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Next Storm/Next Snow Forecast Discussion from the Cherrywood Observatory – January 4, 2019

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

Forecast Discussion:

Mild weather has invaded. In the wind chill maps (where actual temperature and wind speeds combine to give you a physiological sensation of colder temperatures) there is an interesting warmer signal down hill from the Rockies with calm air and the compressional heating of the air (darker blues around and east of the Longmont dot - Figure 1 and 2).

The surface front and pressure lines (isobars) are hinting that there is high pressure in the western states (there are a few H's again- Figure 3). Beautiful stuff!

Figure 1: Wind chill map for the U.S. from Thursday afternoon. From weatherunderground.com

Figure 2: Wind chill map for the Western U.S. states from Thursday afternoon. From weatherunderground.com

Figure 3: The current surface map from Thursday PM and the Weather Channel.

The longer range forecast:

The ridge dominates the west into the weekend. It is holding on strong early Saturday (Figure 4). The meteogram from Weather5280.com (figure 5) shows the trough in Figure 4, off the California coast, moving in later in the weekend creating western CO snows. Some showers may sneak off the mountains to the I-25 corridor... we'll see as we get closer.

Later next week (7-9 days from now) a bigger temperature drop arrives with increased rain/snow chances (Figure 5). The GFS gives Longmont 4-5 inches of snow (total) over the next 10 days. (Alert: do not place monetary wagers on 10 day forecasts!).

Figure 4: The 500mb forecast upper air analysis for Saturday AM. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.

Figure 5: 10 day meteogram from weather5280.com for DIA.

Figure 6: The forecast accumulated snow map from the GFS and weather5280.com for Colorado, for the next 10 days.

Current Weather

Partly sunny

Partly sunny

65°F

UV Index
4 Moderate
Pressure
29.84 Steady
Visibility
8 miles
Dewpoint
27 °F
Humidity
23%
Wind
WNW 14.7 mph
Gust
26.5 mph
Wind Chill
65 °F

Hourly Forecast

Today
4 PM
65°F
Showers
Today
5 PM
66°F
Intermittent clouds
Today
6 PM
65°F
Intermittent clouds
Today
7 PM
63°F
Intermittent clouds
Today
8 PM
59°F
Mostly clear
Today
9 PM
56°F
Mostly clear
Today
10 PM
53°F
Clear
Today
11 PM
52°F
Clear
Tomorrow
12 AM
50°F
Mostly clear
Tomorrow
1 AM
49°F
Mostly clear
Tomorrow
2 AM
48°F
Partly cloudy
Tomorrow
3 AM
48°F
Partly cloudy

7 Day Forecast

Mostly cloudy w/ showers

Tuesday

66 °F

Windy with variable cloudiness; a brief shower or two this afternoon


Partly cloudy

Tuesday Night

45 °F

Partly cloudy


Mostly cloudy

Wednesday

73 °F

Warmer with some sun, then turning cloudy


Rain and snow

Wednesday Night

36 °F

Breezy in the evening with a shower in spots followed by rain and snow showers late


Rain and snow

Thursday

46 °F

Cloudy and chilly with a couple of showers of rain or snow


Mostly cloudy

Thursday Night

33 °F

Mostly cloudy


Mostly cloudy w/ showers

Friday

52 °F

Warmer with some sun, then turning cloudy; a little rain in the afternoon


Rain and snow

Friday Night

32 °F

A little snow at times; rain mixed in early


Rain and snow

Saturday

50 °F

A morning rain or snow shower in spots; otherwise, cloudy and cool


Mostly cloudy

Saturday Night

34 °F

Areas of low clouds


Sunrise and Sunset

Sunrise
6:20 AM
Sunset
7:41 PM

Based on AccuWeather data