In Brief:

We enjoy one more day in the 80’sF – then a vigorous cold front passes over Longmont around noon Friday. With it comes thunderstorms (not looking severe at this time). We cool about 20-30F degrees and may pick up 1- 1.50 inches of rainfall over the next 10 days.

Forecast Discussion:

For fun, now that we are hitting 80’sF down here, let’s look at this snow-year in review (Figure 1). We are still quite a bit above average for the date (at least one ski resort is going to try to stay open until June). We are at 159% of normal snow pack with a statewide average at 14.6 inches of snow. Last year, on this date, we had about 1/3rd an inch of snow left over the state.

Today (Thursday) the next (really wet) storm is crashing into the west. Flooding has begun in California already (Figure 1). The mountains will wring out most of the moisture before it gets here. We will still hit the lower to mid 80’sF today (Figure 3) with a chance of an afternoon hit-or-miss thundershower moving off the mountains to the northeast.

The Longer Range Forecast:

The front arrives midday Friday with a good amount of precipitation and thunderstorm activity (Figure 3). Without enough moisture in place- the severe weather is expected to remain out on the Nebraska and Kansas border and eastward (Figure 4). We’ll watch to see if this changes. The GFS shows the southwest to northeast storm tracks on Friday giving us between 0.25 and 0.5 inch of water (Figure 5). The model agrees with 0.25 inch of water.

The model gives us about 1.50 inches of water over the next 10 days (Figure 3) while the GFS (Figure 6) gives us 0.75 to 1 inch of water over these 10 days. We’ll see if anything changes as the weekend approaches.

Figure 1: The snow season trace averaged over all of Colorado. Green line is normal. Black line is 2018-2019. From NRCS and SNOTEL.
Figure 2: The forecast surface map for Friday PM from NCEP.
Figure 3: the graphical forecast for the next 10 days for Longmont, CO from
Figure 5: the forecast accumulated precipitation map from the GFS and for Colorado,over the next 3 days.
Figure 6: the forecast accumulated precipitation map from the GFS and for Colorado,over the next 5 days.
Previous articlePolice, Citing Stats & Surveys, Continue Encrypting Radio
Next articleLongmont Police Report: May 15, 2019
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.

Leave a Reply