In Brief:

Our hottest days of the next 10 day period are upon us (Thursday/Friday). Places on the Plains will reach 100F while we hover in the mid to upper 90’sF. Some moisture returns (monsoonal flow) and temperatures cool to reflect it…afternoon thunderstorms return for the rest of the 10 day forecast window.

Forecast Discussion:

For Wednesday, a weak cool front has pressed into northeast Colorado (Wednesday is posting day – Figure 1). This cooled us into the 80’sF Wednesday. That pushes off Thursday and an upper level ridge (blue line over the state and closed circle over the state in Figure 2) begins to dominate. We see mid to upper 90’sF here (and 100’sF not far out on the Plains). This heat will be about 10-15F above normal by Thursday afternoon.

The Longer Range Forecast:

That upper level high will drift off a bit to the east and the clockwise circulation around the high will allow some tropical moisture to ooze into the state (monsoonal-like moisture). Afternoon thunderstorms return Friday and the story becomes a broken record – days and days of highs in the lower 90F’s, lows in the 60’sF with afternoon storm chances.

Figure 1: The southwest U.S. surface frontal analysis map from the
Figure 2: The 500mb forecast upper air analysis for Thursday PM. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.
Figure 3: the graphical forecast for the next 10 days for Longmont, CO from
Figure 4: The forecast temperature at the surface from normal map from the GFS and for Colorado, Thursday afternoon.
Figure 5: the forecast accumulated precipitation map from the GFS and for Colorado, for the next 3 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 – . 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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