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The Next Storm/Next Snow Forecast Discussion from the Cherrywood Observatory - August 30, 2017

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

Discussion:

A subtle change is on the way!

There is still some smoke from the Pacific northwest making the sky a little milky as the airflow is out of the northwest and then southward across the state (Figure 1) . Figure 2 shows the expected future track for the remains of Harvey.  It isn't headed out quickly, but it is beginning to pull away from Houston Tuesday PM.  Figure 3 shows the upper air pattern with our high center now anchored over the Great Basin but the red line shows the change.  That trough will shift the ridge westward away from us, allow a cool front to knock temperatures into the 80's in Longmont Thursday, and help to move Harvey on its way.

Figure 1: The 500mp map from Tuesday PM. The grey line shows the air flow from the northwestern U.S.

Figure 2: The National Hurricane Forecast center forecast for tropical system Harvey.

Figure 3: The 500mb forecast map for Thursday morning showing the trough beginning to cut into the ridge. This will also help move Harvey out of its position.

 

In a look at the longer range:

By Friday morning (Figure 4) Harvey has pulled into the lower Mississippi Valley and the cool front has swept down the Front Range. The high center is off the Oregon coast, temporarily. That relief is temporary too.  The high is back (Figure 5) and strong by Sunday morning.  We might see an all time record high temperature on Sunday.  But another cool front may knock us back to the 80's on Monday/Tuesday.

Figure 4: The GFS forecast 500mb map for Friday morning. Red line shows the trough cutting into the high pressure ridge. Harvey remains are the red L.

Figure 5: GFS forecast for Sunday morning - the 500mb pattern again.

Current Weather

Cloudy

Cloudy

61°F

UV Index
2 Low
Pressure
29.8 Rising
Visibility
8 miles
Dewpoint
38 °F
Humidity
42%
Wind
NNW 6.7 mph
Gust
15.2 mph
Wind Chill
61 °F

Hourly Forecast

Today
3 PM
64°F
Thunderstorms
Today
4 PM
62°F
Mostly cloudy
Today
5 PM
60°F
Intermittent clouds
Today
6 PM
57°F
Mostly cloudy w/ t-storms
Today
7 PM
55°F
Intermittent clouds
Today
8 PM
53°F
Thunderstorms
Today
9 PM
51°F
Cloudy
Today
10 PM
49°F
Cloudy
Today
11 PM
47°F
Cloudy
Tomorrow
12 AM
46°F
Cloudy
Tomorrow
1 AM
45°F
Cloudy
Tomorrow
2 AM
44°F
Mostly cloudy

7 Day Forecast

Partly sunny w/ t-storms

Wednesday

68 °F

A shower in spots this morning, becoming breezy this afternoon with a couple of thunderstorms


Thunderstorms

Wednesday Night

37 °F

A thunderstorm this evening; otherwise, mostly cloudy


Intermittent clouds

Thursday

62 °F

A blend of sun and clouds


Mostly cloudy

Thursday Night

38 °F

Mostly cloudy


Partly sunny

Friday

64 °F

Some sun; breezy in the afternoon


Partly cloudy

Friday Night

36 °F

Partly cloudy


Partly sunny

Saturday

66 °F

Partial sunshine


Mostly clear

Saturday Night

41 °F

Clear to partly cloudy


Mostly cloudy

Sunday

78 °F

Rather cloudy and warmer; breezy in the afternoon


Mostly cloudy

Sunday Night

43 °F

Rather cloudy


Sunrise and Sunset

Sunrise
5:59 AM
Sunset
7:56 PM

Based on AccuWeather data