In Brief:

We have daily afternoon chances of rain and thunderstorms Saturday through Wednesday with below normal temperatures. Heaver rain amounts are expected Monday and Tuesday. Some severe weather (hail and high winds are the primary risk) is possible Sunday afternoon.

Forecast Discussion:

The front is in place down the Plains and up into the Foothills (Figure 1). This has stabilized the atmosphere significantly (Saturday afternoon). Moisture is more limited (especially north of I70) with precipitable amounts only around 0.63 inches this morning at DIA. Except where the lucky thundershower travels, most locations will see less than a 1/10th of an inch of water today (Saturday afternoon) and severe weather is not expected (Figure 3).

The Longer Range Forecast:

Tomorrow (Sunday) we have a couple of periods of rainfall – around noon and around sunset – possible (Figure 2). There is a Marginal Risk (1 on a scale of 1-5) for thunderstorms to create damaging hail and high winds over NE Colorado.

The GFS gives most locations under 1/2 inch of water over the next 5 days with lucky locations getting 1-2 inches (Figure 5). The NAM, over the next 2.5 days, shows how very spotty this convective precipitation will be (Figure 6).

Figure 1: The forecast surface map for Sunday AM from NCEP.
Figure 2: the graphical forecast for the next 10 days for Longmont, CO from weatherunderground.com
Figure 3: The severe storm weather forecast for the U.S. from the Storm Predication Center in Norman, OK. Made Saturday for Saturday.
Figure 4: The severe storm weather forecast for the U.S. from the Storm Predication Center in Norman, OK. Made Saturday for Sunday.
Figure 5: the forecast accumulated precipitation map from the GFS and weather5280.com for Colorado,over the next 5 days.
Figure 6: the forecast accumulated precipitation map from the NAM and tropicaltidbits.com for Colorado,over the next 2.5 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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