10 PM Update Saturday 3/23:

The previously described short wave will be rolling over the state today (Sunday) kicking off a chance of rain and thunderstorms, some containing small hail, mainly after 5pm Sunday and ending by 11pm. A little taste of Spring weather now that Spring has started – and before the 70’sF hit later this week. I’ll have my camera with me for any thunderheads that form… (Note, presently, severe weather is not expected in Colorado.)

figure 1 update: The day 2 forecast made Saturday for Sunday of severe weather and convection regions from the NWS Storm Prediction Center in Norman, OK.

End 10pm Update 3/23

Forecast Discussion:

I’m barreling down the interstate typing on a wifi hotspot from the back seat. But we’re getting an update done!

We drove through a blinding (but geographically small) snow storm near Flagstaff Thursday PM. That storm system hit Colorado on Friday and even produced a significant land spout near Eads. What excitement!

Figure 1 shows (by Sunday morning) that we are between systems, but another low is dropping moisture to the west of our state. Try as I could, my graphics program would not save the (even flattened) trough and ridge lines in Figure 2, but the big picture is the large ridge in the west with an active southern branch of the jet stream bringing many small ripples of energy over the state. That means mountain snows and rain showers on the plains. And a warming trend.

Over the next 48 hours, we’ll see a dusting or coating of snow near Longmont with night time precipitation. We might pick up up to 1/4th of an inch of water during that time (Figures 3 and 4).

The longer range forecast:

That ridge takes hold and we rocket to the 70’sF by mid-week. Oh that will feel good – even Phoenix wasn’t that warm this week. Out further in the week, we have indication of a big trough returning and more rain and snow with cooler temperatures, but we’ll look at that when I return to normal forecasting duties in a couple of days.

Figure 1: The forecast surface map for Sunday AM from NCEP.
Figure 2: The 500mb forecast upper air analysis for Sunday PM. Pink dot is Longmont. Red lines are troughs, blue lines are ridges. (Missing this time, no matter what i did.)
Figure 3 : the forecast accumulated snow map from the GFS and weather5280.com for Colorado, through Sunday PM.
Figure 4 : the forecast accumulated precipitaiton map from the GFS and weather5280.com for Colorado, through Sunday PM.
Figure 5: the graphical forecast for the next 10 days for Longmont, CO from weatherunderground.com
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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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