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Thursday Update: Longmont Weather Forecast: Up and down temperatures; dry for a long time

The Video Forecast for this Week

In Brief:

We warm mid week, cool week's end, warm again as next week starts - but all times remain dry.

Thursday Update:

As an update to the video above, I was correct, the model had been restarted and did not have a 'memory' of the smoke load in the atmosphere at the start of those runs.  There IS a ribbon of smoke entering Colorado from the remaining western fires for the next few days (Figure 1, smoke at all levels and Figure 2, smoke at the surface).

I thought that was odd!!

Figure1u_09232021
Figure 1 update: smoke at all levels Thursday noon from the HRRR and NOAA.
Figure2_09232021
Figure 1 update: smoke at athe surface Thursday noon from the HRRR and NOAA.

End Thursday update.

Wednesday Update:

The forecast is on track with dry 80's, clear skies and little smoke. Enjoy!

End Wednesday update.

Forecast Discussion:

Passing short waves and a wander in the dominant high-pressure ridge out west will make the temperatures waver between the 60s now to the upper 80s at week's start (Figure 1). Our last big trough is departing as of Monday evening(Figure 2). There is plenty of dry air ready to move in as this trough moves on (Figure 3).

Figure1_09202021
Figure 1: the 10 day graphical forecast from weatherunderground.com for Longmont, CO.
 
Figure2_09202021
Figure 2: the 500mb upper air forecast map for Monday noon from the GFS and tropicaltidbits.com
Figure3_09202021
Figure 3: the water vapor satellite image from NOAA from Monday PM. White/purple is moist air, red/brown is very dry air.

The Longer-Range Forecast:

The heat and ridge peak on Sunday in the upper 80s. The ridge will pass right over Colorado again (Figure 4). Over the next 5 (Figure 5) and 10 (Figure 6) days, things just stay nearly totally dry.  This dryness is expected to hold through the start of October. Hopefully, this column will remain interesting the next two weeks!

  • Fall begins Wednesday at 1:20 p.m., September 22nd this year.

  • Programming note:  I plan to take the last week of October off for my first real vacation in almost two years.  Thanks for your patience!
  • Weather 5280 has also begun their First Snowfall Predication contest, if you want to take a stab at it.

 

Figure4_09202021
Figure 4: the 500mb upper air forecast map for Saturday noon from the GFS and tropicaltidbits.com
Figure5_09202021
Figure 5: the 5 day precipitation total from the GFS and weather5280.com
Figure6_09202021
Figure 6: the 10 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

Sunny

Sunny

94°F

UV Index
5 Moderate
Pressure
30.19 Falling
Visibility
8 miles
Dewpoint
45 °F
Humidity
18%
Wind
E 3.4 mph
Gust
8.3 mph
Wind Chill
94 °F

Hourly Forecast

Today
4 PM
93°F
Mostly cloudy
Today
5 PM
93°F
Mostly cloudy
Today
6 PM
91°F
Cloudy
Today
7 PM
88°F
Cloudy
Today
8 PM
85°F
Partly sunny
Today
9 PM
81°F
Partly cloudy
Today
10 PM
76°F
Partly cloudy
Today
11 PM
72°F
Partly cloudy
Tomorrow
12 AM
70°F
Partly cloudy
Tomorrow
1 AM
69°F
Partly cloudy
Tomorrow
2 AM
68°F
Partly cloudy
Tomorrow
3 AM
66°F
Partly cloudy

7 Day Forecast

Mostly cloudy w/ showers

Sunday

93 °F

Thickening clouds with a passing shower this afternoon


Partly cloudy

Sunday Night

64 °F

Partly cloudy


Mostly cloudy w/ t-storms

Monday

95 °F

Some sunshine giving way to clouds with a thunderstorm in the area late in the afternoon; thunderstorms can bring hail and damaging winds


Partly cloudy w/ t-storms

Monday Night

59 °F

A thunderstorm in spots in the evening; otherwise, clear to partly cloudy; thunderstorms can bring hail and damaging winds


Intermittent clouds

Tuesday

92 °F

Intervals of clouds and sunshine


Partly cloudy

Tuesday Night

60 °F

Partly cloudy


Partly sunny w/ t-storms

Wednesday

84 °F

Times of sun and clouds with a thunderstorm in the afternoon; thunderstorms can bring hail and damaging winds


Mostly cloudy

Wednesday Night

58 °F

An evening thunderstorm; otherwise, mostly cloudy


Cloudy

Thursday

81 °F

Cloudy with a thunderstorm in spots in the afternoon


Intermittent clouds

Thursday Night

58 °F

Partly cloudy


Sunrise and Sunset

Sunrise
5:42 AM
Sunset
8:30 PM

Based on AccuWeather data