In Brief:

After a chance of a late evening splash of rain and maybe a rumble of thunder, we remain mostly dry for the next 10 days with above normal temperatures (but not really hot either). Quiet is the word of the day.

Forecast Discussion:

The upper air map shows a big trough to the west, but dry air dominates the state (Figure 1). A pinch in the isopleths (black lines) show a wind speed maximum approaching tonight (yellow oval). That “jet streak” acts like a vacuum cleaner and lifts the air a bit. Some showers are possible zipping across the northern parts of the state tonight. The HRRR is unimpressed by rainfall amounts (Figure 2) while the weatherunderground model gives us 0.05 inch (Figure 4).

We dry out Sunday and stay just at normal temperatures for a day as the trough pulls by (Figure 4).

The Longer Range Forecast:

The cut-off low that was going to dump lots of water and snow on the state next week has a different plan. The GFS now shows it digging far south into northern Mexico (Figure 3). That feature won’t matter much to our weather story now.

The week ahead will be about 5-10F above average as temperatures go with some better heat next weekend as another west coast trough pumps southwest winds across the state (Figure 5). I’ve highlighted days at or above 80F in Figure 4. There isn’t much exciting going on. Sorry!

Happy First Day of Fall Monday! The Autumnal Equinox officially arrives at 1:50 p.m. MDT

Figure 1: The 500mb current upper air analysis for Saturday PM. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.
Figure 2: the 12 hour precipitation total forecast from the HRRR and weather5280.com through 1am.
Figure 3: The 500mb forecast upper air analysis for Wednesday AM. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.
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 Saturday AM. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.
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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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