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The Next Storm/Next Snow Forecast Discussion from the Cherrywood Observatory – July 19th, 2018

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

Forecast Discussion:

Sorry, it is hot. And is going to be hot through Saturday. And dry.

Figure 1 shows the dry air over eastern Colorado Wednesday PM. We have a high pressure center located overhead again for today (Figure 2). And the center of the upper air ridge right over head again (blue line next to the Longmont pink dot in Figure 3). We are just in the doldrums of summer for a bit.

The temperature anomaly this afternoon will be maximal along I-25 with down-slope flow adding to the compressional heating is shown in Figure 4.  This looks to be 10-15 degrees above normal. That puts us in the 99°-102° F area. Oh my.

Figure 1: the water vapor satellite image from Wednesday PM. Reds/Oranges are dry air, greys/whites are moist air regions.

Figure 2: The forecast surface map for Thursday midday. From NCEP.

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

Figure 4: surface temperature anomaly for Colorado for Thursday PM from the GFS and weather5280.com

The longer range forecast:

Though some moisture may return, it won't be much and the ridge will hold strong until Saturday passes. Sunday will see our next cool down and better chance of storms as an upper level trough sends a cold front down (Figure 5). Hold on, this is not Phoenix, it does cool down at times.

Figure 5: The 500mb forecast upper air analysis for Monday AM. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.

Current Weather

Mostly cloudy

Mostly cloudy

49°F

UV Index
1 Low
Pressure
29.89 Falling
Visibility
7 miles
Dewpoint
44 °F
Humidity
83%
Wind
NW 1.1 mph
Gust
2.1 mph
Wind Chill
49 °F

Hourly Forecast

Today
8 AM
48°F
Intermittent clouds
Today
9 AM
54°F
Partly sunny
Today
10 AM
60°F
Intermittent clouds
Today
11 AM
68°F
Intermittent clouds
Today
12 PM
75°F
Intermittent clouds
Today
1 PM
77°F
Intermittent clouds
Today
2 PM
75°F
Thunderstorms
Today
3 PM
73°F
Cloudy
Today
4 PM
73°F
Cloudy
Today
5 PM
72°F
Cloudy
Today
6 PM
68°F
Cloudy
Today
7 PM
65°F
Cloudy

7 Day Forecast

Mostly cloudy w/ t-storms

Thursday

77 °F

Turning cloudy, warm; breezy, a stray thunderstorm this afternoon


Thunderstorms

Thursday Night

47 °F

A thunderstorm in spots this evening; otherwise, considerable cloudiness


Thunderstorms

Friday

69 °F

Mostly cloudy and not as warm with a couple of thundershowers


Thunderstorms

Friday Night

44 °F

Cloudy with a couple of thundershowers


Rain

Saturday

46 °F

Chilly with periods of rain and a thunderstorm


Rain and snow

Saturday Night

39 °F

Cloudy with rain, mixed with a little snow late


Mostly cloudy

Sunday

59 °F

Mostly cloudy and warmer; a stray afternoon thundershower


Partly cloudy

Sunday Night

36 °F

Partly cloudy


Mostly sunny

Monday

71 °F

Mostly sunny and warmer


Partly cloudy

Monday Night

39 °F

Partly cloudy


Sunrise and Sunset

Sunrise
6:07 AM
Sunset
7:50 PM

Based on AccuWeather data