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Friday Update: Longmont Weather Forecast: Winds leave with a touch of snow Monday/Tuesday

The Video Forecast for this Week.

In brief:

A couple of inches of snow around Interstate 25 Saturday followed by warm normal temperatures the rest of the week.

Friday Update:

The wind came and is becoming a memory. The Monday/Tuesday snow chances are still quite minimal in the models. We don't get snow along I-25 (or rain) according to the GFS (Figure 2 update below).  There is a hint of more snow next Friday/Saturday, but that is a long way out. Temperatures won't vary much either, the highs will be in the 40's each day though the weekend.

 

Figure1_01152021Figure 1 update: the 5 day (10:1 ratio) total snowfall forecast from the GFS and weather5280.com

 

End Friday Update.

Tuesday Update:

The last storm did over perform my forecast with 3 to 4 inches of snow around Longmont.  Hurray for the moisture, boo for my busted forecast.

As we work our way through a new week, there will be strong winds (and warming on Wednesday) as a dry trough passes aloft. Figure 1 update shows the strong winds on the Plains Thursday at noon.  The windy periods are also circled in Figure 2 update. In fact, the NWS has issued the following:

...HIGH WIND WATCH IN EFFECT FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY AFTERNOON...

* WHAT...Northwest winds 30 to 40 mph with gusts up to 65 mph possible.

* WHERE...Northeast Weld County, Central and Southern Weld County, Morgan County, Eastern Adams and Arapahoe Counties,
Logan County, Washington County, Sedgwick County and Phillips County.

* WHEN...From late Wednesday night through Thursday afternoon.

 

Figure1u_01122021Figure 1 update: the 10m wind speeds around noon Thursday from weathe5280.com and the GFS.

 

Figure2u_01122021Figure 2 update: the 10 day graphical forecast from weather5280.com for Longmont, CO.

We have pretty mild temperatures ahead (for January at least) and a chance of rain/snow on the weekend (it is not a large storm as it looks now - Figure 2 update).  There is a possibility of a coating of snow over the next 6 days (Figure 3 update).  But then precipitation might come as light rain with temperatures in the 40's expected over the weekend.

 

Figure3u_01122021Figure 3 update: the 6 day (10:1 ratio) total snowfall forecast from the GFS and weather5280.com

 

End Tuesday Update.

 

Forecast discussion:

The upper air trough has now dug down to the Four Corners area and will be sending a brief shot of up slope flow into the Front Range communities Saturday PM (Figure 1 below).

 

Figure1_01092021Figure 1: The 500mb upper air forecast map for Saturday PM from the GFS and tropicaltidbits.com

The bulk of the light snow will fall over the south-central counties of Colorado, but some will accumulate around Longmont (Figure 2).

 

Figure2_01092021Figure 2: The forecast surface analysis for late Saturday PM from NCEP.

The peak snow chances arrive between 3 p.m. and 2 a.m. (Sunday) with temperatures Saturday remaining near freezing (Figure 3).

 

Figure3_01092021Figure 3: The 10-day graphical forecast from weather5280.com for Longmont.

Snowfall roundup:

The weatherunderground model gives us 1 to 2 inches of snow (Figure 3).
The GFS gives us 2 to 3 inches of snow (Figure 4).
The NAM gives us 1 to 2 inches of snow (Figure 5).
Finally the HRRR — up to 10 p.m. — gives us 0.5 to 1.5 inches of snow (Figure 6).

I'm comfortable with about 1.5 to 2.5 inches around here.

 

Figure4_01092021Figure 4: The three-day (10:1 ratio) total snowfall forecast from the GFS and weather5280.com

 

figure5_01092021Figure 5: The three-day (10:1 ratio) total snowfall forecast from the NAM and weather5280.com

 

Figure6_01092021Figure 6: The 15-hour (to 10 p.m.) (10:1 ratio) total snowfall forecast from the GFS and weather5280.com

 

The longer-range forecast:

The weather becomes quiet again next week. Temperatures trend toward the high end of normal for this time of year.  There are no suspicious storms to watch for in the models — yet!


Current Weather

Clear

Clear

25°F

UV Index
0 Low
Pressure
30.35 Steady
Visibility
10 miles
Dewpoint
17 °F
Humidity
73%
Wind
N 0 mph
Gust
0 mph
Wind Chill
25 °F

12 Hour Forecast

Today
5 AM
23°F
Cloudy
Today
6 AM
23°F
Cloudy
Today
7 AM
23°F
Mostly cloudy
Today
8 AM
25°F
Mostly cloudy
Today
9 AM
26°F
Intermittent clouds
Today
10 AM
28°F
Intermittent clouds
Today
11 AM
32°F
Intermittent clouds
Today
12 PM
35°F
Partly sunny
Today
1 PM
36°F
Partly sunny
Today
2 PM
36°F
Mostly sunny
Today
3 PM
37°F
Mostly sunny
Today
4 PM
35°F
Mostly sunny

7 Day Forecast

Intermittent clouds

Tuesday

37 °F

After a cloudy start, sun returns


Clear

Tuesday Night

24 °F

Clear


Intermittent clouds

Wednesday

56 °F

Times of sun and clouds


Clear

Wednesday Night

32 °F

Clear


Mostly sunny

Thursday

50 °F

Sunshine and patchy clouds


Intermittent clouds

Thursday Night

25 °F

Partly cloudy


Intermittent clouds

Friday

43 °F

Intervals of clouds and sun


Intermittent clouds

Friday Night

25 °F

Partly cloudy


Intermittent clouds

Saturday

41 °F

Intervals of clouds and sunshine with a chance for a couple of snow showers


Mostly cloudy

Saturday Night

11 °F

Colder with areas of low clouds


Sunrise and Sunset

Sunrise
7:19 AM
Sunset
5:04 PM

Imagery


Based on AccuWeather data