Models like that at weatherunderground.com (Figure 2) have backed off, again, on how much snow we’ll get. This run only shows 1-3 inches. The reason Longmont and North Denver to Fort Collins may get skipped is down- slope flow. Really significant down-slope flow. Remember, this flow of air off the mountains compresses the air, warms the air, and suppresses rainfall/snowfall due to the ‘drying’ that occurs in this process. Figure 4, the GFS, shows this powerful snow-hole along I-25 very clearly with just a coating to 1 inch of snow by Thursday. The GEM (Figure 5) keeps the NE quadrant of the state quite dry and again only gives us 1/2 to 1 inch. Figure 6, the NAM, gives us 4-5 inches, but areas around us 9-12 inches (just a few miles away to the east and west).

If you ARE hoping for a snow day, all hope is not lost. Much can change as we lock down the temperatures and actual eventual path of the low. It is still about 2 1/2 days away.

After that storm we return to normal temperatures and dry conditions. It might start to feel like spring for Spring Breaks all around.

Figure 1: The forecast surface map for Monday PM from NCEP.
Figure 2: the graphical forecast for the next 10 days for Longmont, CO from weatherunderground.com
Figure 3: the animation of the Sunday “take” on the mid-week storm from the GFS and weather5280.com
Figure 4: the forecast accumulated snow map from the GFS and weather5280.com for Colorado, through the next 4.25 days.
Figure 5: the forecast accumulated snow map from the GEM and tropicaltidbits.com for Colorado, through the next 4.25 days.
Figure 6: the forecast accumulated snow map from the NAM and tropicaltidbits.com for Colorado, through the next 4.25 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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