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Next Storm/Next Snow Forecast Discussion from the Cherrywood Observatory – September 22-23, 2019

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

In Brief:

After a chance of a late evening splash of rain and maybe a rumble of thunder, we remain mostly dry for the next 10 days with above normal temperatures (but not really hot either). Quiet is the word of the day.

Forecast Discussion:

The upper air map shows a big trough to the west, but dry air dominates the state (Figure 1). A pinch in the isopleths (black lines) show a wind speed maximum approaching tonight (yellow oval). That "jet streak" acts like a vacuum cleaner and lifts the air a bit. Some showers are possible zipping across the northern parts of the state tonight. The HRRR is unimpressed by rainfall amounts (Figure 2) while the weatherunderground model gives us 0.05 inch (Figure 4).

We dry out Sunday and stay just at normal temperatures for a day as the trough pulls by (Figure 4).

The Longer Range Forecast:

The cut-off low that was going to dump lots of water and snow on the state next week has a different plan. The GFS now shows it digging far south into northern Mexico (Figure 3). That feature won't matter much to our weather story now.

The week ahead will be about 5-10F above average as temperatures go with some better heat next weekend as another west coast trough pumps southwest winds across the state (Figure 5). I've highlighted days at or above 80F in Figure 4. There isn't much exciting going on. Sorry!

Happy First Day of Fall Monday! The Autumnal Equinox officially arrives at 1:50 p.m. MDT

Figure 1: The 500mb current upper air analysis for Saturday PM. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.
Figure 2: the 12 hour precipitation total forecast from the HRRR and weather5280.com through 1am.
Figure 3: The 500mb forecast upper air analysis for Wednesday AM. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.
Figure 4: the graphical forecast for the next 10 days for Longmont, CO from weatherunderground.com
Figure 5: The 500mb forecast upper air analysis for Saturday AM. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.

Current Weather

Mostly sunny

Mostly sunny

72°F

UV Index
8 Very High
Pressure
29.99 Falling
Visibility
8 miles
Dewpoint
44 °F
Humidity
36%
Wind
E 2.8 mph
Gust
6.4 mph
Wind Chill
72 °F

Hourly Forecast

Today
3 PM
74°F
Mostly sunny
Today
4 PM
76°F
Mostly sunny
Today
5 PM
75°F
Mostly sunny
Today
6 PM
72°F
Mostly sunny
Today
7 PM
69°F
Mostly sunny
Today
8 PM
65°F
Intermittent clouds
Today
9 PM
61°F
Mostly cloudy
Today
10 PM
58°F
Mostly cloudy
Today
11 PM
56°F
Mostly cloudy
Tomorrow
12 AM
53°F
Intermittent clouds
Tomorrow
1 AM
51°F
Partly cloudy
Tomorrow
2 AM
49°F
Mostly clear

7 Day Forecast

Mostly sunny

Wednesday

76 °F

Mostly sunny, pleasant and warmer


Partly cloudy

Wednesday Night

42 °F

Patchy clouds


Mostly cloudy w/ t-storms

Thursday

74 °F

Becoming cloudy; breezy in the afternoon with a thunderstorm in spots


Cloudy

Thursday Night

49 °F

Considerable cloudiness


Showers

Friday

67 °F

Mostly cloudy with a couple of showers


Thunderstorms

Friday Night

46 °F

Cloudy with showers and thunderstorms


Rain

Saturday

50 °F

Chilly with periods of rain


Rain

Saturday Night

39 °F

Cloudy with steady rain becoming intermittent


Mostly cloudy

Sunday

59 °F

Mostly cloudy and warmer; a stray afternoon thundershower


Partly cloudy

Sunday Night

38 °F

Partly cloudy


Sunrise and Sunset

Sunrise
6:08 AM
Sunset
7:49 PM

Based on AccuWeather data