In Brief:

The forecast is becoming summer-simple: high temperatures around 90F each day with a greater or lesser chance of afternoon thunderstorms coming off the mountains. Our most stormy afternoons appear to be Tuesday (post day for this column) and Friday- Saturday. We do cool to the lower 80’sF briefly Saturday.

Forecast Discussion:

The dark green outline shows the deeper moisture (as it begins to move out of the state – Figure 1). The lighter green line outlines very dry air to our west. The chance of severe weather is marginal just north of Longmont up through Ft. Collins etc. (not shown).

The Longer Range Forecast:

We spend a few hours in the lower 90sF Wednesday and Thursday before we cool to the mid 80’sF then lower 80’sF Friday and Saturday. Afternoon storm chances are low, but still exist.

The 4th of July Forecast:

I have a red asterisks at about 9pm on the charts Figure 2 and Figure 3. The weatherunderground model has us at ab out 76F at 9pm with a 4% chance of showers and 25% cloud cover that is decreasing. The GFS based 7! Timer model (Figure 3) has us at about 63F with cloudy skies and showers occurring. It begins to clear after midnight. There is some clear disagreement – we’ll keep an eye on it!

Figure 1: the water vapor satellite image (browns/reds are dry air, whites and light grey is moist air, purple/blue is ice and high cloud tops). From the NWS.
Figure 2: the graphical forecast for the next 10 days for Longmont, CO from weatherunderground.com
Figure 3: The 2.5 day sky conditions forecast from 7! Timer (the GFS).
Figure 4: the forecast accumulated precipitation map from the GFS and weather5280.com for Colorado, up to July 4th morning.
Figure 5: the forecast accumulated precipitation map from the GFS and weather5280.com for Colorado, up to July 4th late night.
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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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