Update 8am: Next Storm/Next Snow Forecast Discussion from the Cherrywood Observatory – April 22, 2019

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Est. Reading Time: 2 minutes
Figure 6: the forecast accumulated precipitation map from the NAM and tropicaltidbits.com for Colorado and areas east and south, through the next 2 days.

In Brief:

Today (Monday) is mostly cloudy, cool, with showers at time. We warm slowly with dry weather to the end of the week when we reach 80F again.

Forecast Discussion:

8am Update:

All the models and the NWS forecast are trending toward only a sprinkle or two today under cool stable cloudy skies with a bit of fog possible. The GEM model is the only one that still brings in about 1/10th of an inch. It is an outlier – we won’t see much more water from this system. I received just over 2/10th of an inch of water here in NE Longmont.

End 8am Update.

The weather situation over the next 24 hours is fairly complex. There is cool air in place (diminishing shower chances), some cool air aloft (but not much – aiding in showers a little bit), some up slope flow (aiding in showers), and a front draped nearby (aiding in showers). (Figure 1)

The models are quite confused as well. The weatherudnerground.com model have showers possible most of the day Monday – but it doesn’t give us much precipitation (an under-done 0.01″ – Figure 2).

The HRRR, in contrast- just through 8am – gives us about 0.10″ (Figure 3).

The old reliable GFS, for the next 48 hours – has us in a dry (Figure 4) hole as it did 24 hours ago- but we’ve had almost a quarter inch in the thunderstorms that came through Sunday afternoon (we got our egg hunt done just in time!)

To see how different the models are, the GEM has over 1/2 inch more fall over the next 2 days (Figure 5) while the NAM (Figure 6) gives us about 0.10″.

As for snow – there is just a bit in the higher mountains and- maybe- a coating in Boulder and Lyons over the next day (Figure 7).

The Longer Range Forecast:

Figure 2 – again, takes us back to 70F on Tuesday and warms us to 80F by Friday. There are only tiny chances of afternoon showers now and then – mainly Thursday. There is another storm to watch at the end of the weekend (similar to our set up right now!).

Figure 1: The forecast surface map for Monday noon from NCEP.
Figure 2: the graphical forecast for the next 10 days for Longmont, CO from weatherunderground.com
Figure 3: the HRRR precipitation prediction up to 8am Monday from weather5280.com
Figure 4: the forecast accumulated precipitation map from the GFS and weather5280.com for Colorado, through Tuesday night.
Figure 5: the forecast accumulated precipitation map from the GEM and tropicaltidbits.com for Colorado and areas east and south, through the next 2 days.
Figure 6: the forecast accumulated precipitation map from the NAM and tropicaltidbits.com for Colorado and areas east and south, through the next 2 days.
Figure 7: the forecast accumulated snowfall map from the GFS and weather5280.com for Colorado, through Tuesday night.


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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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