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The Next Storm/Next Snow Forecast Discussion from the Cherrywood Observatory – October 22nd, 2018

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

Forecast Discussion:

With an extreme-gorgeous-weather-warning being issued (not a real thing), one always must look ahead at the flies that may come. There are two tropical systems off the Mexican coast (Willa and Vicente (not Vincent as I typed in the graphic below)) that will feed moisture into the trough that is approaching (Figure 1). Tuesday AM we are still under the ridge with the tropical systems and trough just starting to interact (Figure 2). The surface map at this time shows Willa and Vicente down south and some moisture making it up to the four corners and western slopes (Figure 3).

For Wednesday, the trough is here and the weakness in the upper-air pattern is in central Mexico (Figure 4). This same model shows heavy rains in Mexico, Texas (they don't need it), and New Mexico. We have some moisture making it up a bit into Wyoming; east of the Rockies (Figure 5).

The total rainfall for Longmont is still really small. The GFS (Figure 6) gives us nearly nothing. The weatherunderground model shows 0.01 inch. Snow levels will remain up in the mid to higher mountains.

Figure 1: The tropical overview map for the Western hemisphere from weatherunderground.com

Figure 3: The 500mb forecast upper air analysis for Tuesday AM. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.

Figure 3: The forecast surface map for Tuesday AM. From NCEP.

Figure 4: The 500mb forecast upper air analysis for Wednesday AM. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.

Figure 5: The surface forecast map for Wednesday AM. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.

Figure 6: The forecast accumulated precipitation map from the GFS and weather5280.com for the next 5 days (through Friday morning).

The longer range forecast:

Temperatures don't change much through Saturday next weekend, then the upper-air pattern sinks southward and we get more troughy, cooler and a touch wetter. Nothing notable, but it is a change from the near perfection of this weekend.

Figure7: 10 day meteogram from weather5280.com for DIA.

Current Weather

Partly sunny

Partly sunny

51°F

UV Index
1 Low
Pressure
29.68 Rising
Visibility
7 miles
Dewpoint
27 °F
Humidity
39%
Wind
W 8.5 mph
Gust
17 mph
Wind Chill
51 °F

Hourly Forecast

Today
8 PM
49°F
Showers
Today
9 PM
47°F
Partly cloudy
Today
10 PM
45°F
Partly cloudy
Today
11 PM
43°F
Partly cloudy
Tomorrow
12 AM
41°F
Mostly clear
Tomorrow
1 AM
40°F
Mostly clear
Tomorrow
2 AM
39°F
Mostly clear
Tomorrow
3 AM
38°F
Mostly clear
Tomorrow
4 AM
37°F
Mostly clear
Tomorrow
5 AM
36°F
Partly cloudy
Tomorrow
6 AM
35°F
Partly sunny
Tomorrow
7 AM
37°F
Intermittent clouds

7 Day Forecast

Partly sunny w/ showers

Tuesday

60 °F

Times of clouds and sun with a couple of brief showers beginning at midday; windy


Partly cloudy

Tuesday Night

35 °F

A shower in spots this evening; otherwise, partly cloudy and colder; there can be frost in the normally colder spots


Intermittent clouds

Wednesday

58 °F

Cool with times of clouds and sun


Mostly cloudy w/ showers

Wednesday Night

39 °F

Increasing clouds with a shower in spots late


Partly sunny w/ showers

Thursday

56 °F

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


Partly cloudy

Thursday Night

40 °F

Partly cloudy


Mostly cloudy

Friday

63 °F

Mostly cloudy and warmer


Clear

Friday Night

42 °F

Clear


Mostly sunny

Saturday

68 °F

Mostly sunny


Mostly clear

Saturday Night

43 °F

Mainly clear


Sunrise and Sunset

Sunrise
5:52 AM
Sunset
8:02 PM

Based on AccuWeather data