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The Next Storm/Next Snow Forecast Discussion from the Cherrywood Observatory – December 9, 2017

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

Forecast Discussion:

3-2-1 ...let the unusually beautiful weather begin again. Figure 1 says it all. There is a big ridge of high pressure in the western states and no precipitation anywhere except up in the Great Lakes and the extreme southeastern states.

Figure 1: Current surface map from weatherunderground.com from Friday PM.

The longer range forecast:

Figure 2 and 3 are the upper air patterns for this morning (Saturday) and then the forecast for Friday morning at the end of the week.  The ridge (with a small trough deep down south) dominates the West all week and a deep trough dominates the East all week.  It is really impressive how little things change.

With the jet stream flowing from the northwest to the southeast, we are back to the regime where fronts of various strengths will drift into the state all week.  In figure 4, I've drawn the weaker fronts (with little wind and little cooling) in thin blue lines.  The thickest blue lines denote the stronger wind shifts and temperature drops.  There is roughly one-a-day except for Tuesday and Friday.  The dryness continues, temperatures hover around 15-20 degrees above normal, and my forecast discussions may remain sort of short this week.

Figure 2: The upper air forecast 500mb map for Saturday morning.

Figure 3: The upper air forecast 500mb map for Friday morning.

Figure 4: The 10 day graphical forecast for Longmont from weatherunderground.com

Current Weather

Partly sunny

Partly sunny

51°F

UV Index
5 Moderate
Pressure
29.49 Steady
Visibility
8 miles
Dewpoint
18 °F
Humidity
28%
Wind
W 11.9 mph
Gust
27.4 mph
Wind Chill
51 °F

Hourly Forecast

Today
11 AM
53°F
Showers
Today
12 PM
54°F
Cloudy
Today
1 PM
55°F
Cloudy
Today
2 PM
56°F
Cloudy
Today
3 PM
57°F
Cloudy
Today
4 PM
57°F
Cloudy
Today
5 PM
56°F
Cloudy
Today
6 PM
55°F
Cloudy
Today
7 PM
55°F
Cloudy
Today
8 PM
53°F
Mostly cloudy
Today
9 PM
51°F
Intermittent clouds
Today
10 PM
49°F
Intermittent clouds

7 Day Forecast

Showers

Monday

57 °F

Winds gusting past 40 mph; a brief shower or two this morning; otherwise, cloudy and cooler


Intermittent clouds

Monday Night

41 °F

Partly cloudy


Partly sunny w/ showers

Tuesday

58 °F

A couple of showers in the morning; otherwise, windy and cool with times of clouds and sun


Partly cloudy

Tuesday Night

33 °F

Partly cloudy


Intermittent clouds

Wednesday

60 °F

Times of clouds and sun


Mostly cloudy

Wednesday Night

38 °F

Increasing clouds


Partly sunny w/ showers

Thursday

56 °F

Times of clouds and sun with a couple of showers; cool


Cloudy

Thursday Night

37 °F

Cloudy


Mostly cloudy

Friday

62 °F

Mostly cloudy and warmer


Mostly clear

Friday Night

36 °F

Mainly clear


Sunrise and Sunset

Sunrise
5:53 AM
Sunset
8:01 PM

Based on AccuWeather data