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The Next Storm/Next Snow Forecast Discussion from the Cherrywood Observatory – August 14th, 2018

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

Forecast Discussion:

We are a weather pattern in transition now.  Moisture is coming back into the western US (but it is not a lot yet). Figure 1 shows a strip of very dry air still down the plains near the Front Range foothills (us). The moisture in the western Colorado Rockies did kick off a few showers in the afternoon Monday.

What is interesting is the severe weather and convective outlook from the SPC for Monday. Compare the pattern in Figure 2 with the satellite image of moisture in Figure 1.  That same dry strip shows up as a region with no convection possible (and nothing ultimately formed).

For late tonight, with a stationary front still parked up in Wyoming, we do have a bit more moisture in the mountains and a chance of showers. These 'might' drift over the I-25 communities this evening (Figure 3).

We will still have to deal with smoke. It is pouring in from the west (primarily) - though it is not as thick over Longmont today as it could be (like the northern tier of states) - Figure 4.

Figure 5 shows the storm and severe storm potential for today.  With a bit more moisture (but with cooling caused by the weakening upper level ridge and the smoke over head) we'll see some storms possible over most of the state (except for the Kansas border) - Figure 5.

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

Figure 2: the day 1 SPC thunderstorm and severe weather forecast made Monday (valid Monday).

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

Figure 4: The HRRR (high resolution rapid refresh) model forecast of smoke at all levels for Tuesday noon.

Figure 5: the day 2 SPC thunderstorm and severe weather forecast made Monday (valid Tuesday).

The longer range forecast:

More moisture arrives with easterly surface winds and the upper level trough gets closer to the state.  That should create some severe weather along I-25 on Wednesday.  More about that, and the additional rains and storms (especially the hail this weekend), and the overall cool down- tomorrow.

Figure 6: the day 3 SPC thunderstorm and severe weather forecast made Monday (valid Wednesday).

Current Weather

Partly sunny

Partly sunny

57°F

UV Index
4 Moderate
Pressure
29.85 Falling
Visibility
7 miles
Dewpoint
46 °F
Humidity
66%
Wind
NNE 1.1 mph
Gust
3.2 mph
Wind Chill
57 °F

Hourly Forecast

Today
10 AM
63°F
Partly sunny
Today
11 AM
68°F
Partly sunny
Today
12 PM
73°F
Intermittent clouds
Today
1 PM
77°F
Intermittent clouds
Today
2 PM
76°F
Cloudy
Today
3 PM
75°F
Cloudy
Today
4 PM
73°F
Cloudy
Today
5 PM
70°F
Cloudy
Today
6 PM
68°F
Cloudy
Today
7 PM
65°F
Cloudy
Today
8 PM
62°F
Thunderstorms
Today
9 PM
59°F
Cloudy

7 Day Forecast

Mostly cloudy

Thursday

77 °F

Turning cloudy; warm


Thunderstorms

Thursday Night

47 °F

A thunderstorm in spots this evening; otherwise, considerable cloudiness


Thunderstorms

Friday

70 °F

Mostly cloudy and not as warm with a couple of thundershowers


Thunderstorms

Friday Night

43 °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


Partly sunny

Monday

71 °F

Partly 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