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Thursday Update: Longmont Weather Forecast: Typical Colorado summer settles in

The Video Forecast for this Week

Thursday update:

A few places saw significant rainfall Wednesday (Figure 3 update).  Today will be a bit drier as the moisture plume is better placed over the mountains and western slopes. 

 

Figure3u_07222021Figure 3 update: the 1 day precipitation total July 21-22 from NOAA

 

End Thursday update.

Tuesday update:

We are enjoying a very typical summer pattern this week. Temperatures are just a few degrees above normal due to the proximity of the big western U.S. ridge.  The moisture plume mentioned below is now back covering the entire state.  Each afternoon, thunderstorms will fire in the early afternoon in the mountains and drift (slowly) eastward (Figure 1 update).  There is some concern of flash flooding over the newer burn scars.  Smoke is sneaking back down the eastern side of the Rockies (Figure 2 update) even as some clearing tries to push in from the southwest (dashed arrow).

 

Figure1u_07202021Figure 1 update: the 10 day graphical forecast for Longmont, CO from weatherunderground.com

 

Figure2u_07202021Figure 2 update: the HRRR smoke forecast for Tuesday afternoon from NOAA

 

End Tuesday update.

Monday update:

Not much to add today, but a plume of moisture that has been giving the western slopes of Colorado a bit more daily moisture is going to drift east. Afternoon thunderstorm chances pick up for the rest of the week (Tuesday and on). A bit more of a north and northeast air flow aloft will will bring some more smoke out of the flow north of us back to the Colorado plains.

End Monday update:

 

In Brief:

Standard summer heat, a few wandering afternoon storms and the smoke thins.

Forecast Discussion:

Settle in for pretty unremarkable Colorado summer weather. Figure 1 shows temperatures sit at just a degree or two above normal with just a small chance of afternoon storms now and then. The chance of severe weather in Colorado, on Friday, is limited to locations east of I-25 out on the plains (Figure 2).

The pattern in the upper atmosphere will not change much for a while. The high-pressure center and ridge axis sit just to our west (barely). We have a fair amount of sinking air under this ridge that will limit thunderstorm formation in the afternoon (Figure 3). Thankfully, this now shuttles smoke from the western states up into Canada and down to our east, for the most part (Figure 4). You should see some more blueness in the sky.

 

Figure1_07162021Figure 1: the 10 day graphical forecast from weatherunderground.com for Longmont, CO.

 

Figure2_07162021Figure 2: the risk of severe weather from the Storm Prediction Center, Norman OK for Day 1, Friday.

 

Figure3_07162021Figure 3: the 500mb upper air forecast map for Saturday noon from the GFS and tropicaltidbits.com

 

Figure4_07162021Figure 4: the HRRR smoke at all levels forecast map for Saturday afternoon from NOAA.

 

The Longer-Range Forecast:

Little changes for the rest of the week. The GFS gives northern Colorado very little precipitation over the next five days (Figure 5). Sorry, the weather isn't more entertaining right now!

 

Figure5_07162021Figure 5: the 5 day precipitation total from the GFS and weather5280.com

 


About the Author: John Ensworth

John Ensworth used to work from Longmont as the PI for the NASA through the IGES (The Institute for Global Environmental Strategies). He now teaches technology, algebra, astronomy, meteorology, film school, and Lego robotics to middle/high school.
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Current Weather

Mostly sunny

Mostly sunny

95°F

UV Index
2 Low
Pressure
29.87 Falling
Visibility
8 miles
Dewpoint
40 °F
Humidity
15%
Wind
ESE 2.9 mph
Gust
6.7 mph
Wind Chill
95 °F

Hourly Forecast

Today
7 PM
90°F
Intermittent clouds
Today
8 PM
86°F
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Today
9 PM
82°F
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Today
10 PM
79°F
Intermittent clouds
Today
11 PM
75°F
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Tomorrow
12 AM
72°F
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Tomorrow
1 AM
69°F
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Tomorrow
2 AM
68°F
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Tomorrow
3 AM
67°F
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Tomorrow
4 AM
66°F
Intermittent clouds
Tomorrow
5 AM
65°F
Intermittent clouds
Tomorrow
6 AM
64°F
Intermittent clouds

7 Day Forecast

Partly sunny

Thursday

95 °F

Very warm with sunshine mixing with some clouds


Intermittent clouds

Thursday Night

64 °F

Partly cloudy


Partly sunny w/ t-storms

Friday

89 °F

Partly sunny with a thundershower in spots in the afternoon


Clear

Friday Night

61 °F

Clear


Partly sunny

Saturday

93 °F

Partly sunny


Clear

Saturday Night

56 °F

Clear


Partly sunny

Sunday

89 °F

Partly sunny with a stray thunderstorm


Clear

Sunday Night

57 °F

Clear


Partly sunny

Monday

93 °F

Partly sunny


Clear

Monday Night

57 °F

Clear


Sunrise and Sunset

Sunrise
5:36 AM
Sunset
8:33 PM

Based on AccuWeather data