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The Next Storm/Next Snow Forecast Discussion from the Cherrywood Observatory – September 1, 2017

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

Forecast Discussion:

The forecast of the last few days is still right on track. Things were quiet Thursday night, but clouds were increasing and a few showers were wandering around the state. There were more up near the Wyoming border.  Showers are expected across Colorado into the early hours of morning (Figure 1) before the trough, pushing the cool front along, passes and we get sinking air behind it shutting off the rain chances early Friday (see Figure 2).

Figure 1: The NCEP forecasted surface analysis map showing chances of rain Friday before dawn.

Figure 2: The forecasted 500mb pattern from the GFS model for this morning (Fri. AM).

In the longer range:

The ridge is back with a vengeance by Saturday afternoon and really getting strong on Sunday (Figure 3). The high center is right over Northern Colorado. We very well might break the record high of 95F for the date. The good news is the trough over the Great Lakes in the eastern U.S. deepens and the ridge retrogrades westward giving us a flow of Canadian air down the Plains by Tuesday and Wednesday next week (Figure 4).  We may even get a bit of cooling on Monday from this change. Figure 5 shows the 24 hour precipitation accumulation Monday into Tuesday next week.  The remains of both tropical systems Lidia and Harvey are still barely on the map (Harvey's remains are just exiting Maine at that time). There some precipitation over northern Colorado, but more rain over southern Colorado at the end of the Labor Day Holiday Weekend.

Figure 3: The Sunday morning forecasted 500mb pattern from the GFS model.

Figure 4: Tuesday 500mb forecast map from the GFS. LIght blue line shows cooler airflow.

Current Weather

Sunny

Sunny

70°F

UV Index
1 Low
Pressure
29.89 Falling
Visibility
8 miles
Dewpoint
41 °F
Humidity
35%
Wind
N 4 mph
Gust
7.4 mph
Wind Chill
70 °F

Hourly Forecast

Today
7 PM
69°F
Mostly sunny
Today
8 PM
65°F
Intermittent clouds
Today
9 PM
62°F
Mostly cloudy
Today
10 PM
58°F
Mostly cloudy
Today
11 PM
56°F
Mostly cloudy
Tomorrow
12 AM
53°F
Intermittent clouds
Tomorrow
1 AM
51°F
Partly cloudy
Tomorrow
2 AM
48°F
Mostly clear
Tomorrow
3 AM
46°F
Mostly clear
Tomorrow
4 AM
44°F
Clear
Tomorrow
5 AM
43°F
Mostly clear
Tomorrow
6 AM
41°F
Mostly clear

7 Day Forecast

Mostly sunny

Wednesday

75 °F

Mostly sunny, pleasant and warmer


Partly cloudy

Wednesday Night

41 °F

Patchy clouds


Mostly cloudy w/ t-storms

Thursday

75 °F

Turning cloudy, warm; breezy, a thunderstorm around in the afternoon


Thunderstorms

Thursday Night

49 °F

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


Showers

Friday

70 °F

Mostly cloudy with a couple of showers


Thunderstorms

Friday Night

46 °F

Cloudy with showers and thunderstorms


Rain

Saturday

50 °F

Chilly with periods of rain


Rain and snow

Saturday Night

39 °F

Cloudy with rain, mixed with a little snow late


Mostly cloudy

Sunday

59 °F

Mostly cloudy with a stray thundershower in the afternoon


Partly cloudy

Sunday Night

36 °F

Partly cloudy


Sunrise and Sunset

Sunrise
6:08 AM
Sunset
7:49 PM

Based on AccuWeather data