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The Next Storm/Next Snow Forecast Discussion from the Cherrywood Observatory – November 1, 2017

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

Forecast Discussion:

Welcome to the holiday season!  It is a straight shot, through some turkey, to a Christmas Eve/Christmas Day snow forecast. Well that is some time away still...

Halloween did see some measurable snow fall in the morning.  That adds to our 10% statistic going forward. Figure 1 shows that the snow totaled about 1/4th to 1/2 inch across town. Boulder picked up 1/4th to 1" of snow. Figure 2 shows Estes Park received 1/4th to 3/4ths of an inch.  Berthoud to Fort Collins picked up a Trace to 1/4th inch.

Halloween night was mostly clear; enough to show the Moon, a couple planets, and a double star, from the observatory. We had 140ish trick-or-treaters!

A real ridge doesn't establish itself over us, but the jet stream stays to our north (the green line is the center of the flow in Figure 3). So we stay somewhat seasonally warm. Various degrees of down-slope flow will warm us more than the upper air pattern would normally allow.

Figure 1: Tuesday AM CoCoRaHS new snow reports at 7am. Boulder County.

Figure 2: Tuesday AM CoCoRaHS new snow reports at 7am. Larimer County.

Figure 3: Forecast 500mb upper air map for Wednesday PM. Center of the jet stream (cold north, warm south) in light green. Red lines= troughs, Blue lines = ridges.

Longer range forecast:

The trough way off in the Gulf of Alaska in Figure 3 builds southward off the West Coast of the U.S by the end of the week (Figure 4) but the center of the flow is still to our north (green line again). Figure 5, the jet stream/green line has finally drifted south cooling us down and the trough is closer increasing lift over the region and bringing us our next chance of rain and/or snow early next week.  We'll watch all this as a quite week plays out.

Figure 4: Forecast 500mb upper air map for Friday PM. Center of the jet stream (cold north, warm south) in light green. Red lines= troughs, Blue lines = ridges.

Figure 5: Forecast 500mb upper air map for Monday PM. Center of the jet stream (cold north, warm south) in light green. Red lines= troughs, Blue lines = ridges.

Current Weather

Mostly cloudy

Mostly cloudy

70°F

UV Index
0 Low
Pressure
29.98 Falling
Visibility
8 miles
Dewpoint
41 °F
Humidity
34%
Wind
WSW 4.9 mph
Gust
11.1 mph
Wind Chill
70 °F

Hourly Forecast

Today
8 PM
68°F
Showers
Today
9 PM
64°F
Showers
Today
10 PM
61°F
Partly cloudy
Today
11 PM
59°F
Partly cloudy
Tomorrow
12 AM
58°F
Partly cloudy
Tomorrow
1 AM
57°F
Partly cloudy
Tomorrow
2 AM
55°F
Partly cloudy
Tomorrow
3 AM
54°F
Partly cloudy
Tomorrow
4 AM
52°F
Partly cloudy
Tomorrow
5 AM
51°F
Partly cloudy
Tomorrow
6 AM
50°F
Partly sunny
Tomorrow
7 AM
53°F
Partly sunny

7 Day Forecast

Mostly cloudy w/ t-storms

Saturday

77 °F

Increasing cloudiness and not as warm


Partly cloudy

Saturday Night

50 °F

Partly cloudy


Mostly sunny

Sunday

81 °F

Sunshine and patchy clouds; breezy in the afternoon


Mostly clear

Sunday Night

49 °F

Mainly clear


Partly sunny w/ t-storms

Monday

70 °F

Not as warm with times of sun and clouds; a thunderstorm in spots in the afternoon


Thunderstorms

Monday Night

46 °F

Cloudy with a couple of thundershowers


Thunderstorms

Tuesday

60 °F

Mostly cloudy and cooler; a couple of afternoon showers and a thunderstorm


Intermittent clouds

Tuesday Night

37 °F

Partly cloudy


Partly sunny

Wednesday

73 °F

Pleasant and warmer with partial sunshine


Mostly clear

Wednesday Night

40 °F

Mainly clear


Sunrise and Sunset

Sunrise
5:41 AM
Sunset
8:13 PM

Based on AccuWeather data