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The Next Storm/Next Snow Forecast Discussion from the Cherrywood Observatory – December 5, 2017

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

Forecast discussion:

I've re-set up the Christmas decorations that blew around Sunday night in the breezy sunlight of Monday.  Today we have a ridge off the west coast, another ridge a bit off the east coast and a tilted trough draped across the center of the nation.  With a wavelength like this, the waves and troughs (red and blue lines) won't move (progress) to the east very quickly (Figure 1). And they don't.

Figure 2 shows a rapid series of brief fonts passing over the state each day, today, tomorrow and Thursday.  The first two cool us down - the second might give us a sprinkle/dash of snow.  I'm not counting on it.  Those are caused by smaller ripples in the overall flow.

Figure 1: 500mb upper air forecast map for Tuesday PM.

Figure 2: 10 day graphical forecast from Weatherunderground.com

The longer range forecast:

Figure 2 shows the next two cool downs and associated few-hours-of-gusty-winds (bottom graph).  On Friday, the front begins a warm advection (air moving from one place to another across the land) process that warms us nicely for the weekend. Figure 3 also shows how far east the western ridge finally moves that also contributes to the nice weekend.  Then it stays quiet beyond that.

Fantasy Christmas Day Forecast (from Accuweather.com):

12/24  50F/14F partly cloudy     12/25  43F/13F mostly sunny.

Figure 3: 500mb upper air forecast map for Saturday AM.

Current Weather

Mostly cloudy

Mostly cloudy

38°F

UV Index
0 Low
Pressure
29.79 Rising
Visibility
8 miles
Dewpoint
29 °F
Humidity
69%
Wind
N 2.8 mph
Gust
5.5 mph
Wind Chill
36 °F

Hourly Forecast

Today
5 AM
36°F
Intermittent clouds
Today
6 AM
34°F
Intermittent clouds
Today
7 AM
36°F
Intermittent clouds
Today
8 AM
38°F
Intermittent clouds
Today
9 AM
41°F
Intermittent clouds
Today
10 AM
44°F
Intermittent clouds
Today
11 AM
47°F
Intermittent clouds
Today
12 PM
49°F
Intermittent clouds
Today
1 PM
51°F
Intermittent clouds
Today
2 PM
52°F
Intermittent clouds
Today
3 PM
52°F
Intermittent clouds
Today
4 PM
51°F
Intermittent clouds

7 Day Forecast

Partly sunny w/ showers

Friday

52 °F

Cooler with times of clouds and sun; a couple of showers late this afternoon


Showers

Friday Night

34 °F

A couple of showers this evening; otherwise, cloudy


Mostly cloudy

Saturday

60 °F

Mostly cloudy


Intermittent clouds

Saturday Night

34 °F

Partly cloudy


Intermittent clouds

Sunday

62 °F

Periods of clouds and sun


Mostly cloudy

Sunday Night

33 °F

Becoming cloudy


Showers

Monday

52 °F

Cloudy and cooler with occasional rain; windy in the afternoon


Intermittent clouds

Monday Night

29 °F

Windy in the evening; partly cloudy


Mostly sunny

Tuesday

61 °F

Mostly sunny and milder


Clear

Tuesday Night

29 °F

Clear


Sunrise and Sunset

Sunrise
6:48 AM
Sunset
7:23 PM

Based on AccuWeather data