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The Next Storm/Next Snow Forecast Discussion from the Cherrywood Observatory – December 22, 2017

This content was originally published by the Longmont Observer and is licensed under a Creative Commons license.

Forecast Discussion:

Here is a brief look at the next storm. We'll best see what the Thursday storm did once the reports come in Friday morning (since 7am is the reporting time).

Figure 1 shows the actual temperatures Thursday PM and they are dropping into the teens in Colorado and much of the upper Plains. Snow reports tomorrow...

Figure 1: Current temperatures Thursday PM from the weatherunderground.com site.

The longer range forecast:

By Saturday morning, another frontal push is coming down the Plains and snow is again possible in northern Colorado (Figure 2). With the super cold air remaining to our distant east, the storm shouldn't have as much punch as we expected. The GFS (Figure 3) shows about 1/2 inch. Figure 4 has the WPC version, and it is about 1 inch. Finally, the NAM (Figure 5) also has us at about 1 inch.

Longmont forecast:  Friday PM and Saturday:  0.5" to 2" of snow.

Part of the problem is that the temperature drop is now not as significant as expected locally. The Friday and Saturday highs are now both expected to get above freezing, which might melt some of our snow! The departure from normal, according to the NAM, is shows in Figure 6. Things aren't too unusually cool around here anymore, in the forecast. We'll watch to see if our White Christmas is in danger.

Figure 2: The forecast surface analysis map for Saturday AM.

Figure 3: The GFS total snowfall between Thursday PM and Saturday PM.

Figure 4: the WPC model snowfall total forecast at 50 percentile PM Thursday PM to Sunday PM.

Figure 5: The NAM total snowfall forecast from Thursday PM to Sunday PM.

Figure 6: The NAM temperature anomaly for Saturday AM.

Current Weather

Light rain

Light rain

41°F

UV Index
1 Low
Pressure
29.85 Rising
Visibility
7 miles
Dewpoint
31 °F
Humidity
68%
Wind
S 2.3 mph
Gust
5.2 mph
Wind Chill
41 °F

Hourly Forecast

Today
10 AM
44°F
Showers
Today
11 AM
47°F
Mostly cloudy w/ showers
Today
12 PM
49°F
Intermittent clouds
Today
1 PM
51°F
Intermittent clouds
Today
2 PM
52°F
Intermittent clouds
Today
3 PM
53°F
Intermittent clouds
Today
4 PM
51°F
Intermittent clouds
Today
5 PM
49°F
Intermittent clouds
Today
6 PM
47°F
Mostly cloudy w/ showers
Today
7 PM
46°F
Intermittent clouds
Today
8 PM
43°F
Cloudy
Today
9 PM
41°F
Showers

7 Day Forecast

Partly sunny w/ showers

Friday

53 °F

Sun and clouds with a couple of showers; cooler


Showers

Friday Night

33 °F

A couple of showers this evening; otherwise, cloudy


Mostly cloudy

Saturday

60 °F

Mostly cloudy


Intermittent clouds

Saturday Night

33 °F

Partly cloudy


Intermittent clouds

Sunday

59 °F

Periods of clouds and sun


Mostly cloudy

Sunday Night

33 °F

Mostly cloudy with a thundershower in spots


Showers

Monday

52 °F

Occasional morning rain; otherwise, cloudy and cooler, becoming windy in the afternoon


Intermittent clouds

Monday Night

29 °F

Windy in the evening; partly cloudy


Mostly sunny

Tuesday

61 °F

Milder with sunshine and patchy clouds


Clear

Tuesday Night

29 °F

Clear


Sunrise and Sunset

Sunrise
6:48 AM
Sunset
7:23 PM

Based on AccuWeather data