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12/1 8:30am Update: Next Storm/Next Snow Forecast Discussion from the Cherrywood Observatory – Nov 29- Dec 1, 2019

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

In Brief:

Happy Thanksgiving everyone (Figure 0)! It will remain below freezing today with partly cloudy skies and no new snow (but a foot is sitting around). The mountains get another big snow hit tomorrow but we may see nothing to **maybe** an inch. The big news is very strong winds blasting the state for 12-18 hours on Saturday. This will blow snow around and create hazardous ground conditions, difficulty driving, snow drifts etc. Beyond that we go to the 40'sF for highs and enjoy a boring week with a very slow melt.

12/1 8:30am Update:

We are High and dry today with decreasing winds and increasing temperatures. We break freezing for a bit (but we're starting off in single digits in places around town). This week gives us 40'sF for highs - the melt will be slow. I'm eager to return to the land of snow and ice!

Figure 1 update: The current surface analysis map from the Weather Channel Sunday morning.

End 12/1 8:30am Update.

Forecast Discussion:

There still is a foot of snow out there - oh boy. A wide trough-y pattern dominates the western U.S. (Figure 1) with short waves rippling through it. A very strong juicy storm will dump about 2-3 inches of rain on me in the desert. By Friday night the next storm is dumping a lot of mountain snows from Montana to Arizona, California to Colorado. We will experience s down slope drying flow. You can see the big 'hole' in the precipitation shield east of the mountains (Figure 2). We have our best chance of snow flurries from about 3pm to 9pm Friday. Figure 4 shows spots of at least a coating to maybe an inch of snow around town. Some neighborhoods won't see any new accumulations.

The big news is the increase in wind speeds over the state as the low wraps up to our east. The period of high winds will dominate most of Saturday (yellow box - Figure 3). Winds start Friday late afternoon into Saturday and continue to evening. Figure 5 shows winds blasting 30-45 mph near town. The National Weather Service has issued the following high wind watch.

High Wind Watch
Issued: 5:00 AM Nov. 28, 2019 – National Weather Service

...HIGH WIND WATCH IN EFFECT FROM FRIDAY AFTERNOON THROUGH
SATURDAY EVENING...

* WHAT...West winds 35 to 45 mph with gusts up to 80 mph
possible.

* WHERE...Northern and Central mountains and foothills to include
Boulder and Jefferson counties.

* WHEN...From Friday afternoon through Saturday evening.

* IMPACTS...Strong winds will blow around unsecured objects.
Tree limbs could be blown down and a few power outages may
result. Travel will be difficult for high profile vehicles.

* ADDITIONAL DETAILS...Areas with snow cover could have reduced
visibility due to blowing snow, especially over the higher
terrain along I-70. Cautions is advised for travelers.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts and warnings for updates on this
situation. Fasten loose objects or shelter objects in a safe
location prior to the onset of winds.

The Longer Range Forecast:

We're still pretty cold Sunday (but dry) - then we settle into the 40'sF for the week with no storms on the horizon (but we've seen how that can change, so keep checking back here!).

Figure 0: Turkey Gif.
Figure 1: The 500mb forecast upper air analysis for Monday night. Pink dot is Longmont. Red lines are troughs, blue lines are ridges.
Figure 2: The forecast surface map for Friday night from NCEP.
Figure 3: the graphical forecast for the next 10 days for Longmont, CO from weatherunderground.com
Figure 4: 10:1 (snow to liquid) snowfall totals through for the next 3 days from the GFS and weather5280com for Colorado made Monday morning.
Figure 5: wind speeds at the surface for a 6 hour period surrounding noon Saturday from the GFS and weather5280com for Colorado made Thursday morning.

Current Weather

Rain

Rain

48°F

UV Index
0 Low
Pressure
29.72 Rising
Visibility
7 miles
Dewpoint
44 °F
Humidity
84%
Wind
NNE 4.2 mph
Gust
8.3 mph
Wind Chill
47 °F

Hourly Forecast

Today
8 PM
56°F
Thunderstorms
Today
9 PM
53°F
Thunderstorms
Today
10 PM
50°F
Thunderstorms
Today
11 PM
48°F
Thunderstorms
Tomorrow
12 AM
46°F
Cloudy
Tomorrow
1 AM
46°F
Cloudy
Tomorrow
2 AM
45°F
Cloudy
Tomorrow
3 AM
44°F
Rain
Tomorrow
4 AM
44°F
Cloudy
Tomorrow
5 AM
44°F
Rain
Tomorrow
6 AM
44°F
Rain
Tomorrow
7 AM
44°F
Rain

7 Day Forecast

Mostly cloudy w/ t-storms

Friday

69 °F

Variable cloudiness with a couple of thundershowers this afternoon; gusty winds and small hail can accompany any downpour


Thunderstorms

Friday Night

41 °F

Cloudy; a couple of showers and a thunderstorm this evening followed by periods of rain late; gusty winds and small hail can accompany any downpour


Rain

Saturday

44 °F

Chilly with periods of rain and a thunderstorm; travel in the foothills and mountains will be slippery due to snow


Rain and snow

Saturday Night

36 °F

Cloudy with rain, mixed with a little snow late; travel in the foothills and mountains will be slippery due to snow


Mostly cloudy

Sunday

61 °F

Mostly cloudy and warmer


Intermittent clouds

Sunday Night

36 °F

A thunderstorm in spots in the evening; otherwise, partly cloudy


Partly sunny

Monday

71 °F

Partly sunny, pleasant and warmer


Partly cloudy

Monday Night

45 °F

Partly cloudy


Mostly sunny

Tuesday

73 °F

Pleasant with sunshine and patchy clouds


Partly cloudy

Tuesday Night

40 °F

Partly cloudy


Sunrise and Sunset

Sunrise
6:06 AM
Sunset
7:51 PM

Based on AccuWeather data