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Next Storm/Next Snow Forecast Discussion from the Cherrywood Observatory – March 21-22, 2019

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

Forecast Discussion:

I begin my trek back across the cactus dotted lands of Arizona and New Mexico where tall stick-like things are saguaro instead of cell towers. In other words, I'm posting 2 days at once since I won't have internet for a day.

The upper level ridge (= nice, warm, dry weather) is to be replaced by a series of short waves rippling across the state. The first is now looking juicer than it did yesterday (more moisture). This front isn't very cold so it is bringing a lot of rain showers to the desert southwest (Figure 1). For Thursday, a cutoff low rolls into Nevada/Arizona/Utah. That will pump some moisture our way and kick a short wave our way as well (Figure 2). Figure 4 shows this ripple giving us a better chance of low-land rain showers (and more mountain snows) in Colorado Friday and Friday night. This model gives us about 1/10th an inch.

The longer range forecast:

The next system (again, mostly rain with the warmer temperatures) arrives Sunday into Monday (Figure 4). The complex (read: messy) upper-air pattern for Sunday PM (Figure 3) has plenty of not-so-strong ripples of moisture.

Through the next 6 days, the mountains get 4-10 inches in places. Boulder may get a coating of snow Sunday PM, but we miss on the any significant snow accumulation (Figure 5). For rainfall, there is another down-slope hole around Denver to Boulder but we might see .05 to .25 inch of rain. (note that the weatherunderground model in Figure 4 gives us about 4/10th's an inch of rain over this time.)

Figure 1: The forecast surface map for Thursday PM from NCEP.
Figure 2: The 500mb forecast upper air analysis for Thursday PM. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.
Figure 3: The 500mb forecast upper air analysis for Sunday PM. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.
Figure 4: the graphical forecast for the next 10 days for Longmont, CO from weatherunderground.com
Figure 5 : the forecast accumulated snow map from the GFS and weather5280.com for Colorado, through Tuesday midday.
Figure 6 : the forecast accumulated precipitation map from the GFS and weather5280.com for Colorado, through Tuesday midday.

Current Weather

Mostly cloudy

Mostly cloudy

51°F

UV Index
0 Low
Pressure
29.77 Steady
Visibility
8 miles
Dewpoint
25 °F
Humidity
37%
Wind
SW 3.2 mph
Gust
7 mph
Wind Chill
51 °F

Hourly Forecast

Tomorrow
12 AM
45°F
Showers
Tomorrow
1 AM
43°F
Intermittent clouds
Tomorrow
2 AM
41°F
Intermittent clouds
Tomorrow
3 AM
39°F
Intermittent clouds
Tomorrow
4 AM
37°F
Intermittent clouds
Tomorrow
5 AM
36°F
Intermittent clouds
Tomorrow
6 AM
34°F
Intermittent clouds
Tomorrow
7 AM
35°F
Intermittent clouds
Tomorrow
8 AM
38°F
Intermittent clouds
Tomorrow
9 AM
41°F
Intermittent clouds
Tomorrow
10 AM
44°F
Intermittent clouds
Tomorrow
11 AM
47°F
Intermittent clouds

7 Day Forecast

Partly sunny

Thursday

65 °F

Partly sunny


Intermittent clouds

Thursday Night

34 °F

A shower in spots late this evening; otherwise, partly cloudy


Partly sunny w/ showers

Friday

53 °F

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


Showers

Friday Night

33 °F

A couple of showers in the evening; otherwise, cloudy


Mostly cloudy

Saturday

60 °F

Mostly cloudy


Intermittent clouds

Saturday Night

36 °F

Partly cloudy


Intermittent clouds

Sunday

62 °F

Times of sun and clouds


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


Sunrise and Sunset

Sunrise
6:50 AM
Sunset
7:22 PM

Based on AccuWeather data