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The Next Storm/Next Snow Forecast Discussion from the Cherrywood Observatory – February 9 , 2018

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

Forecast Discussion:

The heat ends and the next cold front moves in around dawn today (this post goes live at 1am).  From Figure 1, you can see that the warmest temperature for today happened a minute after midnight.  Figure 2 shows the departure from normal -cold temperatures in blue -for midday today.  The NWS expects that cold air to bump up against the foot of the foothills (my blue line and question marks).  Where low clouds form, mainly north of Denver and possibly around Longmont or I-25 and then eastward, there will be periods of freezing drizzle. If it gets dark outside, expect a thin coating of ice. (Thank you Matt Makens on Twitter @MattMakens).  Freezing drizzle and snow chances increase during the evening commute then become a pretty extended period of light snow showers much of Saturday.

It isn't much water or snow (1-3" when all is done) but it is suddenly cold and any ice that glazes things first, will make travel a mess.

Figure 3 is the temperature departures from normal for midday Saturday.  You can see that the cold air is just deep enough to drain into the mountain valleys and passes.

Figure 1: 10 day graphical forecast from weatherunderground.com for Longmont.

Figure 2: Surface temperature departure from normal (white) - oranges and yellows are above normal for midday today. Blues are below normal. Added line is more likely western extent of cold air. From weather5280.com

Figure 3: Surface temperature departure from normal (white) - oranges and yellows are above normal for midday Saturday. Blues are below normal.From weather5280.com

The longer range forecast:

The graphical forecast from China's weather service has us cloudy through Saturday night with the greatest chance of light to moderate snow showers after 2pm on Saturday (Figure 4).

Figure 5 is the GFS take on snowfall totals.  It has us in the 1-2 inch range by Sunday morning.

Figure 6 is the WPC 50th percentile probabilistic forecast. We are in the 1-2 inch area there by Sunday night.

Note, in Figure 1, our Tuesday-ish storm is performing the standard fade-to-nothing trick.

Figure 4: The 7! Timer Chinese model showing snow period 2pm to midnight Saturday.

Figure 5: The total snowfall between Thursday PM and Sunday morning from the GFS. From tropicaltidbits.com Longmont is the pink dot.

Figure 6: The total snowfall between Thursday PM and Sunday night from the WPC. From weather5280.com Longmont is the pink dot.

Current Weather

Mostly cloudy

Mostly cloudy

51°F

UV Index
0 Low
Pressure
29.77 Steady
Visibility
8 miles
Dewpoint
25 °F
Humidity
37%
Wind
SW 3.2 mph
Gust
7 mph
Wind Chill
51 °F

Hourly Forecast

Tomorrow
12 AM
45°F
Showers
Tomorrow
1 AM
43°F
Intermittent clouds
Tomorrow
2 AM
41°F
Intermittent clouds
Tomorrow
3 AM
39°F
Intermittent clouds
Tomorrow
4 AM
37°F
Intermittent clouds
Tomorrow
5 AM
36°F
Intermittent clouds
Tomorrow
6 AM
34°F
Intermittent clouds
Tomorrow
7 AM
35°F
Intermittent clouds
Tomorrow
8 AM
38°F
Intermittent clouds
Tomorrow
9 AM
41°F
Intermittent clouds
Tomorrow
10 AM
44°F
Intermittent clouds
Tomorrow
11 AM
47°F
Intermittent clouds

7 Day Forecast

Partly sunny

Thursday

65 °F

Partly sunny


Intermittent clouds

Thursday Night

34 °F

A shower in spots late this evening; otherwise, 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