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Next Storm/Next Snow Forecast Discussion from the Cherrywood Observatory – November 10, 2019

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

In Brief:

With a stunningly beautiful Saturday unfolding and with Sunday not looking bad either, the next cold front rolling in around sunset Sunday will be a brief cold slap in the face for Monday. Freezing rain and maybe about an inch snow (give or take) will make Monday very slippery. It is also looking bad for those wanting to see the Transit of Mercury from NE Colorado. :-( We return to seasonable and dry weather after that.

Forecast Discussion:

The closest precipitation is two states away as a warm wonderful high pressure system dominates (Figure 1). I'd say stop reading and get out and take a walk, but you do need to keep an eye on the next storm.

We will have a weak front come through this afternoon (the first dot/dash blue line in Figure 2) that starts our next cool down. Sunday will only reach lower 60'sF (but will still be very nice - above average for this time of year which is a high of 57F and a low of 34F). The main front slams through around 4-5pm Sunday and comes in dry and windy (Figure 3).

To alert everyone, the National Weather Service has issued a hazardous Weather Outlook (Figure 4):

This hazardous weather outlook is for northeast and north central

.DAY ONE…Today and Tonight No hazardous weather is expected through tonight.

.DAYS TWO THROUGH SEVEN…Sunday through Friday
After mild temperatures and dry conditions Sunday, a strong cold
front will push onto the northeast plains late Sunday afternoon
and Sunday night. Drizzle along with areas of freezing drizzle
can be expected Sunday evening with light snow for the overnight
period into Monday morning.
Snow will gradually diminish late
Monday morning with clearing skies Monday afternoon and
Monday night. There is also the possibility for areas of fog
across the plains late Monday night into Tuesday morning. Much
warmer for Tuesday through Friday with dry conditions.
Spotter activation will not be needed today or tonight.

Snowfall Roundup:

The weatherundeground model gives us frozen precipitation, but doesn't print out a measurable amount of snow (Figure 2).
The GFS (Figure 6) gives us about 1/2-1 inch.
The GEM (Figure 7) gives us about 1/2-2 inches.
The NAM (Figure 8) gives us about 1-2 inches.
Note, freezing drizzle will have a greater impact on travel with the main period of precipitation occurring between 9pm and 9am (Figure 2).

The Longer Range Forecast:

We warm right back up Tuesday as the ridge returns on Tuesday to normal temperatures.
Our next storm comes in after three minor-ish cool fronts roll through Thursday, Friday and Saturday. The third will be powered by upper level troughs coming into phase Saturday (Figure 9) and should create another chance of rain/snow/ice.

Transit of Mercury Invitation:

You may still stop by at the Cherrywood Observatory between 7am and 11:04am Monday to safely view the planet Mercury cross the face of the sun (a tiny dot moving very slowly) but the weather conditions are looking worse and worse. Figure 5 shows total cloud cover until 2pm, after the event. I'll post an update when other cloud model data comes in (but Figure 2 makes the clouds look bad all morning as well).

Figure 1: The current surface analysis map from the Weather Channel Saturday morning.
Figure 2: the graphical forecast for the next 10 days for Longmont, CO from
Figure 3: The forecast surface map for Sunday evening from NCEP.
Figure 4: Hazardous Weather Outlook from the NWS posted here Saturday morning.
Figure 5: The 2.5 day sky conditions forecast from 7! Timer (the GFS).
Figure 6 : The forecast snowfall totals for the next 3 days from the GFS and weather5280com for Colorado made Tuesday noon.
Figure 7: The forecast snowfall totals through Tuesday morning from the GEM and for Colorado.
Figure 8: The forecast snowfall totals through Tuesday morning from the NAM and for Colorado.
Figure 9: The 500mb forecast upper air analysis for NEXT Saturday morning. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.





UV Index
0 Low
30.06 Steady
6 miles
42 °F
NW 2.1 mph
3.7 mph
Wind Chill
53 °F




78 °F

Abundant sunshine, pleasant and warmer

Mostly clear

Tuesday Night

52 °F

Clear to partly cloudy

Partly sunny


80 °F

Partly sunny

Mostly cloudy w/ t-storms

Wednesday Night

52 °F

Cloudy this evening with a shower or thunderstorm in spots, then partly cloudy late

Partly sunny w/ t-storms


75 °F

Times of clouds and sun with a thunderstorm in spots in the afternoon

Mostly clear

Thursday Night

52 °F

Clear to partly cloudy

Mostly sunny


85 °F

Mostly sunny and warmer; a thunderstorm in spots in the afternoon

Partly cloudy

Friday Night

56 °F

Partly cloudy

Intermittent clouds


87 °F

Very warm with clouds and sunshine; a shower or thunderstorm in spots in the afternoon

Intermittent clouds

Saturday Night

56 °F

Mild with increasing clouds

Sunrise and Sunset

11:36 AM
2:20 AM

Based on AccuWeather data