In Brief:

Temperatures 15-20F above normal are the norm for a couple more days with high pressure stacked up through the atmosphere. Friday, a deep trough moves in kicking off storms and cooling us to below normal levels and returning a chance of rain for much of next week.

Forecast Discussion:

We have high pressure over the state today and weak winds (Figure 1). Overhead in the upper atmospheric map (Figure 2) the center of the ridge line is almost overhead. This will past to the east today changing the flow aloft from northwest flow to a southwest flow. That changes the drift direction of the afternoon storms that move off the mountains and warms us a bit more (Figure 3). There is a chance of afternoon thunder showers everyday around time of maximum heating (2-5pm).

The Longer Range Forecast:

Friday we see the change occur with a deep trough moving in from the west (red line digging towards us in Figure 4). We’ll keep an eye on the amount of moisture that can make it in by Friday to see IF we may see severe weather nearby (Figure 3). From Saturday on into next week we hover in the 60’sF for highs with many chances for rain again. More later!

Figure 1: The forecast surface map for Wednesday PM from NCEP.
Figure 2: NCEP 500 mb upper air map from Tuesday PM. Blue lines are ridges, red lines are troughs.
Figure 3: the graphical forecast for the next 10 days for Longmont, CO from weatherunderground.com
Figure 4: The 500mb forecast upper air analysis for Wednesday morning. 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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