In Brief:

With a ridge overhead, we soar to the 80’s F for a couple of days. Moisture returns with the heat – so afternoon thunderstorms (we’ll have to watch the severe chances) return today (Thursday) as well. A cool front comes in for the the weekend. We cool to the 70’s F and have pretty good daily chances of rain and thundershowers.

Forecast Discussion:

Widely scattered storms will form in the mountains and move eastward this afternoon (Thursday- Figure 1). High pressure at the surface and aloft mean heat – temperatures in the mid to upper 80’s F.

Meteorologist Matt Makins (via Twitter @MattMakens) posted some interesting statistics. “Interesting Denver weather tidbits: In 2018 through June 10th, we had 12 days in the 90s. Yet in 2019 through June 10th, we have yet to hit the 90s and have only been 80°+ 8 times.”

There are no 90’s+ F in the forecast and longer range models show the cool (and moist) conditions will continue for a number of weeks to come, overall (Figure 2).

The heat Thursday will be about 7 to 9 degrees F above normal (Figure 3). Thursday and Friday are the warmest days.

With heat and moisture – will we see severe weather return? Figure 5 shows a Marginal Risk (1 on a scale of 1-5) out on the Eastern Plains. We HAVE seen this get expanded westward on the day of the event a number of times. I’ll update this post if the SPC changes the western boundary.

The Longer Range Forecast:

Similar to Thursday, there is a chance of severe weather out on the Plains on Friday as well (Figure 6). It doesn’t extend back to the I-25 folks, but that might change.

The cool down on Saturday (Figure 4) knocks the temperatures to some 6-8 degrees F below average.

Figure 2 shows that there are elevated chances of rain beginning Friday and continuing to Monday (green box). The coolest period spans Saturday to Monday (black box). Over the next 5 days, the GFS gives about a quarter of the state up to 1 inch or more of rain and a lot of folks 1/2 inch or more rainfall. Don’t trust any one spot (like the pink dot for Longmont where there is exactly 1/2 inch of water) but this pattern and overall rainfall highlights are probably reliable.

Figure 1: The forecast surface map for Thursday night from NCEP.
Figure 2: the graphical forecast for the next 10 days for Longmont, CO from weatherunderground.com
Figure 3: The forecast temperature departure from normal map from the GFS and weather5280.com for Colorado, Thursday PM.
Figure 4: The forecast temperature departure from normal map from the GFS and weather5280.com for Colorado, Saturday PM.
Figure 5: The severe storm weather forecast for the U.S. from the Storm Predication Center in Norman, OK. Made Wednesday for Thursday.
Figure 6: The severe storm weather forecast for the U.S. from the Storm Predication Center in Norman, OK. Made Wednesday for Friday.
Figure 7: the forecast accumulated precipitation map from the GFS and weather5280.com for Colorado,over the next 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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