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The Next Storm/Next Snow Forecast Discussion from the Cherrywood Observatory – February 19 , 2018

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

Forecast Discussion:

Here we go. It is storm time.

But first, Sunday (as has been so common with these storms) - we had a ridge and strong down slope winds.  Longmont hit 66F while areas around Denver reached 70F.

Figure 1 shows that the front rolled in around midnight this morning.  Temperatures keep dropping, overall, all day today and into Tuesday. The initially shallow cold air may create some pre-dawn freezing drizzle or freezing fog before jet dynamics and more moist & cold air flows in getting steady snow going around noon to 2pm today.  Healthy snow rates continue until after midnight Tuesday AM then drier air flows in.  Snow flurries are still possible on into Wednesday AM.

Figure 2 gives you a snapshot of the storm Monday evening.  As discussed yesterday, the storm will feature banded snowfall features.  My call is that everyone from central Denver up to Fort Collins will see 2-4 inches of snow.  Southern Denver is more like 1-3 inches of snow.  Estes Park should see 3-7 inches of snow.  BUT where these banded features form (and that may not be easy to nail down until things get started- but Boulder, southern Larimer, and part of Weld County has been 'under the gun' in a number of model runs recently) one could see double those snow amounts; 4-8"+.

Figure 3 is the GFS take and the banded features are visible.  We are under one of those bands and are getting 4-5" of snow in this run.

Figure 4 is the WPC 50th percentile accumulation idea and we are around 4-5" here.

Figure 5 is the NAM - and we are on the north side of a band here, and in the 3-4" area.

Temperatures will be shockingly cold (especially after our pleasant, if windy, weekend).  Figure 6 are the temperatures Tuesday AM and Longmont is in the single digits (also in Figure 1).  Figure 7 are the temperatures Wednesday AM and we are in the upper single digits (also in Figure 1).  Get ready for COLD!

Figure 1: The first part of the 10 day graphical forecast from weatherunderground.com for Longmont.

Figure 2: The current surface weather forecast for Monday evening from the GFS and tropicaltidbits.com

Figure 3: The total snowfall forecast from Sunday PM to Wednesday AM from the GFS and weather5280.com

Figure 4: The total snowfall forecast from Sunday PM to Wednesday PM from the WPC 50th percentile confidence and weather5280.com

Figure 5: The total snowfall forecast from Sunday PM to Wednesday AM from the NAM and tropicaltidbits.com

Figure 6: The surface temperature forecast for Tuesday AM from the GFS and tropicaltidbits.com

Figure 7: The surface temperature forecast for Wednesday AM from the GFS and tropicaltidbits.com

The longer range forecast:

There are hints of a storm at the end of the week, but it doesn't look very big.  Temperatures this week will remain largely below normal. More after this storm clears!

Current Weather

Mostly cloudy

Mostly cloudy

63°F

UV Index
1 Low
Pressure
29.75 Falling
Visibility
8 miles
Dewpoint
24 °F
Humidity
22%
Wind
W 5.9 mph
Gust
13.7 mph
Wind Chill
63 °F

Hourly Forecast

Today
6 PM
61°F
Partly sunny
Today
7 PM
58°F
Partly sunny
Today
8 PM
55°F
Intermittent clouds
Today
9 PM
51°F
Intermittent clouds
Today
10 PM
48°F
Intermittent clouds
Today
11 PM
45°F
Intermittent clouds
Tomorrow
12 AM
43°F
Intermittent clouds
Tomorrow
1 AM
41°F
Intermittent clouds
Tomorrow
2 AM
39°F
Intermittent clouds
Tomorrow
3 AM
38°F
Intermittent clouds
Tomorrow
4 AM
37°F
Intermittent clouds
Tomorrow
5 AM
36°F
Intermittent clouds

7 Day Forecast

Partly sunny

Thursday

65 °F

Partly sunny


Intermittent clouds

Thursday Night

34 °F

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