Forecast Discussion:

High pressure at the surface and a ridge aloft mean mild weather continues to rule. A juicy storm is impacting the West Coast of the U.S. (Figure 1), but that will spend itself by the time it reaches the western slopes of Colorado (we’ll check on snow amounts in Figure 3).

Figure 1: The forecast surface map for Saturday PM. From NCEP.

The longer range forecast:

There might be a few sprinkles or snow flurries that make it over the mountains down onto the plains and I-25 Sunday night or Monday morning, but down slope flow warming will counter the cool front’s cooling.  We just don’t change much in temperature the next 10 days (Figure 2).

A check on the GFS and the next 10 days of snow for the state, things have dried out a lot in a couple of forecast days.  Figure 3 shows Longmont only getting a dusting to 1/2 inch of snow over the next two ‘storms.’

That creates a nice segue to checking on our state drought index map (Figure 4). The edges of boulder county are starting to see abnormally dry conditions.  The southwestern counties are still in extreme to exceptional drought conditions.  We need snow!!

The atmosphere is in a mild El Nino/ENSO state (Figure 5) and is expected to have a good chance of remaining in that state into later this year. Historically that implies slightly above normal precipitation chances this season (January- March) for northern Colorado and even better chances for southern Colorado.  Temperatures are expected above normal for the state through the next three months as well (Figure 6).   Lets bring on that precipitation!


Figure 2: the graphical forecast for the next 10 days forecast for Longmont, CO from
Figure 3: The forecast accumulated snow map from the GFS and for Colorado, for the next 10 days.
Figure 4: The current drought index map for Colorado issued Jan 3, 2019 from NOAA/NWS/NCEP/CPC
Figure 5: The forecast ENSO index through ASO (August/September/October 2019) from the IRI/CPC.
Figure 6: The forecast precipitation and temperature trends from a presentation by NOAA.
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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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