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Next Storm/Next Snow Forecast Discussion from the Cherrywood Observatory – December 17, 2018

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

Forecast Discussion:

According to the Sunday surface map (Figure 1) - we seem to have high pressure around.  (I did *not* photoshop in all those H's). We are dry with abnormally high temperatures. Let's look at the next storm...

Figure 1: The current surface map from Sunday PM and the Weather Channel.

The longer range forecast:

The big western upper air ridge finally begins to break down at the end of the week (the red trough cutting into the western U.S. in Figure 2). A weak trough will kick up strong winds Wednesday (Figure 3) - then the main-event-cold front hits Friday afternoon. After that we do get a chance of snow Saturday evening, Sunday morning and a hint of a Christmas morning snow (just a 10% chance of precipitation, don't rent a photographer yet).

The GFS (Figure 4) has snow down to Lyons and Boulder by Christmas Day with more snow down to Loveland north of us. From the ECMWF model (Figure 5) we get, not the snowfall between now and then, but the forecast of snow on the ground for Christmas Day. We are in the 1/2 to 1 inch area with good mountain snows and even a stripe east of us off into Kansas. You can also check this map to see where friends around the country may see snow. There aren't many locations due to all the warmth this week over much of the nation.

Figure 2: The 500mb forecast upper air analysis for Friday PM. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.

Figure 3: the graphical forecast for the next 10 days forecast for Estes Park, CO from weatherunderground.com

Figure 4: The forecast accumulated snow map from the GFS and weather5280.com for Colorado, through Christmas Day.

Figure 5: The forecast actual snow on the ground map from the ECWMF model and weatherbell.com for Colorado, through Christmas Day.

Current Weather

Cloudy

Cloudy

51°F

UV Index
0 Low
Pressure
30.17 Rising
Visibility
7 miles
Dewpoint
44 °F
Humidity
78%
Wind
WNW 2.2 mph
Gust
4.2 mph
Wind Chill
51 °F

Hourly Forecast

Today
11 PM
48°F
Intermittent clouds
Tomorrow
12 AM
47°F
Intermittent clouds
Tomorrow
1 AM
45°F
Intermittent clouds
Tomorrow
2 AM
45°F
Intermittent clouds
Tomorrow
3 AM
43°F
Intermittent clouds
Tomorrow
4 AM
42°F
Intermittent clouds
Tomorrow
5 AM
41°F
Intermittent clouds
Tomorrow
6 AM
40°F
Intermittent clouds
Tomorrow
7 AM
42°F
Intermittent clouds
Tomorrow
8 AM
46°F
Mostly sunny
Tomorrow
9 AM
52°F
Mostly sunny
Tomorrow
10 AM
57°F
Mostly sunny

7 Day Forecast

Mostly cloudy w/ showers

Tuesday

63 °F

Turning cloudy and cooler; a passing afternoon shower or two


Partly cloudy w/ t-storms

Tuesday Night

40 °F

A couple of evening thundershowers; partly cloudy


Mostly sunny

Wednesday

76 °F

Pleasant and warmer with sunshine and patchy clouds


Partly cloudy

Wednesday Night

42 °F

Patchy clouds


Mostly cloudy w/ t-storms

Thursday

73 °F

Becoming cloudy; breezy in the afternoon with a thunderstorm in spots


Cloudy

Thursday Night

48 °F

A thunderstorm in spots in the evening; otherwise, considerable cloudiness


Showers

Friday

69 °F

Mostly cloudy with a couple of showers


Thunderstorms

Friday Night

46 °F

Cloudy; thundershowers in the evening followed by periods of rain late


Showers

Saturday

53 °F

Cloudy and cooler with a couple of showers


Showers

Saturday Night

39 °F

Cloudy with occasional rain and drizzle late


Sunrise and Sunset

Sunrise
6:10 AM
Sunset
7:48 PM

Based on AccuWeather data