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The Next Storm/Next Snow and Lunar Eclipse Forecast Discussion from the Cherrywood Observatory – January 31, 2018

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

Forecast Discussion:

The eclipse is here (just a few hours after this post goes live at 1am).

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Here is where I'll call the Go or No Go depending on clouds:   We are a Go!

Note: There are batches of clouds moving in from the west, so we still might miss portions of the eclipse, but I'm set up and aligning telescopes now!

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Figure 1 is the image of the Earth's shadow in space.  You can see the very light penumbra is much larger than the dark umbra and that part of the eclipse begins at 3:50am.  It is very difficult to notice, so I'm starting the viewing when the dark orange bite begins to appear at 4:48am.

The National Weather Service is not optimistic, in their forecast discussion, they say:

Also increased cloud cover tonight. Satellite imagery shows there 

should be a break in the cloud cover late this evening and after

midnight. This will be short lived as the next batch of Pacific

moisture moves in behind it and brings more cloud cover 09z-12z. (Translation 2am to 5am.)

Figure 2 is a close up on the weather for the day.  We have a cloud maximum during the eclipse before a brief partial clearing. Then the clouds increase and rain, ice and snow chances (though low in totals) pick up after 6pm.

Figure 3 is the graphical forecast for astronomers from clear sky chart/Canada - and it has haze/high clouds but little in the way of thicker clouds.

Figure 4 is the top line as a future satellite image and we have a big batch of clouds that has passed to the east and some clouds approaching from the west.  The eclipse will be very low in the west.  That would normally make it harder to see (cloud cover looks thicker as one looks low on the horizon) - but we can also get a strip of clear skies during down-slope conditions just east of the Rockies.

Figure 5 shows very hazy conditions (second line in map/satellite view form)- so dimmer objects like galaxies and star clusters might not look very good.

Figure 6 is the future satellite image from the GFS and it has us under thick clouds, but there is clearing to the west that might allow us to see the eclipse under the western cloud edge.

Figure 7 - is a pretty reliable cloud chart for the Front Range, by my observation. It has us overcast, but a small fraction of clearing around 5am (and clouds on either side of that hour).

Looking back at the storm for tonight into Thursday morning - we are on the edge of a dusting to an inch of snow.  There may be a brief period of evening rain, followed by freezing rain as the cold air comes in, before light snow begins. Travel might get nasty tonight.

Figure 1: The Earth's shadow in space and the moon's trip through it. From the Universal Workshop http://www.universalworkshop.com/

Figure 2: A closeup of the graphical forecast from weatherunderground. Eclipse time in orange.

Figure 3: Clear sky chart forecast for the Cherrywood Observatory. Pink dot is the eclipse.

Figure 4: The clear sky chart map view of forecasted clouds during the eclipse.

Figure 5: The clear sky chart map view of forecasted haze/transparency during the eclipse.

Figure 6: The GFS total cloud fraction forecast satellite image. Longmont is the pink dot.

Figure 7: The 7! Timer forecast with cloud amount on top line. Pink dot is the eclipse.

Figure 8: The total snow accumulation between Tuesday night and Friday morning from the GFS and weather5280.com

The longer range forecast:

We have another small chance of snow on Saturday PM and Sunday... but it is not exciting.  Temperatures will bounce up and down from seasonal to cold now and then. We'll follow all that after the eclipse and this small storm passes.

Current Weather

Cloudy

Cloudy

41°F

UV Index
1 Low
Pressure
30.21 Rising
Visibility
7 miles
Dewpoint
31 °F
Humidity
66%
Wind
ESE 1.7 mph
Gust
4 mph
Wind Chill
41 °F

Hourly Forecast

Today
8 AM
41°F
Partly sunny
Today
9 AM
45°F
Mostly sunny
Today
10 AM
49°F
Mostly sunny
Today
11 AM
53°F
Mostly sunny
Today
12 PM
55°F
Mostly sunny
Today
1 PM
59°F
Mostly sunny
Today
2 PM
61°F
Partly sunny
Today
3 PM
63°F
Partly sunny
Today
4 PM
64°F
Intermittent clouds
Today
5 PM
66°F
Intermittent clouds
Today
6 PM
64°F
Intermittent clouds
Today
7 PM
62°F
Intermittent clouds

7 Day Forecast

Partly sunny

Saturday

66 °F

Partly sunny and not as warm


Mostly clear

Saturday Night

40 °F

Clear to partly cloudy


Mostly cloudy

Sunday

76 °F

Mostly cloudy and warmer; breezy in the afternoon


Mostly cloudy

Sunday Night

47 °F

Rather cloudy; breezy late


Windy

Monday

60 °F

Very windy; cloudy and cooler


Intermittent clouds

Monday Night

43 °F

Partly cloudy


Intermittent clouds

Tuesday

62 °F

Windy with times of clouds and sun


Partly cloudy

Tuesday Night

36 °F

Partly cloudy


Mostly cloudy

Wednesday

60 °F

Turning cloudy


Intermittent clouds

Wednesday Night

35 °F

Partly cloudy


Sunrise and Sunset

Sunrise
5:55 AM
Sunset
7:59 PM

Based on AccuWeather data